Electricity

Now this is an interesting subject. The finca is nowhere near a grid connection and trying to negotiate with the local power company and other landowners just doesn't add up financially or any other way. So we intend to use solar and water to generate our power. This isn't particularly a cost saving option since the set up costs are high and the batteries need replacing every 10-15 years (not cheap). However, with no alternative other than living in a cave-like existence, lets get on with it.

Plenty of sun is always a good option for solar power. Living 20kms from the Costa del Sol, we've plenty - apart from winter. Then the sun dips below the hill to the south and from around mid-November to early February we get around 3 hours good direct sunlight. Unless its cloudy and rainy, then we don't. We can try and counteract this by (going somewhere warm for the winter) or cut down our electric requirements. We can also up the pv array size to have more panels so that we can collect more and then have larger batteries to store it all. However, the costs go up proportionately (if not more) so there becomes a cut-off point.

But we have lots of water in winter! Hydroelectricity! Since the site is on a hill above the river all we have to do is channel water to create a head and put a small turbine at the bottom. Easy-peasy. Well....not quite. We've ID'd the best point give us a head of around 35m and we reckon we can get achieve a flow of circa 25 litres per minute. This should be sufficient to drive a BabyStream turbine to give 30-40 watts per hour. Since this will be 24 hours a day, its a good old bit of power. All we need to do now is design it, buy the kit and build it.

For the solar part of our generation, we intend to use the side of the main ramp that faces south to mount 6 pv panels. We were considering a further 2 panels up the hill to catch the early/late sun in winter, however, not sure we need to do this now. (If your wondering why we don't put all our panels up there, its logistics. An array of pv panels needs to be pretty secure since it acts like a sail; as the wind whips across that area in winter we would need to use a lot concrete and there isn't a easy way of getting it up there. Also there will be a transmission loss to the batteries.) 

We're listing all of our electricity usage including toothbrush chargers so we can start to come up with a system size. It will be solar initially and then we can add the hydro part later. We could use wind to drive a turbine but it (the wind) isn't reliable enough to warrant the cost of set up.

For the hydro part we've decided on an area that has been neglected and totally overgrown for many years. Originally I thought there might be a couple of ancient terraces beneath the mat of greenery. We enlist Richard to set to and strim the area to see what lies underneath. Wow! A couple of hours later and he has smashed his way through and down about six terrace levels. We are now almost down to the river. Its a beautiful area previously hidden. More importantly we are now able to achieve a much greater head of water - about 50-55 meters. More meters mean more watts. The next job is to clear a way from the very top so that I can run a pipeline all the way down and then measure the flow.

June. The pipe is now all the way down and the water gushes out well enough. I may try and run an independent pipeline all the way from the river source. Definitely early morning work since the temperatures are up now. The biggest problem with the site of the turbine is its distance from the batteries: so that we don't lose power we need a reasonable thickness of copper cable to transmit the current up to the batteries, a distance of around 100 meters. Copper is expensive sufficiently so to make the hydro solution untenable if require, say, 16mm cables. For this reason we may have to consider the wind option. The trouble is, we don't really understand how much wind we have during winter. We may just get the solar part in for the winter coming and measure the wind during the winter. We need to buy an anemometer which, of course, isn't cheap so we have opted for a handheld one and I'll measure the wind during the day. A tad tedious.

Having enlisted my brother to build the 'power station' otherwise known as Drax D, (something he had been dreaming about doing apparantly), we now have to get it completed, dry and secure to house the thousands of euros worth of solar equipment. So, as of mid November, we are starting to get some utilities in place. I'm so excited I think I'll have another glass of wine....

On the hydro front, that is increasingly becoming unrealistic unless we suddenly get some really useful info on how it can be achieved both from a cost perspective and practicality. I'm measuring wind at the moment (no sniggering from the back of class!) to see whether a wind turbine is going to be viable.  

End of November 2006 and we can now experience the unusual sensation of just plugging things in without having to exert ourselves to start the generator. Luxury. The solar panels are up although we have had a slight hiccup with the tracking assembly. Unfortunately, our installer (Brian) was misled by some crass documentation which led him to believe the panels were to be mounted horizontally. They should be vertical which in turn means the mounting poles that are nicely set into good sized lumps of concrete, are wrong. Nothing that an angle grinder and a spot of welding can't sort out! (Brian, by the way, has done an otherwise immaculate job.)

As for the actual equipment, we are starting with 6 Kyocera 125 watt panels to see how we go. The mounting frames for the tracker units take 4 panels each so we can expand if we want more solar power (rather than having a separate wind turbine). The tracker units follow the sun on an east to west arc and will be set for winter sun. They can be manually altered for summer sun. The charge controller for the panels is an Outback Mx60 and gives a detailed display of whats going on from the panels. This links through to a Victron 24 volt charge controller/inverter rated around 3000 watts. This allows charging of the batteries via the generator as needed and, of course, produces our 230volt AC power.  The batteries are 12 Hoppeke 2 volt 940 amphours units. Some friends have 650aH batteries and are running everything successfully with those so we are hoping to have sufficient power - assuming we can charge them in winter!  

By the time tax is added, loads of miscellaneous electrical bits and Brian's time then the bill is circa €17,000. Gulp!!!! The batteries should have a life expectancy of around 12-15 years. So the ongoing costs at today's prices amount to €4,200 for a new set. Not cheap but we do not have much of an alternative.

We have now added a small 20 watt panel to each tracking unit solely to power the tracker's battery system and, therefore, its decision making electronics. This will, hopefully, avoid problems from the charge controller unit giving variable voltage data to the panels (thereby causing malfunctions).

Hopefully, a final adjustment by Brian who has fitted a battery temperature sensor that adjusts the amount of charge to the batteries depending. I'm hoping the batteries will stay at a reasonably continuous temperature during the summer since I have constructed a shade over the power house. Its quite nice to sit under as well!

For anyone in southern Spain who needs or is interested in solar power, then I can recommend Brian. He has set up a website; follow the link as they say.