First let’s start with the basics of solar batteries. To put it simply, they store excess electricity generated by solar panels. That stored energy can power your home when your solar panels aren’t generating energy, including nights and cloudy days. They also can power your home when the power grid goes down.
It’s important to note that in most installations without a battery your home will not be able to utilize the electricity generated from your solar panels when the grid goes down. Because your solar panel system is wired into your electric company’s grid, they will stop producing energy if the power goes out for any reason. This is a safety mechanism that will allow the utility company’s workers to repair the lines during an outage without fear of being electrocuted. AC-coupled batteries like the Powerwall and SunVault automatically disconnect your system from the grid when the power cuts out and use the solar panel system or battery bank to power your critical loads. This allows your solar panels or battery to operate as a code-compliant off-grid electrical system until the utility company can turn your power back on.
Another big selling point for solar batteries is the 30% federal solar tax credit, which you can apply towards the final price.
Powerwall or SunVault?
Let’s take a look at each battery and see how they stack up to each other. These two different batteries share a lot in common. Both are AC-coupled, which makes both easier to install into an existing solar panel system. The two batteries are designed to use primarily for emergency backup. Also, both feature simple-to-use apps that allow you monitor your home energy system in real time and make changes to the way they dispense power throughout the day.
Tesla Powerwall
Tesla has designed this AC battery system for residential and light commercial use. It utilizes a lithium-ion battery that runs much quieter and cleaner than a conventional gasoline back-up generator. There’s no exposed vents that expel heat or visible wires making it a safer solution for households with kids or pets.
Here are the Powerwall’s technical details:
- Energy Capacity: 13.5 kWh, can be combined together with up to 10 Powerwalls
- Power: 7kW peak / 5kW continuous; seamless backup transition; pure sine wave output
- Size: 45.3” L x 29.6” W x 5.75” D
- Installation: Floor or wall-mounted
- Warranty: 10 years
The Upside:
The Powerwall has become the biggest name in solar batteries since launching in 2015. It sports a sleek design and mounts nicely to the wall. Multiple Powerwalls can be stacked together to boost storage capacity and power more appliances throughout your home or business. Also, the Powerwall is one of the least expensive solar battery options on the market.
The Downside:
Its lower price has created a waitlist for the Powerwall. Depending on when you order one from Tesla, it could take months before your Powerwall arrives. Also, the Powerwall requires multiple electric boxes and additional parts to meet local electrical codes. These add-ons take up space, limiting your ability to work them into a workable design scheme while leaving you fewer options for concealment.
SunPower SunVault
This system comes in two parts, the SunVault Battery and the Hub+. The Hub+ acts as the “brains” of the system, with the battery usually mounted next to it on the wall. When the SunVault debuted in 2021, SunPower envisioned it as a rival to the Powerwall, with many of the same features and a comparable power profile.
Here are the SunVault’s technical details:
- Rated Energy Capacity: 13 kWh up to 52 kWh when mounted together with a second SunVault battery
- Power: Continuous Power: Up to 13.6 kW
- Size: Energy Storage System = 63” L x 26” W x 15” D, Hub+™ = 46” L x 17”W x 6” D
- Installation: Wall-mounted
- Warranty: 10 years
The Upside: The SunVault seamlessly integrates into any SunPower solar panel system. It’s able to share the same app to monitor and manage power that the solar panels use. Your SunVault also would share the same Complete Confidence Warranty as your SunPower solar panel system, which makes getting the entire system serviced in case of a problem much simpler. SunVault batteries also typically run at a cooler temperature than their competitors, which increases the likelihood for the batteries to perform at top capacity for a longer period of time.
The Downside: SunVault batteries have a slightly higher price tag than the Powerwall.
Powerwall or SunVault?
Several variables will factor into which battery will work best for your solar installation. Here at Good Energy Solutions, we stand behind both battery systems and see the benefits of adding either one to your energy plan. Our consultants can work with you to choose the right option for your solar installation based on price, power needs, maintenance and longevity. If you would like to talk with one of our solar consultants about battery backup systems for your home or business, contact us here.
This blog post was updated on 5-18-23 to reflect changes with the federal tax credit.
Question for the GES team. Let’s say you have an existing SunPower setup without the SunVault battery. Would the addition of the SunVault replace some of the existing gear from the SunPower install? For instance, would the Hub+ consolidate some of the panels of the existing install and also host the PVS monitoring application?
Thanks for the question Mike. The short answer is yes.
From our solar designer: “The long answer is… The Sunvault Hub+ has 3 integrated panel boards. The first internal panelboard is for your non essential loads that are too large for the ESS to back up. The second internal panelboard is for the circuits you want to be backed up in a grid outage. There can be a maximum of 200A total of Overcurrent Protection Devices/Breakers tied to this panel. This panel is also the point of connection for the ESS/Batteries. The third and final internal panelboard is dedicated to the Generation from the Solar Circuits. This panel can accommodate 64A of continuous solar output. If you have additional solar, it will need to be placed on the non-backup side. There is an internal monitoring device for the solar generation panel. This will replace the existing PVS6 device. Unless you have in excess of 64A continuous solar. Then the additional circuits tied to the non-backup panel will require a separate PVS6 device.”
If you have any more questions, please feel free to reach out to us at https://goodenergysolutions.com/contact-us/
Our solar designer added a caveat to his initial response, “Utility and AHJ requirements for our area require a Solar AC Disconnect as well as a Battery Disconnect and ESS Unit Disconnect. This requires us to parallel all PV Output Circuits into an AC Combiner Panelboard. The output from these combined circuits then goes to a Fused AC Solar Disconnect, which then terminates onto the Generation Panelboard inside the HUB+ unit.”