Solar Battery

Along with panels and inverters, batteries are rapidly becoming an essential component of modern solar systems. Solar batteries have many benefits and can be of critical importance for homeowners looking to protect themselves against power outages. However, solar batteries may not be a great fit for everyone, so it’s worth exploring the pros and cons to pairing a solar system with a battery.

The Basics

At the most basic level, solar batteries allow power produced by a solar system to be stored for use at a later time.

All solar systems produce power at different times than homeowners use it. Solar systems will typically overproduce during the middle of the day compared to what the homeowner needs. This extra production is back-fed to the utility grid through a program called net energy metering. By selling their excess power to the grid, homeowners accumulate credit that can be used to offset the power they draw in at night when the solar panels aren’t producing power.

When a solar system is paired to a battery, homeowners have the option to use their extra electricity to charge up their battery instead of sending it back the grid.

The Benefits

So, why pay for a solar battery when the grid is there to credit you for your excess power anyway? As it turns out, there are several key advantages to pairing your solar system with a battery.

Protection Against Power Outages

For most homeowners, the single biggest benefit of solar batteries is the ability to have backup power during a grid outage.

If you have a solar system without a battery and you experience a power outage, the solar system will automatically shut off. Electrical code requires that solar systems shut down during power outages so they don’t accidentally backfeed live power to the grid if the utility company has workmen trying to fix the lines. 

By contrast, with a solar and battery system, an additional device called a backup gateway is also installed that allows the house to “island”, or isolate, itself from the grid. 

The moment the outage occurs, the gateway instantly detects the event, disconnects the home from the grid, and turns on the battery. The system then becomes a closed loop, where the battery powers the home’s backup circuits and the solar panels recharge the battery.

In this respect, solar batteries can function very similarly to home generators, except they’re far better in every measurable way. Check out our other article on the top ten reasons solar batteries are better than generators.

Time of Use Savings

Many utilities around the country are moving towards time of use rate plans for their residential customers. These rate plans more accurately reflect the changes in wholesale power prices throughout the day. Typically, these plans have peak charges during the late afternoon and early evening, when demand spikes as everyone goes home after the workday and increases their power consumption. The off-peak times are during the middle of the day, when solar systems everywhere are producing excess power, and overnight, when demand is lowest.

Time of Use Chart

This difference in rates not only affects the cost of power that homeowners draw from the grid, but also the value of the excess power that homeowners backfeed to the grid. This means that homeowners on time of use rate plans receive less credit for their extra power generated during the day than they pay for power they draw in during the evening. As a result, homeowners can owe money to the utility company at the end of the month even if their solar system met 100% of their power demand on a net basis.

This is where the additional savings from solar batteries comes in. Rather than backfeeding excess solar power when it’s less valuable, batteries allow homeowners to store their excess power on-site and feed that power into the house at night, which reduces the amount of power they need to draw from the grid during the highest-cost time of day.

The amount of additional savings that a solar battery will provide depends on several factors, including how much electricity the homeowner uses, what time of day they use that power, and the structure of their specific rate plan. Head over to the main page and schedule a call with one of our Energy Advisors to see your customized solar and battery savings.

Self Consumption & Energy Independence

Pairing their solar system with a battery also allows homeowners to use far more of their own clean energy. Without a battery, homeowners will send a significant percentage of their solar power to the grid during the day, and then draw in dirty grid power at night. With a battery, homeowners are able to produce, store, and use their own clean power around the clock. This not only provides the satisfaction of being more self-powered by clean energy, it also enables significantly more energy independence by reducing reliance on the grid. Tesla found that adding just one of their batteries to a solar system increased the amount of solar energy consumed by the home by over 50%!

The Incentives

Solar batteries may be eligible for both state and federal incentives, depending on the specifics of the installation.

The primary incentive currently available for batteries is the federal investment tax credit, which is currently set at 26%. That means you can claim 26% of your total solar and battery project cost as a tax credit for your federal income tax for 2020. Importantly, this tax credit is only available when the solar and battery components of the system are installed together. As always, we recommend speaking with your tax professional regarding eligibility for the federal tax credit.

The other biggest incentive for solar batteries is California’s Self-Generation Incentive Program, or SGIP. This state program offers an additional rebate for homeowners installing batteries who have particular backup needs. These include being located in Tier 2 and Tier 3 fire areas, needing backup for medical equipment, meeting low-income thresholds, etc. Our Energy Advisors would be happy to assist any California homeowners looking for more information on the state’s SGIP program.

The Options

So, what are the options when it comes to solar batteries?

The most common batteries on the market today are the Tesla Powerwall, LG Chem, and Sonnen. Check out our individual articles for deeper dives on each of these products.

Homeowners can also purchase multiple batteries if they want to. The right number of batteries depends on a number of factors, including the size of the solar system, the amperage of circuits that need to be backed up, and the desired backup duration. Speak with one of our Energy Advisors if you’d like to find out the right combination for you.

The Future

Solar batteries have become an important aspect of modern solar systems, and their importance will only grow over the coming years. Battery capability will continue to advance as prices continue to fall. Electric utilities are increasingly turning to batteries to stabilize their grids, with some utilities even paying homeowners for access to their home batteries to dispense power to the grid when it’s needed most. Without question, solar batteries are here to stay.