So You’re Thinking About Going Solar for Your Business… Smart Move.
You already know it’s good for the planet and locks in your energy costs for decades. But here’s the part most people mess up: they either install way too little (and barely notice the savings) or way too much (and tie up cash they didn’t need to).
The truth? Getting the size right is the difference between “yeah, it’s nice” and “holy crap, this is printing money.”
I’ve helped hundreds of business owners size their systems properly, and I’m going to walk you through exactly how we do it — no fluff, no sales pitch, just the actual process.
Why Getting the Size Right Actually Matters (A Lot)
- You’ll get your money back faster (we’re talking 5–8 years instead of 12+)
- You won’t waste money on panels you don’t need
- You’ll grab every dollar of tax credits and rebates available
- You’ll have room to grow later (EV chargers, new equipment, bigger facility) without having to redo everything
Get it wrong, and you’ll either leave savings on the table or have a system that’s too big and takes forever to pay off.
The 5-Step Process We Actually Use (With a Real Example)
Step 1: Look at Your Real Energy Usage (Not Guesses)
Grab your last 12–24 months of electric bills. Seriously, do it right now.
Look for:
- Total kWh used per year
- Your peak demand (kW) — this is huge for commercial bills
- Which months are the highest (summer AC? winter heating?)
Pro tip: Call your utility and ask for your “interval data” or “hourly load profile.” Most will email it to you for free. This is gold.
Real Example – Phoenix Warehouse Annual usage: 120,000 kWh/year Average bill: ~$1,500/month ($18,000/year)
Step 2: Decide What You Actually Want Solar to Do
Be honest with yourself:
- “I want my electric bill basically gone” → aim for 90–110% offset
- “I want a 5-year payback no matter what” → probably 60–80% offset
- “I just want to look green and cut costs a bit” → 40–60% offset is fine
- “I’m adding 10 EV chargers next year” → plan for the future load now
Most of our clients want their bill gone. That’s what we’ll use in the example.
Step 3: Do the Actual Math (It’s Easier Than You Think)
The simple (and surprisingly accurate) formula:
Annual kWh needed ÷ Production Ratio = System Size in kW
The “Production Ratio” is how many kWh one kW of solar makes in your location per year.
Rough numbers:
- Phoenix/Tucson: 1.6–1.8
- California (most areas): 1.5–1.7
- Denver: 1.6–1.7
- Texas: 1.4–1.6
- Midwest: 1.2–1.4
- Northeast: 1.1–1.3
- Seattle/Portland: 1.0–1.2
Phoenix Warehouse Example: 120,000 kWh ÷ 1.6 = 75 kW system
That 75 kW system will produce ~120,000 kWh/year → basically zero bill.
Want only 50% offset? 60,000 kWh ÷ 1.6 = 37.5 kW system (~$9,000/year savings instead of $18,000)
Step 4: Check If Your Building Can Actually Handle It
75 kW = about 180–190 standard panels Each panel needs ~20 sq ft → ~3,800 sq ft of good roof space
Questions to ask:
- Is your roof south, southeast, or southwest-facing? (Ideal)
- Any shading from trees, parapets, or neighboring buildings?
- Is your roof less than 15 years old and in good shape?
- Can it handle ~4–5 lbs per sq ft extra weight?
If roof space is tight → use higher-efficiency panels (more $/watt but fewer needed) or go ground-mount if you have land.
Step 5: Run the Money Numbers (This Is the Fun Part)
Average commercial price in 2025 (before incentives): ~$2.40–$2.80 per watt
75 kW system = $195,000–$210,000 gross cost
Federal ITC (30% in 2025): –$60,000 Possible state/local incentives + bonus depreciation: another –$30k–$50k
Real net cost: ~$100,000–$120,000
Annual savings: ~$18,000 Payback: 5.5–6.7 years
After that? Free electricity for the next 20+ years. Total 25-year profit: easily $400k–$600k+ depending on rate increases.
Quick Reference: Typical System Sizes by Business Type (2025 Estimates)
| Business Type | Annual Usage | Typical System Size | Notes |
| Small Retail/Coffee | 30k–60k kWh | 20–40 kW | Often roof-limited, 50–70% offset common |
| Restaurant | 80k–150k kWh | 50–90 kW | Huge refrigeration + cooking loads |
| Warehouse/Distribution | 100k–250k kWh | 70–150 kW | Big flat roofs = perfect for 100% offset |
| Office Building | 150k–400k kWh | 100–250 kW | Daytime usage = perfect solar match |
| Manufacturing | 500k+ kWh | 300–1,000+ kW | Often ground-mount, huge demand charges |
The Stuff That Changes the Final Number
- Net metering rules in your state (California NEM 3.0? Arizona? Texas? Makes a difference)
- Future growth plans (add EV fleet → add 20–50% more capacity now)
- Panel degradation (we usually plan for 91% production in year 25)
- Whether you can use bonus depreciation this year
Real Talk on Costs (2025 Pricing)
| Component | % of Total | What It Is |
| Panels + Inverters | 50–55% | The actual hardware |
| Labor + Installation | 20–25% | The hard (and skilled) work |
| Permitting/Engineering | 10–15% | Boring but necessary |
| Profit/Overhead | 10–15% | Installer stays in business |
What You Should Do Next Week
- Pull your last 12–24 months of bills
- Email me or any good installer your annual kWh and address → get a real proposal
- Get 3 quotes (yes, really)
- Ask each one: “What size for 5-year payback?” and “What size to kill my bill?”
Most Common Questions I Get
Q: Can I just add more panels later? A: You can, but it’s usually 30–50% more expensive per watt. Size it right the first time.
Q: What about cloudy days/night? A: You stay connected to the grid. Excess sunny-day production offsets night/cloudy usage via net metering. No batteries needed for most businesses.
Q: Does solar increase my property value? A: Yes. Studies show $20–$30 in added value for every $1 in annual energy savings.
Q: How much maintenance? A: Almost none. Wash them once or twice a year if dusty. Inverter replacement around year 12–15 (~$15k–$25k for a big system). That’s it.
Ready to stop guessing and get the exact right size for your business?
Drop your annual kWh and city in the comments or DM me — I’ll tell you within minutes what size you actually need and what it’ll save you. No sales pitch, just numbers.
