Battery Retrofit
Add a battery to your existing solar.
A battery retrofit adds storage to a solar system you already own, so you can capture the value your panels are currently giving away and gain backup power for outages. ETW Energy retrofits batteries — including the Tesla Powerwall and Enphase batteries — onto existing solar across Texas, Illinois, Utah, and California, whether or not we installed the original system.
If your solar was designed back when exporting to the grid paid well, the rules have likely changed underneath it. A retrofit is how you adapt without starting over.
Why retrofit a battery now
Many existing solar systems were sized to send extra production to the grid for a generous credit. In several markets, that credit has dropped sharply — California’s NEM 3.0 is the clearest example — which means the energy your panels export is now worth much less than it once was.
A battery changes the math. Instead of exporting cheap and buying back expensive, you store your own daytime production and use it at night. You also get something your grid-tied panels alone cannot provide: power that stays on during an outage.
Will a battery work with my system?
Most existing solar systems can accept a battery. The right approach depends on your current inverter and how the system was wired:
- AC-coupled retrofit: the most common path — a battery with its own inverter is added alongside your existing system, working with nearly any solar setup.
- DC-coupled retrofit: in some cases the battery ties into the solar on the DC side, which can be more efficient but depends on your equipment.
How the retrofit process works
We start by reviewing your existing system — equipment, wiring, production history, and what you want out of a battery. From there we design the retrofit, handle permitting and any utility paperwork, and install with our own crews. The goal is a battery that fits the system you already have, not a reason to tear it out.
Frequently asked questions
Can you add a battery if you didn’t install my solar?
Yes. We retrofit batteries onto existing systems regardless of who installed them. We review your current equipment first to choose the right approach.
Will a battery work with my existing inverter?
Usually. An AC-coupled battery brings its own inverter and works with almost any solar system. If your equipment supports a DC-coupled design, we will weigh that option too.
Why would I add a battery to solar that already works?
Two reasons: in markets like California, exporting to the grid now pays little, so storing your own power is where the value is; and a battery gives you backup during outages, which grid-tied solar alone cannot.
Do I have to back up my whole home?
No. A retrofit can target essential circuits or aim for whole-home backup, depending on your goals and budget. We size it to what you actually want to keep running.
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