Consumption first
The calculator converts your bill or monthly units into a daily energy requirement.
Size the system around
how you use power.
Use your electricity bill or monthly units, then refine the estimate with tariff, effective sunlight, shading and expected future demand.
Site factors next
Effective sunlight and shading adjust how much useful energy each installed kilowatt can produce.
Survey confirms
Roof geometry, structure, export policy and equipment choice still need site-specific engineering.