You have requested solar quotes from one or more installers, and now you are staring at a multi-page document filled with kilowatts, production estimates, financial projections, and warranty terms. It can be overwhelming — but understanding your solar proposal is critical for making a smart decision and avoiding costly mistakes.
This guide walks you through every section of a typical solar proposal, explains what the numbers mean, and tells you what to watch out for.
Section 1: System Specifications
This section describes the physical equipment being proposed.
System Size (kW)
The total capacity of your system in kilowatts (kW). This is calculated by multiplying the number of panels by each panel's wattage.
Example: 18 panels x 400W = 7,200W = 7.2 kW
What to check: Make sure the system size is appropriate for your electricity consumption. A well-designed system should offset 80 to 100 percent of your annual usage. Undersized systems leave savings on the table. Oversized systems produce excess credits that may be reconciled at lower wholesale rates.
How to verify: Look at your annual electricity usage (kWh) from your utility bills, then divide by the expected production factor for Colorado (approximately 1,550-1,650 kWh per kW per year). The result is the approximate system size you need.
Solar Panel Make and Model
The proposal should specify the exact panel manufacturer and model, not just "Tier 1 panels" or "premium panels."
What to look for:
- Manufacturer name (e.g., REC, QCell, Meyer Burger)
- Model number
- Wattage per panel
- Efficiency rating
- Warranty terms (product and performance)
Red flag: Vague panel descriptions. If the proposal says "400W panels" without specifying the manufacturer and model, ask for details. Some installers use this ambiguity to substitute cheaper equipment.
Inverter Make and Model
Same as panels — the inverter should be clearly specified.
What to look for:
- Manufacturer (Enphase, SolarEdge, SMA)
- Model number and series
- Type (microinverter, string inverter with optimizers, or standard string inverter)
- Warranty duration
Key consideration: If the proposal lists a string inverter, ask about shade tolerance and what happens if one panel is underperforming. If your roof has any shading concerns, microinverters or power optimizers are strongly recommended.
Panel Layout
A reputable proposal includes a diagram showing exactly where each panel will be placed on your roof. This layout is typically generated using satellite imagery and design software.
What to check:
- Panels should be on south, southwest, or southeast-facing roof surfaces when possible
- The layout should avoid vents, skylights, chimneys, and other obstructions
- Setbacks from roof edges should comply with local fire code
- The number of panels in the layout should match the system specification
Battery (If Applicable)
If a battery is included, verify the brand, model, usable capacity (kWh), and warranty.
Section 2: Production Estimate
This is one of the most important sections of your proposal. It tells you how much electricity your system will generate.
Annual Production (kWh)
The total energy your system is expected to produce in a typical year. For Colorado, a well-designed 7 kW system should produce approximately 10,500 to 11,500 kWh per year.
What to check: Divide the annual production by the system size to get the production ratio (kWh per kW). For Colorado, this should be between 1,500 and 1,650 kWh/kW. If the ratio is significantly higher, the estimate may be overly optimistic. If it is lower, the design may not be optimized.
Monthly Production Breakdown
Most proposals show expected production for each month. Colorado production peaks in May-July and dips in December-January. This is normal and expected.
What to check: Compare the monthly production to your monthly electricity usage. In summer months, production should exceed consumption (building net metering credits). In winter months, consumption may exceed production (using those credits). Over the full year, the numbers should roughly balance.
Production Guarantee
Does the installer guarantee the production estimate? A production guarantee means that if your system underperforms the estimate, the installer will investigate and remedy the issue.
What to look for: A written guarantee that the system will produce at least a specified number of kWh in year one (and ideally beyond). At ProGreen Solar, our production guarantees are backed by detailed engineering analysis and we stand behind every estimate.
Section 3: Pricing and Costs
Gross System Cost
The total price before any incentives or credits. This should include all equipment, installation labor, permits, engineering, and interconnection.
What to check: Divide the gross cost by the system size in watts to get the cost per watt. For Colorado in 2026, expect $2.50 to $3.50 per watt for a quality installation. Below $2.50/watt may indicate lower-quality equipment or cut corners. Above $3.50/watt may be overpriced unless premium equipment or complex installation factors apply.
For detailed pricing benchmarks, see our Colorado Solar Cost Guide.
Incentives and Credits
- Federal ITC (30%): Should be clearly calculated as 30% of the gross system cost
- State/local incentives: Any applicable Colorado or utility rebates
- Property tax exemption: May be mentioned but does not reduce your upfront cost
Net System Cost
Gross cost minus all incentives. This is your true out-of-pocket cost (for a cash purchase) or the amount to be financed.
Financing Terms (If Applicable)
If the proposal includes financing:
- Loan amount
- Interest rate (APR) — fixed vs. variable
- Loan term — typically 10 to 25 years
- Monthly payment amount
- Dealer fees — some loans include origination fees (1-5%) that are rolled into the loan amount. These are not always transparent — ask specifically about dealer fees.
Red flag: If the quoted interest rate seems unusually low (below 2%), check for dealer fees. A "0.99% loan" with a 25% dealer fee actually costs you significantly more than a straightforward 5.5% loan.
Section 4: Savings Projections
Year 1 Savings
The estimated electricity bill savings in the first year. This is calculated by multiplying your expected production by your current electricity rate.
What to check: Make sure the savings calculation uses your actual electricity rate, not a national average. Colorado rates vary by utility — Xcel Energy rates are different from Colorado Springs Utilities or United Power.
25-Year Savings Projection
Most proposals project savings over 25 years, factoring in electricity rate increases and panel degradation.
What to verify:
- Utility rate escalation: Most proposals assume 2-4% annual increases. Colorado's actual average has been 3-4% per year. An assumption above 5% may overstate savings.
- Panel degradation: Verify the annual degradation rate used. It should match the panel manufacturer's specifications (typically 0.25-0.5% per year for premium panels).
- Net metering terms: Ensure the savings calculation reflects your actual utility's net metering policy.
Payback Period
The number of years until your cumulative savings equal your net system cost. For Colorado, expect 6 to 8 years for a cash purchase and 8 to 12 years for a financed system.
What to check: Make sure the payback calculation accounts for the federal tax credit. Some proposals show payback without the ITC, which is misleading for customers who qualify.
Section 5: Warranty Details
Panel Warranty
Look for both a product warranty (covering manufacturing defects) and a performance warranty (guaranteeing minimum output over time).
Best in class: 25-year product warranty with a linear performance guarantee of 90%+ at year 25.
Inverter Warranty
- Microinverters (Enphase): 25 years
- String inverters with optimizers (SolarEdge): 12-25 years (depending on extended warranty)
- Standard string inverters: 10-12 years
Workmanship Warranty
This is the installer's warranty on their labor — the quality of the installation itself, including roof penetrations, wiring, and racking.
What to look for: A minimum of 10 years. Better installers offer 25-year workmanship warranties. At ProGreen Solar, we warranty our workmanship for the life of the system because we stand behind the quality of our installations.
Roof Penetration Warranty
Specifically covers any roof leaks caused by the panel mounting. This should be a minimum of 10 years.
Red Flags to Watch For
Pressure Tactics
"This price is only good today" or "Sign now before the tax credit expires" are pressure tactics. The 30 percent ITC is available through 2032 — there is no urgency for immediate signing. A reputable installer gives you time to review and compare.
Unrealistic Production Estimates
If one proposal estimates significantly higher production than others for the same system size, something may be off. Compare production ratios (kWh/kW) across proposals.
Hidden Costs
Ask explicitly: "Does this price include permits, interconnection, monitoring, and all labor?" If any of these are excluded, you will face unexpected charges.
Escalator Clauses (Leases/PPAs)
If reviewing a lease or PPA proposal, look for annual payment escalators. A 2.9% escalator doubles your payment over 25 years. Make sure the escalated payment is still lower than projected utility rates.
Vague Equipment Specifications
Proposals should name specific panel and inverter models. "Tier 1 panels" or "premium microinverters" without specific names leave the door open for substitutions.
How to Compare Multiple Quotes
When evaluating multiple proposals:
- Normalize to cost per watt — Compare the gross cost per watt across proposals using the same (or comparable) equipment.
- Compare production estimates — Higher production at the same system size means better design or more optimistic assumptions.
- Compare warranties — Especially workmanship warranties, which vary significantly between installers.
- Check the equipment — Ensure you are comparing equivalent equipment across proposals. A cheaper quote with lower-tier equipment is not an apples-to-apples comparison.
- Evaluate the company — Check reviews, years in business, installation volume, and whether they use in-house crews or subcontractors.
Get a Transparent Proposal from ProGreen Solar
At ProGreen Solar, our proposals are designed for clarity and transparency. Every line item is explained, every assumption is documented, and every number is backed by data. We do not hide fees, inflate production estimates, or use pressure tactics.
Request your free proposal or call us at (303) 484-1410. We will walk you through every detail and answer every question until you are completely comfortable with your decision.
