The 6-Step Emergency Solar Checklist I Use When Clients Need Power Fast

I coordinate emergency solar installations. When a tree takes out the power lines and the client has a well pump or a medical device, you don't have weeks to decide. This is the checklist I run through when the customer needs power in 48 hours—or less. It's six steps, and the order matters. I've built this list from a lot of nighttime calls and a few March 2024 mornings I'd rather forget.

Step 1: List the loads and set a budget

Start with what absolutely has to run. Lights? Fridge? Wifi for the kids' school? Maybe a sump pump. Don't just guess—write down the wattage and estimate how many hours a day. That number, not the size of the house, determines everything else. When I first started doing emergency installs, I assumed you always max out the inverter to “be safe.” Three oversized systems later, I realized you're just paying for unused capacity.

What does a solar system cost? As of early 2025, my typical emergency quote for a whole-house backup setup—a 10kW to 12kW inverter, 10-15kWh of battery, plus installation materials—lands between $12,000 and $20,000 before tax credits. That's not a formal quote, but it gives you a number to start with. If you only need the fridge and a modem, you can get by for a third of that. I had a client last year who kept asking for “the biggest system,” and I had to walk him through why a 5kW setup would cover his needs for $7,000 less.

Step 2: Choose the inverter topology first

There are three types: grid-tie, off-grid, and hybrid. For emergency backup, you need off-grid or hybrid—a pure grid-tie inverter shuts down when the grid drops. In my experience, the Growatt 12kW off grid inverter is one of the most common units I spec for a 3-4 bedroom home with moderate loads. It's not the only option, but it handles most situations without overcomplicating the install.

Why do I check the inverter type before anything else? Because the battery selection and panel wiring follow from that. A 12kW unit gives you room for a well pump or a short AC window run. For a smaller emergency setup, a 5kW can be enough—and it's noticeably cheaper. Don't buy the biggest one just because it's in stock. A colleague made that mistake in July: ordered a 15kW unit for a tiny cabin, then had to wait six weeks for a separate 5kW to arrive because the 15kW couldn't efficiently charge his battery bank.

Step 3: Match the battery voltage and capacity

With the Growatt 12kW unit, you'll often pair it with the Growatt APX HV battery. The “HV” means high voltage, and that matters—the inverter's battery port is tuned for a specific voltage window. Mixing a high-voltage battery with a low-voltage inverter, or vice versa, is a classic mistake that costs hours and sometimes shorts out the BMS.

For capacity, I usually start with 10kWh for overnight basics. Actually, make that 12kWh if the client wants to run a fridge and a deep freezer. I want to say that calculation is based on 80% depth of discharge for most lithium batteries, but don't quote me on that exact percentage without checking the datasheet. The point is, don't undersize. If you have a 12kW inverter but only 5kWh of battery, you'll exhaust the storage before the sun comes back—and your emergency system becomes a paperweight.

Step 4: Keep a portable backup (jump starter or power bank)

Not every load needs the main system. Once the solar battery is wired, you still might need to charge a phone while you're troubleshooting, or jump-start a truck. That's where portables come in. There are two main types of jump starters and portable power banks: compact lithium-ion jump starters designed for vehicles, and larger battery banks that can run small electronics for hours. I keep one of each in my work truck. In a pinch, a portable power bank can also power a router overnight if the main system needs to be shut down for maintenance.

The jump starter is the one people forget. It's smaller than a power bank, but it can also charge a phone and power an LED light. If your installer is climbing on the roof to connect panels, a dead battery in the work truck is not something you want to discover.

Step 5: Add an exterior surge protector

This is the step people skip when they're rushing. After a storm, the next lightning strike could come at any moment. An exterior surge protector installed at the main panel or directly outside the inverter is cheap insurance. Without it, a single surge can fry the inverter's control board and take down the whole system. I've seen that happen—twice in one month. Now it's non-negotiable on every emergency install.

Where exactly should it go? For a typical home, install it between the main breaker panel and the inverter, or at the meter base if the local utility allows it. Check your electrical code, because some jurisdictions have specific requirements. The point is to protect the expensive parts both from external surges and from switching transients when the generator or grid comes back online.

Step 6: Verify the system before signing off

Walk through this list with your installer:

• Is the equipment physically in stock and on the truck? (I once had an order that showed “in stock” online but wasn't actually available—the installer had to source a different model.)
• Is the installer licensed for the electrical work in your area?
• Is the battery state of charge above 20% before you connect it?
• Have you tested the off-grid switchover? Press the “test” button—don't assume it works because the lights are on.
• Do you have the installer's direct number for the first 24 hours after the install?

Common mistakes I still see

Oversizing is the biggest one. I compared two jobs last year: one house got a 15kW inverter for a 3kW load, and another got a 5kW with the same battery. The first house paid roughly double for no visible benefit. The second was perfectly comfortable because the battery handled the spikes. That's the contrast that made me stop recommending maximum everything.

Another mistake: assuming the solar panels are the only source. For an emergency system, you need to be able to charge the battery from the grid or a generator, too. A pure solar-only setup won't help if the weather stays cloudy for three days.

Finally, watch out for marketing claims that sound too good. If a company says “free solar” or promises savings that no one else can match, ask for the math. Per FTC guidelines, environmental and performance claims need to be substantiated—if they can't show you the data, walk away. And read the fine print on the warranty: some battery warranties are void if the system isn't installed with a certified surge protector.

I have mixed feelings about emergency installations. On one hand, a fast decision can mean the difference between a warm, dry home and a total loss. On the other hand, a rushed purchase made in panic often leads to expensive mistakes. This checklist works because it forces you to slow down on exactly the two or three decisions that matter most. The rest, honestly, can be fixed later.