Economics

Is micro CHP worth the money?

Try this simple calculation by entering your details in the boxes, to work out how much you can save.

Many people interested in micro CHP are unsure whether it is economically worthwhile to install such a system. This simple calculator is intended as a tool for you to calculate your potential energy savings, based on your current fuel bills. From this you can work out how long it will take to pay back the investment in micro CHP.

Please note that this spreadsheet is provided only for you to undertake an estimate and that each home and household is different. You should satisfy yourself that the result is reasonable.

An example of a simple calculation is shown below for illustration only. It assumes that the system is installed in parallel with the existing power supply and that surplus generation is exported to the grid and any shortfall in requirements is imported from the grid.

Example

WhisperGen (1.0kWe/7kWt) micro CHP unit in an average sized family home with annual heat demand of 21,000 kWh

Annual heat demand	21,000	kWh
Running hours	3,000	hours
Electricity generated	3,000	kWh
Own use of generation	67	%
Unit cost of avoided import	10	p/kWh
Value of avoided import	200	£
Unit value of export	4	p/kWh
Value of export	40	£
Total value of generation	240	£
Additional gas consumed (compared with new condensing boiler)	3,000	kWh
Cost of additional gas consumed @2.5p/kWh	75	£
Net saving = £240-75	165	£
Marginal cost of unit	600	£
Simple payback	4	years

Calculator

This calculation assumes that you are considering replacing your boiler (which has reached the end of its useful life) with either a micro CHP unit or a new 86% efficient (SEDBUK B-rated) gas boiler. It is based on replacing the boiler with a WhisperGen micro CHP unit. You will need to know your gas and electricity costs for a complete year, which you can see from your annual energy bills.

Clicking on the "calculator" button will take you to a Microsoft Excel spreadsheet. You need to have MS Excel installed to run this calculation.

Contact : info@microchap.info

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