Tesla Powerwall and Solar
Last Updated: March 23, 2016
In April of 2015, Tesla Motors announced their new Powerwall home battery pack. Solar enthusiasts were especially excited about the prospect of a lithium-ion battery solution, and Wholesale Solar received numerous inquiries about how well the Powerwall would work with solar panel systems.
There were quite a few naysayers, including a writer from Forbes, who suggested that using the Tesla Powerwall battery in conjunction with a grid-tied solar system would have U.S. consumers paying twice the normal rate per kWh for electricity. That didn't stop rabid fans from pre-ordering the 7kWh Powerwall model causing the item to be "sold out until mid-2016." All this frenzy over a product that hadn't even been mass produced yet.
Tesla was initially offering two sizes: a 7kWh battery for daily-cycle use, and a 10kWh battery for backup power applications. However, in March of 2016, Tesla dumped the 10kWh Powerwall model citing a lack of consumer demand for battery backup. Click previous link to read more details on the Wholesale Solar blog.
Tesla Powerwall Overview
- Updated Powerwall capacities have changed over time. As of March 2016, there is only one Powerwall size remaining: the 6.4 kWh model, designed for daily use. It is priced at $3,000.
- Multiple Powerwalls can be connected together to increase total storage capacity.
- The Powerwall does not include an inverter, which is required to convert DC power to household-usable AC power2.
- New! The SolarEdge SE7600A-US inverter will be compatible with the Powerwall, as indicated by this overview of the SolarEdge StorEdge solution with Tesla Powerwall (PDF).
- There are unverified rumors that the Powerwalls support nighttime charging, but your electricity provider must offer what's called "time-of-use metering" for you to take advantage of nighttime pricing.
Wholesale Solar is paying close attention to this ongoing development. Sign up for our Tesla newsletter below if you'd like to be informed of new developments as they emerge.
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Can I buy a solar system now and upgrade it with a Tesla Powerwall later?
New! Yes. As of early 2016, SolarEdge has indicated that systems running on the SE7600A-US inverter can be upgraded with the StorEdge system and made Powerwall-compatible. Below is a list of systems we sell which use this inverter.
If you're not sure which system is right for you, please give us a call at 1-800-472-1142 and we'll be glad to help you choose.
Powerwall-Compatible Complete Solar Systems
Frequently Asked Questions about Using the Tesla Powerwall with Solar Systems
Are the Powerwalls sold out? When will they be available?
According to Engadget, at least 38,000 Powerwall reservations have been made and that is all the available production until at least mid-2016. Once Tesla's own Gigafactory is up and running next year, production should gradually increase to meet demand.
If you're interested in home backup power and/or solar systems sooner than that, we offer many alternatives that are immediately available to ship. Wholesale Solar has been selling battery backup solutions for more than 20 years, both with and without solar panels, and we will customize the systems to your specific needs.
What are the immediately available alternatives?The Powerwall is an exciting new battery, but did you know there are existing. tried-and-true battery backup solutions that work well, cost less, and are available immediately? The Powerwall is sleek and small, but the best value for home backup power comes from existing lead-acid battery banks. Consider the following options:
Complete Solar-Powered Backup Systems: Battery Bank AND Solar Panels
Complete Solar + Battery Backup Systems (everything you need)
The best of both worlds: A battery backup solution custom-sized to your specific power needs, with enough juice to back up your appliances, AND a complete solar system to charge them with. This can be both grid-intertied or off-grid.
Give us a call at 1-800-472-1142 and our solar technicians will gladly discuss your needs and design a system to meet them.
Battery Backup Kits
Battery Backup Systems (includes inverter and other required components, but no solar)
Professionally designed and built by our experienced technicians, these kits are available in various sizes and include everything you need to provide backup power in an emergency. However, they still need to be charged by an existing power source (such as the grid or an existing solar system).
Battery Bank Only
Batteries Only (no solar or inverter, just the batteries)
For people looking for batteries ONLY, we have ready-to-ship battery banks with capacities from 2 to 100 kWh. Like the Powerwall, an inverter is not included in these battery-only packages and you will still need a way to connect these to your home, which is what the complete systems above offer. This is not recommended unless you're replacing an existing battery bank.
Will the Powerwall work with a solar PV system?
Yes. As of March 2016, we know that SolarEdge's StorEdge systems running on the SolarEdge SE7600A-US inverter will be Powerwall-compatible. Scroll up to see a list of compatible systems. We are not yet sure if other inverters/chargers will be compatible.
How much electricity does the Powerwall store, and what can I back up with it?
6.4 kWh, which is about 20% of an average American household's daily energy use. This is enough to power critical appliances for a few hours in the event of a blackout, but generally not enough to go completely "off-grid" with a single unit. It is possible to chain multiple Powerwalls together for greater capacity.
Some electricity usage examples provided by Tesla: It takes 4.8 kWh / day to run a refrigerator, 5.6 kWh / load for washing and drying your clothes, 0.05 kWh / hour for powering an average laptop.
Can I use more than one Powerwall together?
Yes, although it is currently unclear how many you can link together.
Can I use this battery to take advantage of night-time electricity pricing?
This requires a special "time-of-use metering" agreement with your electricity provider. We suggest asking them about this. Also, 7-10 kWh is insufficient capacity to meet average US household daily needs, so even if your utility allows this, you would need multiple battery packs to fully time-shift your electrical use.
Which inverters are compatible with the Tesla Powerwall?
New! So far, we only know of one inverter that will definitely be compatible: the SolarEdge SE7600A-US inverter. See an example system overview using this inverter, the SolarEdge StorEdge solution and a Powerwall (PDF).
What's the difference between Li-Ion and Lead-Acid batteries?
Lithium-ion batteries (like the Powerwall) offer modestly improved performance characteristics and per-cell longevity, but are more expensive. One of their biggest advantages is energy density: for a given capacity, a li-ion battery can be made physically smaller than an equivalent lead-acid battery.
However, in situations where space is not an issue, lead-acid batteries are a better value (in terms of usable energy per dollar spent). Properly sized and maintained, spreading the workload across several batteries wired together, a lead-acid battery bank can perform as well and last as long as a lithium-ion one, but cost a fair amount less.
- 6.4 kWh Powerwall for $3000 vs our Crown 430 AH 24VDC 10,320 Wh (4) Battery Bank battery bank for just $1,340.
- Or see more options on our battery banks page.
Because the lead-acid batteries we sell have a lower depth-of-discharge (~50% for lead-acid vs lithium-ion's ~80%), which just means you have to size them slightly larger for the same usable capacity in the end. Despite that, they can still be a better value in terms of price per kilowatt-hour of capacity. The Powerwall is physically smaller than our battery bank, but more than twice as expensive.
Please remember that whichever battery pack you choose, you will also need additional components (such as an inverter) to complete your system. We recommend looking at our complete backup power systems instead, where we do the design work for you and include all the required components.
1 A kWh, or kilowatt-hour, is a unit of measurement that indicates how much energy a battery can store. A refrigerator, for example, uses about 1.1 kWh per day. The average US household uses about 30 kWh per day (source: EIA.gov), but that number can vary widely depending on heating/cooling needs and energy efficiency practices. You can usually find your household's usage on your electricity bill, or you can use our electrical load calculator for a rough estimate.
2 To learn more about the differences between AC power (used by household appliances) and DC power (from the Powerwall), see our page "What is the difference between an AC watt and a DC watt?"