---
title: "Solar Panel Profitability Calculator | Numequo"
description: "Estimate solar panel payback time and net return from installation cost, electricity used on site, surplus sales and annual expenses."
canonical: "https://www.numequo.com/conversion/energy-power/solar-panel-calculator/"
locale: "en"
---
[Numequo](https://www.numequo.com/) › [Conversion](https://www.numequo.com/conversion/) › [Energy and power](https://www.numequo.com/conversion/energy-power/)
# Solar Panel Profitability Calculator
Enter the annual output from your installer or a local solar model, then compare self-consumption savings with surplus sales and costs. The preset figures are examples, not current tariffs.
## Input data
- **Installation cost after grants** - type: number; default: 8000; min: 1; max: 100000000; step: 100
- **Expected production (kWh/year)** - type: number; default: 4500; min: 1; max: 10000000; step: 10; From an installer quote or PVGIS
- **Self-consumed production (%)** - type: number; default: 40; min: 0; max: 100; step: 1; Share of solar output used directly
- **Electricity purchase price per kWh** - type: number; default: 0.25; min: 0; max: 10; step: 0.001; Variable energy price, excluding fixed charges
- **Surplus sale price per kWh** - type: number; default: 0.08; min: 0; max: 10; step: 0.001; Enter 0 if surplus earns nothing
- **Annual maintenance and other costs** - type: number; default: 100; min: 0; max: 1000000; step: 10
- **Annual production decline (%)** - type: number; default: 0.5; min: 0; max: 10; step: 0.1; 0.5% is an illustrative research median
- **Analysis period (years)** - type: number; default: 25; min: 1; max: 50; step: 1
- **Currency** - type: choice; default: EUR; options: Euro (€), US dollar ($), Pound sterling (£), Swiss franc (CHF)
## How it works
Year-one benefit = (annual production × self-consumed share × purchase price) + (annual production × exported share × surplus price) − annual costs. Later production falls by the chosen degradation rate. Payback occurs when cumulative net benefits cover the initial cost.
## Quick examples
- **Example project** - Installation cost after grants: 8000, Expected production (kWh/year): 4500, Self-consumed production (%): 40, Electricity purchase price per kWh: 0.25, Surplus sale price per kWh: 0.08, Annual maintenance and other costs: 100, Annual production decline (%): 0.5, Analysis period (years): 25, Currency: EUR
- **More self-consumption** - Installation cost after grants: 8000, Expected production (kWh/year): 4500, Self-consumed production (%): 70, Electricity purchase price per kWh: 0.25, Surplus sale price per kWh: 0.08, Annual maintenance and other costs: 100, Annual production decline (%): 0.5, Analysis period (years): 25, Currency: EUR
- **No payment for surplus** - Installation cost after grants: 8000, Expected production (kWh/year): 4500, Self-consumed production (%): 40, Electricity purchase price per kWh: 0.25, Surplus sale price per kWh: 0, Annual maintenance and other costs: 100, Annual production decline (%): 0.5, Analysis period (years): 25, Currency: EUR
## Understanding your result
This is a scenario, not a guaranteed return. Electricity prices and export contracts are held constant; financing, taxes, inverter replacement and changes in consumption are excluded. Enter an installation cost after any upfront grants. Check your contract and a location-specific production estimate.
Last verified: 29 September 2026 (2026-09-29)
## Sources
- European Commission · PVGIS production estimates
- U.S. Department of Energy · Solar payback factors
- NREL · Photovoltaic degradation rates
## Frequently asked questions
### How is payback time calculated?
Each year, savings and surplus revenue are added and costs are subtracted. The cumulative total is compared with the initial investment, with interpolation within the payback year.
### Is all solar output a saving on my bill?
No. Only electricity used directly replaces purchased electricity. The rest earns the entered surplus price, or nothing if that price is zero.
### Where do I find annual solar production?
Use the yearly kWh estimate in an installer quote or a local model such as PVGIS. Installed power alone is insufficient because orientation, shade and sunshine matter.
### Are tariffs and grants updated automatically?
No. You enter all prices and the installation cost after grants. The projection keeps prices constant; check your contract and current local rules.
## Related calculators
- [Compound Interest Calculator](https://www.numequo.com/finance/savings-investing/compound-interest-calculator/) - See how savings may grow with monthly compounding.
- [Investment Fee Calculator](https://www.numequo.com/finance/savings-investing/investment-fee-calculator/) - Compare how two annual fee rates affect a portfolio’s long-term value.
- [Savings Goal Calculator](https://www.numequo.com/finance/savings-investing/savings-goal-calculator/) - Calculate when you could reach a savings target or how much to save each month.
- [Loan Comparison Calculator](https://www.numequo.com/finance/loans/loan-comparison-calculator/) - Compare two fixed-rate loans by monthly payment, fees, insurance and total cost.
- [Rent or Buy Calculator](https://www.numequo.com/finance/real-estate/rent-or-buy-calculator/) - Compare projected homeowner equity with the renter’s invested capital over time.
- [Rental Property Return Calculator](https://www.numequo.com/finance/real-estate/rental-property-return-calculator/) - Estimate gross yield, net yield, monthly cash flow and cash-on-cash return.
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