Wind turbines and solar panels

When you live in a ‘normal’ house with an unlimited supply of electricity, you don’t even stop to think before you plug something in – at least, we never did. I was a great lover of lamps – we had so many around the house, all on timers so they went on and off automatically. Kettles, irons, microwaves, telly, stereo, hairdryer, food mixer, coffee machine, slow cooker, computers, bread machine, toaster … the list of electrical items we use is endless, and nearly all are probably considered necessary for daily life.

So when you live on solar panels you have to totally re-think what you use, and not just what you use, but when you use it.

The biggest enemy of solar power is ‘the heating element’. Heating elements drain power at an unbelievable rate – I was really taken by surprise by the amount of power they use. So that rules out an awful lot of things – the kettle being the big one for me (being a tea lover!). No iron, no microwave, hairdryer, coffee machine, bread machine, heaters or a toaster – they’re all a huge no no! Instead, we have a stove top kettle, and do the toast in a griddle pan (my new cooker has a grill, which I was quite excited about, but was totally underwhelmed the first and only time I used it). As for the other stuff, well we just don’t have them anymore!

When we were learning about solar systems it became obvious very quickly that it was not as easy as it looks. There are different parts to a system, and balancing out the different parts and calculating what power you think you might need had us producing pages and pages of mathematical equations, and we spent several months of planning before we attempted to install anything.

The house had a very simple control panel, one 100 watt panel, a 150 watt inverter and six 2 volt batteries to store the energy. This set up was used by the previous owner to run the tv for an hour once or twice a week. We were clearly going to need more! We found the original paperwork for the installation of this original system and discovered that everything was 15 years old. Only five of the batteries were working, and the rest were bulging, and definitely at the end of their life. So, we were starting from scratch basically.

On the Internet there are lots of methods of calculating how big your system needs to be. We started by listing what electrical equipment we NEEDED (not wanted!). We needed to know the wattage, voltage and amps of each item, and estimate how long we would use each item each day / week / month / year. Once this calculation is done, you then look and see what items might need to be on at the same time, and from that you can calculate what amount of power you need in any given day. Now, as you can’t discharge the batteries by more than 50% you have to build a system that gives double what you actually need.

So step one – we bought a 2000 watt inverter. We have a 12 volt system here and so we need the inverter to change the current from 12 volt to 240 volts. That was around €800 – wow! You can get much bigger ones, but we calculated that we could run what we needed on this. The big problem with most electrical items is, it might say it’s 5 amps, but to get the item going it actually needs triple the amps. So something you think is pretty light on power can still cause a problem.

The inverter converts the power from 12volts to 240 volts.

The power coming into the inverter from the solar panels is controlled by … the control panel. Now there are two main types of control panel – MPPT and PWM. We chose an MPPT controller as it’s more flexible. MPPT stands for maximum power point tracking. This type of controller looks after the life of the batteries better as it gives just a little more power than you need for what’s on, and the rest is used to maintain the batteries. That may be over simplifying it a little, but you get the drift! When you turn something else on in the house, it diverts the extra power you need to the inverter. The control panel wasn’t too expensive – around €140. You can also buy a combined inverter and control panel all in one now.

The control panel tells you at a glance what state the system is in, and what power is coming in and going out.

So then there’s the solar panels. There are two ways to connect the panels to the controller – in series or in parallel. Always so many choices to decide on when installing a solar system! We have three solar panels totaling 745 watts. The maximum we could have for our controller was 760 watts. Solar panels have come down in price massively and so this part cost around €400. Again, there are different types of solar panels – polychristaline or monochrystaline. The big problem with solar panels is how quickly they lose their effectiveness – we’re probably looking at replacing the panels every 6-7 years.

Lastly, you need batteries to store the energy so you can have power when it’s dark. These are expensive, and need changing about every 8-10 years. We bought 6 batteries which cost about €1100, but they are a decent size. Again, there’s a huge amount of choice of type and size of battery. The control panel’s job is to maintain the batteries – when to pull in power, when to stop, when to stir the batteries to refresh them etc etc.

The batteries are stored in our bedroom – it’s sometimes disconcerting when the fizz and bubble!

Now at this point, I will say that Rog did 98% of the research, and all of the installation! I just couldn’t get my head around volts, amps and watts, so was sitting there chipping in ‘can I run a food processor then?’

All was well, and as we’re in Spain we get a decent amount of sun for much of the year. It is harder in the winter – it gets dark at 5 o,clock and so the batteries get drained much more than in the summer. This is where the candles, oil lamp and solar lights come into their own! We have fitted low energy LED lights in the house, but they are still a drain, and so only use them briefly when we need to rather than leaving them on all evening. We can charge up the solar lights in the day and bring them in the evening. We also have a light we can charge up in the day via usb to use in the evening, which has been more successful than the solar lights! We have to plan what needs charging in the winter on cloudy or rainy days as we can’t have everything plugged in together like we can on a summers day!

So last winter we asked ourselves what we could do to boost our power on cloudy days – and of course, the solution was a wind turbine! It was surprisingly cheap at €130 from Germany. Now, this is where it got complicated. Solar panels output DC power which comes into the control panel and is then converted to AC by the inverter. Wind turbines produce AC power! We wired the wind turbine into the solar panels (I can say we here ‘cos I did actually help!) so all the power from both the solar panels and the turbine combine as they come into the house. This meant fitting a small controller between the wind turbine and the solar panels. This changes the current from the wind turbine into DC to join up with the solar panels, and then the controller / inverter changes it all back to AC. It makes your head hurt doesn’t it!!

We stabilised the pole that the wind turbine sits on with metal wire – it wobbled alarmingly without these!

The net result is that we have enough electricity to live a simple life. We can produce about 7 amps. The average house in the UK has a supply of at least 50 amps to put that into perspective! Most of Roger’s power tools need to run on the generator as the solar system simply can’t handle them, but much of what we do is manual so this doesn’t need to happen often. We are fortunate to have satellite WiFi so I can work, and if we do have a bad weather day, there’s always the generator (a back up is a must have in our situation) – it costs about €1 an hour to run so not too bad. There are days when we literally turn everything off during the day so that we have some power after dark, but the benefit of living in a sunny country is that we don’t have too many days like that!

So, that’s all there is to installing an alternative power system!

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