Practical solar sizing questions
Solar load calculator FAQ
Answers focus on the engineering decisions users actually need to make, not on promising one “exact” system size for every location and installation.
How does this solar load calculator size a PV system?+
The calculator first totals the running watts and daily energy of the appliances you select. It then estimates the PV array from daily kWh, peak sun hours, system losses and inverter efficiency. In Balanced mode it also checks that the array is not undersized relative to the selected daytime running load. All major assumptions are editable.
How many solar panels do I need for a 5 kW system?+
Panel count is the desired DC array wattage divided by the individual panel wattage, rounded up to a whole panel. A nominal 5 kW target therefore needs 10 × 550 W panels (5.5 kWp installed) or 9 × 600 W panels (5.4 kWp installed). Final string design must also satisfy the inverter MPPT voltage and current limits.
Why does the calculator ask for peak sun hours?+
The same PV array produces different energy in different locations and seasons. Peak sun hours are a simple way to represent the available solar resource. Use a representative value for your location rather than treating the default as a guarantee.
How is the inverter size estimated?+
The calculator uses the selected running load, a user-adjustable inverter headroom, the target DC/AC ratio and power factor. It also estimates a separate starting-surge requirement because motors, pumps, refrigerators, compressors and air conditioners can require substantially more power at startup than during normal operation.
How is battery storage calculated for a hybrid solar system?+
Battery sizing starts from the percentage of the selected load you want to back up and the requested backup hours. It then accounts for battery depth of discharge, battery efficiency and inverter efficiency. The result is shown as both usable energy and nominal battery-bank capacity.
Can I use this solar calculator outside Pakistan?+
Yes. The core formulas are location-neutral and the calculator lets you enter local peak sun hours, losses, panel specifications, electrical phase and custom appliances. Utility interconnection, export compensation, electrical codes and installation requirements must still be checked locally.
Is this a final electrical design?+
No. It is an engineering planning estimate. A qualified professional should verify conductor sizing, circuit protection, earthing, short-circuit requirements, inverter surge capability, PV string voltage/current limits, battery BMS limits, structural loading and local utility rules before installation.