The Solar-VRF Savings Calculator

Peak loads use screening factors by building type (e.g. office: 28 BTU/hr·ft² cooling, 24 heating). Annual thermal load = peak × equivalent full-load hours for Mid-Atlantic climate zone 4A (≈850–1,100 cooling, 1,000–1,350 heating). Electricity = load ÷ (3,412 × seasonal COP). We model VRF at seasonal cooling COP 5.0 (residential) / 5.8 (commercial, IEER-22 class) and heating COP 3.1 including defrost — deliberately below nameplate. Existing systems use installed-stock efficiencies (SEER ~11 AC, AFUE 0.80–0.85 fossil).

Production = kW × state yield (MD/DC ≈1,300, VA ≈1,350 kWh per kW per year, PVWatts-class Mid-Atlantic estimates). Recommended array size targets 100% of modeled VRF consumption. Bill savings assume full retail net metering (current policy in MD, DC, and VA as of July 2026). SREC income = MWh × market price — DC ≈ $367.50, MD ≈ $55, VA ≈ $30 (July 2026 markets; volatile).

Installed cost benchmarks: VRF $4,000–$5,800/ton by building type; solar $2.00–$2.85/W — all overrideable in Advanced. Residential federal credits (25C/25D) expired 12/31/2025 and are shown as $0. Commercial solar takes the 30% §48E ITC where timing rules are met (most new starts must be in service by 12/31/2027). Utility rebates use published program values (e.g. Pepco MD $500/ton commercial VRF; EmPOWER residential midstream). Simple payback = net cost after upfront incentives ÷ total annual benefit. If "end of life" is checked, we count only VRF cost above a like-for-like replacement — the economically correct comparison.

It is not a Manual J/N or ASHRAE load calculation; it doesn't see your envelope, glazing, plug loads, demand charges, or rate schedules. It doesn't model heat-recovery simultaneity, battery storage, or MACRS depreciation in payback. It's built to answer one question well: is this worth a real engineering conversation? For sources and full assumption tables, see the 2026 Incentives Guide and README in the project repo.