I manage purchasing for a 120-person engineering and distribution company in Redmond, Washington. My job covers a little bit of everything—roughly $350,000 a year across vendors for facilities, electrical work, and office operations. When leadership said “we should look at solar,” the phrase landed on my desk. I report to both operations and finance, so I got the same question from two directions: Will it keep the building running, and will it actually save money?
After researching solar, battery storage, and EV charging for most of 2024, the most useful thing I can tell you is this: there isn't one right setup. There's only the right setup for your situation. “Does Vivint Solar make good equipment?” and “what does solar cost?” are the wrong first questions. The right one is: which problem are we actually solving?
I've learned to split commercial energy purchases into four scenarios:
- Scenario A: You want lower power bills, and outages are an inconvenience, not a crisis.
- Scenario B: An outage would cost you real money.
- Scenario C: You're adding EV charging and need charger installation.
- Scenario D: You already have battery equipment, and it's getting old.
Here's what each scenario actually means, based on the mistakes I made and the things I double-checked.
Scenario A: You Just Want Cheaper Power Bills
Scenario A is the most common. The power stays on. Nobody panics when a light flickers. You're tired of paying the utility every month and want that number to go down. For this scenario, the rational starting point is a solar array only—no battery, no backup generator.
If that sounds anticlimactic, good. Here's the thing: a battery doesn't create electricity. It stores it. With net metering, your grid-tied array already earns credits for the power you don't use. A battery adds thousands of dollars to the project. It only pays for itself when your utility rate structure rewards shifting when you use power. Many don't.
Which leads to the mistake I made first: I compared quotes by price per watt. When I started evaluating proposals in 2024, I assumed the lowest $/W number was the winner. It wasn't. One proposal came in around $290,000 for a 100 kW array. Another was about $325,000 for 104 kW. The cheaper quote looked great until we adjusted it for two things: it didn't include replacing three inverters in year 12, and its annual production estimate was optimistic. Over a 15-year cost model, the more expensive quote was actually cheaper by roughly $20,000. The price per watt told me almost nothing.
That same thinking applies to the search term “Vivint Solar cost.” You'll see ranges all over the internet. The number only makes sense when you know whether it's a cash purchase, a loan, a lease, or a power purchase agreement (PPA). A lease can have a lower monthly payment and no maintenance responsibility, but the company owns the system. If your organization can't use the federal investment tax credit, a lease or PPA can make sense. If you have tax appetite and cash, owning usually wins. “Cheaper” depends on which column you're looking at.
And this is why researching Vivint Solar company details before signing matters. If you're signing a 20-year lease, you're not just buying panels—you're entering a 20-year service relationship. Vivint Solar was founded in 2011, and Sunrun acquired it in 2021. As of January 2025, the company operates under Sunrun's umbrella. That was a meaningful point when I compared quotes, because the organization that answers the phone in year ten is part of the system you're buying.
Scenario B: An Outage Would Cost You Real Money
Everything in Scenario A changes the moment an outage has a price tag.
I didn't fully appreciate this until the November 2024 windstorm in Western Washington. We lost power for a day. Nothing catastrophic, but shipping stopped, and I watched scheduled deliveries slip. A friend who runs a cold-storage warehouse lost way more than we did. That was the moment I started treating battery backup as insurance, not as an investment.
There's an important difference. Insurance doesn't have a great rate of return. It has an avoided loss. If a four-hour outage costs you thousands of dollars, then a battery that covers your critical loads can be rational even if it never saves a dollar in normal monthly operation. If an outage costs you nothing, skip the battery.
Batteries can also do peak shaving: they discharge during the 15-minute window when your facility draws the most power, reducing the demand charge on your utility bill. That's a legitimate financial use. But it depends on your actual load profile and utility tariff. I'm not 100% sure about rates in your area—ours changed in January 2025—so verify this against your own bill before buying hardware.
One clarification buyers keep asking, and I get it because battery packaging is confusing: is a rechargeable battery a lithium battery? Not automatically. “Rechargeable” describes whether the battery can be charged again. Lithium is a chemistry. A lead-acid battery can be rechargeable. A NiMH battery can be rechargeable. When you're sizing commercial storage, the chemistry and the charge profile matter as much as the capacity rating.
Scenario C: You're Adding Electric Vehicles
EV charging is the scenario that trips the most people, because it feels like it should be sold together with solar. Sometimes it should. Usually, the EV decision should come first.
We looked into EV charger installation Redmond WA for our location because we're adding six service vans. My first search was exactly that: “EV charger installation Redmond WA.” I found plenty of electricians who could mount a charger. What I needed was someone who could do a proper load calculation and knew the local permitting process. That's a different skill from mounting a box on a wall.
Here's the counterintuitive part: don't size solar and battery before you know when your vehicles charge. Our vans come back in the evening and charge overnight. Overnight electricity is usually cheaper on time-of-use rates, and because the sun isn't out, the solar array isn't directly charging the vans anyway. What solar does is offset the building's daytime use, which lowers the overall bill. A battery only earns its cost if it shifts enough energy into a high-rate window to justify the price.
I know this from a near-miss. A bundled proposal showed up with panels, a battery, and chargers in one tidy number. It nearly looked reasonable. Then an energy consultant asked one simple question: “What time do the vans charge?” We didn't know. When we modeled it, the battery in that bundle was sized for six vans charging at maximum power simultaneously—which almost never happens. The actual charging pattern cut the storage we needed by more than half. I only believed the “size the charging load first” advice after that mistake. I should have believed it sooner.
Scenario D: You're Replacing Batteries Instead of Starting From Zero
The last scenario surprised me. You already have battery equipment—a gate opener, an alarm panel, a UPS, a solar-powered sign—and the battery dies. Someone says, “just get a rechargeable battery.”
That's how I ended up with a browser tab open to the question “is a rechargeable battery a lithium battery?” The answer is no, not by default. A rechargeable battery simply means it can be charged. Lithium is the chemistry inside. Many rechargeable batteries are sealed lead-acid. Others are nickel-metal hydride. If you swap one chemistry for another without checking the charger, you can shorten the battery's life or damage the equipment.
Here's a practical example: a 20Ah lead-acid battery in a backup system says 20Ah on the label. A supplier offers a 20Ah lithium battery as a drop-in replacement. Same capacity, same approximate size. But amp-hours are only one part of the spec. You also need voltage, discharge rate, charge profile, and, for lithium, a compatible battery management system. Sometimes a lithium drop-in works fine. Other times the existing charger can't handle the lithium charge curve, and the replacement never fully charges. Buying by the word “rechargeable” instead of by chemistry is how that mistake happens.
The same rule applies in solar storage. If you're expanding an existing battery bank, don't mix chemistries. A lithium iron phosphate battery from one manufacturer is not guaranteed to play nicely with an older battery from another. Get the replacement approved as compatible before you sign.
Which Scenario Are You Actually In?
Here's how to stop guessing. If you can't put a rough dollar amount on one hour of downtime, you're in Scenario A. Buy solar only, and don't let a sales rep add a battery to the proposal “just in case.” If you can name the dollar amount an outage costs, you're in Scenario B, and that number should be on the same spreadsheet as the battery quote.
If you can already picture your vehicles plugged in and charging, you're in Scenario C. Finalize the charger installation first, collect real charging data, then decide how much solar and storage belong in the project. If you're holding a dead battery and trying to figure out what to order, you're in Scenario D. Match the chemistry, not just the label.
Whichever scenario you're in, compare every proposal on total 15-year cost, not price per watt. Include inverter replacement, battery replacement, maintenance, and the assumptions behind the production estimate. It's more work on the front end. It's also the difference between an energy purchase that saves money and one that just feels good.