Full rows only: modules per row × rows × module Wp / 1,000. The row depth is the module slope length × cos(tilt); gaps occupy horizontal space. Setbacks apply to all four edges. No inter-module gaps, obstacles, roof slope, aisle rules, structural limits or automatic shading allowances are included. Use row spacing below to choose a gap; actual layout may fit fewer modules.

Year 1 energy = DC capacity × first-year specific yield. Year n = year 1 × (1 − annual degradation)^(n − 1). The input yield already includes year-one system losses. This is a fixed-yield projection; it does not model hourly weather, tracking, clipping or annual variability. The irradiation calculator supplies monthly climate-based estimates and CSV export.

Each unit-price item = project kWp × 1,000 × quoted price per Wp. Subtotal = line items + other fixed costs; contingency applies to that subtotal. Tax is included only if included in your quotations. Annual roof rent and operating costs belong in the returns tool. A budget is not a supplier quotation.

Annual value = generation × [self-use share × avoided import tariff + exported share × export tariff]. Tariffs and operating costs escalate independently; energy degrades after year 1. Project cash flow deducts operating and replacement costs. Equity cash flow additionally deducts annual end-of-year level-payment debt service; year 0 is the equity contribution. NPV discounts each end-of-year cash flow; IRR is shown only for a conventional investment with a unique root. Payback interpolates the cumulative recovery that remains nonnegative through the modeled horizon, including later replacement expenses. No taxes, subsidies, depreciation, salvage value, transaction fees, time-of-use matching or fixed bill charges. Self-use is an input, not an hourly simulation. NREL SAM financial models cover more detailed project structures.

On level ground, projection = row slope length × cos(tilt), height difference = row slope length × sin(tilt). Gap = the largest shadow component normal to the rows while the sun is in front of the array, sampled every 5 minutes over your solar-time window. Pitch = projection + gap. Only the selected date and time window are checked; below-horizon times are flagged. No terrain slope, finite-row edge effects, diffuse shading or energy-loss model. Solar position uses a simplified declination model, not a surveying ephemeris. NOAA solar geometry reference.

Shadow tip east = −height × sun east / sun up; north = −height × sun north / sun up. Coordinates are relative to the obstacle’s base; shadow direction is opposite the sun. The diagram and 30-minute table describe a vertical point object on horizontal ground. Width, terrain, panel-plane intersections, vegetation, obstructions and resulting energy loss are not modeled. Times are local apparent solar time, not civil clock time.

Resistance uses conductor resistivity at 20°C corrected to the entered conductor temperature. DC/single-phase loop length is twice the one-way route; three-phase drop uses √3 × one-way resistance × current × power factor. AC reactance is set to zero. Loss is I²R for each loaded conductor. Candidate sections meet only the entered voltage-drop limit. A supplied derated ampacity is compared to operating current separately; no automatic ampacity table, protective-device coordination, fault withstand, harmonics or local-code verification is provided. Schneider Electric voltage-drop equations.