This topic is a long one, and for that I apologise. It could be a lot shorter but I wanted readers to be fully aware of what they are getting into, choosing to depend solely on alternative energy instead of the mains. It is nowhere as simple as the manufacturers of this stuff like to make out. But by the end of this article you should be aware of most of the pitfalls and ready to have a go.
Starting with how we got hooked, which goes a long way back now, right to the 1970s, on a trip to North Wales. We’d gone specifically to see a place we’d heard about called the CENTRE FOR ALTERNATIVE ENERGY. It’s situated just outside the town of Machynlleth, which in itself was well-worth the trip, the best wholefood vegetarian café I’ve ever encountered, an equally surreal alternative bookshop next door, plus loads of other equally inspiring alternative and crafts-based small businesses. CAT though, was by far the best. Back then it was still the home for a community of folk interested in living off the grid. They’d rented this deserted slate quarry in the middle of nowhere to experiment with different ideas. As nobody else was doing anything remotely like this then word spread and they opened their doors to visitors. This was in the days before the internet so they weren’t inundated, often we’d go and be the only person, but that was its charm. Being there felt like you were part of what was going on, not at all like visiting a museum or theme park. For example, the coffee bar/ restaurant was their dining room, so basically we got this amazing glimpse of a whole different way of life, and as far as we were concerned it was exactly how we wanted to live. Combine that with it being so hidden away in nature, miles from anywhere, we came away smitten.
Unfortunately getting a life like that wasn’t so easy. Living in a community turned out not to be for us. Which meant having to raise all the money to buy land and build an off-grid home. Another problem was selling our house, which took nine long years. Due partly to the market being at an all-time low throughout, and we were selling what only a few people wanted – a tiny cottage, in a remote unknown location, huge garden, no local facilities. Still it gave us plenty of time to look around, which we did every weekend and holiday. Except nothing ever felt even close. Then when a buyer finally did appear we were totally unprepared as to what to do next. We ended up renting so Maureen could serve out her notice at work, while trying to get some kind of plan together.
CONVERTING A VAN (see also the living in a van (nomadism) page)
Having sold our home, the last thing we wanted then was to waste any of the capital on anything but buying some land and building a new place. But until we found that we had to live somewhere, we also have to be able to travel to search. Living in a van turned out to be the only answer.
Which was fine, except neither of us at that point had the slightest idea about how to do that.
Buying a van without money was solved by exchanging our newish van for a much older one.
Converting it was simply approached step-by-step, but with the three month deadline.
Of all the things we had to consider, providing electricity proved to be the hardest.
Campervans, as opposed a van you have converted, come powered. This is done by installing a secondary 12 volt battery. From this you can use either 12 volt DC appliances (of which there are a vast range), or by using a device called an inverter, which changes the voltage to 220-240 AC, conventional appliances. Keeping this battery charged is done either partly by the van’s alternator, which isn’t very efficient when it has an extra battery to charge, plus you have to drive somewhere. Or (mostly) by plugging into the mains using a hook-up, usually at a campsite.
We didn’t want the expense or constriction of having to find a campsite on a regular basis, so needed a way to procure electricity ourselves that didn’t rely on the alternator. One option was a small petrol generator, which would be useful also when it came to building, but not very healthy or quiet. Had we known at the time you could buy a propane gas version that would have been the perfect solution. Instead all we had left was some form of alternative energy.
It was always our intention to use this kind technology in our new home, but now we were going to have to apply it a lot sooner, and come up with a system that could be used in the van and then the house.
A defining moment. Not only because we were finally on our way to achieving a twenty-five year dream of becoming totally self-sufficient. We were also getting a chance to live for a short while like nomads, totally outside any system, doing it abroad too. While totally reliant on alternative energy.
Looking back now, twenty-two years later and a lot wiser, it was a miracle we survived. Fitting-out the van was stressful enough. There was the time constraint. Weight limits to take into account. Having to do everything using materials that could be salvaged for free or as little as possible. There were no books on the subject then, no internet, and all the local campervan dealers we visited for advice politely told us where to bugger off. Yet despite all that, we managed. Except for the power system, which turned out to be a total disaster.
Right from the start we were in trouble, totally out of our depth, there were so many different choices and decisions to be made. Like which type of generator to go for (wind or solar), what size, what kind of battery and again what size, plus all the other vital bits and pieces. Even though I’d been on a few courses at CAT by then, read loads of books, my actual grasp of how these things worked was pretty much zilch.
There was no time to get up to speed at that point, so I sought a dealer to help go through the options, with the idea that if we bought everything from them they’d throw in a detailed blueprint on how to install it all. In those days there weren’t many dealers, so it didn’t take long to phone them all, but not one was interested. They would sell us anything, or install it for us if we took them the van, but would not design us a system. So in desperation I sought help in the classified ads of the only other source of help then, radical/ alternative magazines. Where among the eternal offers of reiki/ re-birthing/ permaculture courses/ and health supplements, there was one ad claiming to give alternative energy advice.
MISTAKE NUMBER TWO
The person I spoke to sounded knowledgeable, was prepared to supply exactly what we wanted, at a reasonable price, so we decided to go with them, relieved to have that problem solved that so I could get back to the rest of the van conversion. Several weeks later, suddenly realising that we’d heard nothing since, I made another telephone call. There was a problem. They hadn’t even got started. Also, the person I’d spoken to was not working for a company, it was just him in his back bedroom doing this in his spare time. At which point the sensible thing to have done would have been to start. Sadly the stress of everything else was so great I decided instead to hassle him until he got back on track. Which seemed to work, except the bits that did eventually start to arrive over the next weeks were only those he’d ordered direct from wholesalers, nothing else. A fortnight before we were due to vacate the rented flat and sail for Spain, there was still a long list of bits missing, and our contact was no longer answering his phone. It took 12 days to find those, driving around industrial estates in Leeds. Leaving us just two days to fit everything together.
At this point it was December, a week before Christmas, and we were experiencing the kind of weather you’d generally get living in the middle of nowhere of North Yorkshire, absolutely freezing. More so, if that was possible, at seven o’clock in the morning, which is when we started putting the electrical system together, outside, on the driveway of my friend’s house. Neither of us had any real electrical knowledge, so it took us twelve very long cold hours to fit everything according to the instructions, after which we were so exhausted there was no time to check if it actually worked.
The next morning up early again to pack, followed in the afternoon by a party for all our friends, to say goodbye. Leaving the following dawn, in thick fog, to search of a garage that could repair vans, having found during a last-minute check that the bonnet catch had sheared off and there was a worrying leak coming from the hydraulic breaking system.
MISTAKE NUMBER THREE
Three days later, halfway across Northern Spain, we were only just getting to grips with the diagnostic panel on the new power system, when we realised something was wrong, there was no power left in the battery. It took another eighteen months to find out why, during which solving it became an obsession, so much so that all our other problems – being confined indefinitely in such a small space/ our original destination Santiago de Compostela having turned out to be a ghastly nightmare/ not having a phone or postal address or any other means of contact/ alone in a strange country with an equally baffling culture and language we couldn’t even order a coffee in/ and all the while supposed to be searching for a piece of land, which now we hadn’t the slightest idea where to look – were nothing in comparison. We took the van to auto-electricians, sent e-mails and letters to everyone we could think of (including the seller & manufacturers), even asked complete strangers, no-one could come up with an answer as to why the battery was no longer working. Then, to make matters worse, the van’s engine blew up, while we were staying in a remote mountain village of Galicia. There was hardly a shop in less than 40 km, let a garage that could handle a van as big as ours, but the local mechanic agreed to come and take a look, and he had not only trained as an apprentice at Renault in Paris on these kind of engines, he was interested in other problem too. Rebuilt the engine for next to nothing, and finally solved the battery mystery. It was totally dead. What nobody had told us, was it should have been fully charged before being connected/ used. Luckily, as this was going to be very expensive to replace, specifically designed for off-grid use, there was a warranty. If only we could elicit a reply from the manufacturer. That simple task took three months, after threatening them with legal proceedings (thanks to the help of a trading standards officer). Their reply was short and terse. An e-mail referring us to the very small print, the bit stating that any claim has to be first inspected by them, which meant the battery had to be sent back to the UK at our expense, and that the warranty only applies to products used solely in the UK. Very neat. And a lesson for us all. Expect nothing and you won’t be disappointed.
By then we’d had more than our fill of travelling, not finding what we were hoping for, trying to remain sane, so boldly decided to move on. Venture boldly to another country, Portugal. For which we would need a new battery. This was solved once again by our wonderful mechanic, who assured us any ordinary car/ van type would do, plus was affordable. A very special moment. Knowing that finally, with no previous experience, we had actually put all this stuff together and it really did work. Retribution enough. Heading off for yet more adventures, this time accompanied by three feline companions, a reminder of our eighteen months exile in Galicia.
MISTAKE NUMBER FOUR
What happened next proves that things can also get a lot worse rather than better. While we stayed on the move the electrics functioned perfectly, the van’s alternator keeping the battery topped up. And it was summer by then we weren’t using more than we were putting back in. But as soon as we parked up for any length of time the battery was dead again. Why? We’d made an even bigger mistake.
Looking back none of this is surprising. Despite all the hype, especially now, twenty-two years later, alternative energy is an impenetrable science and will always remain so. The province of geeks from another planet. Even my neighbour, who is an electrical engineer for the electricity board, doesn’t understand DC power. During the fitting-out I remember asking the Head Electrician at the West Yorkshire Playhouse (where Maureen was working, and the biggest theatre complex outside London) to tell me what size plug I needed for a particular connection, and he hadn’t the slightest clue what I was talking about.
During our travels we’d not met any other van dwellers/ nomads/ or even conventional campervanners to talk about our problems to. But once we reached the south of Portugal, the Alentejo, they were swarming like flies. Everywhere we went it was like being in an exclusive club, flashing headlights and exchanging waves when passing, and you were never alone when parking up. Not one of those we met had anything like the power system we had. Lots of solar panels, petrol generators, hook-ups. We were the only one with a wind turbine on the roof. And why was this? Because that nutter we contacted who sold us all this stuff, made it sound totally logical. Far more efficient than solar panels, cheaper, a lot healthier, and quieter than generators. Working day & night/ rain or shine. Exactly suited to the region we were heading for, Cape Finisterre, the wettest and wildest part of Spain. He even claimed that his own home was powered by one (an AIR 403/ now X).
Wind turbines. We saw them first at CAT, decades before leaving for Spain, who had loads of them. The UK government even offered grants to get them fitted to conventional houses. DIY stores stock them. The smallest (100-400 watts) even appear to be amazingly efficiently, you only have to breathe on the blades and they start spinning. Okay, 100-400 watts doesn’t sound very much, but when they cost from £700 to several thousand each (and that’s without the tower and all the necessary supporting equipment) then you learn to adapt. What they don’t tell you is spinning blades don’t necessarily mean actual power. In fact to get even a single watt out of an AIR 403/ X requires a minimum of 25-30 km/ hr of wind. And then to charge the battery it has to be constant for 3-4 hrs a day, every day. And for that you get enough power to run a laptop or light. But that’s not all, the wind has to be clean. A strange expression, which means free of any turbulence from surrounding objects (trees, buildings, geography), so effectivelyv needs to be mounted twice the height of any of those, within a radius of 500 ft. The one on our van was just three metres off the ground, it didn’t stand a chance. Let me give you a couple of real life examples. El Pocito is 600 metres above sea-level. The land slopes away steeply (almost vertically), so there’s no obstacles for the prevailing wind for about 60 km. A perfect location for wind power. Yet to ensure a clean airflow we’d still need a 10 m tower to clear the height of the house. Then there’s that small matter of a 25 km/h wind. Doesn’t sound much does it? Well, the only occasion the van turbine did generate electricity (so it must have been at least that then) was when we were driving along a mountain ridge in Galicia, at well over 1000 m, and suddenly a storm engulfed us.
This photo was taken afterwards. When it was possible to stand up again. As we drove along the cliff edge the van was rocking so much we had to stop and wait the storm out. Using the opportunity to connect up the turbine. I nearly lost my arm doing that, the massive blades started turning immediately, before I could get clear. They spun round so fast I thought they’d break up. The noise was pretty awesome too, a kind of screaming (friction on the blades), combined with the vibration down the pole inside the van. At one point the meter inside showed 400 watts of power coming in. This is what is supposed to be normal operating conditions. Luckily the storm passed by as quickly as it had come, and how much power did we generate? Enough to run the coffee grinder for a single espresso.
Time heals. Or at least the pain diminishes. All these years later I would still like to inflict unspeakable acts on that nasty man who advised us. But eventually we managed to sell most of the equipment, at not too much of a loss. Then came El Pocito. Where once again we had to address the whole issue of powering our home using alternative energy, including pumping water up from a borehole. We still weren’t any the wiser, and this time in a foreign country. But it did seem like the world of generating your own power had moved on during that time in nine years, as well as become very more popular in Spain, enough for us to actually meet ten different firms in person. They also came to us. We arranged to meet in a bar in Almonaster la Real then go up to El Pocito (nobody could ever find it alone). Except not one actually wanted got any further than the bar, they all thought it was just a matter of choosing which kit. Not a good omen. They also all came up with a completely different solution. The only thing they did agree on was the price, astronomical. Around fifteen times more than we eventually paid out. Talking to these people, who unashamedly admitted they had no actual experience, was both weird and life-changing. Finally convincing us that we’d do a lot better at everything if we made all the decisions ourselves from that moment on. The power system we came up with for El Pocito is therefore the most efficient and basic possible. Basic because we knew we’d make a lot more (costly) mistakes along the way. Therefore most of the parts are second-hand, much was free from systems long abandoned, any new bits we got from the internet at virtually wholesale prices. Total outlay (on the house system) 1,000 euros (£800).
There has been a lot to learn, and still a way to go. Far more than any books or courses will tell you. But while it’s been stressful, it has also been a positive experience. Enough to feel confident to write about how ours works so others can use that as a base for building their own. But before I get into the technical stuff, a few thoughts about what you need to consider first, when choosing alternative energy over the mains.
Cost. Two of the reasons we wanted to generate our own were: a) alternative energy is a limitless source of free power, so once we’d bought all the equipment there would be no more bills, and (b) if we bought land where there was never any hope of getting a mains connection, it would be a lot cheaper, enough to pay for the entire installation. Both proved to be totally false. In Spain (and some parts of Portugal), land in the countryside is undoubtedly a lot cheaper than say the UK, but only in places where no-one in their right mind would ever want to live. Also, buying the system is not the end of the story.
To start with all this stuff is ridiculously overpriced (even if you do the installation yourself). For example, when we last used mains power our consumption was down to an average of 25 Kw units a month (check with your last bill to appreciate how little that is). To match even that potential, with alternative energy, would require a system costing at least £15,000 (or if you want to work it out for more power, around £600 per Kw unit).
Then there is the depreciation factor. This is something I hadn’t even considered. Nothing lasts forever, especially when it comes from China, so some day it will all have to be replaced. The companies selling this stuff will tell you 10-15 years is the average life expectancy. In reality some bits last a lot longer (panels for instance, but all the time diminishing in efficiency), others a lot less, especially if you have the misfortune to encounter lightning/ high winds/ flooding/ theft/ accidents/ or are just slapdash about looking after it properly. Batteries for example, which can be the most expensive part, could last twenty years, or as little as one, depending on how you treat/ maintain them. Not looking so free or cheap now, eh? Even we, with a system worth 1000 euros had to put aside 100 euros a year to cover replacements, and that’s to generate no more that 5 Kw units a month.
Suitability. Choosing the most appropriate system. Happily (for us) we are not the only ones to have made gross errors in judgement, every installation I’ve seen has at least one glaring fault – panels sited at the bottom of deep dark valleys/ fixed in one position so they only get a few hours of sun each day/ some even facing trees/ wind turbines mounted far too low/ water turbines where the source runs dry for part of the year. But say you did manage to get everything right, then you still have to reckon with the unpredictability factor of the weather. Because no matter how good your site is, how big or expensive the system, no-one can control nature. Take El Pocito for example. On paper it’s a classic solar site. Clear horizon, gets a minimum of eight hours of sun for an average of 300 sunshine days a year. What more could you ask? Well for starters, what about the 65 days when it isn’t sunny? Between Nov-April, half the time there won’t enough power. Dealers & installers will tell you they can cover for this by adding extra panels and more battery capacity, and yes in theory you can do this, but at an extra cost, both upfront and to eventually replace.
Bearing all this in mind the next question should be:
IS ALTERNATIVE ENERGY FOR YOU?
Deep down, are you really just looking for an expensive toy? If you are then probably alternative energy isn’t for you and it would be best to skip the rest of this page. Are you prepared to maintain and repair the system yourself? And more importantly, are you ready to drastically change the way you have used electricity? Because if there is any doubt stick with a mains connection.
When you live conventionally (aka like 99% of people) it can appear impossible to imagine any other way of getting power (or water/ heat/ food). To give you a taste, here’s how we did it at El Pocito.
First priority every day was to charge the battery, which was used for the evenings. Until that was done we did not use any appliances. The battery was an off-the-shelf car/ van type, rated at 250 Ah, and the process took around half an hour in summer to all day in winter. There were two 50 watt solar panels to do this with (wired in such a way to give 100 watts at 12 volts), mounted on a specially designed pole which could be swivelled (see drawings at the end) so it was possible to keep them orientated so they were in line with the sun all day. When the battery had charged, and then only if there was sufficient sun shining, we could use appliances, up to a maximum of 50 watts at a time, and only for as long as there was full power coming in (not on cloudy days). This way the appliances effectively are running directly off the panels (don’t worry if you can’t follow any of this, an explanation will follow). An hour before the sun sets we stopped using appliances. The battery then became our only source of power. I said it was rated at 250 Ahs, but we actually only used 10% of that, 25 Ah. This sounds crazy, but there’s a reason. Lead/ acid battery life is measured in a predetermined number of complete discharges (ie all 250 Ah). If you never let that happen, life expectancy is dramatically increased, possibly by up to 10 years for a lead/ acid battery (25 years for the other more expensive alternative energy types). 25 Ah, for those who have no idea what this means, translates into usable power like this:
25 Ah x the system voltage (12 volts) = 300 usable watt/ hrs.
Meaning, an appliance rated at 100 watts can be run for up to 3 hrs (100 x 3). Okay, doesn’t sound a lot, especially when you consider a battery this size (from a lorry) weighs 66 kg. But if you choose appliances with a low wattage, it is still possible to have some semblance of conventional life. For example, a 8 watt LED light bulb (equivalent to a 60 watt incandescent type) will only consume only 8 watts an hour out of your 300 usable watt/ hrs.
A small laptop (which we use to watch films on), with the sound fed through a car stereo, will perhaps consume 50 watts an hour.
You can also change the equation if required. If an appliance is rated say at 50 watts and runs on 12 volts then it consumes 4.16 Ahs (ie wattage divided by voltage). If the appliance is rated at 50 watts and runs on 240 volts (via an inverter) then it consumes the same amount, voltage isn’t a variable, the wattage is what counts, though the inverter itself will use some power.
On the days when there isn’t any sun you adapt. Either putting off jobs that require electricity, or by using hand-powered alternatives instead. At El Pocito we had a treadle sewing machine as backup. We washed clothes by hand. Had a hand-cranked mincer and coffee grinder. There was a wind-up radio. Candles. Broom. Plus of course a whole spectrum of hand tools.
Commitment. Despite folk now buying panels to fit on their conventional homes to feed into the grid, alternative energy will probably always remain a minority interest, for those who are truly dedicated. Which means you are not going to find a handy local dealer/ installer prepared to design your system properly, or be there when you need them. Nor can this thing think for itself, you have to do all that. From realigning the panels every half hour, to remembering to lock them down each night or if the weather turns nasty. Constantly aware of what is happening so there are no nasty surprises. Panels also have to be kept clean constantly. The battery checked and topped up, at least once a week. If you do all this diligently things will run relatively smoothly. Anything less and the system will end up costing a good deal more and be far less efficient.
HOW TO INSTALL A BASIC SOLAR SYSTEM – FOR TWO PEOPLE
WHAT YOU’LL NEED:
Panels. Buy the best make possible, german or at least an internationally well-known brand, but not BP, their products are terrible. 100 watts of capacity suited us fine, but for the same price today you can get more wattage for the same size panel. 200 watts would be perfect. If you have more than one panel make sure they both have the same number of cells, or you’ll need to fit a diode to ensure the power flows only to the charge controller. Second-hand can often be as good as buying new, all you need to do is check all the cells are still functioning. This can be done by reading the voltage (if it is still connected) or with a multimeter. Each cell generates around 0.55 volts in full sun, so just divide the voltage by the number of cells. Anything over 12 volts will charge a battery but the higher the number the quicker it does this.
Fused switch or plug/ socket. This is to isolate the panels when you need to do maintenance. Make sure they are rated at least 150% of the power that could pass through.
Charge controller or regulator. This is a box of electronics that takes the raw power from the panel(s) and feeds it to the battery, in a way that is safe, charges most efficiently, and cuts off the current when the battery is full. The most up-to-date type uses what is known as mppt technology, which is more expensive than a standard controller but will more than pay for itself in extra performance (especially in the winter). Make sure it comes with the all-important display panel (in volts/ watts/ and amps) and enough cable to have the display located in the house.
Battery. As this can be by far the most expensive part of a system, start out with for the cheapest option and ignore everything dealers & installers tell you, they earn by commission. Stick with 12 volt to begin with, even though there are many other voltages, all far more efficient, but commensurately more expensive. Buy a single battery rather than several, otherwise if one fails they all need to be replaced. I still reckon the ideal storage is 25 Ah (aka 250 Ah), for two frugal people.
Inverter. This is what transforms the battery’s DC voltage into 220-240 volt AC, so you can use conventional appliances (12 volt DC appliances run direct off the battery). Choose a model that produces a sine-wave output. This is more expensive, but sensitive appliances like computers won’t work without it. The output rating depends on what you want to use, we found 100 watts was ideal. Make sure it has silent operation too, as the cheaper models use really loud fans.
Cable. DC voltage has one major drawback, it loses massive amounts of power along the cables, unless you use the appropriate thickness for the distance travelled. For outside use (from the panels) they will need to be fully UV protected.
To work out what size is required, use the following sum:
size in mm2 = 0.0546 x Amps (maximum rating of the panels combined, Amps being watts divided by voltage) x distance (m).
Cable thicker than 2.5 mm2 won’t fit into the terminals of most equipment, so for those you will need appropriately rated/ sized connector boxes at each end to run thinner cable from, or simply cut the end of the cable to fit. Remember that using cables not thick enough will become hot and potentially catch fire.
Not only does everything need to be placed as close together as possible, some will need to be located in the house and some outside, in a building. The inverter should be indoors, so you can switch it off when not in use, as well as the display panel for the charge controller. Everything else is on the other side. We built an extension for those, which also doubled up as the tool-shed, where it was always dry/ cool/ and frost-free.
The solar panels need a mount. Do not fit them to a roof, where it will be difficult to clean, and where they only get sun for an hour a day. Do not buy a mount, use the drawings below to design your own and have it made up.
Main things to bear in mind:
It needs to be able to cope, remain stable, in very high winds.
Swivel at least 270 degrees.
Have a function to adjust the angle of the panels.
Sited as close to the ground as possible to conserve rigidity and make it easy to clean/ maintain the panels.
The charge controller is fixed to a wall, behind which you will need to insert a metal sheet (galvanised or aluminium is perfect) or spacers, to help dissipate the heat. Mount the fused switch nearby. The inverter fixes to a wall too, as does the display panel (at a height it can be read easily from a distance). You’ll also need sockets, for the 12 volt appliances and the 240 volt supply, located as close to the rest of the equipment as possible. Mark the 12 volt socket clearly so you can see which is the positive (+) pin. Do this with all your 12 volt appliances, otherwise they could be destroyed (see below). Polarity is not an issue with 240 volt appliances.
Important stuff to remember. People will tell you 12 volt DC electricity is safe. Wrong. If you accidentally, allow the positive to connect with the negative, using anything that conducts electricity (metal, wet hands, etc), it becomes a lethal force and can even melt metal. DC electricity and equipment also only works when you connect everything correctly. If you don’t, and are very lucky, nothing happens, but usually everything gets fried and your precious investment is a worthless piece of junk. Always remember: RED is for LIVE (+), and BLACK is NEGATIVE (–). If you are worried that bare cable ends might touch during installation then tape over them temporarily. When connecting the battery cover the clamps that bolt onto the battery poles with a cloth while waiting, leave nothing to chance. Wear latex gloves. Whenever connecting the battery (and this applies with cars too) always attach the positive first. Disconnecting, remove the negative first.
1) Start by doing the cabling between the charge controller and the 12 volt socket for the house.
2) Then the cable from the charge controller to the battery clamps, but don’t fit them to the battery.
3) Then the cable between the inverter and the clamps, again don’t connect.
4) Followed by the cable between the fused switch and the battery clamps, again don’t connect.
5) Next the cable between the display panel and charge controller.
6) Finally, after first making sure the switch is in the OFF position, and the panels are covered with something lightproof, fit the cable between the fused switch and the solar panel(s). Do not join panels to each other, instead connect them by running a short length of cable from each to a connector box.
7) When that’s all done, having checked everything at least twice, then it’s almost time to make the final connection (to the battery). First though, ensure the terminals on that are clean/ shiny (a wire brush is perfect for this), and smear them with some Vaseline to prevent corrosion. Fit the positive (+) clamp first, tightening with a spanner, then the negative (-). If you’ve done all this correctly (no loud bang/ bright flash/ or puff of blue smoke) then the charge controller LEDs should light up correctly, and the display panel show the voltage in the battery. DO NOT connect any appliances yet, as the battery still has to be fully charged first. To do this open the fused switch to the panels, align the panel(s) with the sun, and check with the display panel for a voltage/ wattage.
Aligning the panels. This is really easy (though it took me a year to work out). Somewhere on the mount will be a shadow when it is in the correct position, always use this. The correct tilt/ angle should work the same way.
Before using any appliances ALWAYS make sure the battery is fully charged first. Make this a daily mantra.
Charging the battery. The path the sun travels across the sky varies in height and distance each and every day. Lower and shorter in the winter, higher and longer in the summer. How often you need to go and align them is therefore something you have to develop a feel for, usually around 30-60 minutes. The display panel (if you have one) will tell you what is happening. During the charging phase you will see the wattage coming in, and you need to wait until that stops rising, or the voltage reaches 14.8, which is the highest the voltage is ever going to go, after which it will drop back to a value specific to your particular battery. If you don’t know what this is, charge the battery all day (do not use any appliances) then two hours after dark read the figure on the display panel. At El Pocito 100% was 14.2. Once you reach that figure, if it’s still sunny, you can use appliances. If the voltage drops below 14.0 switch off all appliances.
Using the battery at night. Once you know the 100% voltage, you need then to work out what 90% is, so you know you have consumed the maximum 10%. The simplest method to do this is to choose a 12 volt appliance (not 240 v, as the inverter consumes some power too) and run it for the appropriate amount of time, then after 30 minutes (for the voltage to settle) read what it is. For example:
a 250 Ah battery will give 25 Ah of usable energy. In watt hours that is 25 Ah x 12 (the voltage) = 300 watt hrs. Therefore a 100 watt appliance should be run for 3 hours.
The only other thing you need to know about the battery is how to check the acid levels. This can be really difficult. What I did was cut a short piece of brightly coloured plastic pipe, measured the exact distance from the top of the inspection hole to the maximum level mark, then threaded a piece of stiff wire through the pipe at that point, so when it was inserted the wire rests on the top of the inspection hole, while the bottom of the pipe should just touch the liquid. If it doesn’ top up with distilled water. A word of warning, this is acid you are working with, so always wear appropriate gloves and old clothes. And have a bottle of baking soda mixed with water (until it becomes a paste) handy to neutralise any spills.
And that’s about it. If you have any questions or advice please do not hesitate to get in touch.
click below for pdf copies of the drawings above
MAKING YOUR OWN 12 V APPLIANCES
Once you’ve accepted that a good quality car radio can be just as good to play and amplify CDs as an expensive 240 volt stereo system, using conventional high quality speakers, then there’s no limit to what else can be fashioned from recycling 12 volt bits and pieces. It’s a lot cheaper too, and uses far less energy.
Our first foray into this world began when it was clear we’d need a FAN, to keep cool indoors during the hottest weeks in July and August at El Pocito. Generally the walls were thick enough to maintain a pleasant working temperature, but if outside remained at over 40 C for more than a few days then there’s nothing you can do. I trawled the internet, found plenty of fans, a fair number 12 volt too, though few with low enough wattage to run directly off our tiny panels. They were all very expensive as well. Then as I was using our ancient laptop, I became aware of a rather pleasant breeze emanating from underneath. Possibly just the thing. A mention on the blog, asking if anyone had any redundant computers from which the fan could be removed, resulted in a package, and I set to work.
They are both from a desktop computer. Measuring 92 mm square. And the voltage/ amps clearly marked. Both obviously are 12 volt. One uses 0.3 amp (amps x volts = 3.6 watt), the other 0.56 amp (6.72 watt). Wired in parallel (red to red, black to black) that means they will need 10.32 watts, hardly anything at all. They did require some kind of base though, to hold them upright when spinning. Using a scrap piece of galvanised sheet I made what you can see in the photo below. Not as elegant as I’d hoped, but it does the job and the fans are sufficient to keep the temperature from rising.
More appliances as I think of them.