How do Solar Panels Work for My Home?
So, what does a solar panel actually do, and what does the installation do for my home? Is it a magic flat plate that you shine sunlight on, and electricity comes out? Well, in really simple terms, yes, it’s just that the magic is actually physics and a little bit of chemistry. No rabbits out of hats here!
So, first off – the technical bit – the solar panel itself. The technical term is photovoltaic panels, which is why you see them called PV panels sometimes. Photo comes from the Greek for light, and voltaic comes from Volt, the unit of potential difference, or one of the electricity units if you prefer. Solar panels are made from two different types of silicon, called P-type and N-type silicon, which means that the silicon has been “doped” with another element, such as antimony, boron, or aluminium . Some of these produce “gaps” in the atomic structure of the silicon (does anyone else remember O-level/GCSE chemistry?), meaning electrons can move between the layers of silicon, sometimes over what’s called the photovoltaic bridge. When light hits these layers of silicon, it transfers energy to these electrons, making them move across the photovoltaic bridge. This is what generates the electricity from the solar panel.
So, moving on from the theory, what about the practical stuff? What happens if the sun isn’t shining, or if there’s snow or leaves on the panels? Well, if it’s cloudy, don’t worry, your solar panels are still producing electricity! However, they will generate at a reduced rate, as direct sunlight means more of the solar energy is hitting the panels than indirect sunlight. If anything is blocking the surface of the panel, such as leaves, then generation will be severely impacted however. Snow is an interesting one: it depends on how deep it is, as it is translucent and lets some light through. Broadly, the clearer the panel the better of course!
However, the question remains “ How does my house get to use the energy?”
Any spare production that the house does not use goes back to the grid and is metered. Under the new Smart Export Guarantee that comes into force on 1st January 2020 you will get paid for this by your utility firm. Currently companies such as Octopus Energy are paying 5.5p per kWh generated.
So, let’s talk numbers, specifically money and costs. Can you go totally off-grid and stop receiving electricity bills with solar panels? Well, in theory yes, but that’s probably going to cost a lot more than just alleviating your consumption with an installation. Sizing of the system would be important in this case, as would having sufficient battery storage to deal with overnight consumption if desired.
In general, you’ll still get electric bills if you’ve got a solar system, but you’ll notice a dramatic reduction in your consumption from the grid as the solar installation takes the load. Every kWh your system produces and that you use means one more kWh you did not buy from the grid – with continual price rises in energy over the years the average payback for a correctly sized solar system is often around 7.5 years with an initial cost of £4-6,000 for a normal standard domestic system and you will normally make back 4 times the total cost of the installation over the term of the warranted panel output – or circa 12-15% ROI which is a lot better than the 1% interest your bank pays you.
Finally, let’s talk about a couple of fringe factors: will solar panels work in a blackout situation, and what kind of operational and maintenance costs are associated with them? The blackout question is slightly tricky: it depends on how your system is hooked up. If you’re grid-connected, as is likely, then any kind of grid disturbance will prevent the panels from feeding into the household network. However, if it’s not grid-tied, and on a standalone network, it will work perfectly well. Finally, let’s talk maintenance. Broadly, apart from having someone come out and give them a wash every year or so (or doing it yourself if you don’t mind heights!), there’s no operational costs to a solar installation.
So, are your solar panels magic black boxes? Any sufficiently advanced technology is indistinguishable from magic, as they say…