Solar Companies Inflating Numbers? Here's How to Spot It

We see it constantly in DC: Solar companies presenting quotes with inflated production numbers, unrealistic savings estimates, and projections that simply won't materialize. Homeowners choose them because the numbers look better. Then reality sets in. Here's how to spot the difference between realistic and inflated estimates.

The Solar Marketing Game in DC

Here's the truth: Some DC solar companies will tell you anything to close a deal.

A homeowner gets three quotes:

• Company A: "Your system will produce 9,500 kWh/year. You'll save $42,000 over 20 years."
• Company B: "Your system will produce 11,200 kWh/year. You'll save $58,000 over 20 years."
• Company C: "Your system will produce 8,800 kWh/year. You'll save $38,000 over 20 years."

Most homeowners pick Company B because the numbers sound the best. But Company B is lying.

How Solar Companies Inflate Numbers

1. Unrealistic Weather Assumptions

Google and NREL use average historical weather data — rain, clouds, winter days all factored in. Some companies use "optimal weather" assumptions where it's sunny 90% of the time. In reality, DC gets plenty of clouds.

The trick: Use a slightly higher "solar irradiance" number (how much sun hits your roof) than what real 20-year averages show. This inflates production by 10-20% right off the bat.

2. Zero Soiling Loss (Dirty Panels)

Solar panels get dirty. Dust, pollen, bird droppings, leaves. Realistic soiling loss in DC is 2-4% per year (panels lose 2-4% efficiency just from being dirty). Some companies ignore this entirely. "Your panels won't lose efficiency due to dirt." False.

The result: Overestimate of 2-4% every single year. Over 20 years, that's massive.

3. No Degradation or Minimal Degradation

Solar panels degrade (lose efficiency) over time. Real degradation is 0.5-0.8% per year. A 20-year-old system produces about 85-90% of what it did new. Some companies assume 0% degradation or only 0.2%/year (which is unrealistic).

The result: Inflates long-term production by 2-4%.

4. Ignoring Shading

Trees, buildings, chimneys, vents, and roof features cause shading. Realistic shading loss: 5-20% depending on your roof. Some companies assess shade too optimistically or worse — ignore it entirely.

The result: Overestimate of 5-15%+ if shade is ignored.

5. Overstating Inverter Efficiency

The inverter converts DC electricity (from panels) to AC electricity (for your home). Realistic efficiency: 95-97%. Some companies use 98-99%.

The result: Small but cumulative overestimate of 1-2%.

6. Ignoring DC-Specific Issues

Pepco interconnection issues can cause curtailment (your system is shut down during high-production periods). Some companies in congested areas completely ignore this. Result: You think you'll produce X, but you actually produce less.

Real Example: The Inflated Quote

How to Spot Inflated Estimates

Red Flag #1: Production Much Higher Than Google Solar Check

Use sunroof.withgoogle.com and enter your address. Google shows a realistic baseline estimate. If a company's estimate is 20%+ higher than Google's, be skeptical.

Why? Google has no incentive to oversell. They use conservative assumptions based on historical weather data.

Red Flag #2: No Mention of Soiling or Degradation

Any honest solar proposal should include:

• Assumed annual soiling loss (2-4%)
• Panel degradation rate (0.5-0.8%/year)
• Shade analysis with specific percentages
• Inverter efficiency specs

If the proposal doesn't mention these, that's a major red flag.

Red Flag #3: "Industry-Leading" or "Optimized" Efficiency Claims

Phrases like "our proprietary system," "industry-leading efficiency," or "optimized production" often mean inflated estimates. Real solar production follows physics — there's no magic here.

Red Flag #4: Vague Energy Production Estimates

Honest quotes show:

• System size in kilowatts (kW)
• Expected annual production in kilowatt-hours (kWh)
• Year-by-year degradation model
• Monthly/seasonal production breakdown

Vague quotes ("your system will save you money") are red flags.

Red Flag #5: "Eliminates Your Bill" Without Mentioning System Size

A company promises to eliminate your entire Pepco bill without clearly stating the system size (in kilowatts) needed to do it. This is the most common lie.

Here's the reality:

• Small roof (3-4 kW system): Can offset 40-60% of your bill
• Medium roof (5-6 kW system): Can offset 60-80% of your bill
• Large roof (8-10 kW system): Can offset 100%+ of your bill (produces more than you use)

The trick solar guys use: "We'll eliminate your Pepco bill!" without mentioning it requires a 10 kW system — and your roof might only fit 6 kW. By the time you realize, you're already in the contract.

What to ask: "What system size (in kW) is required to eliminate my bill? Does my roof fit that size?" If they won't give you a specific number, or if the number is larger than what fits on your roof, they're being dishonest.

The SREC Income Problem (DC-Specific)

This is critical in DC: Many solar companies inflate savings estimates by assuming high SREC income that won't materialize.

DC SREC prices: Today ~$370/credit, but projected to fall to $100-150 by 2035. Some companies use today's high prices in 20-year savings projections. That's dishonest.

Ask directly: "What SREC income do you assume in Year 5? Year 10? Year 20?" If they assume prices stay at $370, they're inflating.

What Realistic Estimates Look Like

Here's what you should see in a realistic, honest proposal:

• ✅ Production within 10-15% of Google Solar Check estimate
• ✅ Clear breakdown: soiling loss (2-4%), degradation (0.5-0.8%/year), shade analysis (specific %), inverter efficiency (95-97%)
• ✅ Year-by-year energy production table showing degradation over 20 years
• ✅ Conservative SREC assumptions (pricing declines over time)
• ✅ Pepco rate assumptions (showing increases, not static rates)
• ✅ Monthly production breakdown (showing summer higher than winter)
• ✅ Clear financing terms (loan APR, PPA rate, warranty details)
• ✅ Professional tone, no pressure language, happy to answer technical questions

The Bottom Line

Solar is a real investment with real savings. But you only get those savings if the estimates are honest.

Don't fall for the highest production numbers. They're not "better" — they're just inflated. You want the honest numbers. Over 20 years, being honest matters.

Here's Your Action Plan:

1. Check Google Solar Check — Get your baseline realistic estimate (2 minutes)
2. Get 3+ professional quotes — Compare estimates, not just prices
3. Compare to Google — Any estimate 20%+ higher is suspicious
4. Ask for detailed methodology — How did they calculate production? Soiling? Degradation? Shade?
5. Ask about SREC assumptions — What price do they assume? Does it decline over time?
6. Trust the conservative estimate — Better to be pleasantly surprised than disappointed