How does the cost of a diesel generator compare with grid electricity?

The short answer

Divide the p/litre of diesel by 3 and you won’t be far out.

The longer answer

• 1 litre of diesel contains 10.25kWh of energy

• The electrical efficiency of a diesel generator varies a lot but a modern one running at mid-low load will be c. 30%

So, lets say diesel is 150p/litre, divide by 10.25 = 14.6p/kWh of fuel. Then divide by 30% = 49p/kWh of electricity generated; pretty close to 1/3 of the p/litre price of diesel.

OK, you’ve got to add in maintenance and depreciation or rental costs. But faced with grid electricity costs of c. 60p/kWh over the next 12 months (if you’re lucky) a good old ‘oil burner’ could be worth considering.

Note: a recent change to the ‘rules’ means you might have to use white diesel nowadays.