Author: Wholesale Solar

Wholesale Solar of Mt. Shasta, CA, is an employee-owned company specializing in the design and distribution of custom solar systems and components. Since launching in 2002, Wholesale Solar has helped thousands of DIY homeowners achieve lower power bills and energy independence. Learn more at
Pros and Cons of Solar Power

Pros and Cons of Solar Power

Derk @ Wholesale Solar
Derk Shelly, Solar Tech at Wholesale Solar

We’re huge advocates for solar energy, but we recognize it isn’t the right solution for everyone. While solar is sustainable and ultimately cheaper than utility power in the long run, it also requires a significant up-front investment and doesn’t work for every property / roof type.

The ultimate question is whether the advantages of solar power outweigh the disadvantages. In this article, we’ll present the pros and cons of solar energy so that you can decide if going solar makes sense for you.

Advantages of Solar Power

  • Energy independence
  • Eliminate electric bill
  • Profitable investment
  • Strong government incentives
  • Sustainable
  • Low maintenance
  • Improves property value

Disadvantages of Solar Power

  • Expensive up front
  • Takes up space
  • Energy storage is expensive
  • Not right for every property
  • Makes less sense if you rent

Advantages of Solar Energy

1. Energy independence

Traditionally, most people depend on the utility company to supply them with power. When the grid goes down, going without power for an extended period of time can be a helpless feeling.

If you own a solar system with energy storage, you can keep generating power during emergencies. That peace of mind is invaluable if you live in a place with an unreliable power grid, or are regularly threatened by severe weather conditions like tornadoes and hurricanes.

Utility power also restricts people who want to live off the grid, like a remote hunting cabin. Solar can generate energy where it would be too expensive to run power lines.

It’s liberating to have complete control over where and how you produce energy. And with electricity costs rising, it also feels great to lock in a fixed rate for your electricity over the next few decades.

2. Eliminate your electric bill

Who doesn’t love one less bill coming out of their paycheck? With a properly sized system, you can drastically reduce or completely eliminate your electric bill.

Even if you extend your payback period by taking out a loan to finance your project, you still enjoy reduced electricity costs from the moment you flip the switch on your PV system.

This is the most exciting part of solar for many people: bringing the system online and watching their power bill disappear.

3. (Grid-tied) solar is a profitable investment

If you buy a grid-tie system (the type of system you build if you have access to power lines), you can expect your investment into solar to turn a profit in the long run.

Assuming the national average for cost of electricity, it would take about 6.08 years to recoup your investment into a $10,000 system. Beyond that point, you start to generate a profit from your system.

In fact, over the 25-year life of the solar panel warranty, we estimate you would earn $31,031 on energy bills after clearing the initial payback period.

4. Lucrative government incentives

The investment into solar becomes even more appealing when you take government incentives into account. State and federal programs are in place to encourage people to invest in renewable energy. Claiming these can put a ton of cash back in your pocket.

The main incentive is the 30% federal tax credit for going solar. Under this program, you are eligible to receive 30% of the total installed cost of your system as a tax credit at the end of the year.

This credit is a dollar-for-dollar reduction of your tax liability. Every dollar in credit is a dollar less that you pay in taxes at the end of the year. So if you buy a $10,000 system and receive a $3,000 credit, you will owe $3,000 less in taxes at the end of the year.

While the federal tax credit is the largest solar incentive, don’t skip out on local incentives, either. Depending on where you live, certain jurisdictions offer local incentives that can be claimed in addition to the federal credit.

5. Sustainability

A sustainable energy source is one that we can use without depleting the source of power. Oil and gas are not sustainable, because we consume those resources as we use them.

In contrast, solar is sustainable because the source of energy (sunlight) is constantly replenished. We can use solar energy without worrying about whether we will deplete the Earth’s natural resources for future generations.

6. Low maintenance

Solar systems don’t have a lot of moving parts. As a result, they rarely break down or require maintenance to keep them running optimally.

Panels are warrantied to last 25 years, but many have a much longer lifespan. (See our article “How Long Do Solar Panels Last?” for a study on the true lifespan of panels.) You rarely, if ever, need to fix or replace panels.

It’s common to replace your inverter at least once over the life of your system, as inverters are typically warrantied for 10-15 years. But that’s about the only scheduled maintenance you will encounter for grid-tied systems.

Off-grid systems are a bit more complex because they must include batteries, which often require routine maintenance. Specifically, flooded lead-acid batteries (the cheapest option available) must be checked and refilled with water regularly to keep them functioning properly.

However, building a grid-tied system eliminates the need for batteries, so most people will rarely need to check in on their system for maintenance or replacements.

7. Improves property value

Studies of the real estate market have proven that homes equipped with a solar power system sell for more than their non-solar counterparts.

In fact, the Lawrence Berkeley National Library conducted research that shows that solar homes fetch an extra $14,329 on average, a 3.74% increase over non-solar homes.

It’s no question that solar power systems substantially increase property value. Home buyers see solar as a major selling point, and they’re willing to pay a premium to move into a solar-powered home.

Disadvantages of Solar Energy

1. It’s expensive to get started

Solar is expensive – at least up front. To build a system that would power the average American home (which uses 897 kWh of electricity every month), you might pay $8,000-$10,000 depending on the products you choose.

That doesn’t include the cost of shipping or installation.

Of course, you’re paying for at least 25 years of energy production up front. In the long term, you break even on the investment and start to make money, but that doesn’t change the fact that not everyone has thousands of dollars in their pocket to get their solar dreams off the ground.

The up-front cost is the main barrier to going solar. Financing options are available, and the payback period is quite favorable even when you take interest into account. However, not everyone wants to be on the hook for loan payments.

2. It takes up a lot of space

Standard solar panels measure 39” wide by either 66” to 72” tall (for 60-cell and 72-cell panels, respectively).

To offset the national average of 897 kWh of electricity per month, you’d need at least 24 panels. In an 8×3 configuration, that system will be 26 feet wide by 44 feet tall. That’s going to take up a lot of room on your roof or in your yard.

Most people opt for a roof mount because it takes advantage of space that would otherwise go unused. If you need to design around odd angles and obstructions, you can always split the panels into sub-arrays, like our customer Luis did when he built his system:

Wholesale Solar customer Luis split his system into sub-arrays to work around the shape of his roof. We featured it as our Install of the Month in September 2018.

3. Energy storage is expensive.

Batteries are the single most expensive component to a solar power system. Not all systems require batteries, but they become mandatory when you go off the grid. They are also required if you need to supply backup power to your grid-tied property.

(Grid-tied systems don’t automatically provide backup power during outages. That’s a common misconception. For backup power, you need a grid-tie system with energy storage – essentially, a battery designed to work with grid-based systems.)

Expect to pay a lot more money when you add batteries to a system. Battery banks cost at least a few thousand dollars, and if you buy high-end lithium batteries for a full-scale off-grid system, that’s easily a 5 figure investment into the batteries alone.

Furthermore, batteries don’t last as long as the other parts of your system. Lead-acid battery warranties range from 1 to 7 years, meaning you’ll replace them 4 or 5 times before the panel warranty is up.

Lithium batteries justify their high price tag by lasting 10-15 years, but you’re still in for at least one replacement over the life of your system.

4. It’s not right for every property

Not every property is a good fit for solar power.

Some properties are simply too cramped to find any space to build a system. Others are covered in shade and wouldn’t get the sunlight required to generate enough energy.

While there are technologies like shade optimizers and custom racking to mitigate these concerns, they only accomplish so much. If you don’t have anywhere to put your panels, it’s going to be a real challenge to make solar work for your home.

5. It’s better if you own your home (and won’t be moving for a while)

Solar can be a profitable investment, but the payback math assumes you’ll be living in the same property for the full duration of the 25-year warranty.

It takes several years to break even on the initial cost of the system before you start to pocket the savings from your energy bill. Solar makes a lot less sense if you don’t own your home, or have the urge to move within the next few years.

The good news is that because solar increases property values, you are likely to recoup your investment into the system when you go to sell your home. But most people who go solar do it because they want to be self-sufficient and generate their own (less expensive) electricity for the next few decades.

Think about whether you’ll stick around for a while in your current property before you make the long-term investment into solar.

Questions? Consult with a solar expert.

Still not sure if the advantages of solar outweigh the disadvantages? You can always schedule a consultation with one of our expert design techs. We’ll answer questions, clear any design hurdles, and help you decide if solar is right for you.

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Grid-tied vs. off-grid solar: are you sure you want to live off the grid?

Grid-tied vs. off-grid solar: are you sure you want to live off the grid?

Todd Evris, Senior Sales Tech @ Wholesale Solar
TODD EVIRS, Senior Sales Tech at Wholesale Solar​

Let’s clear up one of the most common misconceptions in the solar industry: the idea that you must go “off the grid” to go solar.

This article will explain the different types of solar power systems: grid-tied vs. off-grid.

Many people call us looking for help going “off the grid.” But when we explore their motivations a bit more, we find that what they actually want is to ditch their utility company.

Really, they want to go solar to be independent, generate their own power, and stop paying money to the utility every month.

If this sounds like you, read on. Because you can accomplish all these things without going off the grid. It’s called grid-tied solar, and it’s the preferred type of solar system for any property that has access to power lines.

Why? Because it’s cheaper. No, really, it’s a lot cheaper. You should always build a grid-tied system when you have the option to do so.

Let me explain why.

Grid-tied vs. off-grid: what do these terms really mean?

The difference between grid-tied and off-grid solar revolves around where you store the energy you generate.

Every system needs a place to store energy so that it can be used on demand. Your panels only generate charge when the sun is out during the day, but you still need a way to turn the lights on in the evening.

With grid-tied systems, the energy you generate is sent into the utility grid. Your panels feed electricity into the grid, which can be distributed to other people in your area.

In return, you receive a credit for the energy you generate, which you can use any time. Think of it like a transaction at the bank: you are allowed to withdraw as much as you deposit. This is what allows you to keep the power on when the sun goes down.

Off-grid systems are different. With no access to the utility grid, you must find another solution to store energy.

For that, you’ll need to add a battery bank to your system. Batteries provide dedicated energy storage. Without any access to power lines, batteries are mandatory for off-grid solar systems.

In summary: grid-tied systems store energy in the power grid, while off-grid systems store energy in batteries.

When in Doubt, Go Grid-Tied

It doesn’t cost anything extra to store electricity in the grid. But adding batteries to an off-grid system is a significant extra cost.

In fact, batteries are the most expensive part of a solar system. They represent as much as 30-40% of the cost of an off-grid system.

Batteries alone are a 4-5 figure investment. For that simple reason, we always recommend connecting a grid-tied system if you have the option.

Why spend thousands of dollars on batteries if you don’t need them?

What about Energy Storage Systems?

Right now you might be thinking, “what if I’m connected to the grid but still need energy storage?”

For that, there’s a third system type. It’s called grid-tied with battery backup (a.k.a. energy storage systems).

These systems connect and store energy in the grid, but they also include batteries. There are two reasons you might want to add energy storage to a grid-tied system:

  • Store backup power in case of outages (useful if you live in an area with an unreliable power grid or severe weather)
  • Store energy so you can use it or sell it later (useful if you live in an area with a certain utility billing structure, such as time of use rates, high demand charges, or no net metering)

The same caveats apply: batteries aren’t cheap, and adding them to your grid-tie system lengthens your payback period. But in some places, it’s invaluable to add security against harsh weather, outages, and inflated electricity costs.

Energy storage systems provide extra peace of mind and help you get the most out of the electricity you generate. It’s up to you to decide if it’s worth it to spend more on your system for the added flexibility.

Continue Your Research

Have any more questions about the process of going solar? Check out our Getting Started Guide, a crash course on the basics of designing and installing your solar energy system.

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What is a kilowatt hour?

What is a kilowatt hour?

Todd Evris, Senior Sales Tech @ Wholesale Solar
TODD EVIRS, Senior Sales Tech at Wholesale Solar​

Kilowatt hours measure energy usage and production.

If you’re thinking about going solar (or just want some advice on how to reduce your energy consumption), you’ve probably come across the term kilowatt-hours.

But exactly what is a kilowatt hour? And why do we need to know how many we use each month?

First things first: What is a kilowatt hour?

A kilowatt-hour (kWh) is a measure of how much energy you use over a set period of time. It determines how much you pay for electricity each month, since the utility company bills you on a cost-per-kWh basis.

Here’s how it works.

Every appliance has a rating which measures how many watts of power it uses. For example, an oven may be rated at 2000 watts, or 2 kilowatts. (1 kilowatt equals 1000 watts.)

If you cook something in that oven for 30 minutes, here’s how to calculate the total energy used:

2 kilowatts x 0.5 hours = 1 kilowatt-hour (kWh) of energy used.

To determine how many kilowatt-hours an appliance uses, simply estimate how long you use it each day, then multiply by the wattage rating.

Easy so far. But how can you use this information?

Measuring Electricity Cost Per kWh

Utility providers track your usage with a meter and bill you based on total kilowatt-hours consumed.

In America, the average cost of electricity is about 12 cents per kWh. However, that can fluctuate based on where you live as well as what time of day you use the electricity.

Many utility providers bill variable rates for Time of Use (called TOU rates). If you are familiar with the concept of surge pricing, that’s what this is: electricity costs more when lots of people are using it.

There’s less demand during the day, so the rate is lower. When people come home from school and work, the rate goes up because the demand is higher.

You can usually find the breakdown of TOU rates on your utility provider’s website, or right on the electric bill.

But it might be quicker to measure how those costs average out based on your usage patterns. Divide your monthly payment by your total kWh usage to get your average cost of electricity:

$130 electric bill / 1,237 kWh used = 10.51 cents per kWh

How Kilowatt Hours Factor into Solar System Sizing

Understanding kilowatt hours is key to being able to design a system that works. Without that information, your system might be too small to cover your entire energy bill (or too large, in which case you’re just throwing money away and diluting the value of your investment).

So we use your kilowatt-hour usage as the starting point in the system design process. Once you know how much energy you use, you can size your system components to match usage demands.

Our solar cost calculator can provide a ballpark system size and cost based on your kWh usage. You can also read about the math behind this formula in full detail in our article: “How Many Solar Panels Do I Need?”

To get an accurate calculation, there are a few things to take into account:

  • Average monthly usage
  • Peak usage (it will spike when it’s snowing or 100 degrees outside)
  • Future changes in energy usage patterns

Your system should be sized to cover you year-round. Make sure to take a year’s worth of usage into account, since freezing winters and 100+ degree summers tend to skew the usage data.

Also, carefully consider whether your usage will increase in the future. If you plan to have kids, build a new shed on your property, or buy an electric vehicle, those things will eat up a lot more energy and your kWh usage will climb.

You don’t need to build for future usage now, but it helps to plan your system with expansion in mind. Certain pieces of equipment are designed to facilitate expansion, like microinverters and lithium batteries.

Read more: Best Grid-Tie Solar Inverters >> | Best Solar Batteries >>

Why kWh usage is so important for off-grid properties

When you’re connected to power lines, finding all this information is simple. Just grab your latest electric bill. Your provider prints your kWh usage on your bill every month, and some list their cost-per-kWh rates as well.

This makes it easy to do the math on system size. You can also drop the number into our solar cost calculator for a quick ballpark cost and sizing estimate.

Off-grid systems are different.

When you go off the grid, you likely won’t have a precedent to figure out how much energy you will use. Instead, you’ll need to fill out a load evaluation sheet, listing each appliance manually and estimating how much you will use them each day.

Daily kWh usage is crucial to building a system that can supply uninterrupted power to your off-grid property.

You don’t want to look at your yearly usage, but rather your needs on a day-to-day basis. The goal is to store enough power to cover yourself if any problems arise (like severe weather or equipment failure).

People tend to store about a day’s worth of power in their battery bank, and lean on a generator for backup. But you can plan for more cushion with your battery bank if you want the extra peace of mind.

To estimate daily usage, find the kWh usage (wattage x hours in use each day) for every large appliance in your off-grid home and add them all together.

The total is your daily usage, which can be used as the basis to size your system:

Daily kWh Usage ÷ Sun-Hours ÷ 0.9 (inefficiency factor) = Minimum Solar Array Output

How to Use Your kWh Usage to Estimate the Cost of Solar

Got your kWh usage on hand? Plug that info into our solar cost calculator to see how much it might cost you to go solar.

Grid-tied systems tend to pay for themselves quickly. It’s reasonable to expect to break even on your investment within 5 years.

Off-grid systems cost more and come with different expectations. Unlike grid-tie systems, the value in off-grid systems isn’t necessarily making a profit from your investment.

Instead, it should be viewed as a means to generate energy where there is no access to power lines. To determine whether off-grid solar is the right choice, you should compare it against the cost of other methods to generate power, like wind turbines or gas generators.

Interested in solar, but not quite sure where to start? Download our Getting Started Guide to get up to speed with the essentials.

Install of the Month – September 2018

Install of the Month – September 2018

Congratulations to our September Install of the Month winner Luis M! Luis first got in touch with us back in the middle of 2017 to build a grid-tied system on his Spanish tile roof.

Luis lives in Covina, CA (near Los Angeles) where the cost of electricity is nearly 35% higher than the national average. Facing electric bills well over $250 during the sweltering summer months in Southern California, he was eager to run the math on solar energy to find out whether it was worth the investment in the long run.

When he did the math, he found that he would save $3,000 a year in electricity costs alone. After claiming the 30% Federal Tax Credit for investing in renewable energy, he knew it would cost around $12,000 to get a system built and installed.

That meant his investment would pay for itself in less than 4 years—pretty appealing, given the 25-year wararnty on the solar panels.

“At a 7% return, he figured that money was worth about $1,050 per year on the stock market. But it would return over $3,000 a year in energy savings. Even with the penalty for cashing out from the retirement fund early, it was worth it.”

Luis didn’t have the budget to buy the system outright, and he didn’t want to be on the hook for loan payments. So he did something a bit unusual: he pulled $15,000 from his retirement fund.

At a 7% return, he figured that money was worth about $1,050 per year on the stock market. But it would return over $3,000 a year in energy savings. Even with the penalty for cashing out from the retirement fund early, it was worth it.

Once he decided to pull the trigger, he had to figure out how to mount the system on his beautiful Spanish tile roof. For that, we set him up with the Quick Mount flashing system. Rather than cutting tiles to fit them for hooks, the entire tile is replaced with the fitted Quick Mount base.

Luis took a slow and steady approach to installation, working around the unbearable summer heat (made worse by his tile roof retaining heat). He was determined to complete the installation with his family members, which saved him about $4,000 in labor on the project. 

Once it was completed, the payoff was immediate: his first electric bill came out to negative $4.40, with the utility company owing him a credit for the surplus electricity he produced.

“[Finishing the project] felt good, but not as good until you get the first electrical bill: -$4.40. That was back in February. By the time it gets full sunlight hours, it should produce an extra 10% of electricity close to 950Kw this month.”

-Luis M.

Here’s what Luis had to say about his project:

What type of solar system did you install?


What was your primary reason for adding solar to your home?

It made a lot of sense to install a solar system by my self, not only for the savings in the electricity bill but it’s also great for the environment.

Did you have any previous DIY experience?

Yes, but not in solar installations. I learned everything from the how-to videos on the website.

What was the most difficult part of the installation?

The summer heat, it was very hot on my tile roof.

I was also a little worried for the Santa Ana winds. I solved that worry by keeping the post separation to no more than three feet. Not that it was required, but just for peace of mind.

How many helpers did you have?

I only needed two people (family) on the actual panel installation. I didn’t want to drop one.

Did you hire a contractor?

Only for the actual final electrical connection from the inverter to the main panel. I did run all the conduit.

Were there any unforeseen additional parts or tools you needed?

At the end, I wanted to make sure I could monitor the whole system on the web, and I added a wireless link myself. Now I can check and monitor the solar system on my iPad.

How long was the full installation process?

Well, I added extra posts, I was in no rush. It took me six months for a 22-panel system. Let’s break it down: it took an average of 1 hour to install a post, times 48 post. Rails took about a couple of days, and panels two days this time with two people helping. Conduit and wires took a couple of days by my self. Then the final electrical was the electrician and their assistant.

The reason it took so long it was because of the summer temperatures and the tile roof. I had to replace the tiles I broke on the process. No big deal.

How did it feel to get your solar project finished?

It felt good, but not as good until you get the first electrical bill: -$4.40. That was back in February. By the time it gets full sunlight hours, it should produce an extra 10% of electricity close to 950Kw this month.

Who else did you consider before choosing Wholesale Solar?

I couldn’t afford to have my panels installed by a solar panel company. ( I had three estimates done). I also did not have any cash available.

What I did was, I took $15,000 from my Roth IRA. Let me break it down for you: that money makes an average of 7% a year on the stock market = $1,050. With my $15,000 solar system, it is going to create at least $250 a month, that’s $3,000.00 per year cash savings. I get $5,000 back from the government, that put the system at a cost of $10,000. Plus let’s add the penalty for cashing money out of your retirement, $1,500.00 in this case. Now the cost is $11,500, divided by $3000 a year of electricity savings. In 3 years 9 months, the system will pay for itself. In other words my investment of $15,000 is producing a 20% return on my money as I write this. By the way, after 3 years 9 months my system is going to give me net $3000 a year to put back in my IRA.

What was your total cost to install solar?

The solar system cost me around $13,000 at Wholesale Solar and around $2,000 for the extra help. That is $15,000. I calculated I did save about $4,000 worth of work myself.

How much did you save on your taxes?

A third, about $5,000.

Components in Luis’s custom system:

Luis's Solar Breakdown:

  • System Cost: $13,000
  • Cost of Labor: $2,000
  • Yearly System Output: 9,807 kWh per year
  • Total time to install: Estimated 80-100 hours over a 6-month timeframe
  • Federal Tax Incentive: Qualifies for $5,000 U.S. Federal Tax Credit
  • Utility Rates: 16 cents/kWh

It’s Your Turn

Thinking about making the switch to solar? Download our Getting Started Guide for a crash course on how to buy a solar energy system that covers your needs.

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The Federal Solar Tax Credit, Explained in Plain English

The Federal Solar Tax Credit, Explained in Plain English

The 30% Federal Solar Tax Credit can save you thousands when you switch to solar. But how does it work?

We’re here to explain the Federal Solar Tax Credit in plain English. If you want a basic overview of solar incentives without wading through the tax jargon, you’re in the right place.

What is the Federal Tax Credit for Solar?

When you install a solar power system, the federal government rewards you with a tax credit for investing in solar energy.

A tax credit is a dollar-for-dollar reduction of the income tax you owe. $1 credit = $1 less you pay in taxes. It’s that simple.

A quick but necessary disclaimer: we’re solar experts, not tax accountants! We do our best to give accurate advice, but please check with a professional to be sure you’re eligible to claim the credit.

For example, let’s say you owe $5,000 in federal taxes this year. If you claim a $3,000 tax credit, that pays off part of your liability. You would be left to pay just $2,000 in taxes after the credit is applied.

It’s different than a refund, because you have to owe taxes to claim the incentive. But since most people owe taxes, most people end up being eligible.

How much money do I save with the Federal Tax Credit?

Right now, the tax credit is worth 30% of your total system cost. This includes the value of parts and contractor fees for the installation.

If it costs $10,000 to buy and install your system, you would be owed a $3,000 credit.

You are only allowed to claim the credit if you own your system. This is why we’re strongly opposed to solar leasing if you can avoid it. If another company leases you the system, they still own the equipment, so they get to claim the incentives.

You still get the benefits of cheap, renewable energy. But missing out on the tax credit is a huge blow to getting a positive ROI from your system.

It makes more sense to finance instead. You’re still on the hook for a loan, but you retain rights to the incentives that help make solar such a sound investment.

How Long Will the Tax Credit Stay in Effect?

As the saying goes, “all good things must come to an end.”

Soon, the federal government will begin trimming back on its 30% tax credit incentive.

The credit steps down in value over the next few years, until it disappears completely for residential customers in 2022. Here’s the value of the federal tax credit over the next five years:

  • 2018: 30%
  • 2019: 30%
  • 2020: 26%
  • 2021: 22%
  • 2022: 0% (10% for commercial projects)
The rate of the federal tax credit for solar installations through 2022.
The Federal Tax Credit is slated to be phased out by 2022.

You can claim the credit in the same year you complete the installation.

The tax credit plays a major part in the return on investment you see from going solar. It won’t be around forever, but the good news is you still have at least another year to capitalize on the full 30% credit.

How do I claim the Federal Tax Credit?

So let’s get to the good stuff. What do you need to do to actually get your hands on this money?

Our first bit of advice is to keep all your receipts from the start. The more you spend on your project, the larger your credit – make sure to keep track of everything!

Here are some of the expenses that you are allowed to claim:

  • Solar equipment
  • Freight shipping costs
  • Solar consulting fees
  • Professional installer fees
  • Electrician fees
  • Engineer fees
  • Tools bought or rented
  • Wiring, screws, bolts, nails, etc.
  • Equipment purchased or rented (scaffolding or a man-lift, for example)
  • Permitting fees
  • Permitting service costs

Costs will vary depending on the approach you take to installation. Hiring a contractor is an expense that can be claimed.

You can also choose to install the system yourself. Although you can’t claim your own labor as an expense for the credit, you still come out far ahead on overall project costs.

The graph below shows a comparison of the total installed costs (post-Federal Tax Credit) of the same exact system when you choose to DIY, hire locally, or source the work to a national installer:

Solar Installation Costs after Federal Tax Credit has been applied

How to File Form 5695 With Your 1040 Individual Tax Return

Once you’ve spent the money, you’ll need to prove it to the government to claim your tax credit. For that, you need IRS Form 5695 to claim the residential energy credit.

If you file your own taxes, use the steps below to claim your Residential Renewable Energy Tax Credit. (You can find an in-depth walkthrough of this process with visual aids on EnergySage’s website.)

  • Gather all your expense receipts and put them in a safe place.
  • Confirm you are eligible for the tax credit. (If you own the system and owe taxes, you’re probably eligible. Check with a tax specialist if you’re not sure.)
  • Complete IRS Form 5965 to add up your renewable energy credits.
  • Add your renewable energy credit information to your typical form 1040.

That’s it!

We hope this serves as a good introduction to the Federal Tax Credit and helps you navigate the research process. If you need help from a solar designer, get in touch with us for a consultation. We’re happy to walk you through any questions you may have.

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Review: SolarEdge HD-Wave Inverter with Integrated Electric Vehicle Charger

Review: SolarEdge HD-Wave Inverter with Integrated Electric Vehicle Charger

Courtney Johnston, Purchasing Manager at Wholesale Solar
Courtney Johnston, Purchasing Manager at Wholesale Solar​

Today we’re going to take a quick look at a new offering in our product line: the SolarEdge HD-Wave 7.6K inverter with an integrated electric vehicle (EV) charger.

SolarEdge is our default inverter choice for most grid-tied solar systems, and the 7.6 kW size is our best-selling model. You can read more about why we like SolarEdge in our review of the best grid-tied inverters on the market.

The model we’re looking at today has the exact same features as that best-selling model, with one addition: an integrated port to charge your electric vehicle. Check out the video to see how it works:

SolarEdge SE7600H HD-Wave with EV Charger Inverter Overview

All of the guts for the electric vehicle charger are right in the box. There is no extra work involved to install the EV Charger. Just mount the inverter on the wall, plug in the charging cable and you’re good to go.

The best part about this inverter is that it’s flexible. The car charger works even if you don’t have solar installed. The inverter works even if you don’t need to charge an electric vehicle. Neither function depends on the other to work properly.

You can start with one purchase (either the solar system or the electric vehicle), then add the other down the line. There’s no extra wiring or circuit breakers to install, and you don’t need to fear incompatible equipment.

The charge cable is sold separately and can be added any time you purchase an electric vehicle.

SolarEdge also plans to launch a 3.8 kW inverter with an EV charger. We stock the 7.6kW version in our warehouse, and the smaller configuration is stocked at SolarEdge and ready to ship on demand.

The 3.8 kW will be your choice if you want to get into a smaller system or just plan to add a few panels to your existing array.

With either option, the most interesting application we’ve seen for this product so far is building a solar power carport.

The basic idea: build the carport for shelter where you park, then mount the solar panels on top to start generating energy. The carport should be sturdy enough to double as a foundation for your system.

You can build the structure with your own design, or get a custom order from SunModo, a company that designs custom carports for solar applications.

Mount the HD-Wave with EV charger somewhere on the carport, and voila! You’ve got a nice little place to park, generate solar power and charge your electric vehicle.

It’s a simple but brilliant solution if you’re considering solar, and already have (or plan to buy) an electric vehicle. And it’s pretty easy to install as a DIY project, even by yourself.

Where traditional inverters can weigh 65 to 75 pounds, the new HD-Wave inverters only weigh about 25 pounds. The car charging cable (sold separately) only weighs about 12 pounds, and you simply latch it on when you’re ready to use it. One person can set up the whole system.

This is a fairly new product, but we’ve already seen some really interesting builds with these new hybrid units. We can’t wait to see what you come up with!

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The Best Grid-Tied Inverters for Solar Power Systems (2018 Edition)

The Best Grid-Tied Inverters for Solar Power Systems (2018 Edition)

Cheyenne Minard, Senior Sales and Design Tech
Cheyenne Minard, Senior Sales and Design Tech at Wholesale Solar

We recently published our recommendations of our favorite off-grid inverters you can buy for solar applications.

It quickly became one of the most popular articles on our site. So now we’re back with its counterpart: a review of the best grid-tied inverters you can buy in 2018.

These are the inverters you would use in a traditional home or office system – any property that has access to power lines and can connect to the utility grid.

We put together a video to highlight our picks. You can also keep reading for more detailed analysis, current prices and key product specs.

Here’s our review of the best grid-tied solar inverters you can buy on the market in 2018:

Best Inverters for Solar (Grid-Tie)

Best Grid-Tied Microinverter

Best Grid-Tied String Inverter

Best String Inverter with Optimizers

Best Storage-Ready Grid-Tied Inverter

Why Do I Need an Inverter?

If you’re just getting into solar, let me quickly explain what an inverter does.

The inverter is like the brain of your solar system. It manages the flow of power throughout your system.

When panels collect energy from the sun, they generate DC (Direct Current). But home appliances use AC (Alternating Current).

At its core, the inverter has a simple job: it converts captured DC power into usable AC power.

Beyond that basic functionality, some inverters have extra features that make them more suitable for specialty applications. Let’s take a look:

Best Microinverters for Grid-Tied Systems: Enphase IQ7

  • Price: $186 apiece, which includes a mandatory Q cable for each panel. Total cost comes to 78 cents/watt.
  • Peak Efficiency: 97.6%
  • Individual Panel Monitoring? Yes
  • Best for: starting with a small system and expanding in the future. Also great if you have multiple places to build on your roof and want to split the system into sub-arrays.

The concept of microinverters is simple: pair an inverter with every panel.

The benefits are fairly easy to understand as well. There are two cases where you should use microinverters:

  1. You want to start with a small system and be able to expand down the road.
  2. You want to monitor each panel independently.

In some ways, when you pair a microinverter with a panel, you’re creating a self-contained single-panel solar energy system. Each will produce power regardless of how many panels you have.

We recommend the Enphase Microinverter for these applications. As of the time of publication (September 2018), these currently range from $145-$215 apiece. You would pair them with a panel ranging up to 300 watts, which will cost you another $250+.

Each inverter and panel pairing works out to around $450 (fluctuating by ~$100 depending on which products you pick). This does not include the cost of mounting or wiring the system.

So how does the math look when you’re trying to build a full-sized system?

Let’s say it would take a $10,000 system to completely offset your energy bill, but right now, your budget is only $3,000.

If you want to cancel out a portion of that bill right away, you might get about 5-6 panels with microinverters on them. You’d start saving money on electric bills right away, and you can easily add on to it a few years down the road until you hit your target of 100% energy offset.

The ease of installation is another nice side benefit. Microinverters use standard AC wiring, which is cheaper and easier to work with.

In all, microinverters make it possible to get started with solar and build out your system at your own pace. But that scalability comes at a slightly higher price than other options.

If you have the budget to build a complete system from the start, we’d recommend going with a more cost-effective option: a string inverter.

Best String Inverter: SMA Sunny Boy

  • Price: $1775 (23 cents/watt)
  • Peak Efficiency: 97.5%
  • Individual Panel Monitoring? Not by default (you can add optimizers for extra cost, but you lose the Secure Power Supply feature by doing so.)
  • Best for: complete grid-tied systems in full sunlight.

A string inverter is a single unit that hooks into a string of solar panels. Our recommendation in this category, the SMA Sunny Boy, is sized to support strings in the range of 6-14 panels.

String inverters are your least expensive option, and they thrive in the right conditions.

The main issue with string inverters is that when shade falls on one panel, the efficiency drop translates to the other panels in the string. So if you have 10 panels in a string, and one gets shade, all 10 will drop to the reduced output of the shaded panel.

But what if you have space to build a system that will never fall under shade?

If you have land with plenty of unobstructed space, this is going to be the cheapest and most effective inverter for most systems.

If you live on a city block with buildings or trees casting shadows on your panels…not so much. You’d never get close to the expected output from your system.

But if you’re sure you have enough room to build away from obstructions, go with the SMA Sunny Boy inverter. It’s a reliable string inverter that is far cheaper than other options assuming you meet the requirements.

Depending on the model, the Sunny Boy inverters have either 2 or 3 inputs, which means you’ll have either 2 or 3 strings of panels wired to your inverter.

The SMA Sunny Boy also comes with a neat feature: a 2000 watt Secure Power System (SPS). The SPS is a feature unique to the SMA brand.

The SPS acts like a small backup power source in case of outages. While it’s not a long-term solution, the SPS powers a dedicated 120v outlet that can power up to 2000 watts during the day if there is solar power available.

You can also buy optimizers and pair them with the inverter. This will help mitigate the shade problem, but as a tradeoff, you lose the SPS functionality.

It makes sense to add the optimizer if you previously built an SMA system, then needed to retrofit the array due to new obstructions. Adding optimizers onto the panels would be easier and more effective than ripping out and replacing your whole inverter.

However, if your goal from the start is to get the most output from a partially-shaded array, we would recommend a different inverter for that purpose.

Best String Inverter w/Optimizer: SolarEdge HD-Wave

  • Price: $1475, plus mandatory P400 optimizers at $67 per panel. Works out to 41 cents/watt for a 24-panel system.
  • Peak Efficiency: 99%
  • Individual Panel Monitoring? Yes
  • Best for: a broad variety of grid-tied solar applications. You get the convenience of centralized design, paired the flexibility of panel-level monitoring. It’s the best mix of features and price.

Our best-selling residential grid-tied inverter is the SolarEdge line, a string inverter with optimizers.

This is our go-to grid-tied inverter option because it offers the best of both worlds. You get the lower cost of a central string inverter combined with the individual panel monitoring offered by microinverters.

For that reason, it works in a broad range of applications. In most cases, it’s simply the best combination of features and cost you can find in a grid-tied inverter.

The system is shade-tolerant thanks to the optimizers attached to each panel. And it’s cheaper than microinverters once you scale to at least 8 panels (the minimum string size compatible with SolarEdge inverters).

In the end, SMA and Enphase are tailored to a specific application. The SMA Sunny Boy needs full sunlight, and Enphase microinverters are more appropriate if you start with a small system.

For other grid-tied applications, our default recommendation is the SolarEdge line. It’s the workhorse of the industry: nothing too flashy about it, just versatile, reliable and easy to use.

Our most popular size is the SolarEdge 7.6 kW HD-Wave inverter, but they come in a range of 3.0 kW to 11.4 kW options for residential systems, with higher capacity options available for commercial use.

Best Grid-Tied Inverter With Storage Capacity: SolarEdge StorEdge

  • Price: $2575, plus mandatory P400 optimizers at $67 per panel. Works out to 55 cents/watt for a 24-panel system.
  • Peak Efficiency: 98%
  • Individual Panel Monitoring? Yes
  • Best for: grid-tied systems with energy storage, which protects against power outages and allows you to store power and use it later.

Our last recommendation is the SolarEdge StorEdge inverter system. It’s a grid-tied inverter that is configured to work with energy storage. The StorEdge inverter is available in two sizes: 3.8kW and 7.6kW. It works with SolarEdge optimizers and has all of the same features as that system.

If you want to add battery backup to protect against power outages, you’ll need a storage-ready inverter to manage your system.

Energy storage systems have been gaining steam in recent years. In California (the state we call home), 20% of all grid-tied solar systems included an energy storage solution.

Aside from protecting against emergency outages, energy storage has another purpose. You can take control of your power, storing it for later or sending it into the grid.

This is used in areas where the utility bills have either time of use (TOU) charges, residential demand charges, or where the utility won’t buy your power.

Many utility providers charge higher rates during peak usage periods (typically evenings, when everyone is home from work or school). With a storage solution, you can store energy you generate for use during peak periods.

You can even sell excess energy you generate back to the utility company for a profit. This solution is popular in areas with unreliable power grids and variable utility rate plans.

The great thing about the StorEdge system is that you can expand into energy storage at any time. It works as a standard grid-tied inverter, and if you choose to add batteries later, it can easily adapt into a storage-ready inverter by adding 1 or 2 of the LG Chem RESU10H batteries.

Another good pick for storage-ready inverters is the Magnum MicroGT. It provides backup power like StorEdge does, but in microinverter form. It’s also configured to work with a broader range of batteries, whereas the StorEdge limits you to one battery (the LG Chem).

However, the MicroGT doesn’t comply with rapid shutdown requirements in California and Hawaii, which prevents us from recommending it in all applications. But it’s definitely a strong contender.

These are both great picks if you need energy storage now, or think you’ll opt into that choice down the road.

This article was updated on 10/2/2018. For our most current prices, take a look at the inverters page in our shop.

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What are the Best Solar Panels? (2018 Edition)

What are the Best Solar Panels? (2018 Edition)

BRENT HILTON, Senior Design Technician at Wholesale Solar​

How do you find the best solar panels for your system?

It’s not an exact science. “Best” will mean different things to different people.

You may care about efficiency and long lifespan. You might want to support American-made goods.

Or maybe you just want the cheapest one that works.

We’re going to put our two decades of system design experience to good use to bring you handpicked recommendations of the best solar panels on the market in 2018. And if you prefer your info in video form, we put one of those together too:

Best Solar Panels - 2018 edition

Before we go over our methodology, here’s a sneak peek at our picks. (Let’s be honest, you’re here for product recommendations, so we won’t make you scroll too far.)

Best Budget Panels:

Best American Panels:

Best Premium Panels:

Best Panels for Remote Applications:

Best Panels for Industrial Use:

How to Pick the Best Solar Panels for Your Project

There are a handful of factors that influence how good panels are. Here are the main things you should look at when you research solar panels:

Cost per watt

For most people, budget is the primary factor influencing decisions during the design process.

Panels come in all different sizes. Full-sized panels typically fall in the range of 275-400 watts, though there are also smaller panels for specialty off-grid applications.

The great equalizer is cost-per-watt. Divide the panel price by how many watts it outputs. You’ll get a “true” pricing number, which you can use to compare all panels on a level playing field.


There are two different warranty categories – performance and workmanship.

The performance warranty guarantees your panels will work above their rated efficiency for the duration of the warranty. Most manufacturers promise their panels will work at or above 80% efficiency after 25 years.

25 years is the industry standard, but a few manufacturers offer longer performance warranties of 30 years.

Then there’s the workmanship warranty. This protects against manufacturing defects and other physical problems with your panels.

The workmanship warranty is shorter than the performance warranty. A generous workmanship warranty gives a great indication that the manufacturer knows they are putting out a reliable product.

The industry standard workmanship warranty is 10 years, with some companies offering 20-year guarantees.


A solar panel’s efficiency rating refers to the amount of sunlight the panel can convert into usable energy. 14-22% is an acceptable efficiency range for panels produced by major manufacturers.

This relates directly to the output of a solar panel (in watts). For example, a SolarWorld 290w panel is 17.3% efficient, while their 300w module is 17.89% efficient.

Temperature Coefficient

Solar panels are tested in ideal conditions. When manufacturers measure panel output, they perform tests inside a climate-controlled factory.

Obviously, the real world is going to introduce less-than-ideal conditions. During those sweltering days in the dead of the California summer, your system will lag behind its rated efficiency.

The impact temperature has on true panel output is the temperature coefficient. The coefficient measures how much efficiency is lost for each degree above or below ideal test conditions.

We’ll give an example in Celsius, because that’s what most manufacturers measure: energy loss per 1°C temperature change.

For example, let’s say a panel was tested at 45° C, but its current temperature is 55° C. If the temperature coefficient is 0.4% Wp (Watt power), you can multiply that by the difference in temperature (10° C). That panel is operating 4% below its rated efficiency on that particular day.

There are separate temperature coefficients for voltage, amperage, and wattage. Certain types of solar panels like monocrystalline can perform slightly better at higher temperatures.

The temperature coefficient usually isn’t the most important variable to focus on unless you are in an area that gets extremely hot. This is because heat reduces the efficiency of your solar panels, making them operate at a reduced output.

Company History

The longevity and reputation of the panel manufacturer play a part in our recommendations. What good is a warranty if the company goes out of business before they get a chance to honor it?

For that reason, we look at companies with a stable track record in the solar industry. Every product on this list is produced by a major manufacturer that we don’t expect to disappear any time soon.

UL Listed

Underwriters Laboratories is an organization that has been around for over 100 years. UL sets standards and performs safety tests to ensure products are safe for public use.

Solar panels must be certified to UL 1703 standards if they are being installed on your home.

What are the best solar panels on the market in 2018?

Without further ado, here are the best solar panels you can buy for a variety of applications. The info in this article is current as of September 2018.

Best Value Solar Panels: Astronergy 325W

  • Cost: $225 (69 cents per watt)
  • Workmanship warranty: 10 years
  • Performance warranty: 25 years
  • Efficiency: 16.8%
  • Degradation: -0.7% / year
  • Temperature coefficient: -0.408% Wp
  • # of cells: 72
  • Cell type: Poly

Looking for panels that won’t break the bank? Astronergy makes the best solar panels you can get from a pure value perspective.

Of the major module producers, Astronergy has the lowest cost-per-watt panels we’ve found. Their 325W panel retails at $225 (at the time of publication), which shakes out to just over 78 cents per watt.

A few of our employees run their home systems on Astronergy panels, and we also picked them for the system that powers the Wholesale Solar flagship office.

Their 16.8% efficiency is very respectable at this price point, and the warranty is on par with industry standards.

Astronergy also sets their warranty program apart from other companies by offering third-party insurance. Should they ever go out of business, the warranty would still be valid from the third-party provider.

That’s more for peace of mind than anything. Astronergy is a part of one of China’s largest electronics manufacturers. We expect them to be around for a long time to come.

But the extra bit of insurance on the warranty coupled with the low price point makes these panels a popular choice.

Best American-made Solar Panels: SolarWorld 295W

  • Cost: $265 (90 cents per watt)
  • Workmanship warranty: 20 years
  • Performance warranty: 25 years
  • Efficiency: 17.59%
  • Degradation: -0.35% / year
  • Temperature coefficient: -0.39% Wp
  • # of cells: 60
  • Cell type: Mono

SolarWorld is the oldest module manufacturer in America, and they still make some of the best panels around. We’re looking at the SolarWorld 295W as our pick for best American-made solar panels on the market.

There’s a lot to like about these panels.

They’re American-made, and the degradation rate is 0.05% better than our premium LG panels (which are 50% more expensive than these SolarWorld panels).

SolarWorld also gets bonus points for their generous warranty structure. The 20-year workmanship warranty doubles the industry standard of 10 years. It’s nice to have that extra peace of mind to protect against equipment failure down the road.

If you have your heart set on buying American-made panels, the SolarWorld line is the most efficient panel you can find at this price point.

Best Premium Solar Panels: LG 360W

  • Cost: $590 ($1.64 per watt)
  • Workmanship warranty: 25 years
  • Performance warranty: 87% efficiency after 25 years
  • Efficiency: 20.8%
  • Degradation: -0.4% / year
  • Temperature coefficient: -0.3% Wp
  • # of cells: 60
  • Cell type: Mono

LG doesn’t just make solar equipment; they’re one of the leading electronics manufacturers in the world.

We feature LG’s 360W panel in our premium packaged systems. They are super space-efficient, packing more output into a 60-cell panel than most 72-cell panels on the market are capable of producing.

Every solar project is different, and some people have the challenge of building a system in a compact space. For example, you may only have room for 10 panels on your roof. These LG panels will help you squeeze as much output as possible out of the limited space available to you.

They also have a long lifespan. At -0.4%/year, the degradation rate of these panels is 0.3% better than our featured Astronergy 325W panel.

That may not sound like a lot, but when you work the math out, it means LG panels will retain 7.5% more efficiency than Astronergy panels at the 25-year mark.

And LG’s solar panel warranties are a thing of beauty.

Where most companies aim for a 10-year workmanship warranty, LG covers the full 25 years.

On the performance warranty side, LG ensures their panels will still be 87% efficient after 25 years. That’s a stronger promise than the standard 80% after 25 years.

What are the best solar panels for off-grid systems?

We get this question a lot: is there any difference between panels for off-grid and grid-tie properties?

There is a bit of nuance to the answer.

The panels themselves can always work regardless of system type. There is no such thing as “off-grid panels” or “grid-tied panels” specifically.

However, panels must be paired with other components and sized accurately, especially in off-grid systems.

Historically, off-grid systems have used PWM charge controllers, which required that you match 12V solar panels with a 12V battery bank.

Now, most modern off-grid homes will use an MPPT charge controller, which can adjust the incoming PV voltage to work with almost any solar panel.

However, there are still string sizing considerations based on the panel and charge controller specs. All of the components must be supplied with the appropriate voltage and current. Batteries add another layer of complexity for off-grid systems, since the array must be sized to sufficiently recharge the batteries without overcharging them.

There are also a handful of panels that are designed specifically for off-grid applications:

Best Solar Panels for RVs / Mobile Applications

Solar is also a great solution for mobile applications like RVs and boats. But you’ll need smaller panels to work around any space constraints.

The solution for this is SunPower 50W and SunPower 100W flexible panels.

The lower profile helps you find the right configuration with limited space available. And since these panels can bend up to 30 degrees, they can flex around curved surfaces to make the most of the space you have.

These panels are lightweight, easy to install and perform well in low light. They’re built to adapt to rough and changing conditions that come with living life on the road.

At just over $2.50 per watt, they’re more expensive than traditional panels (even the premium LG panels). But it’s a fair tradeoff for a mobile-ready solar panel solution built to perform in harsh conditions.

Best Solar Panels for Small-Scale Industrial / Remote Applications

The last category we’ll look at is the best solar panels for small-scale remote applications.

These tend to be used to power remote equipment for a variety of industries:

  • Lighting
  • Telecommunication
  • Security & surveillance
  • Oil & gas
  • Water pumping
  • Traffic
  • Utility monitoring

A lot of times this equipment is in a remote location (like at the top of a mountain or floating on a buoy in the middle of a lake) and you need a small, self-contained system to keep it running.

We would recommend both Solarland and Ameresco, depending on the application. A few examples:

This represents the high end of the output range for 12-volt panels. Both companies offer a variety of 12V panel options ranging from 1W to 160W. Solarland also has 24V options, including one that goes up to 190W.

For certain industrial applications, you may need panels that are certified for use in hazardous locations. The SolarLand C1D2 (Class 1, Division 2) panels are your go-to choice.

There are 12V options at 45W, 60W and 150W, as well as a 140W panel that produces 24V:

These can also be used on RVs and boats, where you just want a solid panel with glass and an aluminum frame. If you don’t need the flexibility of the Sunpower panels, these are actually cheaper by about 25-50 cents/watt depending on panel size.

That’s it for our recommendations! We think these are the best solar panels you can get for your money in 2018, but prices and product configurations will change rapidly as technology improves.

As you do your research, seek out efficient panels from trusted manufacturers, and calculate the cost-per-watt so you can compare products on a level playing field.

If you follow these guidelines, you’re sure to find the right solar panels to power your system.

This article was updated on 10/2/2018. For our most current prices, take a look at the solar panels page in our shop.

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Discover vs. SimpliPhi: What’s the best lithium battery for solar energy storage?

Discover vs. SimpliPhi: What’s the best lithium battery for solar energy storage?

Jeremy Allen
JEREMY ALLEN, Sales and Design Technician at Wholesale Solar​

When we design off-grid solar systems with lithium batteries, we work with two main brands: Discover and SimpliPhi.

These two manufacturers are major players in the lithium battery market, which is the premium option for solar storage.

In this article, we’ll compare Discover AES vs. SimpliPhi Lithium batteries and give our honest opinion on when you might choose one over the other.

The alternative to lithium would be lead-acid batteries, which are less expensive but don’t last as long or run as efficiently. We review lead-acid batteries alongside lithium options in our review of the best solar batteries on the market.


First, let’s talk about what the two options have in common.

They’re both the same chemistry: Lithium Ferro Phosphate (LFP). LFP is a different type of Lithium battery designed to be very stable and safe, with high output to handle a demanding off-grid environment.

Lithium batteries have some inherent advantages over lead-acid batteries:

  • Longer lifespan
  • No maintenance
  • More efficient power usage
  • More usable storage capacity (deeper discharges)
  • No off-gassing / ventilation

Both Discover and SimpliPhi will offer a stable battery with a long lifespan. You won’t need to check in for regular upkeep like you would with lead-acid batteries.

They are also comparable in price. If you compare Discover’s 48V battery to SimpliPhi’s 48V battery, the cost per kilowatt hour of capacity is almost exactly the same.

At the time of publication, our price for 48V Discover AES batteries works out to $1 per Wh of capacity, while we charge 98 cents per Wh for a comparable SimpliPhi battery.

We compare 48V options because they are the highest efficiency and most cost-effective for most off-grid systems. Also, it just so happens that most household inverters come in 48V, so it makes the most sense to match the battery voltage to commonly used inverters.

It is worth noting that the cost per Wh depends on size and features. Many of our SimpliPhi 24V lithium batteries come in at a lower price point than their Discover counterpart. And of the two, SimpliPhi is the only one who makes a 12V option.

But due to inverter and charge controller specs, the apples-to-apples comparison most people care about is the 48V offering, because most off-grid residences are going to run off of 48V battery banks.

Why choose Discover’s Lithium Batteries?

Discover batteries thrive in large-scale systems. They have two main advantages: battery sizing and ease of installation.

Battery Size

The largest battery SimpliPhi makes has a 3.5 kWh capacity. In contrast, Discover’s largest battery nearly doubles that capacity, at 6.6 kWh. (Remember: even though the sizes are different, the cost-per-kWh is almost identical.)

If you are building a battery bank for a typical off-grid residence, it will take fewer Discover batteries to reach the same target capacity. For example, if you need 26 kWh of capacity, you could do that with 4 Discover AES 6.6 kWh batteries. It would take 8 SimpliPhi 3.5 kWh batteries to cover the same ground.

Ease of Installation

From an installation and wiring standpoint, Discover batteries are also easier to work with. SimpliPhi batteries have stricter cabling requirements.

You’ll need to run each SimpliPhi battery into a busbar, which is a terminal for all your wire connections. The busbar then combines all of the batteries in parallel. The extra cable management can be a pain because all of the wires need to be equal length.

It’s critical that all cables are the same length, because the individual batteries are not communicating with each other directly.

SimpliPhi battery busbar
SimpliPhi's lithium batteries wire into a busbar, which manages the cabling. Image Source

Discover AES batteries don’t have the same strict cabling requirements. They can plug into each other to communicate and synchronize output.

This results in less wire overall and easier installation, because you can connect several batteries together in parallel without needing to run individual wires to a busbar. And because Discover batteries have more capacity, you’ll have fewer batteries to wire together.

All this means that Discover batteries take less time and money to install, and the difference is amplified in larger systems. That isn’t to say you can’t build large SimpliPhi battery banks — only that it’s a bit more tedious to do so.

It’s not a big deal if you’re bringing in an experienced installer to hook up your system. But if you plan to do a DIY install (as many of our customers do), consider that it may be a little more complex to install SimpliPhi batteries on a large scale.

Charge Capability

Discover batteries also have higher output, which means they can charge (and discharge) faster.

Charging current is measured in amps and commonly expressed as a percentage of total battery capacity. For example, if a 100 amp hour battery can output 100 amps, that is a rate of 1C. (C stands for Capacity.)

Here’s how continuous charge and discharge current looks for the two 48v models we are comparing:

  • Discover AES 6.6kWh 48v: 1C
  • Simpliphi PHI 3.5kWh 48v: 1/2C

This means the Discover batteries can handle twice as much charge and discharge current. That likely has to do with differences in the battery management system (BMS) and overall battery design.

The BMS works to manage voltage, current and data logging for your battery bank. These manufacturers use different BMS designs, which may explain why Discover’s batteries charge faster and handle higher current.

This means that Discover batteries can be interconnected for faster charging and higher output. They plug into each other, allowing them to communicate and synchronize charge and discharge current.

SimpliPhi’s batteries act independently. Individual batteries do not communicate or share information.

Why choose SimpliPhi’s Lithium Batteries?

SimpliPhi has a lot going for them as well. As I mentioned before, their small and mid-range lithium batteries come in at a lower cost-per-kWh than Discover’s options.

In fact, Discover doesn’t make a 12V lithium battery, but SimpliPhi does. This would be your go-to battery for mobile use, like powering your RV or boat, or small remote applications like security systems or any equipment requiring a 12 volt power source.

SimpliPhi is more competitive in the 24V territory as well. We sell their 24V lithium battery at $1 per Wh, while Discover’s is $1.15 per Wh of capacity. These batteries might be an appropriate choice for small cottages, cabins and tiny homes.

The rule of thumb is that SimpliPhi shines in applications that don’t require a lot of output. If you need to power lights and charge your phone in a small hunting cabin, we would likely recommend SimpliPhi to save you some money with no real downside.

(It could be a different story for something like a workshop, where you run power tools that demand high power output.)

For small to mid-range applications without intense peak demand, SimpliPhi’s battery sizes are a bit more flexible, and the prices a little bit better.

Discover vs. SimpliPhi: The Verdict

We lean toward Discover for large-scale systems because they’re more space efficient and easier to wire. SimpliPhi has more cost-effective midrange options, and they make a 12V battery, which Discover doesn’t offer.

As far as reliability and reputation go, both companies are solid. Discover has been making batteries since the 1950s, but they are the more recent arrival to the lithium battery space.

SimpliPhi was founded in 2002 with an exclusive focus on lithium battery storage. What they lack in longevity, they make up with laser-focused research and development efforts in the premium lithium battery market. They have quickly earned their reputation as a high-end battery manufacturer.

You can’t go wrong with either product, and we recommend both brands with full confidence.

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8 Costly Solar Mistakes to Avoid When You Design Your System

8 Costly Solar Mistakes to Avoid When You Design Your System

Cheyenne Minard, Senior Sales and Design Tech
CHEYENNE MINARD, Senior Design and Sales Technician at Wholesale Solar​

Today we’re going to look at the most common mistakes we see from beginners who are just starting to research and design their own solar system.

Our goal with this article is to prevent common headaches and (potentially costly) problems that stem from poor system design.

Since we came online in 2002, we’ve talked to tens of thousands of people about going solar.

Many of those calls start the same way: someone’s just had “the epiphany.” They realized solar power not only helps the environment, but is actually cheaper than paying the utility company in the long run.

Sometimes, people are so eager to get started that they dive in headfirst. They research products, calculate a cost estimate, and start sketching panel layouts for their roof.

But solar system design is a lot more complex than it appears on the surface.

So when people try to design a system without doing the research, they sometimes make mistakes. Big, glaring, expensive mistakes.

I touched base with a few of my colleagues to brainstorm the most common solar mistakes and misconceptions people have when they first get in touch with us.

Here are the points that came up over and over again:

1. Improper system sizing

Sizing a solar system is more complex than it appears at face value.

If you’re just starting out with your research, you might think it’s as simple as looking at your latest energy bill, then buying enough panels to cover that usage.

But that would ignore factors like climate, panel orientation, shading, natural efficiency drop, and other things that impact the “true” output of your system.

That’s why we won’t sell complete systems to anyone until they’ve consulted with one of our in-house solar design techs.

During that conversation, we plan your system to account for the variables most people don’t think about. Some common ones are:


Panels have an efficiency rating, and they suffer a 0.5-1% efficiency drop every year. 20 years after you install it, your panels will be 10-20% less efficient. We design a bit of extra headroom into your system to account for the loss of efficiency.


Solar panels are tested in ideal conditions: an indoor factory with temperatures in the mid-70s. In the real world, your system can be exposed to much harsher conditions. High temperatures can reduce the amount of energy you generate.

Your location also dictates how many sun hours you get. The term “sun hours” doesn’t mean “how long the sun is in the sky.” It refers to the amount of time the sun is in the right position to generate peak energy. Most places get 4-6 sun hours per day, and the exact amount influences system sizing.


Inverters and charge controllers have maximum and minimum voltage input windows. Panels and batteries have a voltage rating as well.

Your system needs to be designed at the right voltage based on the equipment being used and what it requires. We also account for things like temperature that can affect voltage and system performance.

If you don’t have the right voltage from your solar panels or battery bank, your system might not perform well or worse – you could damage expensive hardware.

Battery bank sizing

Mismatching your battery bank with your charging source is the most common issue when it comes to batteries, specifically with off-grid system sizing. Your array needs to supply enough power to keep the batteries charged, but not so much that they overcharge.

Too much current could damage your batteries from overcharging. On the other hand, undercharging your batteries can have an even worse effect.

Certain batteries need to be brought up to full charge on a regular basis. Leaving them at empty or partial charge for an extended period of time can cause the batteries to fail prematurely.

2. Confusing off-grid and grid-tie solar

Solar power allows you to generate your own energy, which means you won’t pay for power from the utility grid. People assume this means they will be “going off the grid,” but that’s not accurate.

In reality, most people are looking for a grid-tied solar system.

Here’s the distinction: your panels generate energy, but you need a way to store that energy for later use. If you have access to power lines, you can store the energy you generate in the utility grid. The utility company will credit you for extra power produced, and allow you to pull from the grid when you need it.

Off-grid properties have no access to power lines, so they need another method to store energy. That means off-grid systems need a battery bank to function. Batteries are expensive, but with no option to store power in the grid, they are mandatory for off-grid systems.

The bottom line is that saving money and being independent from the grid are mutually exclusive. Batteries eat into your ROI (return on investment), and grid-tied properties don’t need them.

You don’t need to go “off the grid” to get the benefits of solar power. If your property has access to power lines, grid-tied solar is the smartest option.

Why pay for batteries when the utility grid will take care of storage for you?

3. “Solar prevents power outages!”

You’re generating your own energy, so the lights should stay on during a power outage, right?

Unfortunately, that’s not the case with grid-tied solar systems. Although the power originates from your panels, it is still stored in the public utility grid.

When the grid power goes out, so does yours, because there’s no infrastructure to feed that power to your property.

The remedy for this is a grid-tied system with battery backup. When the power’s on, it functions like a normal grid-tied system. During an outage, a small backup battery bank kicks in to keep the lights on.

It costs a bit more, but the peace of mind is invaluable, especially if you live somewhere with extreme weather conditions or unreliable power from the grid.

4. “Solar is a bad investment” / “Solar isn’t feasible without the tax credit”

Look, solar isn’t cheap. It’s a 4 to 5 figure investment. We know that’s a big commitment.

But electricity from the power company isn’t cheap either, and it’s only going up in price.

The reality is when you look at the long-term value of owning a solar system, most grid-tied systems pay for themselves fairly quickly and actually make you a profit over the life of the warranty.

We explain how to calculate your payback period on our resource center page about the ROI of solar. But here’s the quick version:

Let’s use a system that costs $10,000 (to make the math easy). That would get you something like this 6.6kW system.

You get a 30% tax credit for going solar, so the out-of-pocket cost is $7000.

$10,000 – $3,000 = $7,000

A 6.6 kW system will offset around 900 kWh of energy usage per month. At a typical rate of 12 cents per kWh, that’s a utility bill of $108 per month.

900 kWh * 0.12 = $108

To calculate payback period, multiply this bill by 12 to get your annual energy savings (in this case, $1296). Divide that number into your system cost to calculate your payback period, the time it takes for your system to pay for itself entirely.

$7,000 / $1296 = 5.4 years

This system will pay for itself in about five and a half years. Most solar panel warranties last for 25 years, and inverters for 10 years. After you clear the payback point, your solar system starts to turn a profit for you.

This assumes you perform a DIY installation. If you hire an installer, you might pay them $1 a watt to set up your system. That would make your system cost $16,600 before the credit, and $11,620 after the 30% back. The math changes slightly:

$11620 / $1296 = 8.96 years

A 9-year payback period on a system with a 25-year warranty. Still not bad at all.

“But the tax credit is going away in 2022!” Yup, that’s true. And we hear people say subsidies are the only reason solar makes sense.

So just for fun, let’s try it one more time without the tax credit:

$16,660 / $1296 = 12.8 years

We’ve gone from 5.4 years to 12.8 years by hiring an installer and skipping the tax credit, and we’re still paying off the cost halfway through the life of the system.

Solar costs a fair bit of money up front, but no matter how you slice it, grid-tied solar can pay for itself long before the equipment wears out. The more expensive your power rates are, the quicker the payback period and ROI.

5. Leasing

Solar power is a sound investment…if you own your system.

When you lease your system from a third party through a Power Purchasing Agreement (PPA), the value of that investment pretty much vanishes.

We can think of a few reasons why leasing is a bad deal.

The first thing to understand is the lender owns the system, which means they’re eligible to claim all the incentives. You won’t see a penny from the 30% federal tax credit or any local rebates.

After you’ve been squeezed out of the incentives, you’ll also pay a premium rate to lease the panels, which includes interest. In all, you might find you paid twice as much to lease the system as it would cost to finance and own the system yourself.

Leasing also makes it more challenging to sell your home. You have to transfer the lease to the buyer upon sale. Or, you can pay off the remainder of the lease balance and add that amount to your asking price. Both options limit the pool of potential buyers for your home.

We explain more about why we think leasing is a bad idea in our article: Should you Buy, Lease or Loan?

6. Not planning ahead

I brought up the fact that most panels are warrantied for 25 years. That’s a long time to go without any big changes in your life.

When people start planning their system, everyone thinks about what they need right now. Not as many people think about how their needs will change in the future.

What happens when you have kids, build a new workshop, or buy an electric car that needs charging? You’ll start consuming more energy. So we always tell people to look to the future when you start planning your system.

Some things to think about:

Do you have space to expand the installation if necessary? For example, say your system takes up your whole roof. What happens when you want to add panels later but have nowhere to put them?

Is your system designed to be expandable? People often think, “hey, I’ll just add more panels!” without realizing the other parts of the system, like the inverter, need to be sized to match. Central inverters have a limit to the number of panels they can support, so it’s often not as simple as “just adding panels.”

Micro-inverters are a great option to facilitate expansion for grid-tied systems. They work on a one-to-one basis: each panel is paired with its own micro-inverter. When you want to add on, just pair another inverter / panel pairing and mount them onto your array.

For off-grid properties, you should also think carefully about battery sizing. Depending on the battery type and age, it might not be possible to expand your existing battery bank.

Lithium battery banks can be expanded, but lead-acid batteries have limited options for increasing storage capacity.

The reason? When you add new lead-acid batteries to an old bank, the new batteries absorb the characteristics of the old ones. The new batteries are essentially being aged prematurely.

Lithium batteries are the exception. They have an integrated circuit controlling the charge parameters. The old batteries charge independently from the new ones, so you don’t run into the same issue.

7. Overpaying for installation

When you start to think about going solar, the first option that comes to mind is a turnkey installation from a national provider like Tesla, Vivint, Sunrun, or SunPower.

They offer an all-in-one solution to design your system, source your parts and install it for you. You can’t beat the convenience, but you also pay a premium for the catered experience.

Turnkey installers charge you anywhere from 100-200% of the cost of equipment to install your system. For a system worth $10,000 in equipment, they may charge another $20,000 to install it.

Big solar installers need to charge this premium to cover advertising, office rent, insurance, labor, and other expenses required to run their business on a national scale.

What many people don’t realize is that you can buy packaged solar systems from a wholesale distributor, then build it DIY-style or bring on a local contractor to help with part of the installation.

Working with a local contractor can save you a lot of money if you are willing to organize the project and take on some of the easy tasks. To help you find a local contractor to guide you through your project, we wrote an article about how to find a solar installer you can trust.

If you do choose to take on the project yourself, we also recommend fielding quotes from multiple installers before you choose the one you’re comfortable with. Contractors charge quite a broad range of rates, depending on their specialty as well as the complexity of the project.

Even a rate difference of 25 cents per watt can change the bid by a couple thousand dollars. It’s smart to use a service like Solar Power Rocks to compare quotes from local installers and make sure you’re getting a fair bid.

8. Building a Frankenstein system

Finally, let’s talk about the phone call our system designers dread:

“I have an inverter from eBay and some panels I bought a few years back, can you help me build the rest of my system?”

A fair number of people hold out for great deals and acquire parts slowly over time, until they’re ready to slap all the parts together like some kind of solar-powered Frankenstein’s monster.

But just like with cars or computers, it’s not enough to have parts. You have to have the right parts that are compatible with each other.

Otherwise, you get…

  • inverters that are undersized for your panel output
  • panels that are different sizes and don’t fit together properly on the mount
  • components that don’t wire together because they have different connectors
  • a power center missing essential components like circuit breakers/disconnects, remote control, or monitoring hardware
  • a box of hodgepodge components that no one is willing to support because it was purchased from all over the Internet
  • …and countless other headaches

There’s a lot that can go wrong, but the bottom line is piecemeal systems like these can quickly turn into a disaster. Unless you start with a plan and stick to it, there’s no guarantee the parts you buy will ever work together.

How to Avoid These Costly Solar Mistakes

You might notice that you can’t actually buy a complete system from our website cart. We require that people get in touch for a design consultation first.

Why do we do it this way? Even though we don’t install equipment, we’re still responsible for designing your system properly. If we sold systems with incompatible parts, we’d get a bad reputation in a hurry.

Instead, we run the math on system sizing, plan for inefficiencies, check voltage requirements, provide wiring diagrams, and do whatever else it takes to make sure the system you build is going to work.

For off-grid systems, we even assemble pre-wired power centers in our warehouse so you don’t have to worry about piecing the components together.

Our advice: do as much research as you can to account for all possible variables. But before you pull the trigger on that big investment, run that design by a solar designer first. An experienced set of eyes could help you catch some potentially costly mistakes before it’s too late.

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