Solar PV – the costs and benefits

Last month, I got 2Kw of solar photovoltaic panels installed on our home. The install was seamless, so thanks to the provider https://www.greenelectric.ie/.

A 2Kw installation equates to six panels. Our roof already has solar water heating panels, so I guess a standard install might be 3Kw or more. So how is it going you might ask? As I am an accountant, of course I want to do the numbers. Before I do, lest you need reminding, Ireland is not the sunniest of places, but we do have good daylight – which is key to solar PV. Since the install, the lowest we have generated is 3Kw in one day, the most 13Kw. In terms of daily usage, this equates to a range of about 20% of our needs to more than 100% – depends on the day, as some days we use more energy than others.

So, to the numbers. I am making the following assumptions 1) no revenue from sale of extra power to the grid, 2) a cost of 0.17c per Kw – this is my current costs, 3) 5% annual increase in energy cost and 4) an average of 5Kw generated by the panels each day. I think these are all quite conservative. The cost of the install was about €6,500 net of a government grant, so the question from an accounting view is when do I get my money back? Using a simple Excel sheet and the above assumptions, it takes about 16 years. This is reasonable, given the average life of PV panels is 20-25 years.

There is more to it of course. I will probably save the planet 1.5 tons of CO2 per annum, which is not at all considered in the above numbers. And of course, I will have power for a while in case of a power cut, and can always expand the system to have more batteries. So overall, I am happy as an accountant, but also happy that I am doing my bit for the planet.