Related Links


Integrating solar into the diesel power supply

Volker Wachenfeld

Industries in remote areas with weak or even no grid infrastructure typically use fossil fuel generators to ensure a reliable energy supply. Integrating solar power into diesel-powered systems creates a reliable, resource-friendly and efficient energy supply, as Volker Wachenfeld explains.

Rapid operational readiness and maximum reliability and availability are essential for energy-intensive operations in mining, raw material processing, agriculture, water desalination and other areas. In order to be prepared for power outages and power supply interruptions from the grid, the diesel generators often run constantly. This results in high operating costs and leads to high volumes of CO2 emissions.

Rising diesel prices are motivating many companies to search for ways to minimise their operating costs; reducing fuel consumption is a logical way to do this. In many regions, one liter of diesel fuel already costs more than one US dollar. There are additional costs involved with transporting fuel to remote areas and storing it on-site. In contrast, the cost of solar power systems has dropped sharply over the past few years.

This is why more and more industrial companies seek to benefit from power supply solutions implementing hybrid systems that allow for the integration of cheap solar power into existing diesel power systems. The combination of diesel generator sets and photovoltaics in a hybrid system can reduce operating costs, CO2 emissions and dependence on fossil fuel.

There is great potential for such photovoltaic (PV) hybrid systems, because most industries in remote areas have excellent solar irradiation. In regions with weak grid infrastructure, many industrial businesses are critically dependent on a reliable and cost-effective electricity supply to ensure competitiveness. Integrating high shares of photovoltaics into diesel-powered grids must ensure stable grid operation at all times. To meet increasing energy demand, it is also important that these system solutions are scalable and that they can be adjusted according to current energy demands at any time.

Customised solution for stable and safe energy supply

The key technological challenge for these fuel-saving solutions is the use of smart control engineering to maximise the PV share that can be stably incorporated into diesel grids. Alongside the PV inverters, control devices are the main components. The SMA Fuel Save Controller (FSC), for example, manages demand-based PV feed-in at the interface between the diesel and photovoltaic generator and the load, while leaving the genset control unaffected. “Our experiences with covering different power classes and system topology since our first PV-Diesel-Hybrid systems in 2012 have been consolidated into the second generation of the SMA Fuel Save Controller FSC2.0,” comments Mohamed Mostafa, Head of Product Management at the company. “Customer demand ranges from integrating 100-kilowatt solar power into a fossil-fuel system, up to the multi-megawatt range. So with this second generation, we used product segmentation to serve each application segment.”

SMA developed the FSC M as a simple and affordable complete solution. It is a plug-and-play solution for solar grid feed-in of up to 1 MW of PV power in PV diesel hybrid systems. The FSC L solution for solar grid feed-in of up to 5 MW and optional storage integration is suitable for operators who want to use solar power at night and have additional power smoothing capabilities. An optional storage unit can further increase the proportion of solar power fed into the hybrid system by up to 75% of PV capacity compared to installed diesel genset capacity. This means additional savings on fuel and CO2 emissions. A customised solution for systems requiring up to 50 MW of solar power is fitting for larger islands with weak grid capacity like Puerto Rico, Hawaii or The French Overseas Departments.

In all applications, the photovoltaic inverters operate in wide frequency and voltage ranges, and can adapt their output power depending on grid frequency. The generated solar power, the current operational diesel genset power and the current load states must be measured and assessed. This ensures that, in the event of large load changes or a sudden collapse in solar power grid feed-in, sufficient spinning reserve is always available, preventing reverse power feed-in to the generators.

On average, the investment in a PV-Diesel-Hybrid system pays off in three to five years in sunny regions. This depends, of course, on the size of the photovoltaic power plant, local solar irradiation conditions, load behavior and generator output.

Proven technology in the field

SMA Solar Technology AG, headquartered in Germany and represented in 21 countries, has been developing scalable hybrid energy solutions for the electrification of off-grid regions for more than 30 years and boasts more than 10,000 successfully operating systems worldwide. The commissioning of a solar diesel hybrid system based on the SMA Fuel Save Solution for a chrome ore mine in Thabazimbi, South Africa, in November 2012, marked the first application in the megawatt range.

SMA has also provided a Fuel Save Solution with a battery storage system for a 5 MW PV project in Bolivia. The aim here is to cover about half of the energy demand in the provincial capital of Cobija, which up until now has had to use diesel power from gensets as its sole source of electricity. Thanks to the PV diesel hybrid power plant, this region is now on its way to having its own sustainable energy supply by reducing its dependency on fossil fuels and increasing its electrification rate to 80%. By expanding its power plant to include solar energy, the local electric utility company will save around 1.9 million liters of diesel fuel each year.

“There is great potential for these fuel saving applications, especially in the sunbelt,” says Mostafa. “By the end of 2015 we will have implemented more than 50 projects all around the world like in Barbados, Fiji, Haiti and Egypt.”


Volker Wachenfeld, Executive Vice President Off-grid and Storage, SMA Solar Technology AG.


SMA Solar Technology AG



Share this article

More services


This article is featured in:
Energy infrastructure  •  Photovoltaics (PV)  •  Solar electricity