Have you ever hear of Swanson’s Law?

First reported in the Financial Times, Swanson’s law is the observation that the price of solar photovoltaic modules tends to drop 20 percent for every doubling of cumulative global shipped volume. As shipments have rocketed recently, we are left marvelling at Swanson’s Law: The ever-declining price of Solar PV.

Our World in Data shows this graphically:

Our World in Data

What does this mean for the UK consumer who might be considering whether or not to install some rooftop solar?

To help interpret the graph a little more, the price per Watt was $0.49 in 2017. In 2021 this had fallen to $0.27. Will there be a floor price beyond which the price doesn’t fall?

The wonderful news for consumers is that because of Swanson’s Law: The ever-declining price of Solar PV, solar panels are now extremely low. It is hard to see the price of the panels falling much below their current price (on a unit cost basis), but it is likely that the power rating of each panel will continue to increase, in much the same way as smart phones continue to increase in power year on year.

But like a smart phone, there comes a point where your phone is ‘good enough’ meaning that there is little marginal benefit to be had by upgrading every 12 months.

With a solar panel array the magic happens when you are able to match your electricity usage to the generation on your roof. 2 hours of sunshine on a south facing array in April will be sufficient to provide all the power your home needs for the whole day.

That is why a GivEnergy Home Storage battery is so useful, since if that April day is your classic ‘April showers’, and much of the rest of the day is overcast – it matters not!

Conversely in December, you will be struggling to get more than a few kWh out of your array. But that is OK. Because you’ll charge your battery up overnight on a cheap tariff, and run the house from the battery. The solar array will top up the battery where it can, but the bulk of the work is done by the battery.

So, the battery and the solar array have a symbiotic relationship. Used together they will drive down the cost of the electricity that you use. And they’ll do this for decades.

The final piece of this puzzle is the evolution of electricity tariffs – at Brimstone Energy UK we expect that they will directly incentivise changes in consumer behaviour. Back in the days of the Feed in Tariff, the incentive to earn money from the government led to a boom in UK solar installation (and to rogue traders). Now, the incentives are based on market realities rather than government handouts. Tariffs now incentivise consumers to store electricity generated by solar and to discharge it into the grid at peak hours. In the years ahead we expect this to have a major effect on the market.

Consumers with the capital to install the right equipment in their homes will therefore pay drastically less for their energy. This may have social implications, which is beyond the scope of this article.

Let Brimstone Energy UK be your guide to the Green Energy Transition.

Solar. Storage. Efficiency. Low Carbon Heating