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Solar energy to pump irrigation

See how many panels and how much area the irrigation pump requires for the number of hours it will run on sun.

Pre-sizing and estimating tool: the results do not replace a design, calculation, or report signed by a qualified professional, nor verification against the applicable standards.

Preliminary estimateRevision 12/11/2026
Pump
Location and panel

HSP is the site's average daily irradiation: check the solar atlas for your region. PR usually falls between 0.7 and 0.8.

Cost and savings

System cost and tariff are hypothetical values, for illustration only. Use installer quotes and your property's energy bill.

Economic analysis

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—Panels for the pump
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Power by pumping hours

Photovoltaic power required for each number of pumping hours; the highlighted bar is yours.

Tap the chart to see the values.

Power by site irradiation

Photovoltaic power required in places with different HSP; the dot is your location.

Tap the chart to see the values.

What if the data changes?

Drag the controls to simulate data different from what you entered (from 30% less to 30% more) and watch the result change instantly.

Tap the chart to see the values.

Power and panels by local sun

Photovoltaic power and number of panels for HSP of 4 to 6.5 kWh/m²/day, with the pump and panel you entered.

Step by step with your numbers

The calculation done in steps, with the values you entered.

    Project return

    Improvement cash flow: investment in year 0 and annual savings adjusted by the entered increase, discounted at the minimum attractive rate of return (TMA).

    Tap the chart to see the values.

    The calculation memo gathers this page's inputs, results, equations, assumptions, and references, with fields for project, responsible person, and review. The full report also includes the charts and interpretations, in color. In the print window, choose Save as PDF.

    How to use

    The card Project return shows the payback, NPV and IRR of the investment, with the year-by-year cash flow. The values are hypothetical and should be replaced with yours.

    Enter the pump's power, how many hours it runs per day on sunlight, the site's irradiation (HSP), the system performance (PR), and the panel you intend to use. The calculator shows the photovoltaic power, the number of panels, and the area.

    Worked example

    Pump of 15 kW for 8 hours, PSH of 5 kWh/m²/day, PR of 0.75 and a 550 Wp panel.

    Energy = 15 × 8 = 120 kWh/day. Power = 120 ÷ (5 × 0.75) = 32 kWp. Panels = 32,000 ÷ 550 = 59 panels, in about 153 m².

    Precautions

    • Without a battery, pumping hours must coincide with strong sunlight.
    • Check the pump curve: the actual power may differ from the nameplate.
    • See also the irrigation cost per bag to compare with grid electricity.

    Method, assumptions, and references

    Equations used

    Economic analysis: VPL = −investment + Σ savings in year t ÷ (1 + TMA)^t, with savings adjusted by the annual increase entered; payback is the year in which the cumulative total turns positive
    Daily energy (kWh) = Pump power (kW) × Pumping hours per day
    Photovoltaic power (kWp) = daily energy (kWh) ÷ (HSP (kWh/m²/day) × PR)
    Number of panels = Photovoltaic power (Wp) ÷ Power of each panel (Wp), rounded up

    Assumptions and limits

    • System without a battery: the pump works only with sunlight, and sizing considers the day's energy.
    • HSP and PR are averages; actual output varies with clouds, shading, slope, and temperature.
    • Does not include the inverter, structure, cables, or pump start-up; size the inverter to the pump power.

    Standards and technical documents

    • Brazilian Solar Energy Atlas (INPE and Ministry of Mines and Energy), latest edition, for the site's irradiation.

    Frequently asked questions

    What is HSP?

    Full-sun hours (HSP): the site's average daily irradiation, in kWh per square meter. It is what changes the sizing the most. Check the solar atlas for your region.

    Can I pump at night?

    Not without a battery. That is why pumping must happen during daylight, or the system needs storage.

    What is PR?

    System performance: the fraction of the panels' rated energy that reaches the pump, after losses in cables, inverter, and temperature. A typical value is between 0.7 and 0.8.

    Does this calculation replace a project?

    No. It estimates the order of magnitude. The design must be done by a qualified professional, with the pump curve and site data.