Cotton is the backbone of dryland agriculture across western and central India: more than 11 million hectares under cultivation, India among the world’s two largest producers, 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 the bulk of India’s cotton acreage. 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 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.
Direct answer. A 5-acre cotton farm hits its peak water demand at flowering and boll formation (September–October); a 5 HP solar pump on a 4.8 to 5 kWp (kilowatt-peak) array usually meets that demand, provided the borewell yield and head suit it. The total system costs ₹3 to 3.5 lakh; with the standard 60% PM-KUSUM Component B subsidy (30% central + at least 30% state), the farmer’s out-of-pocket is about ₹1.2–₹1.4 lakh, less where the state adds more, with diesel-saving payback typically in 2 to 3 years. New subsidy applications depend on PM-KUSUM 2.0, as the scheme period ended on 31 March 2026.
Scheme status, October 2026. PM-KUSUM’s sanctioned period ran to 31 March 2026. MNRE has allowed only projects whose PPA was signed, or whose Notice to Proceed was issued, on or before 31 December 2025 to complete, by 31 March 2027, with no extension beyond that date (MNRE office memoranda of 28 March, 25 May and 28 September 2026 on the PM-KUSUM national portal). New Component B applications depend on PM-KUSUM 2.0, which MNRE described in March 2026 as at the proposal stage. The sizing guidance below still applies to any solar pump; confirm with your state implementing agency whether a subsidy window is actually open before you plan around it.
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 to 1,200 mm depending on variety and region (1 mm over one acre is about 4,050 litres, so that is roughly 24 to 49 lakh litres per acre per season, part of it met by monsoon rain), 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 | Relative daily demand | Sensitivity |
|---|---|---|---|
| Germination & seedling | 0 to 25 | Low | Low, over-watering causes damping-off |
| Vegetative growth | 26 to 60 | Medium | Medium, squares form during this phase |
| Flowering | 61 to 100 | High | Critical: flower drop on water stress |
| Boll formation | 101 to 140 | Highest | Critical: boll size and lint length |
| Boll opening & picking | 141 to 180 | Low | Low, excess water reduces fibre quality |
For stage-wise irrigation schedules for your variety and region, see the advisories of the Indian Council of Agricultural Research (ICAR) Central Institute for Cotton Research and your state agricultural university. 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 the weeks 4 to 8 requirement for your acreage from your local irrigation schedule. This is your baseline minimum delivery, not the design point.
Input 2, Flowering-Phase Peak Draw
This is the design point. Take the peak flowering-stage irrigation depth for your region, multiply by acreage (1 mm over one acre is about 4,050 litres), and size the pump to deliver it in 5 to 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 to 40 days and overlaps with flowering. Demand stays at or near the peak. The pump must sustain peak output across 60+ consecutive days without thermal de-rating, which is why ALMM (Approved List of Models and Manufacturers) Indian-made panels and BIS-certified controllers matter more in cotton than in horticulture.
Input 4, Boll-Opening Tail-Off
October-end to November, demand drops sharply. 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 to 6 acres | 60 to 120 ft | 5 HP AC | 4.8 kWp |
| Marathwada (Maharashtra) | 5 to 8 acres | 80 to 150 ft | 5 to 7.5 HP AC | 4.8 to 7.5 kWp |
| Saurashtra (Gujarat) | 6 to 10 acres | 150 to 250 ft | 7.5 HP AC submersible | 6.75 to 7.5 kWp |
| North Gujarat | 5 to 8 acres | 200 to 300 ft | 7.5 to 10 HP AC submersible | 6.75 to 10 kWp |
| Telangana (Adilabad, Warangal) | 4 to 7 acres | 100 to 180 ft | 5 to 7.5 HP AC | 4.8 to 7.5 kWp |
| Raichur–Yadgir (Karnataka) | 5 to 8 acres | 80 to 140 ft | 5 to 7.5 HP AC | 4.8 to 7.5 kWp |
| Guntur–Kurnool (Andhra) | 4 to 6 acres | 60 to 100 ft | 5 HP AC | 4.8 kWp |
DISCOM and KUSUM channels vary by state: Maharashtra runs Component B through Mahaurja (MEDA), Gujarat runs Components B and C through GUVNL and its DISCOMs (GEDA handles Component A), and Telangana’s agency is TGREDCO (formerly TSREDCO). For the Maharashtra application sequence specifically, see KUSUM Maharashtra application 2026. For grid-tied Component C solarisation of existing grid pumps, see KUSUM Component C grid-tied pump.
Pairing Solar Pump with Drip Irrigation for Cotton
A flood-irrigated cotton field consumes 800 to 1,000 mm of water per season. The same crop on drip drops to 450 to 600 mm, a 45 to 55% reduction with no yield loss, and in many trials a 10 to 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: full peak volume, long runtimes, and a large annual diesel bill (Heaven Green estimates ₹1.2 to 1.5 lakh on 5 acres).
- Flood + 5 HP solar pump: same water volume, zero diesel, but field-application losses still 35 to 40%.
- Drip + 5 HP solar pump: roughly half the peak volume, so the pump runs comfortably below capacity, leaving headroom for hotter days; drip emitters deliver to the root zone with small losses.
The drip-plus-solar combination is what unlocks the 2-year payback Heaven Green models for cotton. Drip equipment draws its own subsidy under the central Per Drop More Crop (PDMC) scheme through state agriculture or horticulture departments, and MNRE’s KUSUM guidelines give preference to farmers using micro-irrigation.
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 (of the benchmark or tender cost, whichever is lower) + at least 30% state + farmer 40% or less, and some states have added more to push the farmer share down further. With the scheme period over since 31 March 2026, new sanctions depend on PM-KUSUM 2.0.
| Pump | All-in system cost | After 60% KUSUM | Where the state adds 15% more (75%) | Annual diesel saved | Simple payback |
|---|---|---|---|---|---|
| 3 HP AC | ₹2.0 to 2.3 lakh | ₹80,000–₹92,000 | ₹50,000–₹58,000 | ₹40,000–₹60,000 | 1.5 to 2 yrs |
| 5 HP AC | ₹3.0 to 3.5 lakh | ₹1.2 to 1.4 lakh | ₹75,000–₹90,000 | ₹75,000–₹1.2 lakh | 2 to 2.5 yrs |
| 7.5 HP AC submersible | ₹3.8 to 4.4 lakh | ₹1.52–₹1.76 lakh | ₹95,000–₹1.1 lakh | ₹1.0–₹1.5 lakh | 2 to 3 yrs |
| 10 HP AC submersible | ₹5.0 to 5.6 lakh | Higher: central aid capped at 7.5 HP | Higher: central aid capped at 7.5 HP | ₹1.5–₹2.0 lakh | Longer |
Source: Heaven Green field cost data, with subsidy shares from MNRE’s PM-KUSUM guidelines (central aid is capped at the 7.5 HP level). Diesel savings are Heaven Green estimates for a whole farm and depend on your actual fuel use and local diesel price. For a head-to-head economic model, read diesel vs solar pump ROI.
Beyond direct diesel savings, cotton farmers we work with report two compounding gains: better yields from on-demand irrigation that previously waited for diesel rationing, and lower 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 to 55%.
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4
Choosing non-compliant panels for a lower bid. KUSUM requires Indian-made modules with Indian-made cells. Non-compliant panels fail the state nodal agency inspection and the subsidy release halts.
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5
Not filing the land record (7/12 or pahani) with the application. State agencies such as Mahaurja in Maharashtra and TGREDCO in Telangana ask for current land extracts.
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6
Forgetting the pump-controller warranty. The controller is the most failure-prone component. Under MNRE's specification the whole scheme system carries a 60-month guarantee and 5 years of maintenance; on a self-funded pump, insist on the same.
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 to 55% water reduction
- + 10 to 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 to 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 a large share of drip capex (state-dependent), the smaller solar pump stays within KUSUM Component B’s 7.5 HP central-aid cap, 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 Adani Solar mono-PERC panels sized to meet the September flowering peak.
- BIS-certified VFD (variable-frequency drive) controllers with 5-year warranty, protects against restart spikes.
- AC submersible or surface pumps from Shakti, Lubi, or CRI, depending on borewell geometry.
- KUSUM Component B application filing with the state implementing agency (Mahaurja, GUVNL/DISCOMs in Gujarat, TGREDCO, KREDL, NREDCAP) when windows are open.
- 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 good-yielding borewell and a depth between 80 and 150 feet, a 5 HP AC solar pump on a 4.8 to 5 kWp panel array is the usual sizing for the September–October flowering and boll-formation peak; confirm it against your borewell’s tested yield and head. 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 to 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’s scheme period ended on 31 March 2026, and new Component B sanctions depend on PM-KUSUM 2.0, still at the proposal stage. Under the rules that applied, Component B provided 30% central financial assistance plus at least 30% state share, leaving 40% or less with the farmer; some states added more during specific sanction windows. In Gujarat, Components B and C run through GUVNL and its DISCOMs. For a 5 HP system priced at ₹3.0 to 3.5 lakh, the farmer’s out-of-pocket after the standard 60% subsidy is ₹1.2 to 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 to 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. Under MNRE’s 2023 specification, a 5 HP system on a 4,800 Wp array must deliver at least about 1.7 to 1.8 lakh litres a day at 30-metre total head on a clear day (MNRE solar pump specification), which covers a typical 5-acre cotton farm at peak demand where the borewell can supply it. 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. Some state agencies ask for a declaration that the existing diesel pump will be retired, or for proof after installation; check your state’s conditions. 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 to 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 to 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 to 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 to 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). Under MNRE’s specification the scheme system (including motor-pump set and controller) is guaranteed for 60 months, and typical service life is 8 to 12 years for the motor and 10 to 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.