Sunnova, Batteries, and EV Charging: An 8-Step Procurement Checklist for Business Buyers

Who this checklist is for

I’m an office administrator for a 180-person company. I manage facilities and vendor ordering—roughly $420,000 annually across 11 vendors—and I report to both operations and finance. In 2023, our ops director asked me to screen solar lease proposals, battery storage options, and EV charging for our three locations. I’m not an electrician or a solar engineer. This is the procurement checklist I wish I’d had before the first vendor call.

Use this if you’re comparing a solar lease, a battery calculator result, a build your own solar kit, or a bidirectional ev charger for a business site. There are eight steps. None are technical enough to replace an engineer, but they’ll stop the expensive mistakes I’ve seen and made.

Step 1: Pull 12 months of utility data before you talk hardware

Vendors love to start with panels and inverters. Start with bills. Get 12 months of usage, demand charges, time-of-use periods, and your utility’s interconnection rules. If you don’t have 12 months—say, because you moved into the building in 2024—get as many as you can and ask the utility for interval data.

Checkpoint: you can explain your peak kW, monthly kWh, and when peak pricing hits. If you can’t, any quote is just a guess.

Step 2: Use a calculator as a screen, not a promise

Run the Sunnova battery calculator or any vendor calculator—but treat it as a first filter. Enter your actual utility rate, not the default. Compare the output to your bills. If the calculator says you’ll need a 30 kWh battery and your peak demand says 12 kWh, ask why.

I assumed the first calculator I used was neutral. Didn’t verify. Turned out it defaulted to a rate schedule our utility doesn’t offer. That mistake made the battery look better than it was.

I don’t have hard data on how accurate every calculator is across markets, but based on our two projects, my sense is they’re directionally useful and rarely final. Verify assumptions before you let a calculator shape the RFP.

Checkpoint: the calculator’s inputs match your utility bill and your site’s operating hours.

Step 3: Confirm the inverter and equipment list—don’t assume

If the proposal includes a Sunnova inverter, ask for the exact model, datasheet, monitoring platform, warranty term, and service process. If you’re exploring a build your own solar kit, ask who will design the string layout, who signs off on rapid shutdown, and who handles commissioning.

Mixed equipment is fine if it’s listed and compatible. It’s not fine if the vendor says ‘it should work.’

Checkpoint: you have a single line diagram, equipment list, and written compatibility confirmation before deposits.

Step 4: Size the battery around resilience, not just arbitrage

Ask what the battery is for: backup, peak shaving, demand response, or storing excess solar. Those goals produce different sizes. For LFP battery storage, ask about usable capacity, round-trip efficiency, depth of discharge, and warranty degradation. If the vendor says LFP is always better, ask for the cycling and temperature assumptions.

Can you overcharge a lithium battery? Under normal operation, a certified battery management system (BMS) prevents overcharge. But if someone mixes a DIY charger, a used pack, and an undersized BMS, yes—overcharge is possible. Ask how the system protects against overvoltage, overcurrent, and thermal runaway. For commercial projects, look for UL 9540 or UL 9540A listings and ask how NFPA 855 applies in your jurisdiction.

Checkpoint: the proposal states the BMS, charger, and fire-safety documentation. If it doesn’t, that’s not a detail—it’s the project.

Step 5: Plan EV charging and bidirectional ev charger support early

A Level 2 charger is one thing. A bidirectional ev charger is another. Bidirectional charging can export power from a compatible vehicle, but you need a compatible vehicle, a compatible charger, utility approval, and often a specific meter or program. Don’t let a sales deck turn ‘bidirectional-ready’ into ‘bidirectional today.’

Checkpoint: you have a written list of approved vehicles, charger models, and utility program requirements. If bidirectional isn’t available in your territory yet, note that in the contract instead of assuming it will be added later.

Step 6: Handle interconnection, permitting, and code before signing

Who owns the utility application? Who talks to the AHJ? Who pays for transformer upgrades? If the answer is ‘we’ll figure it out,’ get it in writing. NEC 2023, local fire code, and utility rules can change the design after you’ve signed.

According to the U.S. Department of Energy, commercial solar and storage projects should start with a load analysis and site assessment, not a hardware list (energy.gov). Verify current rules with your utility and local permitting office—requirements change by state and even by feeder.

Checkpoint: permit path, interconnection timeline, and responsibility matrix are attached to the contract.

Step 7: Pressure-test the lease or financing terms

If you’re comparing a Sunnova lease or any third-party ownership model, read the escalator, end-of-term options, buyout formula, roof repair responsibilities, insurance requirements, and assignment clause. For a build your own solar kit, compare warranty labor, not just hardware.

Get at least three quotes. Use NREL’s latest cost benchmark as a starting point (nrel.gov), then verify local pricing. Prices as of early 2025 vary by region, roof type, interconnection cost, and incentives; verify current rates.

Checkpoint: finance and legal have reviewed the total cost of ownership (i.e., not just the monthly payment).

Step 8: Build a 12-month post-install review

Set a calendar reminder for month 1, month 6, and month 12. Check production against the model, battery cycles, charger uptime, and utility bill changes. Ask for a work-order process and response times.

So glad I set a 30-day check on our first EV charger install. Almost skipped it because the contractor said everything was fine. The load-management setting was wrong, and we would have discovered it only after a panel trip.

Checkpoint: someone owns monitoring. It shouldn’t be the vendor alone.

Common mistakes and cautions

• Don’t assume ‘same specifications’ means identical results across vendors. I learned that after two quotes used the same battery size but different inverter efficiency assumptions.
• Don’t sign before you verify invoicing, warranty transfer, and service escalation. The vendor who couldn’t provide proper invoicing cost us $2,400 in rejected expenses once—not on solar, but the lesson carried over.
• Don’t treat a calculator as an engineering study. A Sunnova battery calculator or any online tool is a screen, not a stamped design.
• Don’t mix a build your own solar kit with a leased system without written permission. It can void warranties and complicate interconnection.
• Don’t skip the boring utility call. Five minutes of verification beats five days of correction.
• Don’t assume bidirectional ev charger support is included. Ask for the exact program, vehicle list, and approval path.
• Don’t ignore lithium battery overcharge questions. Ask for the BMS spec and fire-safety listing in writing.

Honestly, I’m not sure why some vendors quote wildly different battery sizes for the same building. My best guess is they use different assumptions about demand charges and outage duration. If someone has a better explanation, I’d love to hear it.