Domain 1: Customer Qualification and Load Analysis
Domain 1 covers the front end of a PV sale: qualifying the customer, reading their electricity use correctly, and converting stated goals into numbers a design can hit. Exam items test whether you can separate kWh (energy) from kW (demand), interpret a rate schedule, and recognize when a customer's goal is unrealistic for the site, budget, or tariff.
Read the bill before the roof
- Identify the rate schedule, seasons, tiers, time-of-use (TOU) windows, demand charges, fixed charges, and non-bypassable charges.
- Residential bills are mostly energy; commercial bills often carry demand charges (kW) that PV reduces only when production coincides with the billing peak.
- Effective rate = total bill / total kWh. Marginal rate = what the next kWh costs or earns during the hours the array produces. Savings math belongs on the marginal rate, not the average.
Qualify goals and constraints
- Ownership and control of the roof or land; lease and easement issues; HOA and historic-district rules.
- Tax appetite for credits and depreciation; financing preference (cash, loan, lease, PPA); credit standing.
- Objectives beyond savings: backup power, resilience, EV charging, carbon, roof replacement timing.
- Planned load growth - a system sized only to last year's usage may be undersized.
Worked example
A customer uses 12,000 kWh/yr. TOU data show 4,800 kWh on-peak at $0.35 and 7,200 kWh off-peak at $0.12. Bill = $1,680 + $864 = $2,544, so the effective rate is $0.212/kWh. If the array produces mostly in the off-peak window and exports earn $0.12, valuing production at $0.212 overstates savings by nearly 77%. Under 1:1 net metering the retail rate applies at true-up, so the $0.212 figure is defensible.
Traps
Quoting annual kWh only; assuming 100% offset erases the bill (fixed and non-bypassable charges remain); confusing kW with kWh; ignoring a planned roof replacement or an expiring incentive deadline.