Introduction
A growing dairy farm in North Devon needed substantially more electrical capacity to support its agricultural operations and a new home on the site. The existing utility connection was single phase, while the planned loads required a reliable three-phase supply.
A conventional grid upgrade was investigated, but the cost was expected to run into the millions. Rather than allow the grid constraint to delay the project, Callidus designed a complete containerised off-grid power system around the farm's actual load profile.
The final system combines:
- 180kVA of Victron inverter capacity
- 500kWh of Pytes V5A Plus lithium battery storage
- 840 x 450W solar panels, providing 378kWp
- Integrated backup generator support
- Remote monitoring and system control
At the time of manufacture, this was the largest pre-built Victron system completed by Callidus.
The Problem
The farm's single-phase connection could not provide the power required for the dairy operation, associated machinery and new residential loads. Agricultural sites can present demanding electrical conditions, including large motors, high starting currents, variable daily demand and equipment that cannot simply be switched off when generation is limited.
The design therefore needed to do more than provide a nominal inverter rating. It had to create a stable three-phase electrical platform, store enough energy for periods of low solar production, accommodate peak loads and retain a dependable backup source.
It also needed to be practical to install. Building the system inside a dedicated container allowed the main electrical architecture to be assembled, programmed and tested under controlled workshop conditions before it reached the farm.
The Solution
Callidus engineered a bespoke containerised energy system in which the inverter, battery, protection, control and monitoring equipment were integrated as one coordinated installation.
180kVA Victron power conversion
The system uses a coordinated bank of Victron Energy inverter-chargers to create the required three-phase supply. The inverter architecture was selected around the site's measured and expected demand rather than a generic package size.
For smaller commercial and off-grid systems, our range of 48V inverter-chargers and complete Victron off-grid energy storage kits shows the same core approach at a different scale.
500kWh Pytes lithium battery storage
The 500kWh Pytes V5A Plus battery bank provides the energy buffer between solar generation and the farm's load. It enables the system to absorb daytime solar production, support high demand and reduce the need to run the backup generator whenever there is a temporary shortfall in renewable generation.
The battery capacity was selected as part of the whole-system design. Useful storage depends on load duration, operating reserve, battery limits, seasonal generation and the required level of resilience. The Pytes Pi LV1 lithium battery provides an example of the modular battery technology used in smaller systems.
378kWp solar array
The farm's solar array consists of 840 panels rated at 450W each, giving a total installed capacity of 378kWp. The array is designed to supply the farm directly when generation is available and charge the battery with surplus production.
Actual output varies with weather, temperature, orientation, shading and system losses, so panel rating alone is not enough to size an off-grid installation. The generation profile must be assessed alongside the site's daily and seasonal consumption. For comparable modules, see our active 450W JA Solar panel pallet.
Backup generator integration
A generator was integrated as a controlled backup source. Its purpose is resilience rather than continuous primary generation. When solar and stored energy are insufficient, the generator can support the load and recharge the batteries according to the configured operating strategy.
Factory Testing and Quality Assurance
Before shipment, the complete power system underwent full-load testing. During the test the system supplied approximately 169kW, with the three phases carrying approximately 57kW, 56kW and 56kW respectively.
This balanced result demonstrated that the inverter system could operate as a coordinated three-phase supply under a substantial real load.
Thermal imaging was used throughout the test to inspect major connections, conductors and equipment. Temperatures remained around 27 degrees Celsius, with no significant heat build-up or abnormal hotspots identified during the test period.
Thermal inspection under load is valuable because a connection can appear mechanically complete while still presenting excessive resistance. Testing in the workshop allows those issues to be identified before transport, although final site commissioning and verification are still required after installation.
Transport and Site Installation
Once workshop testing was complete, the batteries were removed and secured separately for transport. The container was then delivered to the farm for positioning, reconnection and final commissioning.
Pre-building the system does not remove the need for competent site engineering. Foundations, earthing, cable routes, solar connections, generator integration, protection settings and final testing still need to be completed correctly. It does, however, move a substantial amount of complex assembly into a controlled environment and can materially reduce site time and disruption.
The Outcome
The farm now has a dedicated power platform designed around its expansion requirements rather than the limitations of the existing single-phase grid connection.
The project provides:
- A stable three-phase supply for agricultural and residential loads
- 500kWh of stored energy for load shifting and resilience
- 378kWp of on-site solar generation
- Generator backup for prolonged low-generation periods or exceptional demand
- Remote monitoring for operational visibility and diagnostics
- A factory-built system that reduced the amount of complex assembly required on site
Most importantly, the project offered a technically viable alternative to an uneconomic grid upgrade. It gave the customer a route to proceed with the farm development while retaining a system architecture that can be monitored, maintained and reviewed as operating data accumulates.
What Commercial Projects Should Establish Before Choosing Off-Grid Power
A commercial off-grid system should not be selected from inverter and battery headline figures alone. Before equipment is specified, the following should be established:
- Peak and continuous demand: The highest short-duration load can be very different from the normal operating load.
- Motor and compressor starting currents: Agricultural, refrigeration and pumping equipment can impose substantial surge demand.
- Daily and seasonal energy use: Battery capacity must be assessed in kilowatt-hours, not only inverter power in kilowatts or kVA.
- Critical and deferrable loads: Some equipment must remain available at all times, while other loads can be scheduled around generation.
- Available solar resource and installation area: Array size, orientation and seasonal output determine how much energy can realistically be produced.
- Generator strategy: Fuel storage, servicing, automatic start logic, minimum run times and charging power should all be considered.
- Maintenance and fault response: Monitoring, spare parts, access and competent technical support are part of the system design.
- Future expansion: Allowance should be made for realistic increases in demand, but excessive oversizing can add unnecessary cost and complexity.
Planning a Commercial Off-Grid or Containerised System?
The most useful starting point is an accurate load profile. Equipment schedules, measured demand, motor sizes, operating hours, seasonal variation and the consequence of a power interruption all affect the design.
Callidus designs and builds bespoke containerised power systems and hybrid generator solutions for farms, commercial sites, construction projects and locations where conventional grid capacity is unavailable or uneconomic.
Contact Callidus to discuss your load requirements, available generation and resilience objectives.
All commercial electrical and energy storage systems require project-specific design, protection, installation and commissioning by competent persons. Performance depends on the final load profile, operating strategy, site conditions and renewable generation.
