Engineering tools
Energy and backup power tools
Calculators for battery backup runtime and charging time, solar array sizing, panel tilt and orientation, generator sizing and appliance running cost, with the assumptions each one makes spelled out.
Backup power sizing is mostly arithmetic with honest assumptions. These tools make the assumptions visible: depth of discharge, inverter efficiency and the way battery capacity falls at higher discharge currents.
Battery backup runtime calculator
Estimate how long a battery bank will run a load through a UPS or inverter, and the capacity needed for a target runtime, accounting for depth of discharge and inverter efficiency.
Open tool →Battery charging time calculator
Estimate how long a lead-acid or LiFePO4 battery takes to recharge from its present state of charge at a given charger current: the amp-hours to replace, the bulk and absorption stages, a check of the charge rate against the chemistry, and the current needed for an overnight refill.
Open tool →Solar system sizing calculator
Size a solar PV array from your daily energy use and local peak sun hours, allowing for system losses; then the number of panels, the battery bank for the autonomy you want, and the inverter rating for your peak load.
Open tool →Solar panel tilt calculator
Find the best fixed tilt for your latitude, the two-position seasonal tilts, and how much yield an array at your actual roof tilt and compass direction gives up against the optimum, from a clear-sky model integrated over the year.
Open tool →Generator sizing calculator
Size a standby diesel or gas generator from the running load and the largest motor it must start, with the starting method, the set's overload capability, a growth margin and derating for altitude and ambient temperature.
Open tool →Appliance electricity cost calculator
Work out what an appliance costs to run: units per day, month and year from its rated power, the share of the time it actually draws that power, the hours it is used and your tariff, with standby draw and a check against the residential tariff slabs.
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