Battery with solar panels

As the cost of batteries for solar energy drops and the capabilities increase, homeowners are increasingly looking to solar-plus-storage technologies for greater energy independence and resiliency. Natural disasters and extreme weather events in 2017 highlighted power grid vulnerabilities and the benefits of energy storage solutions. 

Solar installers are seeing increased consumer interest in battery technology for solar energy. Once prohibitively expensive, such batteries are plummeting in cost and have gained considerable media attention. The Tesla Powerwall has caused solar battery technology to explode in popularity and capture public interest.

“In Maine, it is common to have grid outages that last for multiple days,” says Chuck Piper, co-owner of Sundog Solar. “We have been getting more inquiries about solar systems with battery backup than ever before. Homeowners are finding this technology increasingly appealing as the prices fall and the technology improves.”

Blackouts and Solar Power

What’s the appeal of solar energy batteries? Your solar energy system needs batteries to operate during a power outage. If the system doesn’t have batteries, it automatically shuts down during a power outage for the safety of your home electronics and utility workers. A battery backup provides energy to your home or business even during a blackout.

The Benefit of Batteries

Grid-tied photovoltaic systems with batteries can operate during power outages or whenever you want to use the stored energy. A critical load panel determines which home electronics will be powered by the batteries during power outages. Homeowners prioritize the most crucial loads until utility service is restored. It is often too expensive to power all appliances, such as air conditioners and entertainment centers, because the capacity of the batteries limits the total energy that can be stored. 

In some utility districts, power can be much more expensive at certain times of the day. Owners of solar systems with batteries can use the stored power when rates are highest, saving money with cheaper solar power.

Battery Basics for Solar Power

When looking into solar batteries, you have a few technologies to choose from, including deep-cycle lead-acid, lithium-ion and saltwater batteries. The most important aspects of battery storage to consider are the battery’s capacity, power ratings, depth of discharge and warranty. The capacity tells you how much energy the battery can store, measured in kilowatt-hours of capacity. The power rating dictates how much power the battery can deliver at a given time. The depth of discharge refers to how much of the battery’s capacity has been used up. For optimal battery life, don’t exceed the depth of discharge as stated by the battery manufacturer.

By Sarah Lozanova

Sarah Lozanova is an environmental journalist and copywriter and has worked as a consultant to help large corporations become more sustainable. She is the author of Humane Home: Easy Steps for Sustainable & Green Living, and her renewable energy experience includes residential and commercial solar energy installations. She teaches green business classes to graduate students at Unity College and holds an MBA in sustainable management from the Presidio Graduate School.