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Solar Quote Comparison Calculator

Enter two installer quotes side by side — get normalized $/watt, 25-year net cost, warranty score, production per kW, and a Best Value recommendation.

Quote A
kW
$
W
yrs
yrs
kWh
%
Quote B
kW
$
W
yrs
yrs
kWh
%
Quote Comparison
Best Value: Quote A
Quote A ✓
$/watt$2.33/W
$/kWh over 25yr$0.050
Production/kW1,400 kWh/kW
Warranty score5/10
Cost/warranted yr$2,800/yr
25yr net cost$-25,121
ITC savings−$4,200
Quote B
$/watt$3.50/W
$/kWh over 25yr$0.068
Production/kW1,533 kWh/kW
Warranty score10/10
Cost/warranted yr$2,100/yr
25yr net cost$-23,547
ITC savings−$6,300
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Extended AnalysisNormalize quotes, warranty comparison & red flag detection
Quote A
$
kW
kWh
yr
yr
yr
Quote B
$
kW
kWh
yr
yr
yr
$/kWh
Normalizing by $/W and $/kWh over 25 years lets you compare quotes with different system sizes fairly. Green bar = better value.
Price per watt ($/W)
Quote A
2.85 $/W
Quote B
2.59 $/W Better
Cost per kWh over 25 years ($/kWh)
Quote A
0.09 $/kWh
Quote B
0.08 $/kWh Better
Production per kW (kWh/kW/yr)
Quote A
1300.00 kWh/kW Better
Quote B
1220.00 kWh/kW
Annual savings estimate ($)
Quote A
1755.00 $/yr Better
Quote B
1647.00 $/yr
Quote A payback
11.4 yrs
Net cost after ITC: $19,950
Quote B payback
11.0 yrs
Net cost after ITC: $18,130

How to Use This Calculator

Enter both quotes side by side

Fill in the details for each quote: system size in kW, total price, panel brand and wattage, inverter type, warranty terms, and estimated year-1 production. The year-1 production figure comes from the installer's solar design software (PVWatts, Aurora, or HelioScope) — it's the most important single number in a quote, as it determines your actual savings. If an installer hasn't provided a production estimate, ask for one before proceeding.

Understand the normalized metrics

Raw price alone is meaningless without context. A $21,000 quote for a 6kW system is actually cheaper per watt than a $14,000 quote for a 4kW system. The calculator normalizes to $/watt, $/kWh over 25 years, and production per kW installed — the three metrics that allow apples-to-apples comparison across different system sizes and configurations.

Read the flags and recommendation

The calculator flags suspicious values: $/W below $1.50 suggests a low-quality or incomplete quote; above $5.00 means you need competing quotes. Production below 900 kWh/kW/yr means either the system is poorly designed or heavily shaded. Short workmanship warranties (under 5 years) are a significant risk indicator. The Best Value badge goes to the quote with the lower 25-year net cost when production data is available.

The Formula

$/Watt = Total Price ÷ (System kW × 1,000) $/kWh over 25yr = Net Cost after ITC ÷ Total 25yr kWh Production per kW = Year-1 kWh ÷ System kW Warranty Score = (Workmanship yrs ÷ 10 × 5) + (Equipment yrs ÷ 25 × 5) Cost per Warranted Year = Total Price ÷ Workmanship Years 25yr Total kWh = Σ Year-N kWh × (1 − 0.5%)^N (for N = 0 to 24) 25yr Net Cost = Net Price + Financing Cost − Total Electricity Savings

The 25-year net cost is the most comprehensive metric — it starts with your net investment after the 30% ITC, adds any loan interest paid, then subtracts the electricity savings generated over 25 years (using 2.5% annual rate escalation and 0.5% annual panel degradation). A negative 25-year net cost means the system has paid for itself and generated profit. The $/kWh metric lets you compare to your current utility rate — if solar's $/kWh is lower than your utility rate, solar wins even before considering future rate increases.

Example

David — Comparing a budget quote vs premium quote for 6kW

David received two quotes for a 6kW system. Quote A is $14,000 with 350W panels and a string inverter. Quote B is $21,000 with 430W SunPower panels and microinverters. Both are in Denver with similar production estimates.

Quote A6kW, $14,000, 350W panels, string inverter, 5yr workmanship, 8,400 kWh/yr
Quote B6kW, $21,000, 430W SunPower, microinverters, 10yr workmanship, 9,200 kWh/yr

Comparison

$/wattA: $2.33/W vs B: $3.50/W
$/kWh over 25yrA: $0.042 vs B: $0.054
Production/kWA: 1,400 kWh/kW vs B: 1,533 kWh/kW
Warranty scoreA: 5/10 vs B: 10/10
25yr net costA: −$4,200 (profit) vs B: −$2,800 (profit)
Best valueQuote A — lower 25yr net cost

Despite Quote A's lower $/kWh and better 25-year net cost, David should weigh the warranty difference: Quote A's 5-year workmanship warranty vs Quote B's 10-year warranty represents real risk exposure. The $7,000 price gap may be justifiable given the better warranty, more reputable panels, and 10% higher production. This is the kind of nuanced comparison this calculator enables.

FAQ

The national average is $2.85/W fully installed before the 30% ITC. Good value is $2.40-2.80/W for standard systems. Premium systems with high-efficiency panels and microinverters typically run $3.20-4.00/W. Anything below $2.00/W warrants scrutiny — it often means budget panels, no monitoring, or excluded permit costs. Anything above $4.50/W is likely overpriced unless it includes battery storage. The after-ITC equivalent for a $2.85/W system is $2.00/W — compare to your utility's $/kWh to assess the deal.
A complete solar warranty has three components: (1) Panel product warranty — covers manufacturing defects; 12-25 years is standard. (2) Panel output warranty — guarantees production doesn't degrade below 80-87% at year 25; virtually all Tier 1 panels include this. (3) Workmanship warranty — covers installer labor, roof penetrations, and system performance; 10 years is the current industry standard. Minimum acceptable: 5 years workmanship, 12 years panel product, 25 years output. Red flag: workmanship warranty under 5 years or from an installer who may not be in business in 5 years.
The estimated production (kWh/year) is arguably the most important number in a quote — it determines your actual savings, payback period, and 25-year return. Two systems at the same $/watt can have very different production if one accounts for shading, roof orientation, and tilt angle more accurately. Ask every installer to show you their design software output (PVWatts, Aurora, or HelioScope) with the production estimate. Compare the production/kW ratio: 1,200-1,800 kWh/kW/yr is typical for most US locations; under 1,000 suggests shading or design issues; over 1,800 in high-sun states (AZ, NV) is possible.
Both have tradeoffs. Local installers: typically lower overhead and more competitive pricing, local knowledge of permit requirements, and you can verify their reputation more easily. Risk: smaller company may not honor 10-year workmanship warranties if they go out of business. National companies (Sunrun, SunPower, Tesla Solar): larger warranty-honoring entity, streamlined process, often higher prices. Risk: less flexibility, sometimes aggressive sales tactics, and some have had financial difficulties. The safest approach: choose a local installer with 5+ years of operation, 50+ local installs, and positive recent reviews — get a lien waiver and ensure the workmanship warranty is with the installer, not just the equipment manufacturer.
Key red flags: (1) No production estimate — any serious installer provides this; refusal means they're hiding something. (2) Price includes "free" battery storage — hidden financing usually embedded. (3) Workmanship warranty under 5 years. (4) No itemized breakdown — you can't negotiate what you can't see. (5) High-pressure tactics or "today-only" pricing. (6) No site visit or roof assessment before quoting. (7) Payment required before permits are issued. (8) $/W price significantly below market without clear explanation — often means budget components or excludes permit/interconnection costs.

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