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?

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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.

Similarities

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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