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I was hoping someone with a little more experiance of solar than me would answer, no takers so here's my best shot.

I have had a 40watt solar panel connected to a 90amp/hr batery, on my T25 for around seven years, it supplies 3 flouresent lamps(total 24w?), a small tv and a large coolbox with electronic management(which is turned off overnight). It just about keeps going for around 2/3 days without running engine.

From your post it would seem you wish to cook from solar as well, if so I think it is impractical to do this on a campervan, you would require large panels and bateries, the cost for buying these and extra fuel used when driving would outway any saving.


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We have an 80 watt solar panel but it was already fitted on the van when we bought it. We have also bought a 300 watt inverter. We use a 15" LCD TV/DVD plus digibox and also charge our satnav and phone and use a laptop and we don't have any problems at all with the leisure battery running flat. We did have a 10" Roadstar TV that we plugged into the 12 volt but this took a lot of power from the battery but the new TV takes hardly anything.
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I too am looking for advice on solar panels. I have just bought my first van and we are looking to venture abroad later this year. Eventually we will be doing a long term tour over the winter and a solar panel seems to be a good idea.


Do they actually power the electrical appliances or do they just keep the leisure batt. topped up?


Can you fit a switch to change from leisure to vehicle batt? I am wanting to keep my alarm on when the van is parked up in my path and over time this will obviously drain the batt.


Is it better to fit it to the roof permenantly, or would a panel fitted to a board and be "movable" be a better idea?


Would a "suitcase" solar panel be any good in the circumstances described?



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I have done a search and it seems info on solar in threads is fairly fragmented so it would be good if anyone would post their real world experiance of solar.

Further to my post above I have realised that I mistakenly said 40w panel this should be 30w. Also it runs trough a regulator as if not would cook battery when there was no current draw.

Before fitting the panel my 90amp/hr battery would last one day suppling the coolbox which has a supposed current draw of 5amp for 2 hours then 1.25amp for 12hours, with 30w panel mounted flat on roof this extends to around 2 or 3 days, a second panel at around £175 would I guess keep up indefinatly.

p.s. for keeping vehicle battery topped up I see no reason why you cannot fit a change over switch, but myself I would fit a heavy cable(incase of forgetting to switch over) and a battery isolator(to be switched off when on site), so both batteries are kept charged, I also seem to recall seeing regultors with sepperate outputs for vehicle and leasure batteries.

As to permament mount or movable this depends how much time or effort you wish to apply, a fixed mount will always be a compromise but is a fit and forget, a movable mount would have to be autotracking which is more expense or you have to manualy move it.


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One of the things you need to factor in is that for half the year you have reduced daylight hours, which will obviously reduce dramatically the power that a panel will supply, on a typical winters day in UK you get around 5-6 good hours of daylight as an average, clouds etc further reduce the panels ability to supply it's rated value, the newer panels are better at coping with reduced daylight, we use panels on equipment that we supply and generally with the above factors we assume the panel to provide around a 1/3 of its rating to be on the safe side for the UK market.

Monocrystalline panels are the most efficient but also the most expensive,

polycrystalline are mid range and amorphous are the least efficient but cheaper.


If you are looking to be totally reliant on self power in your MH then you may need 1-2 large output 200w panel or several smaller 60-80w depending on your power requirements which with the right controller you can add too as finances allow. Mount the panel at a slight angle 10-15 degrees to allow water to run off, this keeps them cleaner in use.


If you do a search for Solar panels on the www there is a wealth of info.



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Thanks for this.


We plan to do some "tests" this summer on hook up sites and without panels and relying on just moving about after 2-3 days. If we can manage I think I will settle for that before commting to major expence.


I have just been talked into a small "windscreen" sized solar panel to replace any power used by my alarm. I'll keep you posted on the results. If it doesn't work you can buy it on e-bay at some point!!

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  • 2 weeks later...

I installed an 80 watt solar panel on the roof of the MH nearly three years ago coupled to one 110 Elecsol carbon fibre battery. In the spring and summer we never run out of power while stationary on Aires for up to 7 days, in the Autumn the Solar output is only sufficient for a two day stay without moving on.


While in Europe for each of our spring and autumn two month tours, our usual electrical load is around 5 hrs using a 15" LCD TV on satellite, and addtionally Satellite radio for around 8 to 10 hrs per day, the radio is a 5" TV with the display turned off, a DVD player, cell phone, camera, laptop charging. The satellite uses about 1.5 amps, the 15" TV uses around 4 amps and the little 5" TV/radio uses less than 1 amp.


This year I have installed a further 110 amp battery and hope that the two 110 amp batteries will give us enough power for longer stays, during the autumn trip.


On a sunny day the 80 watt solar panel provides power to drive the satellite radio and with enough power left over to recharge the batteries, although I have often found that the batteries show a full charge when I have woken up in the morning, I am reliably informed that the sun is out around about 5 to 6 oclock in the morning in late spring as summer approaches.


Regards Terry

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  • 1 month later...
Like others in this forum, I am completely new to motorhomes. So far, I've only had three trips out, all with hook-up. I would like to tour freely and so I've looked at alternative forms of power. Bearing in mind, I'd obviously like to emulate hook-up. So, starting with petrol generators...noisy I suppose and heavy. I know that in some European countries you can't carry petrol, so that option seems to be unviable. Next, look at gas generators. Quieter I assume, but apparently quite expensive if you're trying to pull in 230v. Lastly of course is the solar panel. OK, Eco friendly but what return do you get for your outlay? My fridge will run off gas or electric as will my heater and water heater. Am I looking for too much luxury? Do I need to rough it a bit more? Can I assume that I can rely on my leisure battery to get me through a couple of nights of lighting, TV, heating and showers whilst on the move and then get on to a site with hook-up? My plan eventually is to tour Europe for around six months of the year. Can someone give me a realistic comment on how I can do this as cheaply as possible?
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There is an underlying problem with all of this, which is that we all tend to do things differently, in different places, at different times of the year, have varying preferences in terms of using, or not using, campsite facilities, and eat and cook different things in different ways.  All this variability means that what one person finds ideal is completely useless for someone else.

If you search under the keyword "battery", enter as the author "Clive", and set time to "one year", you will find all sorts information on that topic, which is really where I think you need to start.

Your leisure battery is the energy reserve for your motorhome.  It is better not to try to interconnect this to the starter battery since if you overdo your consumption you can't start your van, which is several times worse than a flat leisure battery! 

The alternator on the engine, and your built in 220V charger, (usually) both automatically re-charge your leisure battery.  The former while you are driving, the latter while on hook up.

If you look at your leisure battery you should see its capacity written on it.  Read Clive's comments on battery charging, battery types, the maximum realistic charge you are likely to get on board, and the maximum extent to which it is safe to run the battery down.  That should tell you how much you can reliably get out of the battery you have, before it will need re-charging. 

If you then look at the rating plates on all your 12V bits and bobs, and make a note of them, plus the wattages of your various lights, you can begin to work out how much you will consume over, say 24 hours.  Just remember Volts (nominally 12) x Amps = Watts.  So, if the consumption is already given in Amps fine, but if it is given in Watts, just divide by 12 to get the consumption in Amps.  1 Amp, consumed for one hour, is one amp hour, and battery capacities are given in amp hours.  Therefore, consider how long you think you'll actually run each item, in hours per day.  Multiply the hours by the consumption in Amps for each item, and you'll have its daily consumption in amp hours.  Add these figures together for all items, and you have your total daily consumption.  Add to this 20 - 40 amp hours per day for your on-board equipment, mainly the heater/water heater and pump.  Divide this figure into the reliable capacity of your battery between charges, and you'll have a rough idea of how many days your battery will hold up before it will need re-charging. 

However, do also look at Clive's comments re the effect the rate of discharge of the battery has on its capacity.  If you draw power from it at a rate greater than about 8 Amps per hour, it won't be able to keep up, and it will become exhausted quicker.

Now you have a rough idea where you stand vis a vis the capacity of your existing habitation battery.  If that seems sufficient for your intended stays, you need do little more.  However, you will need to drive for about an hour to re-charge the battery back to where it started.

The simplest and cheapest way to augment battery capacity is to fit another battery.  For this also, see Clive's comments regarding matching age, type and capacity to the existing habitation battery.  Connected as Clive recommends, this should charge satisfactorily from the existing alternator and charger.  However, since you've now doubled your storage capacity, but your alternator and charger will still charge at the same rate as before, you'll now have to drive for a couple of hours to re-charge instead of just one, or you'll need twice as long on mains as before.

If you want more than double the original reserves, be careful; you may need to fit a more powerful alternator and charger, or add additional charging controls, to avoid overloading either or both.

Ultimately, where and when you use you van will have at least as much impact on 12V consumption as the equipment you take.  Northern Scotland, in good weather, at the end of June, has almost 24 hour daylight.  High in the Alps, in January, not only has short days, but temperatures often as low as -15C.  Scotland in summer, therefore, requires no heater and almost no lighting.  The Alps in winter, on the other hand, will require 5 or so hours per day of lighting and the heating going fill tilt 24/7.  You may well get 5 days from a 90Ah battery in summer Scotland, but you’ll be lucky to get 24 hours from the same battery in the winter Alps!  See what I mean about variability?

Next search is to look as before, but substitute “solar panel” for battery.  What you will find is that solar panels generate less electricity than their nominal outputs would lead you to believe.  Partly this is because of the way their outputs are stated, but mainly because the amount of energy available for them to collect varies with the angle of the sun, from winter to summer, from morning to evening, and because most are mounted horizontally on the roofs of vans where those nice shade giving trees, that keep your van cooler, rob the panel of light.  The obvious solution is a free standing panel on a frame that you can angle, and move round, to keep it pointing at the sun.  The obvious drawbacks are that you become the panel minder, and someone may nick it while you’re out.

Also to bear in mind is the relatively small amount of electricity even quite large panels generate relative to their cost.  There was a comment about green energy.  Solar power is pollution free, but manufacturing the panels very definitely is not!  I have seen one calculation that says current generation panels will never generate the amount of energy used in their manufacture and distribution.  To this must be added some rather nasty chemical by-products to be disposed of!  Not, in reality, so green.  Another quote is that relative to around 200Ah installed battery capacity; the output of a solar panel is a “mere drop in an ocean of electrons”.  What a solar panel will do, and do well however, is keep the batteries charged when the van is not in use.  Invaluable if it cannot be connected to mains.

So, what is the solution?  Well, first to do the sums above, to work out roughly where you think you will stand.  Then take your van off for some trial runs, to see how fast your patterns of use consume 12V power, and how that compares to what your calculations led you to expect. 

The first priority if capacity seems insufficient, really, is to examine what you are doing and how you are using the van.  Are you leaving things on that could be switched off?  You will achieve much by economising, and that costs nothing.  This is still a version of camping, remember! 

Second, depending on the number and type of lights in your van, investigate changing the bulbs for arrays of LEDs, which not only use a fraction of the electricity, but last many times longer.  They cost more, of course, but so does installing additional batteries or solar panels.  Have a look at Maplins' website for an idea of what is available.

Consider whether you need to remain static for so long.  Moving on for an hour or two will change the wallpaper and re-charge your batteries (and you vans!).  The essence of the motorhome is, as Toad of Toad Hall remarked (though Toad’s caravan was to be horse drawn; Kenneth Graham hadn’t heard of motorhomes!), “The open road, the dusty highway, the heath, the common, the hedgerows, the rolling downs.  Camps, villages, towns, cities!  Here today, up and off somewhere else tomorrow!  Travel, change, interest, excitement!  The whole world before you, and a horizon that’s always changing!”  Sorry to go on, but I love that bit!

If none of that will suffice, add a second habitation battery, and if that still won’t do, though it pains me to say it, assuming you have the space and load carrying capacity, get a quiet, preferably gas, generator and use it as little as possible, with great consideration, as far from other people as possible.  Personal opinion, but I think the best use of solar panels is really to keep the leisure, and starter, batteries charged when the van is not in frequent use and cannot be connected to mains while parked.  Unless you roof your van with solar panels, at enormous expense, you won’t come close to the charging capacity of the van’s own alternator or a half decent genny!

Can you survive without gas?  No: but why try?  It is not really that costly, and although there is some pollution, a high proportion of even LPG is hydrogen, so it is less damaging overall than most other portable forms of energy.  Your fridge will need gas when you aren’t on hook up: 12V is, in practical terms, out of the question.  The consumption is around 8 – 10 Amps even for the smaller models, so maybe 4 – 6 hours of you’re lucky.  Cooking by electricity, unless on hook up, is even less feasible.  The lowest consumption cooker I’ve come across is the excellent Remoska (Lakeland), rated at 500W @ 220V.  So, using an inverter, that would amount to 40 Amps at 12V.  It wouldn’t even cook your spuds!  Forget electric space and water heating: out of the question - the consumption is way too great!

Using gas to the maximum is the best way to eke out the capacity of your battery, since it is readily available and is, to all intents and purposes, essential for cooking, heating, water heating and running the fridge.  Air conditioning?  Not on 12V, at any rate not when static.  If it’s hot, get in the shade, preferably under trees, open the windows, and don’t run around at mid-day.  That’s what the siesta is for!  If you’re in a hot place you’ll acclimatise more quickly if you don’t keep cooling your van.  If it’s really too hot for you, head for the hills, or don’t travel so far South, there's all of northern Europe to play in!

When you find somewhere you really want to stay, just look for a campsite.  Pay for a hook up, unwind the awning, get the chairs and table out, re-charge the batteries, use the mains water heater if you have one, use the site toilets and take the strain off the cassette, use the showers and take the strain off the water and waste tanks, do the washing, let someone else do the toilet and shower cleaning, and relax; you are somewhere relatively secure, you won’t be driving off shortly, so you can break out the beers, or that bottle of white, you’ve been carting around in the - now mains powered - fridge!  Chill!

Sorry it was so long: that’s all folks!

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  • 2 weeks later...

You could do worse than having a chat with the people from More Power.

Great company and very helpful indeed, advised me on my setup and they have been proven correct

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  • 2 weeks later...

I couldn't agree with you more Brian, i have looked into the subject of solar energy, i've even got a small back up house system(i get alot of power cuts).

The output of my '17w' panel is poor, even when the sun is out in the winter, it looks quite bright to us yes, but the power output of the panel is well down. In fact the battery discharges during the short winter days so i give it a couple of mains charges.

Without spending alot of money it's not worth faffing about with solar, same as you say, they are ok for keeping a battery topped up.


One more point nobody has mentioned, lead acid batteries hate being discharged, if you discharge them more than 50% regularly, their life will be reduced. You get what you pay for though, gel types are better, and there is another type.. erm... can't remember now but they are expensive.


Good luck everybody

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