Solar PV Residential Model — Evaluate a Home Solar PV Investment in Any of 8 Countries, Including All Local Incentives

Description
If you advise homeowners, sell residential solar installations or evaluate home energy investments, you know the problem: every country has a completely different incentive structure, and a generic payback calculator does not handle any of them correctly. Italy spreads a 50% tax deduction over ten years. The USA gives a 30% upfront tax credit. Germany has zero VAT on hardware plus a KfW grant for batteries. France pays a per-kWp prime upfront. Australia applies an STC rebate at point of sale that already reduces the installer quote. Sweden gives a 15% Grön Teknik credit capped at SEK 50,000 per person per year. No standard spreadsheet models all of these correctly in one place.
This model does.

Open it, select your country and scenario, enter the system size in kWp and the household's annual consumption — and every output updates automatically. Simple payback, Project IRR, NPV, annual bill saving, export revenue, annual tax detrazione where applicable. A full 20-year equity cash flow with panel degradation at 0.45% per year and O&M escalation, correctly reflecting the timing of each incentive. Ready to share with a homeowner, a retailer or a lender.


What makes it different from a generic payback calculator
The incentive engine models the timing and mechanics of each country's support correctly, not just as a percentage reduction on CAPEX. Italy's detrazione fiscale 50% is not an upfront discount — it is an annual cash inflow of €360 per year for 10 years on a €7,200 investment, and the model treats it exactly that way in the cash flow. This changes the payback profile significantly compared to a tool that simply deducts 50% from net CAPEX. The US Federal ITC is modelled as an upfront tax credit reducing net CAPEX in year zero, not as a grant. The UK's zero VAT is embedded in the CAPEX benchmarks since UK installers already quote net of the 20% VAT exemption. Australia's STC rebate is similarly embedded in the post-STC CAPEX figures, while the Cheaper Home Batteries Program rebate of 30% on battery cost is applied separately to BESS. Sweden's Grön Teknik 15% credit is subject to a cap of SEK 50,000 per person per year and is modelled as an upfront reduction within that cap.

The revenue model reflects how residential solar actually earns money. Bill saving on self-consumed energy uses country-specific retail household tariffs. Export revenue uses separate, lower export rates — reflecting the gap between retail and feed-in prices that has widened in most markets. Self-consumption rates default to country benchmarks — typically 35-45% for residential — but can be overridden for site-specific profiling.

The optional BESS module adds co-located battery storage with a single toggle. Battery CAPEX, round-trip efficiency, cycles and degradation are loaded automatically by country and scenario, and the additional bill saving from increased self-consumption is calculated separately alongside any applicable battery grant — KfW 442 in Germany, ITC on co-located storage in the USA, the Cheaper Home Batteries Program in Australia and Grön Teknik 50% in Sweden.


Who this is for
Solar installers and retailers preparing financial proposals for residential customers. Energy advisors and consultants evaluating home energy investments across multiple markets. Banks and green mortgage lenders assessing the financial case for solar-backed lending. Homeowners or building owners wanting a rigorous analysis of a PV investment before signing a contract.


Workbook: README · CONTROL_PANEL · INCENTIVE_CONFIG · PV_INPUTS · BESS_INPUTS · FINANCIAL_MODEL · DASHBOARD.


For custom versions, country extensions or specific requests, contact us at [email protected]