# Solar pump for irrigation: when it makes sense and how to evaluate the project Source page: [https://perinirrigacao.com.br/en/blog/bomba-solar-para-irrigacao/](https://perinirrigacao.com.br/en/blog/bomba-solar-para-irrigacao/) Automatically translated from Portuguese. Our projects, service information and technical references relate to Brazil. Contact us to discuss your location and requirements. [Read the Portuguese original](https://perinirrigacao.com.br/blog/bomba-solar-para-irrigacao/) Planning Solar pumping needs to combine daily volume, head and available energy. See what to check in the project, in the reservoir and in the comparison of alternatives. By Team Perin Irrigação Published in October 29, 2026 (2026-10-29) 11 min read ![Drip system in the Perin Irrigação collection](https://perinirrigacao.com.br/assets/perin/responsive/service-drip-640-055633cbf116.webp) Photograph from the Perin Irrigação collection. ## Before you start Solar pump for irrigation: how photovoltaic pumping works, when it makes sense and what data to gather before requesting a project. **Summary:** The solar pump for irrigation uses energy from photovoltaic panels to drive the motor pump. In an isolated system, this allows pumping without a mains supply at the collection point. The choice depends on the daily volume, the head, the availability of sunlight and the way of distributing or storing the water. See what to evaluate in the project and a hypothetical example of energy calculation. ## How a solar irrigation pump works Photovoltaic pumping brings together the solar generator, power control or conditioning and the motor pump set. The arrangement may include a water reservoir, batteries or other power source. These components depend on the application; There is no single composition for all projects. There are dedicated frequency inverters that convert the direct current from the panels to drive compatible three-phase induction motors. Equipment with MPPT adjusts power capture according to irradiance. In direct solar power, rotation and pumping may vary during the day, depending on the sun, control and hydraulic circuit. Clouds and shading also change the available energy. This is the central point of the decision: checking the **daily volume** and the pressure that the system can deliver under operating conditions. Hydraulic stability depends on sizing and controls, both on the grid and on solar power. In direct solar pumping, without batteries or auxiliary sources, operation may reduce or stop when there is a lack of solar power. ### Water stored in place of batteries An alternative to batteries is to store the pumped water. A paper from the 1st Brazilian Solar Energy Congress (2007) describes this arrangement with an elevated reservoir. In the specific orientation of the S1 line, Lorentz also presents water storage as the first option for nighttime supply. This does not eliminate the assessment of useful volume, autonomy and pressure available for irrigation. ## When the solar pump for irrigation tends to make sense Some scenarios favor solar pumping: - **Collection away from the electrical grid**, when taking energy to the well or dam would require expensive or time-consuming work. - **Water demand concentrated in months of good irradiation**, checked with local data. - **Demand and head compatible with the selected set**, verified in the manufacturer's curves and pumping data. - **Possibility of irrigating by sectors throughout the day**, or filling a reservoir and distributing the water later. It tends to require more study when: - the area needs to be irrigated every few hours, in a fixed shift, or at night; - the discharge height is high and the flow rate is also high, which greatly increases the power of the panels; - the irrigation system needs stable pressure and there is no reservoir or defined pressurization strategy; - There is already an electrical network on site and the alternatives have not been compared. ### Drip and micro sprinkler need stable pressure [Drip irrigation](https://perinirrigacao.com.br/en/gotejamento/) and [microsprinkler](https://perinirrigacao.com.br/en/microaspersao/) must operate within the pressure range specified for the system and emitters. In direct pressurization, variation in rotation can compromise flow and uniformity if the pressure leaves this range. The project must define sectorization, control and operating conditions. An elevated reservoir also needs a sufficient useful difference in level to overcome losses and deliver the required pressure; Additional pressurization may be required. ## How to estimate the power of panels: a hypothetical example An initial energy estimate uses the **daily water demand** (m³/day), the **total head** (in meters of water column) and the **solar irradiation** of the location. A study published in the journal Irriga presents this simplified sequence: 1. **Daily hydraulic energy (Wh/day)** = 2.725 × daily volume (m³) × head (m). The factor 2.725 comes from physics: raising 1 m³ of water 1 meter requires around 2.725 Wh. 2. **Daily electrical energy** = hydraulic energy ÷ efficiency considered for the motor pump. 3. **Panel power (Wp)** = 1.25 × daily electrical energy ÷ hours of full sun (HSP). The study uses the factor 1.25 in this estimate; it is not a universal design margin. **Hypothetical example**, just to show the math: 20 m³ per day, total head of 40 m, combined engine and pump efficiency of 40% and 4.0 HSP in the critical month. The 40% only represents the conversion of the electrical energy received by the motor pump into hydraulic energy, not the output of the panels. The study adopted 25% in its own submersible pump simulation. None of these values ​​are a recommendation for another area. - Hydraulic energy: 2.725 × 20 × 40 = 2,180 Wh/day. - Electrical energy: 2,180 ÷ 0.40 = 5,450 Wh/day. - Panel power: 1.25 × 5,450 ÷ 4.0 ≈ 1,703 Wp. If other assumptions are maintained, doubling the manometric height doubles the result of this calculation. This does not confirm that an approximately 1.7 kWp array would deliver the desired volume in the field. The project must also check the pump curves, the daily irradiance profile, temperature, losses and electrical limits of the modules and controller, not counting the same loss twice. Wp indicates peak power under test conditions, not constant power available throughout the day. The head takes into account unevenness, pressure losses and pressure required at the delivery point. See the article about [how to choose the pump for irrigation](https://perinirrigacao.com.br/en/blog/bomba-para-irrigacao-como-escolher/). ### Use the critical month, not the annual average The irradiation changes throughout the year. Without batteries, sizing based on the annual average could result in a lack of water when it matters most. For irrigation, the critical month is the one in which the combination of low radiation and high water demand is most unfavorable, and it is not always the month with the lowest radiation. O **SunData**, from CRESESB/Cepel, offers monthly daily averages of irradiation in kWh/m²·day, in the horizontal plane and at suggested inclinations, based on the 2017 Brazilian Solar Energy Atlas. These are historical estimates to support the project. The choice of data must consider the location, orientation and effective inclination of the array. One HSP corresponds to the energy of one hour under irradiance of 1 kW/m²: 4 kWh/m² during the day are equivalent to 4 HSP. This does not mean exactly four hours of pump operation. Monthly averages also do not guarantee pumping on every cloudy day; storage and complementary source must be evaluated according to supply needs. The demand for water comes from crop management. The estimate for [evapotranspiration with ETo and Kc](https://perinirrigacao.com.br/en/blog/evapotranspiracao-na-irrigacao/) helps to arrive at the daily volume of each sector in the most demanding period. ## Isolated solar pump, grid power or connected generation Two alternatives usually enter the comparison: - **Electricity network with discount for irrigation.** Brazil's MME Normative Ordinance No. 137/2026 sets guidelines for consumers who meet the specified conditions, with a daily period of 8 hours and 30 minutes, continuous or divided into up to three blocks, outside the hours of 17:00 to 21:30. Confirm eligibility, the agreed schedule and the applicable discount with the electricity distributor before comparing costs. - **Distributed generation connected to the grid.** Law No. 14,300/2022 established the legal framework for distributed micro and minigeneration and the Electric Energy Compensation System. The surplus can be offset or converted into credits according to the rules applicable to the consumer unit. This does not mean full compensation for all charges or supply during a network outage. Pump hours remain subject to management, electrical availability and contracting. The comparison must bring together investment, electrical and hydraulic infrastructure, storage, maintenance, replacements and operating costs over the years. The price of the kit alone does not allow us to conclude which alternative will have the best return. ## Operation and maintenance care Solar-powered systems still require routine checks: - **Cleaning the panels.** Dirt accumulation can reduce generation. A study with modules at UFSM compared different cleaning routines; the results from that location do not define a universal frequency for rural properties. Inspection and cleaning must follow the module manual and the installation's access and safety conditions. - **Shading.** Trees and buildings can shade part of the arrangement. - **Filters and water quality.** Pump with variable speed does not change the filtration requirements of drip irrigation and microsprinkler. The routine of [irrigation system maintenance](https://perinirrigacao.com.br/en/blog/manutencao-irrigacao-periodo-chuvoso/) This also applies to solar systems. - **Inverter protections.** Speed adjustments, dry-running detection, and sleep mode are equipment and design dependent. Electrical services and parameterization must be carried out by technically qualified personnel, in accordance with the manuals and safety procedures. Turning off the power supply does not, in itself, eliminate the generation of panels exposed to light. ## FAQ ### Does a solar pump work on a cloudy day? It can operate at a lower capacity or stop, depending on the irradiance, the equipment and the height to be reached. There is no guarantee of pumping on every cloudy day. The project needs to evaluate the available volume and supply autonomy. ### What is the best solar pump for irrigation? It depends on the daily volume, head, water collection and irrigation system. A pump suitable for filling a reservoir may not be suitable for directly pressurizing a drip sector. ### Do I need a battery to irrigate with solar energy? Water storage can meet this need when volume and pressure have been anticipated. Batteries are an alternative in compatible arrangements, with specific control and protections; They must not be connected directly to a controller without the manufacturer's provision. ### Can I use the electric pump I already have? In some cases, yes. WEG's CFW500 Solar Pump Drive is an example of an application for three-phase induction motors. Electrical compatibility, control and hydraulic operating point must be checked. This possibility does not make any pump or inverter suitable for the system. ## Conclusion The solar irrigation pump must be evaluated by the required daily volume and pressure, sunny conditions, and operation and storage strategy. Hydraulic and electrical design need to work together. Comparison with the grid and connected generation helps you decide based on area conditions and costs. If you are evaluating solar pumping for your area, the team at [Perin Irrigação](https://perinirrigacao.com.br/en/sistemas-de-irrigacao/) can help analyze the case along with the project [localized irrigation](https://perinirrigacao.com.br/en/irrigacao-localizada/). Send municipality, crop, approximate area and water source via WhatsApp [(14) 99824-5219](https://wa.me/5514998245219) or by email contato@perinirrigacao.com.br. ## Sources consulted Research carried out on 10/29/2026. - [OLIVEIRA, G. S.; LIMA, E. F. A.; NUNES, V. F.; FREIRE, F. N. A.; ALMEIDA, A. F. L. Theoretical calculation of a photovoltaic pumping system and simulation of application in family farming. *Irrigates*, Botucatu, v. 1, no. 2, p. 47-52, 2018. Winotec Special Edition. DOI: 10.15809/irriga.2018v1n2p47-52.](https://revistas.fca.unesp.br/index.php/irriga/article/view/3594) - [WEG. *CFW500 Solar Pump Drive: application manual*.](https://static.weg.net/medias/downloadcenter/h6a/h3a/WEG-cfw500-manual-de-aplicacao-solar-pump-drive-10005027808.00.pt.pdf) - [COUTINHO, L. F. C.; BASCOPÉ, R. P. T. Photovoltaic system for water pumping. In: I Brazilian Congress of Solar Energy (I CBENS), Fortaleza, 2007.](https://anaiscbens.emnuvens.com.br/cbens/article/download/1727/1718/1718) - [LORENTZ. *Using batteries with S1 systems*.](https://www.lorentz.de/s/help/2196/using-batteries-with-s1-systems) - [CRESESB/CEPEL. *SunData v3.0*.](https://cresesb.cepel.br/index.php?section=sundata) - [INPE/LABREN. *Brazilian Solar Energy Atlas*, 2nd edition, 2017.](https://labren.ccst.inpe.br/atlas_2017.html) - [BRAZIL. Ministry of Mines and Energy. *MME Normative Ordinance No. 137, of June 8, 2026*.](https://www.gov.br/mme/pt-br/acesso-a-informacao/legislacao/portarias/2026/portaria-normativa-mme-n-137-2026.pdf) - [BRAZIL. *Law No. 14,300, of January 6, 2022*.](https://www2.camara.leg.br/legin/fed/lei/2022/lei-14300-6-janeiro-2022-792217-publicacaooriginal-164335-pl.html) - [FRANCHI, D.; CERVO, E. C.; MIOTTO, M.; GONZATTI, F.; FARRET, F. A. Assessment of the impacts of dirt on photovoltaic modules in the generation of electrical energy. *Latin American Journal of Energy Research*, v. 12, no. 2, p. 42-49, 2025. DOI: 10.21712/lajer.2025.v12.n2.p42-49.](https://periodicos.ufes.br/lajer/pt_BR/article/view/48621) ## From knowledge to your project. In agricultural production or green areas, the project starts with the conditions of your area and the water supply. Tell Perin what you need to irrigate. [Request quote](https://perinirrigacao.com.br/en/#contato)[Chat on WhatsApp](https://wa.me/5514998245219?text=Hello%21+I+want+to+talk+about+an+irrigation+project.)