EngineerBenchTurning daily workshop energy into a solar budget
Solar array size starts with energy use in kilowatt-hours per day, not the highest instantaneous load. Divide daily demand by design peak-sun hours and delivery efficiency to estimate array power. Battery storage is a separate calculation based on daily energy, days of autonomy, and usable capacity.
Peak-sun hours are not daylight hours
Use a location- and season-appropriate estimate of equivalent full-sun hours. A long winter day with weak sun is not equivalent to the same number of hours at rated irradiance. The tool accepts this value; it does not look up weather or shading.
Keep power and energy separate
Running power and starting surge help describe the inverter duty, while kilowatt-hours describe energy storage and generation. This is a daily energy budget, not an hourly production simulation, equipment compatibility check, or complete off-grid system design.
Separating daily consumption from peak demand
A 500 W load used for two hours consumes 1 kWh. A 100 W load used for ten hours consumes the same daily energy, although the required instantaneous power differs. Add the energy of each load over a representative day before estimating an array. Seasonal workshop use, heating, extraction, and idle equipment can change that daily total substantially.
For illustration, 4 kWh per day divided by four peak-sun hours and an 80 percent delivery factor gives a 1.25 kW array estimate. This is a daily balance under the selected assumptions, not a prediction of output on every day. Several cloudy days require a separate storage or backup strategy. Battery autonomy should use the energy actually available after the selected usable-capacity and efficiency allowances. Compare winter and summer assumptions separately where both matter. A system with enough average daily energy can still be unable to supply a large startup load, so check inverter and battery power capability independently.
Formula
Array kW = daily kWh / (sun hours × efficiency). Battery kWh = daily kWh × autonomy / usable fraction.