Solar-Powered Irrigation: How Chitwan Farmers Are Replacing Diesel Pumps with Clean Energy Storage

Nepal's agricultural sector employs over 60% of the workforce and contributes approximately 25% of GDP, yet it remains heavily dependent on diesel for irrigation — one of farming's most power-intensive activities. A single diesel pump running 6 hours/day during the dry-season crop cycle consumes 20–30 litres of diesel daily. With diesel at NPR 148–155/litre, a farming cooperative with 10 pumps can spend NPR 400,000–500,000 per month on irrigation fuel alone. Solar-plus-storage microgrids are changing this equation.

The Situation: Irrigation in Nepal's Terai

The Inner Terai districts — Chitwan, Nawalpur, Rupandehi, and Kapilvastu — account for a significant share of Nepal's paddy, wheat, mustard, and vegetable production. Grid electricity reaches many of these areas, but supply is unreliable during the November–April irrigation season when demand peaks coincide with reduced hydropower availability. Farmers have historically relied on diesel pump sets, many of them aging, inefficient, and requiring constant maintenance.

Pilot Project: Bharatpur Cooperative Microgrid

Arsa Energy partnered with a 47-member farmer cooperative in Bharatpur-14, Chitwan, to deploy a shared solar irrigation microgrid covering 68 bighas (approximately 46 hectares) of irrigated farmland. The system was designed to power four 7.5 kW submersible pumps, one 5 kW surface pump, and basic shed lighting for the cooperative's seed storage facility.

System Design

• 45 kWp ground-mounted solar array (Arsa bifacial panels, east-west orientation)
• 80 kWh Hithium LFP battery bank (central battery room)
• 50 kW three-phase hybrid inverter
• Pump scheduling controller (priority sequencing to avoid simultaneous startup)
• Mobile app monitoring with individual member energy allocation
• Grid connection for off-season battery charging and surplus export
• Fencing and security lighting integrated into the microgrid

How It Works: Coordinated Pump Scheduling

The cooperative's energy management system allocates irrigation slots to each of the 47 members based on their land holdings. Solar generation charges the battery from 6 AM onwards. Irrigation pumping begins at 7 AM and runs through 5 PM using direct solar power, with the battery providing supplemental power during clouds and morning/evening ramp periods. Nighttime irrigation (critical for some high-value vegetables) draws from the battery, which holds enough capacity for 4 hours of continuous pumping after sunset.

First Season Results

Beyond direct fuel savings, farmers reported a 15–20% improvement in crop yields attributed to more consistent irrigation scheduling — previously, irregular diesel supply caused stressed irrigation gaps that affected productivity. The cooperative also used surplus power to power a small grain mill, generating an additional NPR 15,000/month in processing income.

Scaling the Model: Policy Support and Financing

Nepal's Alternative Energy Promotion Centre (AEPC) offers subsidies for renewable energy in agriculture under the Renewable Energy Subsidy Policy. Solar irrigation systems may qualify for 30–50% capital cost subsidies depending on province and cooperative structure. Additionally, Agriculture Development Bank Nepal (ADBN) has specific loan products for farm mechanization that can be applied to solar irrigation microgrids.

If replicated across just 5% of Nepal's diesel-irrigated farmland, solar-plus-storage irrigation could displace 40–60 million litres of diesel annually — representing approximately USD 8–10 million in annual foreign exchange savings and eliminating over 100,000 tonnes of CO₂ emissions.