Cotton is the backbone of dryland agriculture across western and central India — 11.7 million hectares under cultivation, roughly 25% of global production, and a sowing-to-picking cycle that runs five to six months from June to November. Gujarat, Maharashtra, Telangana, Karnataka, and Andhra Pradesh together carry more than 90% of India’s cotton acreage. In 2026, a properly sized PM-KUSUM solar pump — typically 5 HP (horsepower) for the average 5-acre Bt cotton holding — delivers the consistent flowering-to-boll irrigation cotton demands while cutting the ₹50,000–₹80,000 per acre annual diesel bill cotton farmers currently carry. This guide walks through the crop-stage water schedule, HP selection logic, drip pairing economics, and the KUSUM subsidy maths that make solar the default choice for cotton in 2026.
Direct answer. A 5-acre cotton farm needs roughly 3,000–4,000 litres of water per day at peak flowering and boll formation (September–October) — a 5 HP solar pump on a 4.5–5 kWp (kilowatt-peak) array meets that demand reliably. The total system costs ₹3–3.5 lakh; after the 60–75% PM-KUSUM Component B subsidy (30% central + 30% state + up to 15% top-up in cotton-belt states), the farmer’s out-of-pocket drops to ₹85,000–₹1.4 lakh, with diesel-saving payback in 2–3 years.
If you’re a cotton farmer weighing the switch from diesel to solar, the question is rarely whether solar works — it’s which HP rating matches your acreage, water table, and the four distinct demand peaks your crop hits between sowing and picking. That’s the gap this guide closes.
Cotton Crop Water Requirement by Stage
Cotton is not a uniformly thirsty crop. The total seasonal demand is 600–1,200 mm depending on variety and region, but the demand curve has four distinct phases. Getting the pump size right means matching the peak, not the average — under-sizing during flowering directly hits boll count, and boll count is what determines lint yield.
| Crop stage | Days after sowing | Daily water (L/acre) | Sensitivity |
|---|---|---|---|
| Germination & seedling | 0–25 | 100–200 | Low — over-watering causes damping-off |
| Vegetative growth | 26–60 | 300–450 | Medium — squares form during this phase |
| Flowering | 61–100 | 500–700 | Critical — flower drop on water stress |
| Boll formation | 101–140 | 600–800 | Critical — boll size and lint length |
| Boll opening & picking | 141–180 | 200–300 | Low — excess water reduces fibre quality |
Source: Indian Council of Agricultural Research (ICAR) Central Institute for Cotton Research water-management bulletins; corroborated by Cotton Corporation of India cultivation advisories. The takeaway: the September–October flowering-to-boll window is when your pump earns its keep, and it’s the window that dictates HP sizing.
The Cotton Solar Pump Sizing Framework — 4 Crop-Stage Inputs
This is the framework Heaven Green uses across every cotton-belt design. Four inputs, one HP rating. Skip an input and you either over-spend on a pump that idles half the year, or under-size and stress your crop at the worst possible moment.
Input 1 — Vegetative-Phase Daily Draw
Calculate based on acreage × 400 litres/acre at week 4–8. For a 5-acre plot, that’s 2,000 L/day. This is your baseline minimum delivery, not the design point.
Input 2 — Flowering-Phase Peak Draw
This is the design point. Multiply acreage by 700 L/acre to set the ceiling. A 5-acre cotton farm needs 3,500 L/day during September flowering. Size the pump to deliver this in 5–6 sunshine hours — the effective solar operating window between 9 AM and 4 PM during the south-west monsoon’s tail.
Input 3 — Boll-Formation Peak Draw
Boll formation runs 30–40 days and overlaps with flowering. Demand stays at 600–800 L/acre/day. The pump must sustain peak output across 60+ consecutive days without thermal de-rating — which is why ALMM (Approved List of Models and Manufacturers) panels and BIS-certified controllers matter more in cotton than in horticulture.
Input 4 — Boll-Opening Tail-Off
October-end to November, demand drops to 200–300 L/acre/day. Excess irrigation now causes boll rot and stains lint — a costly defect at ginning. Solar pumps allow farmers to throttle naturally (run fewer hours) rather than fighting a diesel pump’s minimum-run cycle.
Match the pump to Input 2; everything else follows. For depth-based sizing where your borewell is deeper than 100 ft, layer this framework over our KUSUM pump size by borewell depth guide.
HP Selection by Cotton Acreage and Region
Region matters because peak-sun-hours (PSH) and water-table depth shift the HP calculation. Saurashtra cotton runs on deeper borewells than Vidarbha; Telangana farmers face fluctuating water tables post-Kharif. The table below is the working chart we hand to KUSUM applicants.
| Region | Typical acreage | Borewell depth | Recommended HP | Array size |
|---|---|---|---|---|
| Vidarbha (Maharashtra) | 4–6 acres | 60–120 ft | 5 HP AC | 4.8 kWp |
| Marathwada (Maharashtra) | 5–8 acres | 80–150 ft | 5–7.5 HP AC | 4.8–7.5 kWp |
| Saurashtra (Gujarat) | 6–10 acres | 150–250 ft | 7.5 HP AC submersible | 9 kWp |
| North Gujarat | 5–8 acres | 200–300 ft | 7.5–10 HP AC submersible | 9–12 kWp |
| Telangana (Adilabad, Warangal) | 4–7 acres | 100–180 ft | 5–7.5 HP AC | 4.8–7.5 kWp |
| Raichur–Yadgir (Karnataka) | 5–8 acres | 80–140 ft | 5–7.5 HP AC | 4.8–7.5 kWp |
| Guntur–Kurnool (Andhra) | 4–6 acres | 60–100 ft | 5 HP AC | 4.8 kWp |
DISCOM and KUSUM channels vary by state — Maharashtra runs Mahaurja, Gujarat runs GEDA, Telangana runs TSREDCO. For the Maharashtra application sequence specifically, see KUSUM Maharashtra application 2026. For grid-tied Component C feeder solarisation (which an increasing share of Vidarbha cooperatives are using to power cluster pumps), see KUSUM Component C grid-tied pump.
Pairing Solar Pump with Drip Irrigation for Cotton
A flood-irrigated cotton field consumes 800–1,000 mm of water per season. The same crop on drip drops to 450–600 mm — a 45–55% reduction with no yield loss, and in many trials a 10–15% yield gain because of stable root-zone moisture. Drip and solar pair naturally: the pump’s lower flow rate (compared with a diesel pump fighting the ridge-and-furrow demand of flood irrigation) matches the steady, low-pressure delivery drip lines need.
For a 5-acre cotton farm:
- Flood + diesel pump: ~4,000–5,000 L/day at peak, 4–5 hours/day runtime, ₹1.2–1.5 lakh annual diesel.
- Flood + 5 HP solar pump: same water volume, zero diesel, but field-application losses still 35–40%.
- Drip + 5 HP solar pump: 2,200–2,800 L/day at peak — the pump now runs comfortably below capacity, leaving headroom for hotter days; drip emitters deliver to root zone with <10% loss.
The drip-plus-solar combination is what unlocks the 2-year payback Heaven Green models for cotton. Most state agriculture departments (Gujarat, Maharashtra, Telangana) layer a separate Per Drop More Crop (PDMC) subsidy on drip equipment — a farmer can stack PDMC with KUSUM in the same season.
Plan your cotton solar pump. Heaven Green’s agri team sizes your 5 HP or 7.5 HP system based on your borewell test report, cotton acreage, and drip layout — and files the KUSUM application end-to-end. Get a free farm assessment →
Cost, KUSUM Subsidy, and 5-Year ROI for Cotton Farmers
PM-KUSUM Component B (individual standalone solar pumps for off-grid farmers) is the dominant pathway for cotton. The subsidy structure is 30% central + 30% state + farmer 40%, with cotton-belt states often topping up to push the farmer share down further. Telangana, Andhra Pradesh, and Maharashtra have all run cotton-specific KUSUM clusters at 75–90% subsidised rates through 2024–25, which has continued into the 2026 sanction cycle.
| Pump | All-in system cost | After 60% KUSUM | After 75% top-up | Annual diesel saved | Simple payback |
|---|---|---|---|---|---|
| 3 HP AC | ₹2.0–2.3 lakh | ₹80,000–₹92,000 | ₹50,000–₹58,000 | ₹40,000–₹60,000 | 1.5–2 yrs |
| 5 HP AC | ₹3.0–3.5 lakh | ₹1.2–1.4 lakh | ₹75,000–₹90,000 | ₹75,000–₹1.2 lakh | 2–2.5 yrs |
| 7.5 HP AC submersible | ₹3.8–4.4 lakh | ₹1.52–₹1.76 lakh | ₹95,000–₹1.1 lakh | ₹1.0–₹1.5 lakh | 2–3 yrs |
| 10 HP AC submersible | ₹5.0–5.6 lakh | ₹2.0–₹2.24 lakh | ₹1.25–₹1.4 lakh | ₹1.5–₹2.0 lakh | 2.5–3 yrs |
Source: PM-KUSUM portal benchmark rates, MNRE Component B 2025–26 sanction notifications, and Heaven Green field cost data. Diesel-saving assumptions use ₹95/L average rural retail and a typical cotton pumping requirement of 800–1,200 L of diesel per acre per season. For a head-to-head economic model, read diesel vs solar pump ROI.
Beyond direct diesel savings, cotton farmers report two compounding gains over 5 years: (a) 8–12% yield uplift from on-demand irrigation that previously waited for diesel rationing, and (b) recovery of ₹15,000–₹25,000 per year in pump maintenance and engine-overhaul costs.
Common Mistakes Cotton Farmers Make
Across the cotton-belt KUSUM installations Heaven Green has audited, the same six errors keep appearing. All of them are preventable with a pre-application checklist.
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1
Sizing on average demand, not peak. Cotton's flowering peak is 2x the vegetative average. Designing for the average means flower drop in September — and that's lint you cannot recover.
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2
Ignoring borewell yield. A 7.5 HP pump on a 2,000 L/hour yielding borewell will short-cycle and damage the motor. Always pair the HP rating to the bore's tested yield.
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3
Skipping drip integration. Solar without drip locks you into flood-irrigation losses. The pump-plus-drip combo cuts seasonal water demand 45–55%.
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4
Choosing non-ALMM panels for a lower bid. KUSUM mandates ALMM-listed modules. Off-list panels fail the state nodal agency inspection and the subsidy disbursement halts.
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5
Not filing the land record (7/12 or pahani) with the application. Maharashtra Mahaurja and Telangana TSREDCO both reject applications missing current-year land extracts.
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6
Forgetting the pump-controller warranty. The controller is the most failure-prone component. Insist on a 5-year controller warranty, not the default 2.
If your farm is large enough that Component A (decentralised ground-mount solar power plants on barren or fallow land) makes sense alongside the pump, read KUSUM Component A landowner — Saurashtra and North Gujarat farmers with surplus acreage often combine the two.
Drip + Solar vs Flood + Solar
Both are valid configurations under KUSUM. The choice usually comes down to capital headroom, drip-line laying labour, and whether the farmer is already running drip on horticulture intercrops.
- + 45–55% water reduction
- + 10–15% yield uplift on Bt cotton
- + Lower pump HP needed (cost savings)
- + PDMC subsidy stack with KUSUM
- − ₹35,000–₹50,000 per acre drip capex
- − Annual clogging maintenance
- + Zero additional capex
- + Familiar field practice
- + Simpler maintenance — just the pump
- − 35–40% field application losses
- − Larger pump HP needed for same acreage
- − No PDMC subsidy access
Verdict. For a 5-acre Bt cotton farm with a working borewell, the drip + 5 HP solar combination is the right answer 9 times out of 10. The PDMC subsidy covers 55–80% of drip capex (state-dependent), the smaller solar pump fits comfortably under KUSUM Component B’s Maharashtra and Telangana sanction caps, and the water-saving lets you irrigate a second season — sometimes a winter pulses or summer fodder crop — that pure flood farmers cannot.
How Heaven Green Energy Designs Cotton Solar Pumps
Heaven Green has deployed solar pumps across the Vidarbha, Marathwada, and Telangana cotton belts since 2019. Our agri-solar team handles the full KUSUM workflow — borewell yield testing, HP sizing against the four-stage demand curve, state nodal agency liaison, drip integration design, and the post-installation O&M cycle.
- Borewell yield + static water level test before sizing, so the pump never short-cycles.
- ALMM tier-1 mono-PERC panels (Adani, Waaree, or Tata) sized to meet the September flowering peak.
- BIS-certified VFD (variable-frequency drive) controllers with 5-year warranty — protects against grid-less restart spikes.
- AC submersible or surface pumps from Shakti, Lubi, or CRI, depending on borewell geometry.
- KUSUM Component B application filing with state nodal agency (Mahaurja, GEDA, TSREDCO, KREDL, NREDCAP).
- Drip integration design with PDMC subsidy paperwork in parallel.
Explore the services that match your project:
- PM-KUSUM solar pump scheme — end-to-end Component B delivery for individual cotton farmers.
- KUSUM complete guide — full subsidy structure, eligibility, and timelines.
- Solar calculator — size your pump and see the post-subsidy cost in 60 seconds.
- Contact our agri team — borewell-based sizing report within 48 hours.
Frequently Asked Questions
What HP solar pump do I need for a 5-acre cotton farm?
For most 5-acre Bt cotton plots with a borewell yielding 3,000+ litres per hour and a depth between 80 and 150 feet, a 5 HP AC solar pump on a 4.5–5 kWp panel array is the correct sizing. This delivers the 3,000–4,000 litres per day demanded at the September–October flowering and boll-formation peak. If your borewell is deeper than 200 feet or your acreage exceeds 7, step up to a 7.5 HP AC submersible. The exact HP also depends on whether you irrigate by flood or drip — drip lowers the peak draw by 40–50% and may allow a 3 HP pump to suffice on smaller plots.
How much KUSUM subsidy is available for cotton-belt farmers in 2026?
PM-KUSUM Component B provides 30% central financial assistance plus 30% state share, leaving 40% with the farmer. Several cotton-growing states — Maharashtra, Telangana, Andhra Pradesh, and Karnataka — have added a top-up bringing total subsidy to 75–90% during specific sanction windows. Gujarat runs a different scheme (Suryashakti Kisan Yojana) with its own ratio. For a 5 HP system priced at ₹3.0–3.5 lakh, the farmer’s out-of-pocket after the standard 60% subsidy is ₹1.2–1.4 lakh; with a state top-up it drops to ₹75,000–₹90,000.
Is solar pump irrigation good enough for cotton’s flowering-stage water demand?
Yes, when sized correctly. Cotton’s flowering and boll-formation peak (600–800 L per acre per day) happens in September–October, which sits inside the high-radiation second half of the south-west monsoon — solar pumps generate at near-peak capacity during exactly the window cotton needs them. A 5 HP solar pump delivers around 80,000–1,00,000 litres per day at 30-metre head, which covers a 5-acre cotton farm at peak demand with headroom. The risk is sizing for the seasonal average instead of the flowering peak — that’s the single biggest mistake we see.
Can I get the KUSUM subsidy if I already have a diesel pump on the borewell?
Yes. PM-KUSUM Component B is available to farmers replacing a diesel pump as well as to those installing a fresh pumping system. The state nodal agency typically requires a self-declaration that the existing diesel pump will be retired (not run in parallel on the same borewell). Some states ask for a photo of the decommissioned diesel pump after installation. The subsidy structure and rates do not change between new installation and diesel replacement.
Does the solar pump work during cloudy weather in the monsoon?
A modern KUSUM-spec pump with a VFD controller continues to run on reduced output during overcast conditions — usually 30–60% of peak — and the controller protects the motor through partial-power operation. During the south-west monsoon (June–September), cloudy days actually correlate with field saturation from rainfall, so the pump’s reduced output coincides with reduced irrigation demand. The only stretches where you may need a contingency are continuous 3–5 day overcast spells in early September, which an on-farm rainwater pond or a small diesel back-up can buffer.
What is the difference between AC and DC solar pumps for cotton?
DC pumps run directly off the solar panels without an inverter, making them simpler and slightly more efficient at low loads. They are best suited to 1–3 HP open-well or shallow-bore applications. AC pumps use a VFD-based controller and are the standard for 5 HP and above — they handle the higher flow rates cotton’s flowering peak demands, work with existing AC submersibles, and are easier to service across the cotton belt where AC pump mechanics are widely available. KUSUM Component B covers both types.
How does drip irrigation change the solar pump sizing for cotton?
Drip cuts seasonal water demand by 45–55% and peak daily demand by a similar margin, which lets you specify a smaller pump. A 5-acre flood-irrigated cotton plot needs a 5 HP solar pump; the same plot on drip can usually run on a 3 HP solar pump, saving roughly ₹80,000–₹1,00,000 in system cost. The drip system itself adds ₹35,000–₹50,000 per acre, partially offset by the Per Drop More Crop (PDMC) subsidy. Net economics favour drip strongly on holdings of 4 acres or larger.
How long does a KUSUM solar pump last on a cotton farm?
The PV panel array carries a 25-year linear performance warranty (with 80% output guaranteed at year 25). The pump motor and controller have a manufacturer warranty of 2–5 years, but typical service life is 8–12 years for the motor and 10–15 years for the controller. Heaven Green provides annual O&M visits to check panel cleaning, controller diagnostics, and wiring integrity — cotton-belt dust and pesticide spray drift make annual cleaning particularly important for output retention.
