Solar vs Diesel Generator for Factories in Bharuch GIDC, 2026 Costs

Diesel generators in Ankleshwar, Panoli and Dahej are there for power cuts, but many units run them far more than they plan to. A DG unit costs about ₹25 to ₹30 in fuel alone. A rooftop solar unit, spread over 25 years, costs about ₹2 to ₹3. They do different jobs, though, and the right answer for most factories is both.

Cost per unit, side by side

	Diesel generator	Rooftop solar
Cost per unit	about ₹25 to ₹30 in fuel	about ₹2 to ₹3 over its life
Upfront cost	lower	about ₹50,000 per kWp
Runs in a power cut	yes	on-grid solar does not, by design
Runs at night	yes	no
Maintenance	oil, filters, overhauls, operator	cleaning, occasional inverter repair
Pollution and noise	yes	none

The diesel figure assumes a well-loaded set making 3 to 3.5 units a litre, with diesel near ₹90. A set running at 30% load uses more fuel per unit, so check your own log book. Divide litres bought in a month by units the set’s meter shows.

Why on-grid solar stops in a power cut

An on-grid inverter disconnects within a fraction of a second when the grid fails. This is a safety rule, so that a lineman working on a dead DGVCL line is not hit by power flowing back from your roof. It means ordinary on-grid solar does nothing during a cut, even at noon.

That is why solar does not replace the DG set. It replaces grid units on normal days, which for most GIDC units is the larger bill.

Running solar and DG together

A DG synchroniser, sometimes sold as a zero-export controller, lets the inverter keep running during a cut by treating the DG set as the grid. It watches the DG load and limits solar so the set always carries its minimum load, usually around 30% of rating, and nothing is pushed back into it.

On a sunny day this can cut diesel use during a long cut by a large share. It needs matching hardware and a design based on your DG rating and load pattern, so it is not something to add as an afterthought. Tell your installer your DG rating at the first site visit.

What it means for a GIDC unit

Take a unit with an 85 kW rooftop. At 4.2 units per kWp per day it makes around 10,700 units a month. One of our GIDC customers saw their monthly bill drop from ₹1.8 lakh to under ₹40,000 with an 85 kW system, with payback under 3 years.

If that unit also runs its DG for 40 hours a month, a synchroniser can let daytime solar carry part of that load. The saving there is at ₹25 to ₹30 a unit, not ₹8, so even a small share adds up.

The post on factory solar in Ankleshwar, Panoli and Dahej GIDC covers sanctioned load, roof sheets and approvals. For a quote, the commercial solar page lists what we need from you.