by Steven Harris

We recently had a great weekend away. We took our camper van to the seaside, and while we were there, we won our first architectural award!

In fact, we won two. First prize for most technically daring, and second prize for tallest. The prizes (from the Royal Society of Architects in Wales and Pembrokeshire County Council) – an annual family membership to CADW, and a Pevsner Guide to Pembrokeshire (plus cuddly dragon toys) – were very welcome.

It’s amazing what you can get for building a sandcastle.

But anyway, when we got back, as suspected given the beautiful weather we’d had, our solar thermal system had boiled over and blown out its glycol.

Even as we were leaving I knew I should have left a heating circuit on. But that’s another story. But that wasn’t all: since we had been away all the sunny weekend, we had not been able to make use of 20kwhrs or so of electricity our PV panels had generated.

So how could it be different?

Well, while we are home it’s all fine. Right now we have two computers going, the washing machine has been running, and I’ve just put a bread on. We also do our best to drink as much tea as is humanly possible during daylight hours. But when we are away, what could our house be doing with all that power?

Our biggest electricity consumers are probably heating in the winter, cooking, washing and appliances. But unfortunately, these are all irrelevant while we are away building sandcastles.

Firstly, it’s summer so we don’t need heat – far from it, with a boiling-over solar thermal system. Cooking – who would eat it? Washing – we wouldn’t want wet clothes hanging around in the washing machine all weekend. Appliances – we are out, so don’t need entertaining. The fridge will be on though, so that might account for a kWhr a day.

If we had a smart home energy management system, some of the energy could be stored and used overnight so no energy need be imported from the grid at all, but unless we had a really big battery room, we could not hope to store a whole weekend’s worth. Also, batteries are expensive, and only give back 70% of what you put in if you are lucky.

So what to do? Well, is it really such a great problem? If we don’t use the electrons, they are not loyal – they are just as happy going back down the wire and looking for a neighbour’s home without PV that can better use them. In energy and carbon terms, this is just as good. They are still displacing electricity that would have had to be generated by fossil means, so this is a good thing.

So there is a partial smart solution to your energy over-supply while you go off building sandcastles; failure is not a problem.

So what would we ask our house if we were going away?

Us: See you Sunday evening, we’re off to the beach for the weekend. Can you feed the cat, check the rabbits have water, and let the chickens in an out. Oh, and can you try and find their eggs, they seem to be laying in odd place at the moment.

House: I suppose you want me to put on a pinny and make you a martini as well! What do you think I am, a robot or something?

Us:  Uh, yes – sorry. I’ll ask the neighbour. Can you just check the fridge is on, then, and switch some lights on and off in the evening to pretend we are in, oh and take messages from those nice people offering loans and payment protection plan claims?

House: Fine! Just call me Marvin then!

You can read all Steven’s past blogs here