Guide
Use household kWh before sizing solar, storage, or EV charging upgrades.
Solar sizing starts with load, not roof area. Energy consumption is the pre-solar diagnostic: understand the bill, reduce waste, then size solar and storage around the load that remains.
Primary keyword: home energy consumption before solar
Solar ROI Explained
Solar sizing starts with load, not roof area. Energy consumption is the pre-solar diagnostic: understand the bill, reduce waste, then size solar and storage around the load that remains.
Use the calculator inputs first, then compare the result against local rates, incentives, roof conditions, and utility export rules.
Annual home kWh = sum of monthly utility-bill kWh, adjusted for planned EV, heat pump, or appliance changes
Electricity rates
EIA
Use as benchmark.
Home efficiency
ENERGY STAR and DOE Energy Saver
Savings depend on baseline equipment and local rates.
Solar production
NREL PVWatts
Use when linking consumption to solar sizing.
Formula Assumptions Data Sources FAQ Related Links
Most homes have a few loads that dominate the bill: air conditioning, electric heating, water heating, clothes drying, pool pumps, refrigeration, and EV charging. Small plug loads matter, but they usually do not decide solar sizing. A good energy estimate ranks loads by kWh first, then looks for behavior, efficiency, or rate-plan changes.
Solar sizing is easier after the household load is visible. If a home uses 900 kWh per month mostly from cooling, the solar design problem is different from a home using 900 kWh because of EV charging and electric water heating. The Energy Consumption Calculator should route users toward Solar Panel Sizing only after showing which loads create the demand.
Before buying panels, batteries, or a charger, test the cheap changes: thermostat schedule, air sealing, appliance runtime, off-peak charging, and replacing extreme loads. Efficiency improvements can reduce the solar system size needed, but they should be modeled as assumptions rather than guaranteed bill cuts.
Solar sizing starts with load, not roof area. Energy consumption is the pre-solar diagnostic: understand the bill, reduce waste, then size solar and storage around the load that remains.
Key assumptions: Monthly kWh should come from bills where possible. Appliance estimates are directional because runtime and equipment age matter. Efficiency improvements reduce solar system size only if they happen before final design.
Important caveats: Keep claims tied to utility bills and DOE/ENERGY STAR guidance; do not guarantee percentage savings for every home.
Open the Electricity Cost Calculator