Available nowStep 1 of 3: model a plant yourselfSee all three steps
Solar Investment Calculator
A public, educational model of a hypothetical solar project — illustrative and modelled, not a real investment opportunity, forecast, or guarantee of return. Start from published, sourced reference values, or enter your own.
The model works in four steps:
Energy. Installed capacity times specific yield: the energy the plant makes in a year.
Size a hypothetical solar plant by its cost
Choose an amount. We treat it as the full cost of a hypothetical ground-mounted plant in Romania at a published reference cost, and show its size, what it could generate and what that equals. Every figure is modelled. Nothing here is an offer, a forecast or advice.
PVGIS county-seat value
Choose a county on the map or in the list above to use its county-seat value. Until then the figures use Romania’s reference value.
County outlines: World Bank Official Boundaries via geoBoundaries (gbOpen, Romania, first-level units), licensed under CC BY 4.0; simplified and projected by Astra. County seat values: PVGIS © European Union, 2001–2026 (European Commission, Joint Research Centre).
Modelled · Capacity of a hypothetical plant
Enter an amount to see the modelled capacity.
At €700,000 per MWp (DC), range €600,000 to €800,000, excluding VAT, including land, development, grid connection and construction. Based on an Astra Electric price set in 2026 for a plant to be built in 2027, plus sourced land and development costs. Romanian projects from 2023 to 2026 have a median near €690,000.
Modelled · Annual generation of that plant, year 1
Enter an amount to see the modelled annual generation.
1,280 kWh per kWp a year, fixed tilt, falling 0.5% a year.
Lower and upper values combine the ends of the cost and yield ranges.
Revenue and return figures for this estimate are under review and are not shown yet.
Modelled · Equivalent to, in year 1 (approx.)
Enter an amount to see what that generation equals.
Every figure here is modelled.
It is not an offer, advice or a real project. Generation, prices (which can turn negative) and costs can differ from what is modelled. The model leaves out construction, grid, counterparty and regulatory risk, curtailment, negative prices, VAT, tax, fees, debt and inflation. It describes the plant as a whole, with no debt, and is not any investor’s cash flow.
The reference values behind these figures
- All-in cost per MWp (DC)
- 700,000 (range 600,000 to 800,000) EUR per MWp (DC), excluding VAT
- Base from a Tier 4 reference construction price by decision d-28ec139b (methodology v2 §12 exception) plus sourced development and land costs. Tier 3 figures are corroborated: the median of seven Romanian project totals from 2023 to 2026 is near €690,000, within 3% of the base. Low end cited from Dama Solar (EIB, GW scale); high end with sell-side development, dearer land and a 5% contingency.
- Sources: Astra Electric, Astra Electric reference model, internal: methodology v2 section 12, decision d-28ec139b, Tier 4; pfnexus, RTB solar PV valuation trends in Romania: ready-to-build buy-side average, H1 2024 (2025-01-05), Tier 3; agrointel.ro, reporting INS, INS 2024 average price of arable land in Romania (2025-12-23), Tier 3; energynews.pro, ENNA solar project: land area for its capacity (2025-04-30), Tier 3; European Investment Bank, Dama Solar financing: all-in cost per MWp at GW scale (the low end) (2026-09-30), Tier 1.
- Specific yield
- 1,280 (range 1,200 to 1,320) MWh per MWp (DC) per year
- Fixed-tilt PVGIS values for Romania; the downside takes the low end and the upside the high end.
- Sources: European Commission, Joint Research Centre, PVGIS 5.3 (SARAH-3) PVcalc, fixed tilt, Romanian sites, queried 2026-10-01 and 2026-10-02, Tier 1; European Bank for Reconstruction and Development, Romanian solar project disclosures (2024-08-21 and 2025-11-27) (2025-11-27), Tier 1.
- Degradation
- 0.5% (range 0.4% to 0.75%) a year
- The Tier 3 report is corroborated by NREL's Tier 1 fleet data. Applied from year 2: year 1 has no degradation.
- Sources: NREL, PV fleet performance loss rates (2024), Tier 1; pv magazine, Report on PV module degradation rates (2024-01-29), Tier 3.
- A Romanian home's yearly electricity use
- 1,800 kWh per year
- Used for an equivalent only, never as a household count.
- Sources: ODYSSEE-MURE, Electricity consumption per dwelling, Romania (2025-11), Tier 2.
- Grid emission factor
- 0.17 t CO2 per MWh
- A national-mix value in a regulated (ANRE-format) label published by a supplier; to be corroborated against ANRE's own publication (methodology v2 §22). Shown as what the grid emits for the same electricity, not as a saving.
- Sources: Romgaz, Electricity supply label for 2025 (ANRE format): Romania's mix, 170.01 g CO2 per kWh (2026-04), Tier 3.
- A full charge of an average EV battery
- 73.6 kWh
- Used for an equivalent only. Tier 3, not yet corroborated by a Tier 1 or 2 source (methodology v2 §22).
- Sources: EV Database, Average usable battery capacity of electric cars, 2026 (2026), Tier 3.
- A phone charge
- 0.019 kWh
- Used for an equivalent only.
- Sources: US EPA, Greenhouse gas equivalencies calculator: smartphone charged (2026-08-04), Tier 1.
Full model: enter your own assumptions
Shared across all three scenarios below — e.g. 25.
Project assumptions
Advanced assumptions (optional)
Leave any of these blank to use the model's neutral default — never a market assumption, just "no effect" (0%, or 100% for availability).
Result
Enter the base scenario's project assumptions above to see modeled results.
Modeled scenario comparison
Each scenario is a distinct, independently entered set of assumptions — not a probability-weighted forecast and not a guaranteed range of outcomes. Downside and upside are only as different from Base as the assumptions you give them.
| Scenario | Projected IRR | Illustrative ROI | Modeled payback |
|---|---|---|---|
| Downside | Project lifetime must be a whole number of years (0 or greater). | ||
| Base | Project lifetime must be a whole number of years (0 or greater). | ||
| Upside | Project lifetime must be a whole number of years (0 or greater). | ||
Methodology & disclosures
This calculator models a hypothetical solar project using the assumptions you enter (Public Solar Calculator Methodology V1.0). It is an illustrative, modelled projection, not a guarantee, a promise, or a prediction of actual results.
- Actual results can differ materially from these modelled assumptions.
- Electricity prices can change — including becoming negative during high-solar-output periods — and the price used here is illustrative, not a market forecast.
- Generation can differ from the modelled assumption due to weather, equipment performance, and site-specific conditions.
- Operating costs can differ from the modelled assumption.
- A real opportunity's PPA, CfD, or merchant-price exposure, financing, ownership structure, and fee structure can all produce a materially different result than this generic model.
- Tax and legal treatment may differ by investor, jurisdiction, and project structure; this calculator does not model taxes.
- This calculator is not financial, legal, or tax advice.
- Actual investment opportunities require project-specific review and due diligence — this tool does not represent, and must not be confused with, any specific, real investment opportunity.
The result shown is project-level cash flow at 100% notional ownership with no financing — this V1 model does not split cash flow across investors, does not model debt, and does not model an actual distribution schedule. It should be read as modeled project cash flow, not as a specific investor's guaranteed income or a projected distribution.
Show the working, step by step
Energy: show the working
What it uses. Two of your inputs, installed capacity and specific yield, and three optional ones, annual degradation, availability and curtailment, if you enter them.
What it works out. Installed capacity is multiplied by specific yield: that is what the plant would make in a year before any loss. Annual degradation lowers it a little further each year after the first. In every year, availability then multiplies it by the share of time the plant can generate, and curtailment subtracts the share the grid does not take: what is left is that year's energy.
Specific yield depends on where the plant is: the same panels make more energy in a sunnier place. The map in the Quick estimate shows how it varies across Romania.
What the next step receives. Revenue receives the energy of every year of the project lifetime.
Revenue: show the working
What it uses. One of your inputs, the electricity price, and one optional one, electricity-price escalation, if you enter it.
What it works out. Each year's energy from the Energy step is multiplied by the electricity price: that is the year's revenue. The price is the illustrative one you choose, not a market forecast. Electricity-price escalation changes it by the same rate every year after the first.
What the next step receives. Costs receives the revenue of every year.
Costs: show the working
What it uses. Two of your inputs, annual O&M and project CAPEX, and one optional one, O&M escalation, if you enter it.
What it works out. Annual O&M is subtracted from each year's revenue: what is left is the year's net cash flow. O&M escalation changes annual O&M by the same rate every year after the first. Project CAPEX is not spread over the years: it is counted once, as an outlay before the first year.
What the next step receives. Result receives the up-front outlay and the net cash flow of every year.
Result: show the working
What it uses. No input of its own: it works with what the three steps before it produce, over the project lifetime you set.
What it works out. The up-front outlay and each year's net cash flow are put in order as one modelled cash flow, for each of the three scenarios you define, Base, Upside and Downside, and the calculator reads its outputs from it. Total cash flow is every year's net cash flow added up, with the outlay subtracted. ROI divides that total by everything paid out. Payback is how long the yearly net cash flows take to make up the outlay. IRR is the yearly discount rate at which the outlay and the discounted net cash flows balance.
What comes out. This is the last step. The calculator shows those outputs, each labelled as modelled: they describe a hypothetical project, not a result any project has achieved.
The Romania map and county values
County outlines: World Bank Official Boundaries via geoBoundaries (gbOpen, Romania, first-level units, simplified release, build 2023-12-12), licensed under Creative Commons Attribution 4.0 (CC BY 4.0). Changes: simplified, projected and joined with PVGIS county-seat values by Astra.
County values: PVGIS © European Union, 2001–2026 (European Commission, Joint Research Centre), PVGIS 5.3, PVGIS-SARAH3 radiation 2005–2023, queried on 2026-10-02 at each county seat for 1 kWp of crystalline silicon, free-standing, 14% system loss, slope and azimuth optimised. PVGIS results are free to use; European Commission content is licensed under CC BY 4.0.
Each county is placed in one of five equal bands between the lowest and the highest county-seat value. A seat in a valley can understate a mountain county (Reșița in Caraș-Severin, Baia Mare in Maramureș), so a value describes its seat, not every site in the county. Choosing a county in the Quick estimate sets its specific yield to the seat's value rounded to 10 kWh per kWp a year; the lower and upper ends keep Romania's reference ratios (1,200 and 1,320 to 1,280). The map is drawn on this website; no map or PVGIS service is contacted.