Expert review of SunPower's SunVault battery

SunPower is a popular brand in solar, thanks to its reputation and the quality of its products, and its solar batteries are no different. There are two types of SunPower storage, the SunVault and the Helix, with the Helix available for commercial use only. 

The SunVault solar battery has been designed to work exclusively with SunPower solar panels and is a perfect addition to the SunPower Equinox solar system. While the SunVault is a relatively new battery, it is a trustworthy option because, like the Equinox system, it will be built, warrantied, and serviced by SunPower.

How does the SunVault storage battery work?

It is easiest to buy an entire SunPower Equinox system - solar panels, battery, and all - instead of adding it to an already-existing SunPower system.

Similar to other solar storage batteries on the market, the SunVault battery stores the excess energy that your solar array produces. It will also supply power to your home in the event of a power outage, or any other time where your solar panels won’t be generating electricity, like at night.

Backup batteries are typically meant to provide electricity for a limited number of appliances in an emergency - and only for a few hours. When you work with an installer during your battery install, you will choose which appliances are important to you to run during a grid outage, such as your fridge or well pump.

Based on these factors, it is then determined how much backup energy storage you will need, meaning you might need more than one battery to provide it. Your battery can also act as a power source during times when utility costs are higher, which is especially useful in locations that have Time-of-Use billing.

You can monitor your energy usage by using the SunPower app, mySunPower. 

What are the technical details of the SunVault?

The SunPower SunVault offers one type of battery, the 13 kWh battery. You can install up to two if you need more backup power, giving you a maximum 26 kWh of energy capacity. 

The SunVault system includes the battery itself, as well as the Hub+. The Hub+ is what controls the energy flow and dictates how the stored energy is used. For example, it can determine when there is no energy available coming from your panels and will then switch to stored energy from your battery.

Feature	SunVault battery
Power rating	6.8 kW
Rated energy capacity	13 kWh
Dimensions	26 x 63 x 15
Cost	$12,000 - $25,000
Warranty	10-year limited warranty

Continuous power rating

The continuous power rating, sometimes just referred to as the power rating, tells you how much electricity a solar battery can release at once for your home appliances to use, measured in kilowatts (kW). The power rating is important because it tells you how many appliances you can run at the same time. 

The SunVault battery has a continuous power rating of 6.8 kW, which is pretty impressive for a solar battery. Most solar batteries on the market today have a power rating of around 5 kW, so a SunVault battery will be able to power a few more appliances than many of its competitors. 

Rated energy capacity 

When shopping for a battery, the capacity rating is one of the most important figures to look for. The rated capacity of the SunPower Sunvault is 13 kWh, which works out to about half of the average American household’s daily energy usage. 13 kWh is a great amount of electricity to have stored up for daily use. 

However, SunPower doesn’t list what the usable capacity of the battery is. The usable capacity tells you how much of the total battery capacity is actually available for you to use once you factor in things like charging efficiency and how much electricity you can discharge before causing damage to the battery. 

Today, most lithium-ion batteries allow you to use all of the energy stored in the battery, so the rated capacity and the usable capacity will be the same. This is likely the case for the SunVault, but we can’t say for certain since Sunpower doesn’t specify in their product brochure.

How much does the SunVault cost?

Batteries are certainly pricey; for a SunVault storage battery you can expect to pay about $12,000 - $25,000, including installation.

Many times, it is impossible to give an exact number for how much you can expect to pay for a battery, SunVault included. The cost of a battery depends on local installation costs, whether or not you are adding a battery to an already existing solar system, installing both the battery and solar panels together, and if you will need one or two batteries. 

The good news is the total cost can be reduced with the federal solar tax credit. The best way to find pricing is to work with a local SunPower-approved installer. They can help you decide how many batteries your home needs and how you can claim local and state incentives. 

How does the SunVault warranty compare to that of other battery brands?

SunPower offers a 10-year Complete Confidence warranty for their solar batteries while their 25-year warranty covers every other component in the Equinox solar panel system. 

The Complete Confidence battery warranty will ensure that the battery will be free of material and workmanship defects, and operate at 70% of its original usable capacity until one of the following: 

• The battery reaches 10 years of age

• The battery releases 38,000 kWh of electricity, or

• The system has gone through 4,000 cycles - whichever comes first

The warranty conditions vary slightly if you install two SunVault batteries instead of one. 

As far as battery warranties go, this one is a little on the low side compared to others on the market. You’ll probably reach 38,000 kWh of electricity released before you reach 10 years or 4,000 cycles. In order to make it to 10 years, you’d only be able to use about 80% of the energy stored in your battery per day, which is definitely doable. But, if you think you might use more than 10.41 kWh per day from your battery, you’ll reach that warranty period sooner than expected. 

The SunVault warranty isn’t bad per say, but competitors like the Tesla Powerwall offer an unlimited cycle warranty, and the sonnenCore offers a 10,000 cycle warranty with a much higher throughput threshold. 

Can you go off-grid with a SunVault?

We suggest not going off-grid with a SunVault. To be truly off-grid, you would need a battery backup system with more usable capacity than 13 kWh. A SunVault battery can help you get closer to energy independence by keeping your lights on during a grid outage, but is not the best option for off-grid living. 

To be completely off-grid, you would need a huge solar panel system and a few storage batteries to provide backup power all night or for many inclement-weather days. For most homes, it is more feasible to remain connected to the grid even if you have a backup battery. The grid will act as your backup source for any times that your home needs more energy than your panels produce or your battery has stored.

Is the SunPower SunVault right for your home?

The SunVault offers a complete storage solution that works with your SunPower Equinox panels to store and provide backup power. 

As for the price, the SunVault system is slightly higher than competitors like the Tesla Powerwall, so it isn’t the most budget-friendly option. It’s also not as accessible as some other batteries, since it can only be paired with SunPower panels, which tend to be more expensive. 

If you currently do not have solar panels and are interested in SunPower, installing an Equinox system and SunVault battery (at the same time) makes sense. SunPower also offers a decent warranty, and the company has been successful within the solar industry for a long time, so you can rely on them to provide you with the customer service you may need - which is key for solar and storage systems that are meant to last a long time. 

Because of their longevity, you are more likely to need to work with customer service over the lifetime of your equipment, making good customer service essential. You can check out reviews of their customer service, solar panels, and more, on our SunPower reviews page.

Your best bet is to work with a local SunPower-approved installer to get pricing and their advice on how to go about purchasing solar-plus-battery-storage for your home.