Does Storing Solar Power's Electricity as Hot Water Make Sense?

Dylan Pankow/CC BY-NC 2.0

Back in 2009, Lloyd argued that solar hot water should be much more of a priority than solar electric (PV). The reason for that was pretty simple—the sun is really good at heating liquids, whereas using electric power to do the same job is not a particularly efficient transaction.

So I am a little up in the air about a new product launched in the UK called Engensa Solar24 which claims to help owners of solar electric arrays to maximize their returns by converting excess electricity into hot water:

Engensa’s first smart home energy product, Solar24 automatically diverts excess electricity produced by solar panels to a customer’s hot water tank rather than exporting it to the grid. Typically, around 50% of home solar electricity is used on site, whilst the rest is exported back to the grid. Now, with Solar24, homeowners can use every hour of solar electricity they generate, saving money on heating as well as electricity bills, and so boost the financial returns of a solar system by up to an additional 10%.

Now you'd think that anything that helps solar array owners make more money would be a good thing when it comes to clean energy, and in some ways it is. But from a big picture perspective, all the talk in the environmental movement about going off-grid has been over-hyped. The grid is an efficient way to distribute energy from where it is produced to where it is needed, without storage and the inevitable losses that this storage entails. And as smart grid technology gets more commonplace, that capacity should only improve.

This may be one of those cases where government subsidies create perverse incentives. If my understanding of UK feed-in tariffs are correct, homeowners get paid for all the electricity they produce—whether they use it or not. As such, there is little financial incentive to feed back into the grid, and so storing some energy, however little, is more economically viable than sharing it with your neighbor.

Tags: Heating | Renewable Energy | Solar Power | United Kingdom