Backup power generated by diesel gensets cost a heck of a lot – somewhere in the vicinity of Rs 15 per kWh. Is it possible to utilize rooftop solar power plants to reduce the amount of diesel consumed?

Yes, you can use solar power plants on your rooftop in sync with your diesel generators and reduce diesel consumption.

The exact amount of diesel reduction benefit you achieve is a function of many factors. But be aware that massive reductions in, or elimination of, diesel consumption is unlikely.


Rooftop solar power plants can reduce diesel consumption up to 40% under ideal circumstances. Under more likely conditions, you can expect to achieve a diesel use reduction of about 20%.


In one of the unique consulting projects Solar Mango did for a solar/diesel hybrid, the client used the rare combination of solar panels + batteries + diesel genset, and that too for a sizable rooftop solar power plant of about 100 kW. Actual use data suggest that they were able to reduce diesel consumption by almost 30%.

Such a reduction for the client was possible owing to two reasons: One, they had a large battery bank, and two, their rooftop solar power plant contributed almost 35% of the total electricity consumed by the company, a relatively large percentage for the commercial/industrial sector.

Data from other installations show a more modest diesel reduction in the range of 15-20%.

While on the topic of solar/diesel hybrids, it is important to optimally design the solar power plant.

Of special importance in the design is sizing of the solar power plant. The sizing should be done such that the diesel genset can operate at high efficiencies most of the time and to ensure that a few other electrical emergencies are prevented.

It is recommended that you go only with those EPCs/system integrators who understand this design concept well for the solar/diesel power plant.


Stuff to Remember

Rooftop solar power plants can work with diesel generators and can potentially reduce diesel consumption by 20-40% for commercial establishments, though their contribution is likely to be lower for factories.