Whole-Home Battery Backup
Home battery backup keeps your lights on when the grid goes down. Certasun installs Tesla Powerwall 3 and FranklinWH batteries across the Chicago area.
How a Home Battery Keeps Your Power On
A home battery stores electricity so you can use it when you need it. If the grid goes down, your battery switches on automatically, often so quickly that you won't notice. No fuel to store, no engine to start, and no noise.
A battery can also lower your electric bill. It can charge when electricity is cheap and power your home when it is not. How much you save depends on how and when your household uses power, and on which utility rate plan you're on. We'll run the numbers for your home using your own usage data.
In our modeling of Chicago-area homes with solar served by ComEd, one battery saved about $1,000 a year on average.
What backup can and can't do. How long your battery keeps you running depends on how much power you use, how much charge the battery has when the outage starts, and, if you have solar, how much sun there is to recharge it. Paired with solar, a battery can keep a home running for days. The batteries we sell can typically back up your entire home. After an on-site assessment, we'll let you know about any exceptions. A home battery should never be relied on to power life-critical medical equipment.
Three Ways to Add a Battery
With new solar
Installing solar and a battery together is the most common choice our customers make. Your solar panels recharge the battery every day. Together, they can cover you through multi-day outages.
Added to the solar you already have
Already have solar panels, whether we installed them or someone else did? We can add a battery without changing your existing panels or inverters.
Without solar
No solar, or a roof that's too shaded for it? A battery on its own still gives you backup power and can still lower your bill.
Two Batteries We Trust
We install whole-home batteries from two manufacturers.
Tesla Powerwall 3
Each Powerwall 3 stores 13.5 kWh of energy. (A kWh, or kilowatt-hour, is a unit of energy: roughly what a refrigerator uses in a day.) It delivers 11.5 kW of continuous power, and you can add Expansion Units, or a second Powerwall 3, for more storage. With Storm Watch, it charges to 100% ahead of severe weather in the forecast. You watch and control it from the Tesla app. 10-year manufacturer's warranty. Most customers already know the name, and it's our most popular choice.
FranklinWH aPower 2
Each aPower 2 stores 15 kWh and delivers 10 kW of continuous power. Every unit has its own inverter, so power adds up as you add batteries. With Storm Hedge, it charges to 100% ahead of severe weather in the forecast. 15-year manufacturer's warranty. FranklinWH is an excellent whole-home battery, and a great choice if you'd simply prefer a different brand.
Not sure which is right for you? Compare Powerwall 3 and FranklinWH →
What a Home Battery Costs
| Before rebate | After ComEd rebate, if you qualify | |
|---|---|---|
| Tesla Powerwall 3 | from $17,500 | from $13,450 |
| FranklinWH aPower 2 | from $19,250 | from $14,750 |
| Prio for Batteries (Tesla Powerwall 3, 10 years) | from $7,800 | — |
Your price depends on how much storage you need. See full pricing and what affects it →
ComEd's Battery Rebate
If ComEd is your utility, you may qualify for ComEd's battery rebate of $300 per kWh of battery capacity, about $4,000 for a Powerwall 3 and $4,500 for a FranklinWH aPower 2. Whether you qualify, and when you can apply, depends on your home. If you already have solar, it depends on when that system was connected to the grid. How ComEd's battery rebate works →
Prio™ for Batteries
Prio for Batteries is a 10-year lease on a Tesla Powerwall 3. You pay for the full 10 years up front. Certasun owns the battery, keeps it running, handles any repairs, and insures it. If its capacity ever drops too low, even after the manufacturer's warranty ends, we'll repair or replace it for the rest of the lease. At the end of 10 years, you can renew, buy the battery, or have us remove it at no charge.
Because Certasun owns the battery, we claim a federal tax credit available only to businesses but can pass along the benefit to you in your lease price. It's available whether or not you have solar; for homes with older solar systems, we'll confirm availability during your consultation. If you're installing new solar and a battery together, our Prio prepaid solar service covers both.
Why Certasun
- Local. We're based in Buffalo Grove and work across the Chicago area. Since 2018, we've installed more than 3,000 systems.
- Well reviewed. 4.7 out of 5 on Google (335 reviews) and 4.5 out of 5 on SolarReviews (200+ reviews).
- Our own crews. Certasun employees install every battery. We don't use subcontractors.
- Clean installs. We plan every install so it looks good.
- We handle every detail. We file the permits and utility paperwork, install your battery (typically in 1–2 days), and coordinate the final inspection.
- Straight answers. We'll show you what a battery will and won't do for your home before you decide.
- 10-year workmanship warranty on every battery we install.
Questions Homeowners Ask
How long will a home battery power my house?
It depends on how much electricity you use and how much charge the battery has when the outage starts. A battery paired with solar can recharge every day, so it can keep going through a long outage. We'll estimate this for your home during your consultation.
Can I get a battery without solar panels?
Yes. A battery on its own gives you backup power and can lower your bill by charging when electricity is cheap. Learn more →
Can I add a battery to solar panels I already have?
Yes, even if another company installed them. Your existing panels and inverters stay as they are. Learn more →
Is a battery better than a generator?
A battery takes over in a fraction of a second; a standby generator typically takes about 30 seconds. A battery is quiet, needs no fuel or weekly test run, and can lower your bill every day, not just during outages. A generator can run as long as it has fuel. Compare battery backup and generators →
Where will the battery go?
Most often in an attached garage. It can also go outdoors. We cannot install it in or next to living space or in the path of a car. We'll choose the best location together, during a site visit.
Will a battery lower my electric bill?
Often, yes, especially if you move to a ComEd rate plan where electricity costs less at some hours than others. We'll recommend a plan based on your own usage. ComEd rate plans explained →
Which ComEd rate plan should I be on with a battery?
It depends on your home, and on whether you have solar. We'll recommend one based on a year of your actual usage.
Last updated: September 30, 2026
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