“How to thrive on a Non 240V Hookup Site”
which is what Newton Grove CL is,
so gain your freedom and give us a try!
This page was created to try to give advice on how to enjoy the non EHU site without giving up the home comforts!
Contributions are from Caravan & Motorhome Club Members, external websites etc
A useful discussion page to visit on the Caravan & Motorhome Club website - Club Together Discussion is "How to Thrive on a non EHU site." The original thread "How to Survive a non 240v EHU site", which was massively interesting and popular with members was mislaid by The Caravan & Motorhome Club when the new website was launched. Another was started by Merve - 16/01/2017 and has now changed to "How to Thrive on a non EHU site."
For Caravan and Motorhome owners considering a solar panel this is a good page to look at click here
There are still many caravanners and motorhomers who don't know about them, awareness is growing as they also move into marine applications and into Europe. They are an alternative to the rented bottles - Calor etc. You buy and own the cylinder, which are translucent (see how much gas is left!), lightweight and user friendly they come in Large 10kg -19.5 litres, Medium 7.5kg -14.5 litres or small 5kg 9.5 litres. The Safefill cylinder is designed to be safe and easy to refill/topup yourself. Safefill Refilling network of retailers is growing. We have 2 near our site at present:
BANBURY TRAILER & CARAVAN PARTS, Thorpe Way, Banbury OX16 4SP, UK +44 1295 277300 www.caravanparts.co.uk
FORGE GARAGE, High St, Lower Brailes, Banbury OX15 5HX, UK +44 1608 685247 www.theforgegarage.co.uk
2017 Safefill latest: All will be much better for Safefill owners with the change in the Petrol Retailers Association "Red Guide" to allow the filling of SAFEFILL bottles on the forecourt. Click to download PDF
As an example the price at the above station on February 2017 was 66.9p per litre, the price online of a 6kg Calor refill bottle £18.89 say 12 litres = £1.57 per litre. So after using approx 182 litres (15+ 6kg bottles) the Safefill bottle cost is covered! and can be using half price LPG
Some comments from users: “can be taken out of a caravan to refill”, “I can always leave with a full gas cylinder every trip”, “doesn't mark your van with rust”
Safefill Map of refilling retailers Note: It has been said that mylpg.eu maybe taking over the Safefill maps etc and when it happens, they will be putting a note that a particular site in Safefill friendly
Safefill FAQ’s & pdf download page
Article from the ACCEO (The Association of Caravanning and Camping Exempted Organisations) Magazine reproduced by kind permission of Merve (Caravanner from Leicestershire) also on CC Club together “HOW TO SURVIVE A NON 240v EHU site”
This is for anyone who maybe interested in going down the road of non EHU. Merve explains what happened to him, his experiences and outcomes when he decided the status quo was not for him and wanted to do things differently.
The last paragraph is not part of his article- just a few pointers from Merve to happy non EHUing!
I have been caravanning since 1985 and up to 2012 I had been happy with the 'status quo' as indeed, we all were, and it would appear the majority still are. That was if you wanted everything working without worry on your caravan, you joined the queue to collect your Calor cylinders and had a 240v hook up stuck in the side of your van. That was the norm. I was happy to do it as I knew no different but with 4 kids, I always had an eye on the price of my caravanning. We did do the odd bit of non EHU caravanning but only for a weekend and always on my knees praying that the battery lasted and the red LED didn't come on which it invariably did!
For me, my journey to 'power independence' started in 2011. Unfortunately, it wasn't because I was a bright young thing with an endless knowledge of modern tech and gadgets, It was for more basic reasons. Although still a few years off retirement, I had started to look at my pension 'pot' and it was slowly dawning on me that the snatch and grab hits by the then Labour government on the private pension funds were going to have a serious impact on my retirement years, as indeed, it had had on so many. The promises of the amounts I would be living on melted away virtually before my eyes. It was a situation many thousands were in, and, if I was to caravan at the intensity that I had promised myself post retirement, I had to find some way of either upping my contributions or finding some way of reducing my costs for this most wonderful of pastimes. But how? The first option was not an option and I had serious doubts that I could shave even a small amount off my caravanning as prices for CC 'Certificated Locations' with Hook Up which were the type of sites I normally headed for were fairly standard in pricing. I had never, at this point, ventured onto a non hook up site for any length of time as the only way of powering the van would have been a generator or the vehicle and I wasn't going down that road! Then there were the sites owned and run by the Caravan Club - they were definitely out, not only because of cost, but because it just wasn't the type of caravanning I wanted to do. Lines of regimented caravans, pegs and the early morning walk to the washroom just wasn't my bag! So things looked pretty bleak from where I stood.
The year passed with me considering my options from time to time and slowly, a plan started to take shape. Although I am by no means what you would describe as a 'techie' I knew enough about what was going on in the techie world to make well informed decisions. The photovoltaic cell had been invented and the mighty Solar Panel had really started to make its presence felt on the world technology stage but more than that, -the technology of them had improved immensely from the first ones produced. Now, instead of direct sunlight producing power they had improved to the point where just light would generate amps. What if I could make my own power and survive on 12v? It would mean sacrifices but beggars can't be choosers and if I could, it would stop the need for the umbilical cord of the Electric Hook Up and allow me to visit sites at a third of the price! Yes, I would still need to use Calor cylinders and they were not cheap having seen them rise year on year but that was just how it was. There wasn't anything else on the market so I couldn't save money on gas cylinders - so, as it had been for years when swopping a Calor cylinder it was 'pay up and shut up' as I believe the saying goes! I wouldn't be paying for electric but I would be using more gas but there would be a definite saving. The figures definitely added up so I pressed on with my plan.
In November 2012, I put my money where my mouth was and had a 135w panel fitted to the roof of my caravan. A second 110ah battery was fitted and Wow, what a revelation, for the first time since I had started caravanning, I found myself no longer running backwards and forwards to the storage site with a newly charged battery to keep my alarm and tracker alive -my battery was fully charged all the time - How much time and diesel was that saving me? - this was working! However, someone else obviously thought my caravan was very nice and 3 months later, my caravan was stolen from a CaSSOA, panel and all! - So I started again.
In May 2013, having purchased my present caravan, I went to the first 'rally' I had ever been to. With my SP on the roof, I was very confident that power was not an issue as I went non EHU and I was right - power wasn't an issue! This was at the Caravan Clubs 'National' at Belvoir Castle and, it was there, that my plans to cut my caravanning costs received another massive boost. On wondering among the various trade stalls, I spotted some cylinders that were similar in appearance to cylinders I had seen elsewhere - made of a resin type material. For a start, I didn't bother asking about them but had made a mental note to return to that stall and ask questions about them which I did. I soon discovered that what I was looking at were Safefill cylinders- these I could fill myself, and they were fitted with the same connection as gas powered cars had, but these were probably even safer with the same 80% cutoff and check valve- I discovered that these cylinders had only just entered the market place in the previous 2 or 3 years- was this manner from heaven? Oh yes it was! But- it was even better than that, you see, Safefill had, in one foul swoop, made the illegal filling of steel cylinders an irrelevance! There was now no need for Mr Fred Karno and his dodgy valve bought from some equally dodgy geezer on the Internet to illegally fill (and commit theft by the way) steel cylinders, which, lets face it, reflects badly on all of us whether we like it or not! This was about OVERT filling and not COVERT filling. This was called Safefill-and that's exactly what it was!
Anyway, I thanked the Patron Saint of caravanning - with a Safefill cylinder on board I now saw my overall costs drop again- this time on the gas side of things as it were- what a marriage- Solar Panels and Safefill cylinders- this was almost to good to be true! Prayers are answered I thought. I bought it there and then - one of the best investments I have ever made! It just keeps on saving me money! So now I could make my own electric and had my OWN cylinder with no more heavy rental charges- I was now paying for the actual gas- not what it was stored in - that was a result! OK, I couldn't use my microwave or indeed my slow cooker, or my electric blanket but from where I was a few months earlier, I had made a quantum leap.
The next year saw me at Arley Hall at the 2014 National but only as a day visitor. Not a bad decision as it turned out as it was a very wet weekend and mud and wellies were everywhere! However, again, it was while I was wondering around the trade stands that I came across my next part of the jigsaw. In a casual conversation with a company selling all things electrical- batteries, sat navs, reversing cameras etc, I explained how happy I was to have achieved what I had over the past few months but that I had lost the use of my microwave but that I couldn't have everything. He asked me what I had on board. I told him. I'll never forget his reply - "With what you have, why the hell haven't you got an inverter?" Although I knew of inverters and what they did, I hadn't at that time considered one "Would an inverter help?" I asked, knowing what the reply would be. Well you'll have your microwave back and it'll power other things if you want them!" Without going into a long diatribe I was convinced and bought a 2000w Pure Sine Wave inverter. It wasn't cheap but what I wanted was to be able to run the microwave and other things that I now realised I could have on board with ease! I didn't want it working at its max - It was big enough to handle the large ampages and it was Pure Sine Wave which meant I didn't have to worry about any sensitive equipment I would have with me like phones, tablets etc, - if they needed a pure sine wave, it was there. I had it professionally fitted by a friend of a friend and I have to say the electrician/electronics engineer did a first class job - and then the fun really started.
June of 2014 saw us leave for Devon where, if I had this right, this would be the most economical caravanning I had ever had and it would be the first full test of the system I had pinned so many hopes on. To make it even better, my 20year old Toyota Hilux Surf tow car at that time had a conversion fitted to it and was powered by recycled veg oil which I got for nothing from people who just wanted to get rid of it! - and I could travel anywhere for 40p - and that was just because I had to use diesel to warm the engine to operating temperature! Please don't start putting veg oil in your diesel cars- this was a proper conversion!
Anyway, the fortnight was a total success. Everything worked as it should including the microwave, vacuum cleaner and the thing I really didn't want to do without- the electric toaster! We have now added a blender to that list! There I was, sitting in a field, away from the world with not an orange cable in sight and enjoying all the comforts of home! I found it difficult to believe. I had to pinch myself! Safefill was just as important as the Solar panel, providing cooking, heating the water, and really importantly as it was a very warm period, driving the fridge!! The Solar Panel refilled what had been used from the batteries and kept us in power and fully charged. The cost? £70 for site fees instead of the normal £196 (£14 a night, 20p of which I estimate would have been for the electricity used had it been an EHU site) - £126 saved and my Safefill was virtually paid for in saved fees from just one fortnight in Devon! (All my investment is now back in my pocket with ongoing huge savings) This is what I had dreamed of and indeed it is what dreams are made of.
What an amazing time of invention and innovation the last few years have been for the caravanner and his ability not only to be able to create his own power but save power too! - Solar panels, LED lighting (which I can't praise highly enough) highly efficient power saving devices, new materials for batteries making it possible for them to hold more charge at much less weight and last, but certainly not least, - the brilliant Safefill cylinder! - what would our forbears have paid for being able to go into the wild completely independent in power? And the future can only get better for the non EHU caravanner as batteries improve and SPs become even more efficient and best of all, when we can all walk into any LPG outlets and know we can fill our cylinders because Safefill cylinders are the industry standard for safe filling? Move over old heavy rusty steel cylinders, you're time has gone, there's a new kid on the block which are lighter, cleaner, doesn't mark your van with rust, you can see how much gas you have at a glance and is a hell of a lot cheaper! What more would you want? Oh yes, and one more thing- much safer with inquisitive children- open a valve on a Safefill cylinder and nothing escapes unless it's attached to a tail! With grand kids about that was a big plus! The new technology is here and not a moment too soon for me!
As far as my 'losses' were concerned, they were solved one by one. The slow cooker was replaced with a Mr Ds Thermal Cooker, which, again, saves power by cooking the contents in their own heat - (raised to temperature by gas from my Safefill of course ) the modern equivalent of the haybox, and what's the problem with a hot water bottle at night if things are a little nippy in Autumn or winter? - not that it should be with the brilliant Alde heating using much cheaper gas from a Safefill cylinder and using only 1 amp to power the pump! There has never been a time in the history of caravanning where things have been made so convenient for us power wise and at a cost that blows the old ways of a few years ago apart! Why would anyone want to have an orange cable anymore? and why oh why would anyone want to rent cylinders of gas where 70-75% is the cost of hiring the cylinder? I passionately believe that if we want to change the system that has had us straight jacketed for so many years, we need to buy things like Solar Panels and Safefill cylinders so we make it impossible for the LPG Giants to ignore us. People power will win in the end. Thinking outside the box pays doesn't it? Happy caravanning.
I would add that it is important to 'balance' the equipment you buy and to make sure it's man enough to do the job you want it to. For instance, there is no good to obtained from a 200w panel if the only thing you have to receive the electricity from it is one 85ah battery- work as it may, the panels electricity will be lost over and above the full charge of the battery. Another reason a powerful SP should be chosen is its ability to charge the leisure battery or preferably batteries during low light periods like winter or in the late evening of a warm summers day- the panel will still be big enough to generate amps where a smaller one would be producing but not in any usable quantities. Another thing to consider is what, if anything, you would want to use that is 240v and what amps that appliance draws. Again, it's no good fitting a 500w inverter if the microwave is a 650w model and the start up wattage is even higher. So choose an inverter that will 'do the job' and leave some slack in the system- you don't want the thing working at its max all the time. I have a 2000w pure sine wave inverter which probably has the handle 800 or 900w maximum- plenty of slack in the system there. Remember, and this is very important, you can't go cooking Sunday lunch in the microwave unless of course it's a bowl of soup and bread! It will of course with what I have heat Two pre made meals very adequately. The appliances we have are all appliances that are used for minutes not tens of minutes. For instance, the toaster is used for about 4 mins. The blender- 1-2 mins. The microwave- 3-4 mins and the vacuum about 6 or 7 minutes. Remember you are on batteries- you can't kick the backside out of them but used properly, an inverter is an extremely valuable addition to any van. So what is a ' balanced' system? Well, all I can do is repeat what I have and many will say they have less on this but more on that and if it works for them then they have what they need. I have 135w SP 2 x 110ah batteries and a 2000w PSW inverter. Would I change anything? I would have a bigger panel not that the 135 is inadequate- it's not but I would want 2 Li ion batteries of the same rating which hold more charge and are half the weight and a large SP can recharge quicker and gives you more leccy to use.
Introducing our new stand-alone Solar Unit that our guests are welcome to use.
This was kindly and successfully trialled in August 2016 by Paul and Lesley during their 10 day stay with us.
We have built this for CAMC members who would not usually consider a basic “off grid” CL but can still enjoy travelling without limits.
With this, visitors can “take the plunge” and try a solar powered arrangement before perhaps buying one for their own outfit.
The Solar unit currently has a 80w solar panel which via a dual battery charge controller charges an internal 220a 12v battery to provide 240v through a 600w sine wave inverter allowing charging or razors, toothbrushes, battery drills, Ipads, phones, laptops, etc up to 5 amps (sorry no microwaves or hair driers!) It also can charge a battery on your vehicle via the smaller 5m charging cables provided or a reserve/backup battery off the vehicle via the heavy duty charger cables.
There is only one of these units so if you would like to use it please reserve it in advance.
We plan to replace the current 80w panel for a 140/150w in the future [as we have found during the winter months on our building solar system you need to almost match the solar panel watts to the battery amps you are maintaining!]
This was all built by Newton Grove (except the trailer frame etc) here are some of the parts used & costs (although we did have a lot of the parts anyway!):
80w AKT monocrystalline Solar Panel - approx £90
Morningstar Sunsaver Duo 25a 12v dual battery solar charge controller with remote meter approx £149
Maplin NIKKIA 600w Pure Sine wave inverter - approx £179
12v fused switched regulator for LED light, 12v 500mm waterproof LED 5050RGB light strip & illumined 12v switch - approx £18
240v exterior IP65 2 gang RCD switched socket - approx £30
Anderson SB50 50a connectors - charging socket and 2x Charging leads - approx £50
Durite Battery isolator switch 300amp - approx £24
220a 12v Elecsol Battery (discontinued), battery terminals, 12v blue LED Voltage panel meter & inline fuse holders - approx £224
Din Rail 2 module boxes and SP/DP MCBs - approx £65
12v 4 way 100a blade fuse box & netural 4 way Bus bar - approx £19
Aluminium sheet, angle, hinges and polycarbonate door - approx £188
Trailer (was irrigation hose reel trailer) - approx £250
Below is a post that was Posted on Caravan & Motorhome Club - Club Together Discussion Forum - 01 October 2012 by JohnTherat (who kindly agreed that we could use it here)
I am writing this article in the hope that the information provided may prove interesting and hopefully informative. It is my intention to keep the subject as simple as possible, but there are certain technical areas that I will need to mention. First let me say that I am not, nor do I claim to be an expert within this field, but I am a degree qualified electronics engineer and if nothing else this should explain my terrible grammar and spelling!
In December 2011 my wife and I joined the world of caravanning (a little late in life but better late than never) we entered the market by buying a 2006 Bailey Pageant Moselle which we love and have enjoyed on a number of lovely club sites. All of these sites had included an electric hook-up; however, during the June bank holiday we visited a five night music festival where there was no electricity. Prior to this event I began to think about alternative energy sources, mainly because I needed the motor mover to move the van off the road and into its storage area, where reversing was impossible due to the limited turning circle and getting stuck in the middle of a single (busy) road was not an option.
My initial thoughts were, “well the leisure battery is charged by the tow vehicle when driving between destinations, but if the journey is relatively short then the charge will be limited.” With this in mind I turned my attentions to alternative independent sources and almost jumped straight into purchasing a small suitcase generator. Now before I enter into this further please allow me to state that I am in no way trying to deter anyone from using a generator, nor am I saying that a generator is not a good method for producing energy. In actual fact (unlike a solar panel) a generator is capable of producing 240 VAC which will run almost every electrical appliance within the caravan including charging the leisure battery, but I had to consider where I could stow it including fuel and oil, then the fact that even though they are relatively quiet running they do produce noise and exhaust fumes and even when cold there must be a smell from the engine. With this in mind, plus the fact that my car boot is reserved for my two chocolate Labradors I decided to research an alternative.
Solar power, I believe, is the only other option currently available, but realistically can a solar panel (PV) provide sufficient energy to recharge the leisure battery bearing in mind that energy will only be generated during the daytime and that the efficiency will depend considerably on a number of factors such as weather conditions, temperature, time of year and physical position or angle relative to the sun? To my surprise I learned that solar panels work best when cool and that they generate a reasonable amount of energy even during cloudy or wet conditions so this was an encouraging start.
So how much energy can I expect to consume during a typical 24 hour day and how much needs to be replenished? Fortunately most of my appliances utilise gas to operate such as the cooker, water heating, fridge and environmental heating. This only leaves the lighting, water pump extractor fan, heat circulation fan and TV to operate off the 12 volts battery (deliberately not mentioning the motor mover here).
My caravan is fitted with a total of 16 lights and originally each light consumed 10 watts of power, a total of 16 x 10 = 160 watts (or 13 amps), however I have dramatically reduced this load by fitting new MR11 12V 140Lum surface mount LED high power day white bulbs (from Future Green Light via ebay), where each emits the equivalent of 25 watts of light but amazingly only consumes 2 watts of power. This has reduced my lighting consumption from 160 watts down to only 32 watts (or 2.7 amps). There is also a warm white option available that would reduce the piercing brightness of the day white lamps, thus set a mellow atmosphere within the living area. It is quite unlikely that all the lights will be on at any one time but for my load estimate I will be using the worst scenario, maximum all on.
The water pump is only used occasionally and is estimated to draw approximately 50 watts (approximately 4 amps). By far the highest power consumption will be the motor mover and the TV, but the motor mover only consumes power for a relatively short period of time (estimated 10 amps in 5 to 10 minutes) and once the caravan is connected to the tow vehicle, most of the energy consumed by the mover would be replenished during the journey even during a relatively short journey. My TV consumes 47 watts (4 amps) so neglecting the motor mover and circulation fans I am going to estimate that the TV will be used for 5 hours and that all the lights will be on for 6 hours, plus the water pump used for 30 minutes. In this case the current drain on the battery would be approximately:
TV 5hrs usage x 4A = 20A
Lights 6hrs usage x 2.7A = 16.2A
Water Pump 30 minutes usage 4Ahr / 2 = 2.0A
Total = 38.2 amps.
Therefore, approximately 36 – 38 Amps will be consumed from the leisure battery each evening/night, now an 110Ah leisure battery in theory should be capable of supplying 110 amps for one hour before its completely flat, therefore by drawing up to 38 amps per night a fully charged battery should be capable holding up for just under three days without charge. This means that the solar panel will have to replenish about 38 amps per day. Hence if the solar system is capable of supplying an average of 5 to 7 amps then it should take about 5.5 hours to recharge.
Choosing the right solar panel:
(What solar panel best suits my requirements, where best to position it and what energy can I expect from the panel?)
From my research I have identified that there are a number of different types of solar panel available and each do the same thing; convert solar radiation into electricity, but each has different characteristics and prices.
The cheapest (and least efficient) type of solar PV is known as "thin film" or amorphous silicon, although this type of PV is cheap you will need a large surface area to obtain a decent amount of energy from it but it is quite tolerant to high temperatures.
Polycrystalline solar PV are made up of a number of smaller silicon crystals. This is rated as being very effective and is generally cheaper. These are usually dark blue in colour and are widely available.
Monocrystalline solar is the most efficient but as you would expect it is more expensive than thin film or polycrystalline solar.
Just to mention, there is also a premium type available called a hybrid or HIT (Heterojunction Incorporating Thin Film) solar. It incorporates a monocrystalline overlaid with a thin film layer which apparently makes the best power conversion efficiency material, but as you would expect this is the most expensive option.
So with all this variety which should I choose?
With the solar panel being such an important part of the system I decided to look towards the Monocrystalline, it being the most efficient but the three major things that dictated my final choice were: physical size, power output and cost. The PV output power is normally quoted in watts but what really charges the battery is current, so to obtain a better understanding it is worth converting the watts to current. Fortunately this can easily be achieved by using a simple equation called Ohms law.
Where Power (Watts) = Current (I) x Volts (V)
With the power output quoted in Watts, we can easily transpose the value from watts to obtain the value of current:
Current (I) = Power (Watts) / Voltage (V).
Remember as previously mentioned the calculated values are based upon perfect 100% efficiency (perfect conditions) Also, to charge a 12 volts battery the voltage will be higher typically 14 to 14.5 volts for a full charge. Therefore, a 100 Watt solar panel would theoretically provide 100/12 = 8.3 Amps.
A good quality mains battery charger would normally be capable of charging batteries something near 5 to 8 Amps so for this reason, including losses in efficiency I decided not to use a solar panel of less than 100 Watts which in “theory” could produce up to 8 Amps
My final choice made, I purchased an SSP-120W 12v PV monocrystalline solar panel from Sunshine Energy, it is housed within an aluminium frame that makes it perfect to mount into my intended position. The panel is supplied with 5m of cable with MC4 type connectors fitted to the ends, which removes the need to calculate the cable size. Also, these cables can be extended but would incur a small (loss) in efficiency due to volts drop over the cable length. The physical dimensions for this panel are 1480mm x 680mm x 35mm and an important factor is that it only weighs 10.1 kg, it’s hi-impact resistant and tolerant to high winds.
Where to fit the PV:
The choice of position for me was a fairly simple one. Fortunately my roof space near the front of the van is large enough to mount the panel and it is slightly angled forward, although not the perfect angle facing the sun this would still be a reasonably good position to capture energy throughout the day without the need to have to rotate it towards the sun. Also, at this elevation it should be better positioned to miss most shaded areas that could otherwise be encountered at ground level.
Naturally not everyone will want to fit a PV to the roof of their caravan or there may not be sufficient room for one, so a ground mounted panel would undoubtedly be just as good but may require more thought when setting up and may have to be rotated periodically towards the sun during the day.
Mounting the panel
As previously stated I have mounted the panel on the caravan roof, but to avoid holes within the roof I have used six special mounting brackets purchased from Lensun, four corner mounts plus two middle to prevent flex or sag at the middle of the panel. With all six mounting brackets secured to the panel’s aluminium frame using self-tapping screws the whole assembly was then carefully positioned in the middle of the roof and glued using Sikaflex 252 adhesive.
There is however (not for the faint hearted) a need to drill one hole large enough for the two cables from the solar panel to enter the van. Here I have used a cable entry housing which is also glued to the roof using Sikaflex 252 that also provides a sound moisture seal. To protect the power cables from sharp edges when entering through the roof I have used a short length of plastic tube over the cables then finally to ensure a perfect moisture seal I applied a liberal amount of caraflex IDL 99 (available from most caravan accessory shops).
From the roof cable entry the two power cables are routed neatly within a small electrical conduit following the original van wiring down to the power distribution box and leisure battery where it meets the solar charge controller.
Solar charge controllers (The brains of the system):
Up to now I have discussed the need to select the right type of solar panel but now I need to consider how the power generated will be applied to the leisure battery.
Lead acid batteries can easily be permanently damaged if not recharged correctly and one example of this would be over charging or boiling it, generally most solar panels output far more voltage than what the battery requires to charge, so for this reason solar panels are not normally connected directly to the battery, instead the energy produced by the panel is regulated by a solar charge controller, which ensures that the battery is safely changed and maintained in its best condition.
Most modern charge controllers regulate the battery charge by what is known as a 3 stage charge cycle.
Stage 1 is known as the Bulk phase, where the voltage rises to the Bulk level (usually 14.4 to 14.6 volts). This is when the battery draws maximum current as the bulk level voltage is reached. Following this phase the absorption stage begins.
During the absorption stage voltage is maintained at between 14.4 to 14.6 volts for a defined time (normally about an hour), during which the current flow gradually reduces as the battery reaches a fully charged state.
After the absorption time phase the voltage is then reduced to the float level (approximately 13.4 to 13.7 volts) and the battery normally draws no more than about 0.2A, until energy is once again consumed and the next cycle begins.
Types of controller:
There really are, in my opinion, only two modern types of charge controller available that are really worth evaluating. The first is a pulse width modulated (PWM) type and the second type is a maximum power point tracking (MPPT) system, commonly known as a tracker. The right choice of controller I believe is paramount to achieve the greatest efficiency.
The simplest type of charge controller outputs a fixed voltage while charging the battery, irrespective of the level of charge in the battery. It then monitors the battery and opens the output circuit once the charging process reaches a certain level. Older charge controllers accomplished this mechanically by using relays, but the more recent charge controllers make use of pulse width modulation (PWM). This process is rather complex so I will simply state that when the battery starts to reach its fully charged state, the amount of power being transferred to it gradually decreases as opposed to it being simply cut off as with the earlier relay types. The battery is then held or floated at its fully charged state by the PWM. This type of charge controller can extend battery life and reduce stress on the battery and will keep it charged indefinitely.
MPPT Maximum Power Point tracking
My initial thoughts when I first encountered the MPPT charge controller (tracker) were that it must be a mechanical device that moves the solar panel to track the sun during the day, but this is definitely not the case.
The MPPT system utilises all the benefits of the PWM system but has one major advantage over the normal PWM charge controller. The MPPT tracks the energy generated by the solar panel, at the same time monitors condition of the battery. It then matches the output of the solar panel to the battery voltage which ensures that maximum current charge (amps) is achieved throughout all the variations during the charge cycle, which means that you are getting nearly the full capacity from the solar panel.
As an example: From a solar panel rated at 100 watts, you would never obtain the full 100 watts from it unless the battery being charged is at the optimum charge voltage.
Using the previously mentioned Ohms law, where power (watts) is equal to volts x amps or P=V*I.
A regular charge controller without the ability to track would have the charge voltage set at a specific value meaning that for only one short instant in time during the charge cycle the maximum current flow would occur.
Let’s say at a battery voltage of 12.4 volts the maximum current flow occurs, where a 100 watt solar panel rated at 6 amps at 16.5 volts (6 amps times 16.5 volts = 100 watts) would only be charging at 6 amps times 12.4 volts = 75 watts meaning that we have just lost 25% of the 100 watts capacity!
The MPPT controller compensates for the lower battery voltage by delivering closer to 8 amps into the 12.4 volt battery maintaining the full power of the 100 watt solar panel, 100 watts = 12.4 volts times 8 amps = 100 watts (P=V*I).
It’s that simple, but as you can see from the example an MPPT charge controller can make the difference between a reasonably good system and a system running at its maximum efficiency.
My final decision made, I purchased a high efficiency 20A MPPT solar charge controller from Photonic Universe Ltd, again via EBay. I have to state here that I could have bought a much cheaper 10A version that would have been more than capable of handling the job, but I opted for the larger model thinking that I may wish to add another solar panel which can easily be achieved by simply wiring more in parallel, however the final result from the 120W panel was amazing making an additional panel unnecessary.
Monitoring the system
Wanting to fully understand the efficiency of my system without the need to fit an ammeter I decided to invest in a MT-5 monitor also from Photonic Universe Ltd, which is designed to simply plug straight into my charge controller via a supplied 2M cable. The LCD monitor provides feedback regarding the energy generated by the PV, the level of charge at the leisure battery and the amount of current flowing into the battery.
The MPPT tracker also has a load output that is designed to drive 12 volts systems direct such as a 12 volt fridge. You can also connect a sign wave inverter to this output to achieve a 240 volts AC supply because the source is derived direct from the leisure battery.
As an experiment I connected a 500 watts sign wave inverter to supply the 240 Volt fridge but as expected the load was 12.5 amps, which is 5 to 6 amps greater than the power generated by the panel. Needless to say that if used constantly this would eventually drain the battery flat, however I do anticipate that when the fridge reaches its optimum temperature the consumption will fall considerably, but realistically I do not believe this could work as a permanent supply.
To conclude, I have since used this system to its full during the music festival it fully maintained the leisure battery despite the fact that it rained the whole time plus the motor mover did the job when I arrived home. I have also used it at a number of sites while using the TV, Radio or CD player plus lights during which time the system has never failed to fully recharge the battery.
The maximum energy observed to date while charging the battery plus holding up the load is 7.8 amps additionally the battery has been constantly charged while the van has been stowed providing me with full power without the need for mains power when stored.
The total cost of this system (less fitting) was little over £400 about the cost of a budget suitcase generator.
12V 120 Watt Solar Panel PV Monocrystalline from Sunrise Energy (ebay) £184.95
20A MPPT Charge Controller from Photonic Universe Ltd (ebay) £129.99
2 Piece (One Pair) mounting blocks from Solar Supplier (ebay) £17.00
4 Corner mounting brackets from Lensunsolar (ebay) £41.83
Roof cable entry from Solar Supplier (ebay) £7.50
Sikaflex 252 Adhesive from allrightbutt £18.50
Remote meter from Photonic Universe (ebay) £31.99
Self-tapping screws General hardware store (Just a few pence).
Note also that as mentioned there is a much cheaper 10A version of MPPT available from the same supplier for £79.99 that will easily handle the 120 watts panel.
John Ratcliffe (Ross On Wye).