What Size Solar System Is Needed for Farm Irrigation?

Reliable electricity is essential for modern agricultural operations, particularly when irrigation depends on electric pumps and water-management equipment. For many farms, irrigation can represent a significant portion of total energy consumption because pumps may need to operate for several hours each day, sometimes during periods when grid electricity is unreliable or diesel fuel is expensive.

This has made solar power an increasingly attractive option for agricultural irrigation.

However, determining the right solar system size is not as simple as choosing a certain number of solar panels. A properly designed solar irrigation system must take into account the irrigation pump capacity, water requirements, operating schedule, local solar conditions, battery storage requirements, and future agricultural development.

For farms in remote or off-grid areas, the challenge is even greater. The system may need to provide reliable power without utility grid support, while also maintaining irrigation during periods of low solar production.

This is where a properly engineered 500kW solar energy system, smaller solar irrigation system, or solar-plus-storage configuration can provide a practical solution depending on the scale of the agricultural operation.

At Tanfon, our approach is to size agricultural solar systems according to actual electrical and operational requirements rather than relying on standardized configurations.

Why Solar Energy Is Becoming Popular for Agricultural Irrigation

Agriculture depends on reliable water availability, and irrigation systems are often among the most energy-intensive loads on a farm.

Traditional power sources such as grid electricity and diesel generators can create several challenges:

• Rising electricity and fuel costs
• Unstable grid supply
• High generator maintenance requirements
• Fuel transportation difficulties in remote areas
• Noise and emissions from diesel generators
• Increasing operating costs as agricultural production expands

Solar power provides an alternative by allowing farms to generate electricity locally.

A solar energy system can supply irrigation pumps, water treatment equipment, agricultural machinery, lighting, refrigeration, farm buildings, and other electrical loads.

However, irrigation has a unique characteristic: the amount of electricity required depends directly on the amount of water that needs to be moved and the conditions under which it must be pumped.

This means the solar system should be designed around the irrigation application rather than simply around the available installation area.

For farms that require irrigation outside peak sunlight hours, battery storage can further improve system flexibility. Excess solar energy generated during the day can be stored and used later, allowing the irrigation schedule to be less dependent on real-time solar production.

What Determines the Size of a Solar Irrigation System?

There is no single solar system size that works for every farm.

The required capacity depends on several technical and operational factors.

1. Irrigation Pump Power

The irrigation pump is usually one of the most important electrical loads in an agricultural solar project.

Engineers need to determine:

• Pump rated power
• Motor voltage
• Three-phase or single-phase configuration
• Starting characteristics
• Daily operating hours
• Number of pumps
• Whether pumps operate simultaneously
• Required water flow rate
• Required pumping head

For example, a farm using one relatively small irrigation pump may require a very different system from a large agricultural operation with multiple high-power pumps running simultaneously.

Pump starting characteristics are particularly important.

A motor may require substantially more power during startup than during normal operation. Therefore, the inverter must be selected based not only on the pump's rated running power but also on its starting and operating characteristics.

This is one reason why simply matching the solar array size to the pump's nameplate rating can result in an improperly designed system.

2. Water Demand and Irrigation Schedule

Electrical demand is closely related to water requirements.

Different crops require different irrigation patterns. Vegetable farms, grain farms, orchards, nurseries, and large-scale agricultural projects may have very different water requirements.

Engineers should therefore understand:

• Required daily water volume
• Irrigation frequency
• Irrigation duration
• Seasonal changes in water demand
• Water source
• Pumping distance
• Required water pressure
• Storage tank capacity

For example, a farm may require intensive irrigation during a particular growing period but substantially less water during other seasons.

This affects both the required solar generation capacity and the amount of battery storage that may be needed.

A properly designed solar irrigation system should therefore be based on energy demand derived from actual water requirements, rather than simply selecting a larger PV array.

3. Solar Resource and Site Conditions

Solar generation depends heavily on location.

A farm in a region with strong year-round solar resources may be able to generate the required energy with a smaller PV array than a farm experiencing substantial seasonal variations in solar radiation.

Site assessment should consider:

• Average solar irradiation
• Peak sun hours
• Seasonal weather patterns
• Rainfall
• Temperature
• Shading
• Available land or roof area
• Panel orientation and tilt
• Environmental conditions

For agricultural projects, ground-mounted PV systems are often an option when sufficient land is available.

However, available space alone should not determine system size.

A large piece of land does not automatically mean the farm needs a large solar array.

The system should first be sized according to electricity demand and then optimized according to the available installation area.

4. Daily Operating Hours

The number of hours the irrigation system operates each day has a direct impact on energy requirements.

For example, consider an irrigation pump rated at 100kW.

If it operates for four hours per day, its basic daily energy requirement is approximately:

100kW × 4 hours = 400kWh/day

This is only a simplified calculation. Actual system sizing must also consider inverter efficiency, pump efficiency, system losses, solar generation conditions, battery charging and discharging losses, and other electrical loads.

Nevertheless, this illustrates why pump power alone cannot determine the size of a solar irrigation system.

The question is not simply:

“How many kilowatts is the pump?”

The more important question is:

“How much energy does the irrigation system need each day, and when does it need that energy?”

That distinction is fundamental to professional solar system design.

How Battery Storage Improves Solar Irrigation Performance

Solar generation naturally fluctuates throughout the day, while irrigation requirements may not always coincide with peak solar production.

Some farms may need to operate irrigation pumps:

• Early in the morning
• Late in the afternoon
• During cloudy periods
• At night
• According to specific crop-management schedules

Battery storage provides a way to separate the timing of solar generation from the timing of electricity consumption.

During periods of strong sunlight, the solar array can supply the irrigation loads while charging the battery with excess energy.

Later, the stored energy can be used to support irrigation or other critical agricultural loads.

This makes a solar system with battery storage more flexible than a PV-only system.

Battery storage can also provide additional resilience when the farm operates in an area with unreliable grid electricity or no grid connection.

For off-grid agricultural projects, the overall architecture may therefore include:

Solar PV + Battery Storage + Hybrid Inverter + Diesel Generator Backup

The exact configuration depends on the farm's load profile and reliability requirements.

What Size Battery Does a Farm Need?

Battery capacity should be calculated from the actual energy requirement rather than selected as a fixed percentage of solar capacity.

Important factors include:

• Required backup duration
• Critical agricultural loads
• Nighttime electricity consumption
• Solar generation profile
• Battery depth of discharge
• Battery efficiency
• Expected operating cycles
• Seasonal energy requirements

For example, a farm requiring only a few hours of backup for critical loads may need considerably less battery capacity than an agricultural facility requiring overnight operation.

For larger projects, a containerized energy storage system may be considered when significant battery capacity is required.

A containerized solution can integrate battery modules, battery management systems, thermal management, fire protection, power conversion equipment, and other components into a centralized energy-storage architecture.

This can be particularly useful for large agricultural projects, remote farms, and other applications where scalable energy storage is required.

A Real-World Example: 500kW Solar Farm System in Papua New Guinea

A practical example from our agricultural project experience comes from Morehead, Papua New Guinea, where Tanfon supplied a solar power system for an agricultural training center.

The site was located in a remote suburban area without access to utility grid electricity. Before the project, the facility relied on a 65kVA diesel generator to supply electricity for the dormitory, farm training facilities, lighting, and water-supply equipment.

The client faced several challenges, including high fuel costs, generator maintenance, noise, and unstable long-term energy expenses.

Instead of simply replacing the generator with a PV array, we designed an integrated hybrid system.

The final configuration included:

• 500kW hybrid solar farm system 
• 430kWh LiFePO4 battery storage 
• 352 × 600W solar panels 
• 500kW MPS hybrid inverter system 
• Intelligent energy management system 
• Diesel generator backup 
• Off-grid configuration for agricultural applications

This project demonstrates an important principle in agricultural solar design:

The solar array, battery storage, inverter, and backup generator must be designed as one coordinated energy system.

During sunny conditions, the solar farm can fully support the facility's daily electricity demand, allowing the agricultural center to operate without using the diesel generator.

During rainy or cloudy weather, the diesel generator automatically provides backup support to maintain electricity availability.

The project achieved 24-hour solar-powered operation during sunny weather, reduced diesel consumption and generator runtime, and improved the facility's overall energy sustainability. The project page reports an estimated ROI of approximately two years.

This is a good example of why agricultural solar projects should not be designed around PV capacity alone.

The system was designed around the actual operational requirements of the farm and training center, with battery storage and diesel backup providing additional flexibility when solar production was insufficient.

Why a 500kW Solar Energy System Is Not Always the Same

The Papua New Guinea project provides another important lesson.

Two farms may both install a 500kW solar energy system, but their actual system configurations can be completely different.

One farm may need:

500kW PV + 200kWh battery

while another may require:

500kW PV + 430kWh battery + diesel backup

The difference depends on:

• Daily energy consumption
• Load profile
• Irrigation requirements
• Grid availability
• Required backup duration
• Weather conditions
• Critical loads
• Future expansion

Therefore, “500kW” describes the nominal power capacity of a system component, but it does not by itself describe the complete energy solution.

For agricultural projects, the relationship between PV capacity, inverter capacity, battery capacity, and load demand is much more important than the headline system size.

How to Choose Between a PV-Only and Solar-Plus-Storage System

A PV-only system may be suitable when irrigation can be scheduled primarily during daylight hours and the farm has sufficient solar resources.

A solar-plus-storage system may be more appropriate when:

• Irrigation must continue after sunset
• Grid power is unreliable
• The farm operates critical electrical equipment
• Solar energy needs to be shifted to later hours
• Backup power is required
• The site is completely off-grid

For remote agricultural projects, combining solar, batteries, and a backup generator can provide a practical balance between renewable energy utilization and power reliability.

The Papua New Guinea agricultural training center is a good example of this approach. The system uses solar as the primary energy source, battery storage to improve energy availability, and a diesel generator as backup during unfavorable weather conditions.

Why a Containerized Energy Storage System Can Benefit Large Farms

As agricultural operations become larger, their electricity requirements can also increase.

Large farms may require electricity for:

• Multiple irrigation pumps
• Water treatment
• Refrigeration
• Cold storage
• Agricultural processing
• Workshops
• Worker accommodation
• Lighting
• Communication systems

In these applications, a containerized energy storage system can provide a scalable approach to battery storage.

Compared with smaller distributed battery installations, a containerized BESS can centralize the energy-storage equipment and simplify system integration for larger projects.

Depending on project requirements, a containerized energy storage system can integrate:

• LiFePO4 battery modules
• Battery Management System
• Power Conversion System
• Thermal management
• Fire protection
• Energy Management System
• Monitoring and communication equipment

This type of configuration is particularly relevant for large off-grid agricultural facilities where substantial energy storage capacity is required.

The Importance of Inverter Selection for Irrigation Pumps

The inverter is another critical component in a solar irrigation system.

Irrigation pumps often use induction motors or other motor-driven equipment with significant starting requirements.

Therefore, engineers should evaluate:

• Rated motor power
• Starting current
• Motor type
• Voltage
• Phase configuration
• Variable-frequency operation
• Pump operating profile

A properly selected inverter should be capable of handling the actual electrical characteristics of the pump rather than simply matching the pump's rated kW.

For larger agricultural systems, hybrid inverters can coordinate solar generation, battery charging, grid electricity, and generator backup.

This creates a more flexible operating architecture and allows the system to respond to changing solar and load conditions.

Why Professional System Sizing Matters

A common mistake in agricultural solar projects is to determine system size based solely on the number of solar panels that can fit on available land.

This approach can lead to either under-sizing or unnecessary oversizing.

An undersized system may fail to meet irrigation requirements during periods of high demand.

An oversized system may increase the initial investment without delivering proportional benefits.

Professional system sizing should therefore follow a structured process:

Step 1: Assess the Electrical Loads

Identify pumps, motors, lighting, refrigeration, water systems, and other electrical equipment.

Step 2: Analyze Operating Hours

Determine when each load operates and how long it runs each day.

Step 3: Calculate Daily Energy Demand

Estimate the total daily kWh requirement.

Step 4: Evaluate Solar Resources

Analyze local solar irradiation and seasonal conditions.

Step 5: Determine PV Capacity

Select an appropriate solar array size based on energy demand and expected generation.

Step 6: Determine Battery Capacity

Calculate how much energy must be stored and for how long.

Step 7: Select the Inverter

Consider both continuous load and motor-starting requirements.

Step 8: Integrate Backup Power

Determine whether the project requires a grid connection or diesel generator backup.

This process creates a system based on actual operating conditions rather than assumptions.

Choosing the Right Solar Partner for Agricultural Projects

Solar irrigation involves much more than purchasing photovoltaic modules.

The long-term performance of the system depends on:

• Proper load assessment
• Equipment compatibility
• Correct inverter sizing
• Battery configuration
• Environmental conditions
• Installation quality
• Monitoring
• Maintenance
• Technical support

For agricultural projects, reliability is particularly important because irrigation failures can directly affect crop production and water management.

A supplier should therefore be able to understand not only solar equipment but also the operational requirements of the agricultural application.

At Tanfon, our agricultural projects cover different operating environments, from remote off-grid farms to larger solar-plus-storage applications.

The Papua New Guinea project demonstrates our approach: instead of relying on a single energy source, the system integrates solar generation, lithium battery storage, intelligent energy management, and diesel backup according to the site's actual requirements.

Final Thoughts

The question “What size solar system is needed for farm irrigation?” cannot be answered by looking at pump power or available land alone.

The correct system size depends on the complete energy profile of the agricultural operation.

Engineers need to consider:

• Pump power
• Water demand
• Operating hours
• Solar resources
• Daily energy consumption
• Battery requirements
• Backup power
• Future agricultural expansion

For a smaller farm, the appropriate solution may be a relatively compact solar irrigation system.

For a large agricultural operation, the requirement may grow to a 500kW solar energy system combined with substantial battery storage and backup generation.

For projects requiring significant energy storage, a containerized energy storage system can provide a scalable architecture.

And where reliable electricity is required beyond daylight hours, a 500kW solar system with battery storage can provide considerably greater operational flexibility than a PV-only installation.

The most important lesson is simple:

The best agricultural solar system is not necessarily the largest one. It is the system that is correctly sized for the farm's actual energy, irrigation, and operational requirements.

With proper engineering, solar energy can reduce dependence on diesel and grid electricity while providing a more reliable and sustainable power source for modern agriculture.

FAQ

How many solar panels are needed for a farm irrigation system?

The number of panels depends on the required PV capacity, panel wattage, local solar conditions, system losses, and daily irrigation energy consumption. A professional load and solar-resource assessment should be completed before determining the final number of panels.

Is a 500kW solar energy system suitable for a farm?

A 500kW solar energy system can be suitable for large agricultural facilities with substantial electricity demand, multiple pumps, processing equipment, or other high-power loads. The appropriate capacity should be determined through detailed load analysis.

What is a 500kW solar system with battery storage?

A 500kW solar system with battery storage combines a 500kW-class solar generation system with batteries that store excess energy for later use. The battery capacity is a separate design parameter and should be calculated according to the required backup duration and energy demand.

What is a containerized energy storage system?

A containerized energy storage system is a packaged battery-storage solution integrated into a containerized enclosure. It can include batteries, BMS, power conversion equipment, thermal management, fire protection, and energy management systems.

Can solar power replace diesel generators on farms?

In some applications, solar can significantly reduce or even eliminate routine diesel generator operation during periods of sufficient solar production. For remote or off-grid farms, a hybrid system with battery storage and diesel backup can provide greater reliability during cloudy or rainy conditions.

Does battery storage improve solar irrigation?

Yes. Battery storage allows excess solar electricity generated during high-production periods to be stored and used later. This is particularly useful when irrigation schedules do not perfectly coincide with solar production.