What is peak sun hours and why does it matter?

Peak sun hours is the equivalent number of hours per day at full 1000 W per square metre irradiance that delivers the same energy as the real, variable daylight. It bundles latitude, climate, and seasonality into one daily figure, so a panel in a sunny region produces far more than the same panel in a cloudy one.

What does the performance ratio represent?

The performance ratio captures real-world losses between nameplate capacity and delivered energy: inverter inefficiency, wiring and soiling losses, temperature derating, and downtime. Well-designed systems run 0.75 to 0.85; the tool defaults to 0.8. Lower it for dusty sites or older equipment.

How is annual kWh calculated?

Annual kWh equals capacity in kWp, times peak sun hours per day, times the performance ratio, times 365 days. It is a standard first-pass estimate; a full yield study models hourly irradiance, tilt, shading, and inverter clipping, but this captures the bulk of the result.

What rate should I use for revenue?

Use the price you would actually receive per kWh: a feed-in tariff, a power purchase agreement rate, or your retail electricity price if the energy offsets on-farm consumption. Self-consumption is usually worth more per kWh than export, so model the split if both apply.

What is the Solar Farm Yield Estimator for Agricultural Land?

Multiply panel capacity in kWp by site peak sun hours and a performance ratio to estimate annual kWh, then value the output at a feed-in tariff or PPA rate. Built for farmers weighing agrivoltaic leases or on-farm solar against crop or grazing income. It runs free in your browser on Gera Tools, with nothing uploaded.

Solar Farm Yield Estimator for Agricultural Land

Name: Solar Farm Yield Estimator for Agricultural Land
Creator: Gera Tools
License: https://creativecommons.org/licenses/by/4.0/

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Putting solar on agricultural land can earn energy income alongside crops or grazing — but only if the numbers work. This estimator turns installed capacity, local sun, and system losses into an annual kWh figure and values it at your tariff so you can compare against current land use.

How it works

The standard first-pass yield formula is:

annual kWh = capacity (kWp) x peak sun hours/day x performance ratio x 365
revenue    = annual kWh x rate (per kWh)

Peak sun hours rolls latitude, climate, and seasonality into one daily number. The performance ratio (typically 0.75–0.85, default 0.8) accounts for inverter, wiring, soiling, and temperature losses between nameplate and delivered energy. The tool ships representative regional sun-hour averages you can override.

What is agrivoltaics and why does the combined model matter?

Agrivoltaics — sometimes called solar farming or co-generation agriculture — places solar panels and active land use on the same ground simultaneously. The combination can yield economic benefits that neither land use achieves alone: the panels generate electricity income while agriculture continues beneath or between the structures. In some configurations the partial shading from panels actually reduces heat and water stress on crops, improving yields of shade-tolerant species in hot, dry climates.

Common agrivoltaic configurations include:

Raised panel arrays — panels mounted high enough for machinery to pass beneath, with arable crops or pasture continuing below
Inter-row cultivation — ground crops or vegetables grown in the rows between fixed-tilt ground-mount structures
Sheep and pollinator grazing — the most common dual-use model; low-growing pasture and sheep integrate naturally with standard ground-mount heights

The revenue comparison for a land use decision therefore needs to account for both the solar income and whatever fraction of agricultural income is retained, not just the solar side.

Worked example

A 500 kWp array at 4.5 peak sun hours per day and a 0.8 performance ratio:

annual kWh = 500 x 4.5 x 0.8 x 365 = 657,000 kWh

At a 0.10 per-kWh power purchase agreement (PPA) rate that is 65,700 per year in solar revenue, before O&M, financing, and grid connection costs. If the same land previously earned 20,000 per year from grazing and a raised-panel agrivoltaic design retains 70% of that income, the combined revenue becomes roughly 65,700 + 14,000 = 79,700 per year — materially more than the agricultural use alone.

Key inputs to get right

Peak sun hours is the most location-sensitive variable. The tool provides regional defaults, but for a serious evaluation use your nearest met station or PVGIS to get a more accurate site-specific figure. A difference of 0.5 peak sun hours per day on a 500 kWp array changes annual revenue by roughly 7,000 at the above rate.

Performance ratio should be set conservatively for agricultural sites where panel cleaning may be less frequent than urban rooftops and where tilt angles are optimised for machinery clearance rather than maximum yield.

Rate selection: use the price you will actually receive — a feed-in tariff, a contracted PPA rate, or your retail electricity price if consumption is on-site. Self-consumption is generally worth more per kWh than export.

Notes

This is a screening estimate, not a bankable yield study. A full assessment models tilt, azimuth, shading, inverter clipping, and degradation over the asset life. Always model the retained agricultural income alongside the solar figures — a pure solar revenue number misrepresents the economics of a dual-use land decision.