Power your home in an outage with solar-powered battery backup.

Tesla Powerwall installed for customer's home in Maine

Tesla Powerwall installed for customer’s home in Maine

Enjoy the sun, even during an outage! The next generation of battery storage has arrived, giving solar customers clean, reliable, and efficient backup power that further lessens their daily dependence on the power grid.

Grid-tied solar electric systems are a great way to save money by using free power from the sun. However, for safety reasons, most grid-tied solar arrays are designed to shut down when they lose grid connection during a power outage. Solar battery storage bypasses this issue by storing excess solar power for later use, and acting as a backup if the connection is lost.

ReVision Energy’s two solar battery solutions, the Tesla Powerwall and the Generac PWRcell, enable you to access the free, abundant power of the sun, even during a grid-failure. We have Tesla and Generac options available in Maine, New Hampshire, Massachusetts, and parts of Vermont. Additionally, ReVision Energy is both a Tesla Powerwall Certified Installer and a Generac PWRcell Certified Installer.

How Do Solar Batteries Work?

Most solar arrays are connected directly to the electricity grid, and any excess electricity produced by your solar panels that is not immediately needed by your home will export into the grid. You will receive credits for this excess power, and on days when your home needs more electricity than your solar panels are making, you’ll use those credits to draw power from the grid.

Adding a battery storage solution to your solar array reduces your dependence on the electric grid, and allows you to continue using solar energy even when the grid is down. Solar batteries work like laptop or cellphone batteries, storing power produced by your solar array for later use. This means that you have a fully charged battery ready to go, powering your house almost instantaneously when and if the grid goes down.

Checkout the video below for an overview of how solar batteries work:

Which battery will I get?

There are numerous applications and options when it comes to installing a battery storage system in your home, and luckily ReVision Energy is full of experts who can help determine the best options for you and your home.

In addition to deciding between Tesla and Generac, your battery backup system will either backup the essential appliances or back up most of the house except for the heavy loads. You can work with your solar designer to decide what loads should be considered “protected loads” or create a list of which loads can be on the “non-protected list.” Refrigeration, water, and some outlets are usually among the list of “protected loads” that can be backed up with a battery when an outage occurs. Electrical heating loads, pool pumps, and hot tubs are usually on the list of “non-protected loads” since they would require a large number of batteries to back up.

Once you identify your home’s protected or non-protected list of loads, these devices will be connected to a sub-panel. If you decide on a protected load panel, those loads will be supplied by the battery and solar system during a grid failure. If it is a non-protected loads panel, those loads will be shed (not energized) during a grid failure.

Pairing solar electricity with battery storage is an excellent option for residential homes, whether you’re powering some loads in your home, interested in more independence from the grid, or simply looking for a cleaner, more efficient alternative to a traditional generator.

Battery or Generator – Which is better when the power goes out?

In New England, where ReVision Energy operates, we are no strangers to outages caused by harsh winter winds and unpredictable storms. Home standby generators tend to be the norm for backup power in utility outages. However, home batteries are becoming an increasingly attractive alternative.

Though generators may be cheaper initially, they are limited by their fuel dependance, maintenance, and service costs. While there are some limits to its power output capabilities, the battery pack generates no emissions, requires no reoccurring maintenance, and can be charged again and again by the sun.

Checkout the comparative table below and see why a battery is a much more viable option than a generator:


Advanced battery energy storage system Fossil Fuel-Powered Home Standby Generator
Maximum peak power (kW) 4.5 – 21 kW  7-10 kW
Energy Storage 10.6 – 40.5 kWhr  Depends on tank size
Duration Forever, if solar is available  Until the fuel runs out
Backup the whole house Possible but usually we design critical loads only for longer run-times  Yes
Backup critical loads forever Yes – just add sun!  No, limited by fuel tank
Noise Quiet – (as loud as refrigerator)  Loud – (as loud as a city street)
Service required None Annual service: oil change and filters
Warranty 10 years  0-2 years
Internet-enabled Yes, included in cost  No
Future smart home ready Yes  No
Future smart grid ready Yes  No
Provides protection against solar regulatory changes Yes¹  No
Requires weekly ‘exercise’ to be available No  Yes
Net Installed Cost $10,000 – $25,000+² $7,000
Plus gas install N/A  $500
Annual service cost (est) None  $200
Annual fuel cost (est) None  $300³
Expected system life 15  12
Total cost for 10 years $10,000 – $25,000+² $18,250

¹ Installing energy storage provides some mitigation of risk associated with future Net Metering uncertainty and other rate design risk by allowing a customer to maximize self-consumption, minimize demand charges or optimize energy use patterns for a possible Time of Use rate.
² Net Cost: Assumes storage is charged by a solar energy system and so is eligible for the 26% federal tax credit. Multiple units will be required for extended runtime or higher capabilities so price range will vary accordingly. Not shown here are state incentives which exist in some areas.
³ Assumes 100 G a year at $3/G propane

While there are some limits to its power output capabilities, the battery pack is infinitely cleaner, can run indefinitely under proper design circumstances, has no recurring maintenance needs, and offers a range of capabilities—such as “self-consumption” of solar power and grid support services—not offered by generators. As technological evolution and fierce competition push down the sticker price of battery backup units, we expect the next 3-5 years will show a seismic acceleration in the adoption of residential battery systems.

What Customers Say

With the Powerwall you can store solar energy generated during the day for use at any time. During the day, the sun shines on your solar panels, charging your battery. At night, your home draws electricity from your battery, powering your home with clean, sustainable energy 24/7.

Installing a Powerwall with ReVision Energy is easy. We take care of everything from system design to permitting, installation, financing, and ongoing customer service.

Powerwall consists of a 14 kWh lithium-ion battery pack, liquid thermal control system, an integrated inverter and software that intelligently dispatches electricity when it’s needed most. The unit mounts seamlessly on a wall or on the ground, and is connected to the grid to export excess energy, maximizing your opportunity for economic benefit.

Kristen and Josh of Rochester, NH had a Powerwall installed and wrote us to say:

Going solar had been a dream for us since we bought our house 10 years ago, but we really wanted to store our energy, too. With the Tesla battery, and our panels, we were able to make that dream a reality! We love that we are able to teach our daughter about alternative energy while providing a cleaner, greener future for her!”

Kate Olson and Matt Cheney, who paired a Powerwall with their solar array at their 1870 farmhouse in Freeport, are also thrilled by the effectiveness of their solar powered battery:

“We live in a relatively rural area where there are power outages. A lot of people get generators for backup, but we’ve never wanted to do that.

Unlike a generator, the Powerwall is completely silent and powers on in a fraction of a second during a grid outage.

For us, we’re excited about capturing energy and creating electricity in general but then there is something nice about feeling like you’re actually using the solar energy you are producing rather than throwing it out to the grid.”

Learn more: https://www.tesla.com/powerwall or Download the Tesla Powerwall Brochure (PDF)

Future-Proof Solar Investments

An image of solar panelsReVision Energy has been following the developments in home battery backup technologies for years. In the early days, the only kind of solar energy systems were off-grid (battery-only) systems, and then with the advent of grid-tied inverters, the obvious benefits of tying up to the grid became clear.

Now, technology has come full-circle, and a grid-tied solar customer can enjoy the benefits of being tied to the grid, with the resilience and independence of having battery support.

Customers who want to maximize the financial savings of their solar investment can start with a straight grid-tied array for maximum savings and lowest upfront cost, then invest later in a home battery backup solution when they are ready. While there is great battery technology on the market already, we expect that this segment of solar technology will rapidly improve over the next 5-10 years.

Battery Backup Photo Gallery