Off-Grid Solar Induction Melting: Operating a Foundry Without Grid Power
Off-grid induction melting sounds impossible until you see it in operation. A foundry in Western Australia has been running a 2 MW induction furnace on solar power with battery storage since 2022, with no grid connection at all. A copper smelter in the Atacama Desert of Chile has been running a 5 MW induction furnace on a hybrid solar-diesel system since 2021. A scrap recycling operation in Mali has been running a 1 MW induction furnace on solar-plus-battery since 2023. The technology is real, the operations are running, and the economics are increasingly attractive for remote sites.
When Off-Grid Makes Sense
Off-grid induction melting makes sense in three situations: remote sites with no grid access, sites with unreliable grid power, and sites where the cost of grid extension is prohibitive. The first case is the most common: mining operations, oil and gas camps, military bases, and remote communities all need metal melting for maintenance and fabrication, and the cost of running a grid line 50 to 100 km to a remote site can exceed the cost of the entire solar-plus-induction system.
The second case is common in developing markets with unstable grid power. Many African, South Asian, and Southeast Asian foundries lose 5 to 20 percent of their production time to grid outages. The cost of the lost production often exceeds the cost of a solar-plus-battery backup system, and the backup system can also supply the bulk of the energy during normal operation.
The third case is common in developed markets where the cost of grid extension is high. In the western United States, the cost of extending a 3-phase line 10 km to a new industrial site can exceed 1 million USD. A solar-plus-battery system at the same site can cost 1.5 to 2 million USD, but the system is independent of the grid and the cost is more predictable.
System Sizing for Off-Grid Operation
Off-grid solar induction melting requires careful system sizing. The solar PV array must produce enough energy over the year to cover the furnace consumption, and the battery storage must be large enough to handle multi-day cloudy periods and night-time operation.
For a 2 MW induction furnace running 5000 hours per year (about 14 hours per day, 365 days per year), the annual energy consumption is 10 GWh. A solar PV array in a high-insolation site (5 to 6 kWh per square meter per day) can produce 1500 to 1800 kWh per kW per year, so the required PV capacity is 5.5 to 6.7 MW. The battery storage must cover 12 to 16 hours of operation at the average power draw (60 to 75 percent of rated power), which is 15 to 25 MWh.
The total system cost for a 2 MW off-grid solar induction melting installation in a high-insolation site is in the range of 12 to 18 million USD, depending on the site preparation, the BESS size, and the control system complexity. The cost is amortized over 20 to 25 years, and the operating cost is dominated by the BESS replacement at year 12 to 15.
Hybrid Solar-Diesel Systems
For sites that need 24/7 operation and cannot tolerate the risk of BESS depletion, a hybrid solar-diesel system is the right answer. The diesel generator provides the backup power, and the solar-plus-BESS covers 60 to 80 percent of the annual energy. The diesel generator runs at 80 to 100 percent load, which is its most efficient operating point, and the fuel efficiency is much better than a continuously variable load.
A 5 MW hybrid solar-diesel system for a copper smelter in Chile includes 12 MW of PV, 15 MWh of BESS, and 5 MW of diesel generation. The system has been running for 3 years with 75 percent solar contribution, and the diesel fuel consumption has dropped by 70 percent compared to the previous all-diesel system. The payback on the solar-plus-BESS investment is 6 to 8 years at the local electricity and diesel prices.
Microgrid Control Systems
The microgrid control system is the heart of the off-grid installation. The system coordinates the PV output, the BESS state of charge, the diesel generator (if any), and the furnace load. The control objectives are: maximize the solar contribution, maintain the BESS state of charge within safe limits, and ensure the furnace always has the power it needs.
The standard control architecture is a master controller that interfaces with the PV inverter, the BESS management system, the diesel generator controller, and the furnace control system. The master controller runs a model predictive control (MPC) algorithm that forecasts the PV output (using weather forecasts and historical data) and schedules the furnace power draw to maximize the solar contribution.
MONTE INTELLIGENCE supplies microgrid control systems for off-grid and hybrid solar induction melting installations. The control system is integrated with the furnace control system, and it provides a single HMI interface for the operator.
Operational Challenges
Off-grid solar induction melting has operational challenges that are not present in grid-connected operations. The first challenge is the BESS state of charge management. A deeply discharged BESS can damage the cells, and the furnace must be throttled back to prevent discharge below the safe limit. The control system must communicate the available power to the furnace operator, and the operator must be trained to manage the load.
The second challenge is the dust and the temperature extremes. Solar PV arrays in remote sites accumulate dust that can reduce the output by 10 to 30 percent. The PV arrays need regular cleaning, and the BESS needs temperature management to prevent thermal damage in hot climates.
The third challenge is the maintenance skill. Remote sites rarely have trained solar PV or BESS technicians, and the maintenance must be done by visiting specialists. MONTE INTELLIGENCE offers a remote monitoring service that tracks the system performance and dispatches technicians when the system requires service.
The fourth challenge is the fuel supply (for hybrid systems). Diesel fuel must be transported to the remote site, and the supply chain can be disrupted. A BESS with 8 to 12 hours of storage can ride through a fuel supply delay, and a backup solar array can keep the BESS charged even when the diesel is unavailable.
Case Study: Off-Grid Foundry in Mali
A scrap recycling operation in Bamako, Mali has been running a 1 MW induction furnace on a solar-plus-BESS system since 2023. The system includes 2.5 MW of PV, 4 MWh of LFP batteries, and a 1 MW grid-connected inverter (the grid is used as backup). The system supplies 75 percent of the annual energy from solar, and the grid supplies the remaining 25 percent. The annual energy cost is 0.06 USD per kWh, versus 0.15 USD per kWh on the grid alone. The system was financed by an international development bank, and the payback is 7 years.
Talk to MONTE INTELLIGENCE About Off-Grid Solar Induction
For buyers considering an off-grid or hybrid solar induction melting installation, MONTE INTELLIGENCE engineering can model the system size, the operating cost, and the carbon savings for a specific site. The model includes the solar resource assessment, the BESS sizing, the control system design, and the grid backup requirements. Visit www.cnlymonte.com/products-solar-induction-furnace.html for product specifications and case studies. For a project discussion, email helenxu@cnlymonte.com with subject line off-grid solar induction and details on your site, furnace size, and operating hours.
