Jon's Solar Panel experience

What were my drivers for purchasing solar panels?

Primarily, I have been extoling the virtues of renewable energy in my work life, but that hasn't been fully implemented in my home life. I therefore thought it was time to put my money where my mouth is and do my bit for the planet too.

So this is a significant home project and the best way to start with these is to ask someone who has recently done the same thing (that and a lot of googling!).  Fortunately, a friend had just taken the plunge and gave us some great pointers. More importantly, they offered references for some local suppliers that they had been in contact with.

My initial research into whether solar panels would work for our house revealed a number of basic tick boxes that needed to be checked to ensure it is physically viable to install Solar PV.

1. Reasonable roof size pointing in an approximate southerly direction - check
2. No Velux windows or obstructions on the roof - check
3. Roof pitch roughly 35 degrees - check

All the above issues can be overcome, but having these in your favour certainly helps.

Then we looked at our current power consumption and tariffs.

Based on our current consumption, plus a little extra for the inevitable electric car or two that will be needed in the future, our annual consumption is approx. 7,200 kWh.

Prior to March 2022, through the excellent shopping/bargaining power of one member of the Winstanley household (not me!), we had an excellent tariff at 16p per kWh.  Along with everyone else, April came and went, prices shot through the roof and we are now on the energy cap tariff of 28p per kWh. Quite a jump. For the mathematically astute, yes that is a 75% increase and a household spend increase from approximately £1,000 per annum to £1,750. Again, another good reason to consider this further.

This formed the basis of my initial enquiries. I contacted four solar PV installation companies in the first instance and, based on responsiveness, price and references, soon whittled this down to one.

The installer we have chosen was excellent in explaining the process and what the relative benefits are.  The initial consultation even included a short science lesson on how it works, including silicon, vibrating electrons, conversion to DC electric and onward conversion to AC (a proper throwback to my 'A' level physics days).

Following an initial survey in December 2021, it was suggested that a 15-panel system would be appropriate which would deliver 5,592 kwh annually (this can vary dependent on the type/quality of panel and the sophistication of the inverter system which optimises the panel efficiency and increases generation - this bit was the limit of my technical understanding!).

In terms of carbon, by way of a very crude calculations this would remove 1,429kg of carbon per annum (were the equivalent amount produced by fossil fuels) and the equivalent of planting approx. 65 trees (calculated using the United States EPA Greenhouse gas equivalencies calculator here)

When it came down to the finances, the solar industry use some standard assumptions about how much of the power generated would be consumed during the day and how much we would feed back to the grid. 

The assumption is that we would use approximately 50% of the 5,592kwh generated and feed the rest back into the grid. I did initially need to look at which companies will offer a reasonable tariff for feeding back into the grid, but I was told that generally a minimum 5p per kWh is the going rate. I have actually settled on Octopus Energy as their Agile Export rate is calculated half-hourly, based on demand and is generally above the 5p/kWh rate.

In very broad terms, this means we should saving half of the 5,592 kwh at 28p/kWh through direct use (instead of drawing this from the grid) and half the 5,592 kwh at roughly 8p/kWh for feeding back into the grid. The total saved is therefore estimated at £1,006 per annum and represents approximately an 11% return on investment for the particular system that we chose (payback over approx. 7-8 years dependent on energy prices).

We did consider battery storage which we could use to store the power generated during the day and then use this power at night.  But for us the cost of the battery did not make this viable at this time and would have significantly increased the payback time. Battery storage price is something I will keep an eye on and hopefully install at a later date when it becomes more affordable.

Something this process has done is given me a much greater understanding of our household energy consumption and when is the best time to use appliances to gain greatest use of the sun. For example, we have found that both our dishwasher and washing machines are clever enough for us to be able to set the inbuilt timer to start at midday when energy generation is at its highest. We are also set up with a Solar Edge account which gives a handy comparison of consumption vs generation vs self-consumption which can be used to plan our electric use (monitoring this can be quite addictive!).

So all in all we are very pleased with our investment, both environmentally and financially, and would recommend this as a good way to save money and reduce carbon.

Next stop - heat pumps and batteries!?!