Metric Republic / Energy & building physics / PV System Size from Annual Energy Demand

PV System Size from Annual Energy Demand

Estimate PV kWp and panel count from annual demand, target coverage, specific yield and panel wattage.

Updated September 2026

How it works

Estimate PV kWp and panel count from annual demand, target coverage, specific yield and panel wattage.

Formula:
Target PV energy = demand·coverage; kWp = energy/specific yield; panels = kWp·1000/panel W.

Before you use the result: Specific yield must reflect location, orientation, shading and system losses.

Practical use

Use verified material data and project geometry. Treat results as planning estimates and compare them with the energy/thermal requirements that apply to the project.

Keep units consistent with the source information.
Use project-specific densities, pack sizes and coverage rates where provided.
Round purchasing quantities to supplier packaging and delivery rules.

How to use this calculator: PV System Size from Annual Energy Demand

Estimate PV kWp and panel count from annual demand, target coverage, specific yield and panel wattage.

Quick workflow

Enter the project values from the latest drawing, specification or verified site measurement.
Check units, material properties, allowances and any code- or supplier-specific parameters before calculating.
Review the result together with the formula, assumptions and the related checks shown on this page.

Worked example

Example inputs: Annual electricity demand [kWh/year]: 6 000; Target PV coverage [%]: 80; Specific annual yield [kWh/kWp·year]: 950; Panel rating [W]: 450.

Using the sample values built into the calculator, the calculation gives approximately: Target PV energy: 4 800 kWh/year; Required PV capacity: 5.053 kWp; PV panel count: 12.

What the result means

Calculation method: Target PV energy = demand·coverage; kWp = energy/specific yield; panels = kWp·1000/panel W.

Before using the result: Specific yield must reflect location, orientation, shading and system losses.

Common questions

What does this calculator do?

Estimate PV kWp and panel count from annual demand, target coverage, specific yield and panel wattage.

Which inputs should I verify?

Key inputs to verify include: Annual electricity demand [kWh/year], Target PV coverage [%], Specific annual yield [kWh/kWp·year], Panel rating [W].

Can I use this result for final design or ordering?

Use the result as a transparent planning or checking aid. Final design, code compliance, supplier selection and project-specific decisions still need to be verified where applicable. Specific yield must reflect location, orientation, shading and system losses.

RELATED TOOLS