Calculator

Photovoltaic Calculator

Calculate annual yield, self-consumption, feed-in, battery-storage effect, annual benefit and rough payback period of your solar PV system. Self-consumption with battery is estimated as an output.

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Inputs

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Roughly estimate how much electricity a PV system can generate per year, how much of that energy is used on site, how much is fed into the grid and how long the investment may take to pay back. It is intended as an initial planning and comparison tool for residential rooftop solar projects and similar small-scale installations.

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System size (kWp)

System size is stated in kWp. 10 kWp means the modules deliver about 10 kW under standard test conditions. Actual annual yield depends on roof area, orientation, tilt and shading.

Yield level of your roof

Choose a rough roof/site assumption. The calculator derives annual yield from this instead of asking for a technical specific-yield value.

Annual household electricity use (kWh)

You can find this number on your electricity bill. The calculator uses it to estimate realistic self-use without and with a battery.

Battery capacity (kWh)

Optional: usable battery capacity. Enter 0 to ignore the battery scenario.

Battery round-trip efficiency (%)

Rough assumption for charging and discharging losses. 90% means that 1 kWh of surplus returns as about 0.9 kWh of usable energy later.

Battery cost ($)

Optional: additional investment for the battery. This helps estimate whether the battery itself roughly pays back.

Electricity price ($/kWh)

Enter your current electricity price per kWh. This determines how much each self-used solar kWh saves.

Feed-in tariff ($/kWh)

Enter the tariff per exported kWh. It is usually lower than your electricity price, so self-consumption often matters more economically.

Investment cost ($)

Total cost of the PV system without battery, ideally including installation, inverter and ancillary costs. Enter the battery separately.

Annual maintenance cost (% of investment)

Allowance for running costs such as maintenance, insurance or reserves. Roughly 0.5–1.5% of investment per year is often used as a first estimate.

FAQ

FAQ about Photovoltaic Calculator

How much electricity does 1 kWp of solar produce per year?

A rough rule of thumb is often around 900 to 1,100 kWh per kWp per year, but the real number depends on location, roof orientation, shading, pitch and system quality.

When does a photovoltaic system pay off?

That mainly depends on installation cost, self-consumption, electricity price and feed-in tariff. The more solar electricity you use yourself, the more attractive the project often becomes.

What is a good self-consumption share?

A higher self-consumption share usually improves economics because electricity used on site is often worth more than electricity exported to the grid. A good value depends on the household load profile and whether a battery is used.

Does this calculator include batteries?

Yes, in a simplified way. Battery storage is included through battery size, round-trip efficiency and battery cost. The calculator does not replace an hourly simulation with load profile, weather data, shading, real charge/discharge behavior, battery degradation or detailed battery maintenance planning.

Are subsidies or taxes included?

No, not individually. Grants, tax treatment, financing costs and regional details are not fully included in this simplified calculator.

Are the results binding?

No. The result is for general information and initial guidance only. For a real project, you should compare offers and, if needed, seek professional advice.

Which matters more: feed-in or self-consumption?

In many cases, self-consumption matters more economically because it offsets expensive grid electricity. Feed-in still matters, since exported electricity can continue to generate value, but direct use is often the stronger driver.

How strongly does electricity price affect payback?

Very strongly. The higher the electricity price, the more valuable each kilowatt-hour of self-consumed solar power becomes. That usually increases annual benefit and can shorten the payback period.

Can I compare different PV system sizes with this calculator?

Yes. That is one of its most useful applications. You can test several system sizes, self-consumption assumptions and cost levels to estimate which setup best fits your household usage.

Is a short payback period the only thing that matters?

No. Roof suitability, technical quality, storage strategy, future self-consumption and long-term electricity savings also matter. A project with a slightly longer payback can still be a very good fit overall.