Here's another instalment of a Science Sunday post for you.

This week gone we saw the Summer Solstice, the longest day of the year on 21st June.

So, we thought it would be interesting to show you what happens at the Dyfi Wildlife Centre on this day with regard to our solar system. We have two in all – a whole-roof PV array and the newly installed PV system in the car park; both systems 'talk' with each other, working in tandem.

So, on 21st June our combined solar system converted 390 kWh of light energy to electrical energy. This is enough to run an average family house for around seven weeks!

Of that 390 kWh, the Dyfi Wildlife Centre used 87 kWh, we saved 14 kWh in a battery for use at night, and we exported the surplus 288 kWh to the grid for others to use. Despite having to pay 30p per kWh to import each kWh of electricity - just like you do at home - we get no payment of the huge amounts of power we send to the grid each year. The government scheme 'Feed-in-Tariff' has ended in the UK.

Our currency is the environment. Not only are we running on near-100% renewable, clean energy we've generated ourselves, we are exporting a huge amount back to the grid for others to use. For every clean kWh we generate, it means that a kWh doesn’t have to be generated elsewhere by burning coal or gas.

On a monthly basis (second chart), in June we only had to import 5% of our energy from the grid, the remaining 95% (yellow and green bars) we generated ourselves.

On a net lifetime basis, we are running well beyond carbon-neutral, almost 30-years before the government target date. Since January 2021 when the system was switched on, we are operating at around 150% Carbon Negative – meaning we are generating enough electricity to run the whole of the Dyfi Wildlife Centre for a year – plus another 50%.

With the new car park PV system having just come on line partly funded by Welsh Government (diolch), we expect this to increase to well over 200% Carbon Positive by this time next year. The surplus clean energy we send back to the grid will be in the range of approx 35 Megawatts (35,000 kWh) per annum.

Now, according to OFGEM figures, that is enough surplus clean energy we're sending to the grid to run a whole terrace of 12 houses with 2.4 people living in each of them for a whole year ☀️☀️☀️