Newer, more efficient solar panels and inverters have been in the news recently, but advancements in solar technology aren’t limited to standard equipment. Energy storage is also moving closer to mass-market adoption, and more installers are offering solar batteries and solar panel battery banks (a.k.a. solar-plus-storage) as an option for homeowners. Solar-plus-storage systems include a battery that captures and stores the excess solar energy generated by the PV system, opening up the possibility of going “off the grid” – a tempting proposition for homeowners who want to sever their connection with utility companies by using renewable energy.
Since solar battery technology is relatively new to the solar market, there isn’t significant solar storage capacity deployed in the U.S. That won’t be the case for long though: between utility and residential installations, solar battery deployment is expected to increase twelve times over in 2015. As solar batteries become cheaper and more accessible for homeowners, more people are wondering, “Can I use solar batteries to go off the grid with my solar panel system?”
What does it mean to go “off the grid”?
Installing solar panels on your roof doesn’t mean that you’re off the grid. Most solar systems can’t consistently generate enough electricity to be a home’s only power source, which is why the vast majority of solar homeowners maintain a connection with their utility company. When you generate more power than you use, your utility gives you a net metering credit on your electricity bill. When you need to, you can then spend your credits to supplement your solar power with electricity from your utility company. If/when you don’t have credits, you’re simply charged the going rate for electricity at that time. For the average solar homeowner, this process typically means you’re generating more power than needed during daylight hours, and less than needed at night.
If your solar panels can generate over 100% of your home’s electricity needs, then the credits you receive from your excess power generation could theoretically cover the costs of electricity needed in low-sunlight periods. However, this process requires that your home still stay connected to the grid. By truly going “off the grid”, you would need to sever your connection to your utility company. By doing this, you would lose the ability to purchase electricity from your utility in low-sunlight periods. This is why your home would need solar batteries installed to stay powered at night.
Can I use a solar panel battery bank to store my excess solar energy?
The battery storage technology that makes it possible to go off the grid does exist. If you install sufficient battery storage along with your solar PV system, you can store any excess electricity at the time of generation and then draw from it as needed later. You may be hearing talk of using “solar panel battery banks” as a means to harness massive amounts of storage capacity in order to become completely independent of the grid. Because off grid projects involve sizing enough energy to power your entire home, you’ll hear battery bank terminology used when a contractor is trying to estimate a total wattage for a combined battery system. In theory, you can find do it yourself methods for storing mass amounts of renewable energy with these connected battery arrays. In practice, however, going off the grid is more complicated than you might think, particularly if you live in an area with significant climate variation.
Residential-scale solar batteries on the market today can store the energy generated during the day for your home to use at night. This can be particularly beneficial in areas where net metering caps have been reached, or in areas where utility companies don’t have good policies for compensating homeowners who generate excess solar electricity.
The trickier proposition is capturing excess electricity generation in the summer, when solar power generation is highest, to use in the winter, when it is at its lowest. According to EnergySage marketplace data, the average solar shopper offsets 86% of their electricity use with their solar system – a significant amount, but not enough to go off the grid. Preventing total power loss in the event of a winter snowstorm or extended overcast days would require a lot of storage capacity, a very large solar panel system, and a significant financial investment to install.
While it is technically feasible to go off the grid with solar batteries, it’s rarely cost effective. In some places, particularly in remote areas, off-grid solar battery systems are the best (or even the only) option. More often, solar shoppers maintain their connection with their utility company, even when they choose solar-plus-storage solutions.
The good news: with or without storage, solar panels can still save you money
While you might not be able to completely go off the grid, solar panels are still a strong investment, and solar battery technology is becoming cheaper every year. With $0-down solar loans and solar leases, you can save money on your electricity bills as soon as your solar system is up and running, and you may even be able to get rebates or production-based incentives for switching to solar energy.
To learn more, use a solar calculator to get an instant estimate of what solar can do for your home. And as with any other major purchase, be sure to comparison shop for solar equipment and financing options before selecting the ultimate installer you plan to use.
This post first appeared on Mother Earth News