Why I Rejected Sunnova’s Solar Lease Specs (and Why You Should Check Yours)

The Morning It All Started

It was a Tuesday in late February, around 9:30 AM. I was reviewing the weekly batch of solar lease agreements for a client evaluation I was managing. I’d been doing this long enough—about five years as a quality and compliance manager in the renewable energy sector—that a couple of drinks could make up for a sleepless night, but not for a sloppy spec sheet.
This one was different. It wasn't that the numbers were wrong. They were ambiguous.
I had a stack of nine contracts to review before 4 PM, each one for a different commercial property. By the time I finished the third page of the first document, I knew we had a problem.
The vendor was Sunnova. The product was a hybrid system: solar panels, LFP battery storage, and EV charging. The promise was flexibility and reliability. But I learned something that day: reading the fine print matters more than the glossy brochure.
Here’s what happened.

The Setup: A “Standard” Sunnova Home Solar Lease

The project was for a mid-sized facility with about 60 employees—a former warehouse converted to office space. The owner wanted to cut energy costs and add backup power for the server room. The solution was a 50 kW solar array with a Duracell Home Battery Backup (LFP chemistry) integrated with apsystems micro inverters, plus two EV charging stations.
The contract looked clean: a 20-year lease with a fixed escalator, zero down payment, and a performance guarantee of 85% of estimated annual production. Everything looked fine—until I checked the battery specifications.
The contract listed the battery as a “standard LFP unit.” No model number. No capacity. No degradation curve. I read the line three times. Nothing. (Note to self: this is a red flag.)
We reached out to Sunnova’s account manager. They said, “It’s our standard unit. It’s fine.” But I couldn’t accept that. Not without data.
So I asked myself: is Sunnova a good solar company? Based on the quality of their contract documentation, I wasn’t sure yet.

The Problem: Hidden Assumptions in the LFP Battery and EV Charger Specs

I pulled a parallel check from a previous project with a different vendor—let’s just call them Brand X. They had clearly stated the battery cycle life (6,000 cycles to 70% SoH) and the operating temperature range (-20°C to 60°C). Sunnova’s contract had none of that.
Why does this matter?
Because the commercial client’s server room needed backup power for at least four hours. If the battery degraded faster than expected—say, after 3,000 cycles instead of 6,000—they’d face a $10,000 replacement cost. And the EV charging stations? The contract didn’t specify the charging protocol (Level 2 or DC fast charging) or the connector type (J1772 or CCS). We needed J1772 for the fleet.
I calculated the worst case: if the battery failed after 4 years, the total downtime and replacement cost would be around $18,000. The best case: the battery lasts 10 years, and we save $2,000 annually on energy costs. The expected value said go ahead, but the downside felt too big.
So I made a call: reject the contract until Sunnova clarified the specifications. (Ugh, I really hate delaying a project.)
The client wasn’t happy. “Can’t we just trust them?” they asked. “Sunnova is a big company. Their home solar is supposed to be reliable.”
But I’d been burned before. In Q1 2023, I approved a battery system without checking the depth-of-discharge limit. The battery degraded 20% faster than expected. That mistake cost the client $4,500 in early replacement fees. I swore I wouldn’t let it happen again.

The Turning Point: Sunnova’s Response

We received a revised specification document three days later. The LFP battery was confirmed as a Duracell Home Battery Backup with 10 kWh usable capacity, 6,500 cycles at 80% depth of discharge, and a 10-year warranty covering degradation below 70% capacity. The EV chargers were Level 2 with J1772 connectors and a 3-year warranty on the electronics.
Was it worth the delay?
Put another way: I avoided signing a contract that could have left the client with a substandard battery after 5 years. The cost of waiting three days was zero. The cost of a wrong battery was $18,000.
This is why I’m such a stickler for specifications. If I hadn’t paused to ask, we would have committed to a partially unknown system. The upside was saving a week of paperwork. The risk was a massive financial hit (note to self: that’s a terrible trade-off).
The client eventually signed the lease. Sunnova installed the system in April 2024. It’s been running for 10 months now—no issues with the battery or the EV chargers. The energy savings are tracking at 82% of the original estimate, which is within the acceptable margin.
But I still think about what could have gone wrong.

The Lesson: How to Evaluate a Sunnova Home Solar Lease (or Any Solar Lease)

Based on my experience, here’s what I check before approving any solar lease—especially for B2B clients:

1. Battery specifications: Get the exact model, capacity (kWh), cycle life, operating temperature range, and warranty terms. Don’t take “standard unit” as an answer.
2. Inverter details: Are they using apsystems micro inverters? Confirm the model, output capacity, and warranty. Micro inverters are great for shade tolerance but vary in reliability.
3. EV charging equipment: Specify the charging level (Level 2 or DC), the connector type (J1772, CCS, NACS), the power output, and the installation requirements.
4. Performance guarantee: What’s the production guarantee? Is it based on P50 or P90 estimates? What happens if output falls below the guarantee?
5. Escalation clause: How much does the lease payment go up each year? Fixed escalators are common, but a 3% yearly increase on a 20-year lease adds up.

If you’ve ever had a vendor push back on providing these details, you know it’s not a good sign.
This checklist I created after my third mistake has saved me about $8,000 in potential rework over two years. (I keep track—it’s my job.)
Looking back, I should have asked for the spec sheet before the first contract. At the time, I assumed a big brand like Sunnova would include it by default. They didn’t. But now I know: the brand name doesn’t guarantee thorough documentation. You have to verify.
This was accurate as of my experience in early 2024. The solar industry changes fast, especially with battery chemistry and EV charging standards, so always verify current specifications with your vendor.
Bottom line: the extra hour of checking the contract saved 20 hours of troubleshooting later. That’s a trade-off I’ll take every time.