The Solar Buyer's 7-Step Checklist: What I Learned Ordering for 3 Office Locations

If you’re an office administrator tasked with evaluating solar for your company—maybe for a single building, maybe for multiple sites—you’ve probably realized this isn’t like buying office supplies or even copier contracts. It’s bigger, it’s technical, and the costs can swing wildly depending on what you actually need.

I’ve been handling purchasing for a 200-person company across three locations since 2020, and when we started looking at solar in early 2024, I had to figure out a system fast. After evaluating four vendors, getting quotes for 450W panels, battery backup options, and even EV charging, here’s the checklist I wish I’d had from day one.

This checklist is for anyone who needs to compare solar proposals for a business or multi-unit property. It’s not about “should you go solar”—it’s about how to compare options once you’ve decided to look. Seven steps, and one of them (step 4) is something most buyers overlook until it’s too late.

Step 1: Confirm Your Load and Roof Capacity First—Not Last

This sounds obvious, but I almost got the order wrong. The first vendor I spoke with asked about our electric bill, and I gave them the total for the whole company across all three locations. That’s wrong. You need data per site, ideally per meter.

• Pull 12 months of utility bills for each location. Don’t estimate.
• Calculate your peak demand (kW) and average daily consumption (kWh). The vendor needs both.
• Check your roof age and warranty. A roof older than 10 years might need replacement before panels go up. That’s a separate budget line item.

Checkpoint: Have you validated the roof condition with a structural engineer or the building owner? If not, pause here.

The question everyone asks is “what’s your electric bill?” The better question is “what’s your consumption pattern by hour and season?” (note to self: actually get the interval data from the utility, not just the monthly summary).

Step 2: Get a Baseline Quote for 450W Panels—But Don’t Stop There

Most commercial proposals I saw quoted 400W or 450W panels. The 450W panels (like the ones Vivint Solar installs) are becoming standard for commercial installations, but pricing varies a lot. In Q3 2024, I saw quotes ranging from $1.80 to $2.60 per watt for the same panel specification, depending on the installer’s labor, warranty, and overhead.

• Panel model and wattage (e.g., 450W monocrystalline).
• Inverter type (microinverters vs. string inverters vs. optimizers—not all are equal for shading).
• Warranty terms: 25-year performance warranty is standard, but check what happens if the company goes under.
• Installation timeline (and what happens if permits are delayed).

Prices as of January 2025; verify current rates at energystar.gov or your local installer. The difference between a $2.00/watt quote and a $2.50/watt quote on a 100kW system is $50,000. That’s not trivial.

Step 3: Understand How a Solar Battery Works—Then Decide If You Need One

This step was a learning curve for me. I knew the basics—battery stores energy for use at night or during outages—but I didn’t realize how much the decision depends on your utility rate structure and outage risk.

• Batteries are expensive. A home battery backup system (like the Vivint battery or Tesla Powerwall) runs $10,000–$15,000 installed for a 10–15 kWh unit, as of Q4 2024.
• They only provide backup for essential loads, not your whole building, unless you install multiple units. Ask the vendor to specify which circuits are backed up.
• If your utility has time-of-use rates, a battery can save money by charging when rates are low and discharging during peak hours. If you’re on flat rates, the financial case is weaker.
• Some states offer incentives for battery storage (like California’s SGIP). Check dsireinsights.org for your area.

The most frustrating part: vendors often present batteries as “no-brainer” add-ons. But they’re a $12,000 decision. You’d think the ROI calculator would be standard in every proposal. It’s not. I had to ask for it separately from three out of four vendors.

Step 4: Verify App Capabilities Before Signing (This Is the Overlooked One)

Most buyers focus on panel specs and price, and completely miss the monitoring app. This was my biggest blind spot. We have three locations, and I need to see production data, battery status, and alarms from one dashboard. Not all solar apps do this well.

• Does it show production per site, or do you need separate logins for each? (I was shocked how many require separate logins—for a multi-site buyer, that’s a dealbreaker.)
• Can it send alerts (e.g., panel down, battery low, inverter error)?
• Is there a public API or export option? If you need to report energy credits to finance, you’ll want CSV or PDF export.
• How long is data retained? Some apps only keep 12 months of history.

Skipped the app demo entirely during vendor selection because I assumed it was all the same. That was the one time it mattered. We ended up with a vendor whose app required a separate login per location, and I had to create a workaround using a shared account (not ideal). Cost us maybe $1,200 in administrative time over the first year.

Checkpoint: Ask for a live demo of the monitoring app before you sign. If they can’t show it live, ask why.

Step 5: Check BBB and Customer Reviews—But Know the Patterns

I’m sure you’ve searched “Vivint Solar BBB” or similar. The Better Business Bureau rating is a starting point, but it’s not the whole story. Here’s what I look for now:

• BBB rating (A+ is good, but check the number of complaints and how they were resolved).
• Patterns in complaints: “Installation delays” and “billing issues” are common industry-wide. “Equipment failure” or “safety concerns” are bigger red flags.
• Review sites like SolarReviews.com or EnergySage, which filter for verified installations.
• How recent are the complaints? A company that was bad in 2021 might have improved. A company with complaints in 2024 is still a risk.

In our case, the vendor we chose had moderate complaints on BBB but responded to every one. The vendor we rejected had fewer complaints but had two unresolved safety-related issues. That was the deciding factor for me.

Step 6: Understand the Financials—Energy Credits, Tax Incentives, and Cost Per kWh

This is the part that requires the most attention to detail. The federal Investment Tax Credit (ITC) offers a 30% tax credit for commercial solar installations (as of 2025; verify with IRS.gov). Some states and utilities offer additional credits or performance-based incentives.

• A 20-year cash flow projection, including: system cost, tax credits, energy savings, and maintenance costs (including inverter replacement around year 10–15).
• An explanation of how energy credits (SRECs, or Solar Renewable Energy Credits) work in your market. In some states, these can be sold for $50–$300 per MWh. In others, they don’t exist.
• The estimated cost per kWh (levelized cost of energy, or LCOE). Compare this to your current utility rate. If the LCOE is higher, question the value proposition (unless backup power is your priority).

The vendor who cost us $2,400 in rejected expenses because their financial model didn’t account for SREC price changes (circa 2023, things have stabilized a bit). Now I verify the assumptions before I share the report with finance.

Checkpoint: Run the numbers yourself using the NREL PVWatts Calculator (nrel.gov/pvwatts). It’s free and it gives you a sanity check on the vendor’s production estimates.

Step 7: Confirm the Installation Process—Including Permits and Utility Interconnection

This is where the timeline lives or dies. I’ve heard from colleagues who had solar sitting in their parking lot for weeks waiting for permit approval. The vendor’s project management matters more than you’d think.

• Who handles building permits (vendor or you)?
• What’s the typical timeline from contract to interconnection? For commercial systems, 8–16 weeks is normal. If they promise less than 8 weeks, ask how they handle permit delays.
• Who is the utility contact person? The vendor should have a designated person to handle interconnection paperwork.
• What happens if the roof needs repairs after installation? Who removes and reinstalls the panels?

We didn’t have a formal approval chain for solar installation at first. Cost us when an unauthorized rush fee showed up on the invoice because the permit was delayed and the vendor charged for rescheduling labor. Should have clarified the “act of god” clause in the contract.

Common Mistakes I’ve Seen (and Made)

1. Focusing only on the panel price. The total cost of installing solar includes inverters, wiring, mounting hardware, labor, permits, and sometimes electrical panel upgrades. These can add 20–50% to the equipment cost.
2. Assuming “zero upfront” means no cost. Lease and PPA agreements often include escalator clauses (e.g., 2.9% annual increase). Over 20 years, that’s significant. Read the fine print.
3. Not verifying ESS Parx login or app integration. If your vendor uses a platform like ESS Parx for monitoring or billing, make sure you know how to access it and what data it provides before you sign.
4. Underestimating maintenance. Panels need cleaning (especially in dusty areas), inverters need replacement, and batteries degrade over time. Budget 0.5–1% of system cost annually for maintenance.

The most important lesson from our process: the cheapest quote was not the best value. In March 2024, we paid $400 extra for rush delivery on a critical component. The alternative was missing a $15,000 event deadline. The “on time” guarantee was worth the premium. I now budget for it.

Pricing and regulatory information current as of January 2025. Verify current rates, incentives, and requirements at energystar.gov, dsireinsights.org, and your local utility company.