Solar + Storage Procurement: An 8-Point Checklist Before You Sign

Who this checklist is for

If you're evaluating solar panels, battery storage, or both, this checklist is for you. It's written for homeowners, small business owners, and commercial property managers — anyone staring at a quote and wondering what's buried in the fine print.

I've spent six years managing a $180,000+ annual energy and maintenance budget for a 45-person property management firm. In that time I've reviewed more than 30 solar and storage proposals across residential and light-commercial properties. I'm not a solar installer. I'm the person who reads the contract, runs the numbers, and finds the $2,300 line item nobody mentioned on the sales call.

Eight steps. Each one has a checkpoint. Let's go.

Step 1: Define your actual energy need (not the one on the sales sheet)

Before you look at a single panel spec, pull 12 months of utility bills. Not the summary — the actual kWh usage month by month. Most quotes I've seen size the system based on an average monthly bill, which conveniently ignores the two summer months when you're running AC for 18 hours a day.

Checkpoint: You should know your annual kWh consumption, your peak demand months, and what percentage of your bill is supply vs. delivery charges. If a sales rep can't explain how their system size maps to those numbers, that's a red flag.

What most people don't realize is that installers often quote a system that covers 90–100% of annual usage but produces a surplus in spring and a shortfall in August. That's fine if your utility offers favorable net metering. Less fine if they don't.

Step 2: Understand solar energy credits and 2025 incentives

Your installer may fold "solar energy credits" into the first-year savings projection. These credits come from net metering — when your system sends excess power to the grid, your meter runs backward and you bank credits. But the rules vary wildly by state, and they've been shifting.

As of early 2025, the federal investment tax credit (ITC) still stands at 30% for residential systems, per IRS guidance. But state-level net metering policies in California, for example, moved to a net billing structure that pays export rates well below retail. If your installer is projecting savings based on 1:1 net metering and you're in a market that's transitioned to avoided-cost rates, that projection is wrong.

Checkpoint: Ask for a line-item breakdown showing assumed solar energy credits for 2025, the assumed export rate, and what happens if that rate changes. If they can't produce that, walk.

I don't have hard data on how many quotes overstate net metering benefits, but based on the proposals I've reviewed, it's more than half. Here's something vendors won't tell you: the savings projection is often the weakest part of the proposal, because it's the hardest to verify after the fact.

Step 3: Evaluate installers and financing models

You'll see two main financing structures: cash purchase (or loan) and lease/PPA. Each has tradeoffs. Leases reduce upfront cost but complicate a home sale. Loans give you the tax credit but add interest. Neither is universally better — it depends on how long you plan to stay and whether you can use the tax credit.

If Sunrun is in your market, you'll find 2024 Sunrun solar company reviews that range from "the lease buyout saved us money" to "customer service went dark after installation." That's true of every large installer. Read 5–10 reviews, look for patterns in complaints, and ignore the 1-star reviews that are clearly about billing confusion rather than installation quality.

Checkpoint: Get quotes from at least three installers. Compare total 25-year cost, not just monthly payment. Ask each one what happens if you sell the house in year 7.

Step 4: Compare inverter types — microinverter vs. string

This is where a lot of homeowners glaze over. Don't. The inverter choice affects your production for 25 years.

String inverters are cheaper — typically $1,000–$2,000 less for a residential system. But if one panel is shaded or fails, the whole string underperforms. Microinverters sit under each panel and optimize individually. They cost more upfront but handle shade and panel mismatch better.

If your roof has tree cover, multiple orientations, or you're planning to add panels later, microinverters usually win on total cost of ownership. If you have a clean south-facing roof with no shade, a string inverter is fine and saves money.

Checkpoint: Ask for both quotes and compare 25-year production estimates, not just sticker price. The microinverter premium is usually $1,500–$3,000 — run the math on whether the extra production covers it.

Step 5: Evaluate battery storage — and separate it from portable lithium

If you're considering battery storage, focus on usable capacity (kWh), continuous power output (kW), and how long it covers your critical loads during an outage. A 17.5 kWh battery like Sunrun's Brightbox, for example, covers most homes' essential circuits for 8–12 hours. Whole-home backup needs two or three batteries.

Here's a clarification that comes up more than you'd think: if you're also shopping for a lithium battery you can carry on a plane or toss in a camping bag, that's a completely different product. Home batteries are fixed, wall-mounted systems. Don't compare them to portable power stations — they serve different purposes and have different safety certifications.

Checkpoint: For any battery quote, ask: usable kWh (not total), round-trip efficiency, warranty cycles, and whether the inverter is included or separate. A battery quote without those four numbers is incomplete.

Step 6: Sanity-check system size against actual output

Panel wattage is a lab number. Real-world output depends on orientation, tilt, shade, temperature, and inverter efficiency. A 400W panel on a west-facing roof in Phoenix might produce 580 kWh/year. The same panel in Seattle produces closer to 380 kWh/year.

You'll sometimes see comparisons to utility-scale renewables — for instance, the length of wind turbine blades now exceeds 100 meters on the largest offshore models. That's impressive engineering, but it's irrelevant to your roof. Residential solar is a different scale entirely. Focus on kWh production per installed kW in your specific location, not headline capacity numbers.

Checkpoint: Use NREL's PVWatts calculator (free, public) to sanity-check any production estimate your installer gives you. If their number is more than 10% above what PVWatts says, ask them why.

Step 7: Read the contract for these five clauses

This is the step most people skip. I've seen it cost clients thousands.

• Escalator clause (leases): Annual payment increases of 1.9–2.9% are common. Over 25 years, a 2.9% escalator adds roughly 40% to your total payments versus a flat rate.
• Buyout formula: If you want to own the system early, how is the buyout calculated? Is it fair market value or a pre-set schedule?
• Roof warranty: Who pays if the installation causes a leak? Get this in writing, not verbal.
• Production guarantee: What happens if the system underproduces by 15%? Is there a refund, or just a service call?
• Transfer terms: If you sell the house, does the buyer have to qualify for the lease? What if they don't?

Checkpoint: Have a real estate attorney or a contract-savvy colleague read the agreement before you sign. I built a one-page clause checklist after getting burned on a roof warranty dispute in 2022 — it took four months to resolve.

Step 8: Plan for monitoring and maintenance before installation day

Solar systems are low-maintenance, not no-maintenance. Inverters typically need replacement around year 12–15 ($1,200–$2,500). Panels need occasional cleaning in dusty climates. Monitoring systems fail or lose connectivity.

Checkpoint: Confirm who monitors production, what the response time is for alerts, and whether inverter replacement is covered under warranty or out of pocket. Get the monitoring app set up on your phone before the installer leaves the driveway.

Common mistakes to avoid

Three things I see repeatedly:

1. Comparing monthly payments instead of total cost. A $99/month lease over 25 years with a 2.9% escalator costs about $42,000 total. A $28,000 cash purchase with a 30% tax credit nets to $19,600. The monthly number hides the real comparison.
2. Assuming the first quote is the final price. It rarely is. Ask about permit fees, main panel upgrades, and critter guard — three line items that appear after you sign if you don't ask upfront.
3. Ignoring the interconnection timeline. Your utility has to approve the system before it can be turned on. In some markets, that's 4–6 weeks. In others, it's 4–6 months. Factor that into your payback calculation.

This checklist reflects pricing and policy as of Q1 2025. Incentive structures and net metering rules change fast — verify current numbers with your utility and a tax advisor before committing.