Photovoltaic energy, batteries and electricity
Here in the UK, sometimes you can get subsidies to upgrade older property, so a few months ago I had a green energy survey done, and then I had a new boiler installed and much thicker loft insulation – the energy savings for these will pay the cost off quickly.
I could also have joined a scheme where electricity from solar panels would be fed into the grid, and the profit from this would repay the cost of the loan over (say) 15 years (I forget the exact details of how it could have worked). However, the surveyor advised me against this, as I could only fit 5 panels on my roof.
Let’s say that the total cost of the scheme would be £ 6,000. This would be spent in four equal quarters each of £ 1,500 –
- ¼ for the purchase of the panels
- ¼ for the scaffolding to the roof
- ¼ for labour
- and finally, ¼ for the transformers and equipment for feed-in to the grid
The surveyors point was that I would need 6 panels to be able to repay the loan. It was a surprise to me that so much of the cost was involved in the transformers, and it started me thinking, especially when I went to a meeting a few weeks later where the speakers recommended setting up small solar systems to charge battery packs, which could then be used to operate small electric vehicles, electric bikes, etc.
It seems to me that there are several main strands to ‘the new electricity”
1. Solar Cell technology.
The technology of photovoltaic cells is continually developing –
- new materials give greater percentage conversion of the sunlight to electricity
- some flexible photovoltaic materials are now available
- some can now be applied to windows – they are “see-through”
- new materials such as perovskite seem to have great potential – with my materials science hat on, it is very interesting that precise crystal structures can now be obtained of very thin sheets of very high strength materials. Perhaps I will write more on this later
However, the solar cells produce a direct current at a low voltage – ideal for charging large battery packs, less good for transforming to 240 volts alternating current for feeding into the National Grid
2. Solar Panels for hot water
Sometimes it is more efficient to make hot water from “old-fashioned” solar panels rather than making electricity, especially if you want hot water as a main product of your building’s sytems. However, you may need to have back-up water heaters if you must have a certain quantity of water every day at a particular temperature.
3. Battery Technology
New materials and techniques mean that batteries are continually becoming lighter, smaller, higher power, and faster charging. An electric car can occasionally be used as a reserve battery for household supply !
4. How we use electricity
This is the key issue, and we may need to re-design .
Most equipment with computer chips runs at a low voltage direct current, usually 5 or 12 volt DC, so, as we go around our houses we will find numerous little transformers – either plug-in to the mains or built-in inside the equipment – for our televisions, computers, phones, stereos, LED lights, etc. 12 V battery packs would be ideal for operating this equipment (except we are not organized to do this yet)
Some household equipment DOES need 240V AC from the mains – kettles, cookers, washing machines, refrigerators (?), vacuum cleaners (?).
We are locked in to our present systems, but, would a hybrid system of solar charging of batteries and residual mains supply be better. I would be interested to hear of estimates of what the saving from reduced transformer use would give.
People living off-grid seem to be taking the lead in many of these.