Free tool

Battery Sizing Tool

Tell us what you want to keep running during an outage and we'll recommend the right battery size — usable kWh, continuous and surge power, and chemistry. Built for Minnesota.

Where are you?

Climate region

Snow cover concern (days panels are buried)

What’s the goal?

Backup duration goal

Whole-home or critical loads?

Solar system size (kW DC, optional)

Roof orientation

What do you want to back up?

Smart defaults are pre-checked. Add or remove items — and edit the watts — to match what really has to keep running during an outage.

Other loads (anything not on the list)

Five free slots — name a load (e.g. “garage fridge”, “shop tools”), set its watts, and check it to include. Empty rows are ignored.

How this tool works

We multiply each load you check by the hours it typically runs during an outage, add a 25% safety margin, and apply a Minnesota snow-cover adjustment (panels can't recharge a battery when they're buried). That gives your daily energy need. From there we size:

Usable storage (kWh) — your daily need × a backup-duration multiplier (about 1 day for essentials, 2–3 days for multi-day, 5–7 for off-grid).
Continuous power (kW) — the running wattage of everything backed up at once.
Surge capacity (kW) — the biggest motor-start spike (well pump, AC compressor, sump) the battery must handle, or the appliance won't start.
Chemistry — LFP (lithium iron phosphate) for every 2026 home: safer and far longer cycle life than older NMC.

If you have solar, we trim the recommendation because your panels recharge the battery on sunny days.

What this tool can't tell you

Whether your electrical panel can support whole-home backup — that needs an electrician and the inverter's pass-through rating (often 200A for whole-home).
Whether your home has unusually high motor surge (old AC compressors, deep-well pumps).
Which Minnesota battery programs you qualify for. Home batteries no longer earn the federal residential tax credit, but you may capture value by enrolling storage in an Xcel demand-response program, and a battery paired with a commercial solar project can fall under the 30% ITC — the Incentive Finder shows what applies.

It's a starting recommendation — we confirm it with a free site walk before you ever sign.

Continue exploring: pair backup with a standby generator, right-size the solar array in the System Size Estimator, or see current Minnesota incentives.

Good questions

Frequently asked.

Why does the tool ask about snow cover?

A solar-plus-battery system recharges during the day from your panels. If snow covers them for days in January, the battery has to carry the load on stored capacity alone — so snow-prone Minnesota homes need 10–30% more capacity than the same loads in a mild climate.

What is ‘surge’ and why does it matter?

Motor-driven appliances (AC compressors, well pumps, sump pumps, fridges) draw 3–7× their running wattage for a few seconds at startup. If the battery/inverter can't supply that surge, the appliance won't start. We size for it — modern systems like Tesla Powerwall 3, Enphase IQ Battery 10C and Sol-Ark handle most home surges.

Does this assume I have solar?

It works either way. Without solar, the battery is sized for stand-alone capacity. With solar, we factor daytime recharge to recommend a smaller, more cost-effective battery.

How many batteries will I need?

We show an approximate unit count at ~13.5 kWh each (Powerwall-class). Essentials backup is often one unit; whole-home with heavy loads usually needs two or more, or a hybrid inverter with stackable batteries.

Is LFP really better?

For homes, yes — lithium iron phosphate (LFP) is safer (far more thermally stable) and lasts more cycles than older NMC chemistry. It's what we recommend and install.

Go boldly

Want a real battery design?

Free, no-pressure assessment — we confirm your sizing on a site walk and show you Minnesota battery incentives.

Get a Free Quote (651) 565-1140