By Vvon Engineering Team | Published | Updated
Size solar irrigation from sustainable water supply, total dynamic head and daily crop demand, then compare storage, controls and operating costs.
Solar EPC & street lighting RFQ checklist (TXT)
Replacing a diesel pump by matching its horsepower label can miss the required duty. Establish the seasonal pumping water level, delivery pressure, flow and daily volume before choosing the pump and array.
Solar pumping can reduce purchased fuel for daytime irrigation, but crop water demand, source sustainability and seasonal weather must determine the design. Lower pumping cost is not permission to over-extract groundwater.
A solar pumping system consists of PV panels, a solar pump controller (MPPT based), and a DC or AC submersible or surface pump. During daylight hours, the panels generate DC electricity that powers the pump directly. No battery is required for daytime-only irrigation. For farms that need to pump at night or store water, an elevated storage tank (gravity-fed distribution) or battery storage can be added.
The work a pump does is flow multiplied by total dynamic head, and total dynamic head is not the depth of the borehole. It is the lift from the pumping water level, which sits below the rest level once drawdown starts, up to the discharge point, plus every metre lost to friction in the rising main and delivery line. A design quoting a rest level measured in September will be short of head by the following March, and the shortfall appears as reduced flow rather than as an alarm.
A useful quotation shows the pump curve and expected daily delivery at the specified head. Horsepower alone cannot establish flow, acreage or price.
| Input | What to provide |
|---|---|
| Water source | Depth, seasonal pumping level and sustainable yield. |
| Delivery | Pipe size/length, elevation and required pressure. |
| Crop plan | Area, season, irrigation method and daily volume. |
| Power and controls | Motor, drive, dry-run protection and alternative supply. |
| Commercial scope | Pump, array, civil work, storage, maintenance and exclusions. |
A surface pump does not lift water. It lowers the pressure above it and lets the atmosphere push, which puts a ceiling of roughly ten metres of water column on the theory and considerably less on a real site once pipe friction, a hot afternoon and a slightly leaky foot valve have taken their share. Where the pumping level stays shallow, a surface centrifugal set on a shallow tubewell is cheaper and easier to repair. Where the dry season table falls away, that pump loses prime in March and the answer has to be a submersible sitting below the water, pushing rather than pulling.
Compare water storage with electrical storage and alternative supply. A suitable reservoir or tank can shift water delivery, but adds structure, land, maintenance, water-quality and pressure requirements. A battery may be appropriate for particular duties; decide from the complete operating case.
Use the local cropping calendar and seasonal pumping levels. Irrigation demand and PV output vary together differently by crop and site; do not assume one Boro month is the worst case everywhere.
| Season | Roughly | Irrigation demand | Design consequence |
|---|---|---|---|
| Boro | December to April | Highest, near continuous | The design point. Size on the March pumping level, not the December one |
| Aus | March to July | Moderate, supplementary | Overlaps the tail of Boro, so peak head and residual demand coincide |
| Aman | July to November | Low, dry spells only | Under-used array and monsoon cloud. Plan a second load or accept idle capacity |
| Rabi vegetables and pulses | November to February | Light and frequent | Small volumes, short intervals: suits a tank and drip layout |
That idle stretch is worth designing for. The same array can carry a homestead load, a small cold room at the collection point or a drinking water supply. Where the site has a utility connection and the distribution company permits it, a net-metered arrangement can absorb the surplus, but a standalone field pump usually has no connection and no way to export. Settle this before the controller is specified, not after the array is up.
Calculate diesel displacement from actual litres, delivered fuel cost, pumping hours and equivalent water delivery. Include pump/controller maintenance, replacement and any finance cost. A generic horsepower-based fuel saving does not establish payback.
What moves that arithmetic is running hours, the distance fuel has to be carried, and whether the pump serves one holding or sells water to neighbouring plots. Around most deep tubewells the operator is in practice a water seller with a command area, which changes the question from how much land you own to how much land the pump must serve.
IDCOL publishes a solar-irrigation programme and lending information. Confirm the current borrower/sponsor structure, eligibility and any financing or subsidy in writing before counting it. For a pump proposal, provide the command area, crop plan, source and tenure records, fuel receipts and water-service arrangement.
A factory array sits behind a gate with a guard on it. An irrigation array stands in an open field, and every component on it has a resale value. This is the part of the design missing from most quotations, and it is why so many rural solar assets stop working for reasons unconnected to the technology.
Agree ownership, water allocation, operator pay, maintenance funding and fault response before handover. Document the arrangement rather than relying on informal community responsibility.
Consult the relevant edition and the documents for the exact equipment and site: FAO: benefits and groundwater risks of solar-powered irrigation; IDCOL: renewable-energy lending terms; JinkoSolar: model datasheets, certificates, installation manuals and warranties; Power Division / SREDA: Net Metering Guidelines 2025, English.
Share your application, equipment requirements and procurement timeline. Our engineers can help clarify the configuration and scope for your enquiry.