The calculation
Installed cash price ÷ rated DC system watts = cash cost per DC watt. Use the same system boundary and units for every proposal. If a quote gives capacity in kilowatts, multiply by 1,000 to express it in watts.
A worked example
Illustrative example: a $24,000 cash proposal for an 8 kW DC array is $24,000 ÷ 8,000 = $3.00 per DC watt. This arithmetic does not establish whether $3.00 is fair, and it is not a reviewed pricing benchmark.
Keep the numerator comparable
If the total includes batteries, roof work or a financing fee, ask the provider to separate those amounts before comparing it with an array-only cash quote. Keep incentives out of the initial comparison unless both proposals use the same verified assumptions.
Check the denominator
Confirm that both proposals use rated DC array capacity. Do not mix DC panel ratings with AC inverter output or annual production estimates. Ask the installer to explain an ambiguous capacity label.
Read the rest of the proposal
Two arrays with the same calculated cost per watt can have different equipment, installation work and warranties. Use the calculation as one field in your comparison, then review the complete scope.
Sources and review
Written by RipOffRadar. Editorial update: . Our checklists are questions to take to a provider; they are not a technical diagnosis or a local price survey.