A first-pass financial model for a solar, wind, hydro or hybrid power plant. Enter your site data and local tariff — get year-one revenue, simple payback, 25-year NPV and IRR.
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This planner is a compressed engineering-and-finance model for a distributed renewable-energy project. It answers the seven questions a lender or investor cares about: expected annual energy production, capital cost, operating cost, revenue at the local tariff, simple payback, 25-year NPV at your cost of capital, and IRR. Every input maps to a data source you can look up in an afternoon — irradiance from NASA POWER or PVGIS for solar, mean wind speed from the Global Wind Atlas for wind turbines, head and flow measurements for micro-hydro, and your own utility bill for the retail tariff.
The core sizing formula is the standard one every solar developer learns cold: annual energy equals installed nameplate (kWp) times site-specific yield (kWh per kWp per year) times performance ratio. Performance ratio bundles inverter efficiency, wiring losses, soiling and temperature derate into one number and typically sits between 0.75 and 0.82 for a well-designed rooftop system in year one, degrading by roughly 0.5 % per year. Wind and hydro use the same shape of formula with different physical inputs — the planner exposes technology presets so you can start from a reasonable default and then tune it to your site.
The revenue model splits generation into self-consumption savings (kWh you use on-site, valued at the retail tariff) and grid export (kWh you send back, valued at the export or feed-in tariff). Under a true 1:1 net-metering regime the two rates are equal; under net-billing or feed-in-tariff regimes they usually differ. Enter both rates from your national regulator or utility website — the same six regulatory questions apply everywhere: is grid-tied generation permitted, what is the ceiling on inverter capacity, is the compensation mechanism net-metering, net-billing or feed-in, what inverter certification is required, who owns and pays for the export meter, and what is the approval timeline.
CAPEX and OPEX should come from real quotes in your market — module and inverter prices vary 30–60 % by country, season and quotation cycle, so a percentage-of-CAPEX shape (roughly 45–55 % modules, 8–12 % inverter, 8–10 % mounting, 15–20 % installation) is more stable than any published local-currency number. OPEX for a rooftop solar system typically runs 1–2 % of CAPEX per year and covers insurance, cleaning, monitoring and a sinking fund for inverter replacement in year 10–12.
The 25-year NPV uses your entered discount rate — usually your commercial borrowing rate, which runs 5–8 % in developed markets and 9–15 % in emerging markets. If IRR clears cost of capital by at least three percentage points, the project passes the hurdle-rate test. Battery storage should be added only when the site has a real resilience requirement — the CAPEX per kWh of stored energy still runs above the retail tariff on a lifetime basis in most markets, so batteries are bought for outage tolerance, not returns.
Divide the total upfront cost by the annual net cash flow (yearly revenue minus yearly running cost). This planner does it live: enter the system size in kW, the daily running hours at full power, your export tariff and the total install cost — the "Years to break even" tile shows the answer. A typical rooftop solar system pays back in 5–10 years.
Anywhere from 10 % (mature market, low tariff) to 25 %+ (emerging market, high tariff, favourable net-metering). The test is whether the calculated IRR exceeds your loan or savings interest rate by at least three percentage points — that clears the hurdle rate any lender or investor applies.
NPV (Net Present Value) is the total profit over the system's lifetime, adjusted for the time value of money. This tool computes 25-year NPV using your entered discount rate: each year's revenue is discounted back to today's money, degraded output is factored in, and the upfront cost is subtracted. A positive NPV means the project earns more than your money would earn elsewhere at the same risk.
Solar panels only produce at nameplate power for a few "peak sun hours" per day — the rest of the daylight hours produce a fraction of that. Peak sun hours vary by country: 5.5 in the UAE, 4.8 in Bangladesh and India, 4.5 in Southern Europe, 2.6 in the UK. The planner's "Which country?" dropdown auto-fills this number, and you can override it for your specific site.
Check your national regulator's current published feed-in tariff or net-metering rulebook. Under a true 1-for-1 net-metering regime, the export rate equals your electricity bill rate. Under a net-billing or feed-in regime it is a separate, usually lower, rate. Utility websites publish the current number — it is the price the grid pays you per kWh you export.
A 10 kW system running 4.8 peak sun hours per day produces about 10 × 4.8 = 48 kWh per day of theoretical output, or roughly 38 kWh/day after real-world losses (system quality ≈ 0.79). Over a year that is around 14,000 kWh. In a sunnier location (UAE, Saudi Arabia) the same system produces 16,000–18,000 kWh/year; in a cloudier one (UK, Netherlands) closer to 8,000–9,000 kWh/year.
Yes. Pick the technology at the top and the planner applies the right performance ratio (0.30 for wind, 0.85 for hydro, 0.79 for solar). For wind, enter the equivalent "full-power hours" per day from an on-site anemometer study. For hydro, use the flow-duration curve's 90-percentile flow to derive hours — a plant that stops in the dry season loses revenue.
The planner covers battery-inclusive projects: pick the "Solar + battery backup" preset and increase the CAPEX by 40–80 % for the battery bank. Batteries usually reduce IRR because the extra CAPEX per stored kWh runs above the retail tariff on a lifetime basis — buy storage for outage resilience, not for return.
The tool solves IRR by bisection over 25 years of degrading cashflow — accurate to within about 0.1 percentage points for realistic inputs. It assumes constant tariffs and constant OPEX. For sensitivity to tariff changes, re-enter the export rate at 80 % of the current value and compare the two IRRs.
Yes. This planner is a first-pass screening tool. Sizing beyond these numbers — on-site anemometry for wind, flow-duration curves for hydro, shading analysis for a partial-obstruction rooftop, structural loading for rooftop mounting, single-line diagrams for grid interconnection — needs a paid feasibility study and a licensed engineer of record for utility approval and inspection.
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