I’ve been running a rigid frame 50W solar panel at home for a number of years to provide 12V lighting with the intention of using it on the caravan and then the campervan but I just couldn’t bring myself to mount such a big frame on the roof of a moving vehicle. After noticing a deal over at BestEcoShop for a Biard 100W Semi Flexible Solar Panel Kit I thought now would be a good opportunity to finally perform a campervan solar panel installation.
The main reason I want solar energy is to keep the fridge running for longer when the van is static over a day/night. The leisure battery is charged by the engine (alternator) while running but unless we book a campsite with an electric hookup it’s not long before the fridge drains the power of the small 70Ah leisure battery. The specially designed 12V Intel B fridge is stated to run at an average of 13W per hour which is dependent on factors such as it’s thermal load (the amount of beer in it) and the ambient temperature so the first thing I did was work out the power required.
… In electrical terms, power (measured in watts, W) equals current (in amps, A) multiplied by voltage (in volts, V). Your battery produces roughly 12V to power your equipment, so to work out the drain on your battery from an appliance, take its power rating and divide by 12 … (see here)
Power drain:
- The 13W fridge draws a current of (13/12) = 1.08A per hour
- 24 hours (1.08 x 24) = 25.92Ah
Power available:
- I’ve purchased a new 110Ah leisure battery
- The 100W Monocrystalline Silicon solar panel should give 5A per hour in good daylight, so maximum 30Ah for 6 daylight hours
- The alternator when driving from site to site (see split charge relay)
- The PMS charging unit when on electric hookup
So the ‘theory’ is good, in 24 hours the fridge will take 30Ah and in 24 hours the campervan solar panel could provide 30Ah if I get 6 hours of daylight. When I don’t get 6 hours of daylight the alternator will be topping up the leisure battery via the split charge relay when driving and when the vehicle is stationary I have 110Ah stored in the battery. However, in practice when it’s raining and cloudy I could run out of power before my 6 pack is chilled 😉
The above shows the Indel B CRUISE 42 fridge specifications and the new leisure battery I’ve fitted with extra in-line fuses. The Biard Solar panel is mounted on aluminium and is flexible up to 30 degrees. I added 3mm double sided foam tape to take up the slack between the ridges of the campervan’s pop top roof to minimise any bouncing.
The solar charge controller is a basic PWM 10A controller, it’s actually just the same as the one I purchased in 2011 so I’m pretty happy with the way it works. I’ve connected it direct to the leisure battery (via a fuse) rather than through the PMS and I’m running an auxiliary 12V socket from the output to supply a few low power items independently of the main system. The controller has a few modes which can be used to detect daylight (through the panel) and can switch lighting on and off or on a timed schedule. I mounted it onto the inside of the wardrobe as I don’t need to monitor the display and it ain’t that pretty.
The auxiliary 12V split socket also has a voltmeter that displays the condition of the battery and also the power being used via it’s two USB slots. It was just over a tenner on Amazon …
Although I purchased some Sikaflex to glue the panel to the roof I changed my mind and decided to use the corner mounting holes. I’ve used external weatherproof silicone to create a water tight and wind tight seal but should I need to remove the panel for any reason then it should come off fairly easily after removing the bolts from the inside. Plus I’m happy that the panel isn’t going to shift at speed on the motorway.
I asked my mate @MartinAedy to do all of the ladder work due to me still recovering from a complete hip replacement and I didn’t want to risk anything!
Inside the pop top the stainless steel fixing bolts and washers aren’t going to cause any issues but I may add a little dome of Sugru to the nut head. I’ve also used Sugru on the cables as they enter the roof (over silicone). These are massive 4mm cables running a total of under 6A so I feel there should be no restriction of current using Sugru on these. The cable holes are off centre to avoid existing internal lighting cables. I used M5 20mm roofing bolts and A2 stainless steel M5 Penny Washers and SS Nylon Lock Nuts.
I’m really pleased with the result. From the ground you can’t really see any indication of a campervan solar panel installation and it’s not going to effect the height restrictions of car parks with height barriers. The solar controller has battery management built into the software and can condition the Leisure battery much better than the alternator does, I’ve already noticed the leisure battery display a much more complete charge level.
I guess only time will tell how well this 100W solar panel is going to cope with our demands and I’ll update this post once it’s been fully tested under load.
Disclaimer: I’m not an auto electrician and don’t suggest you follow what I’ve done here unless you use the correct size cables and fuses for your installation. I’ve used 17amp auto cable with 10amp fuses where I’ve needed to extend from the cabling provided in the kit. Also, don’t ever lick battery terminals.
UPDATE August 2015: We’ve just returned from two weeks away with the campervan. For the first week the van sat in a carpark and wasn’t driven, the ‘full’ fridge stayed at a constant temperature and the battery hardly ever dropped below 100% capacity in the day! Even in heavy cloud and rain the panel seemed to be powering the fridge without touching the battery and then the battery would take over at night. The second week we used LED lighting and even 12 volt hair straighteners (well my wife did) and the battery was always full by the end of the day.
I’ve started a Pinterest board called 12 Volt Living and aim to keep it updated with products that help with a 12v power supply.
UPDATE April 2017: Well, the panel fitted failed. I contacted the company and they sent a new panel free of charge. This is great service from the company but it still meant I had to remove the old panel. It came off easily with just the silicone being used – If I had glued it, it would of removed all of the roof paint. The silicone is a pain to remove by carefully using a Stanley blade, but can be done with a little bit of time and care.
Before I re-fit the new panel I’m investigating adding an air gap between the panel and roof by using strips of aluminium cross section that would allow bolts to be re-positioned along the bars. I found that the new panel had the holes in different places so I can’t just re-bolt it on. Here are a few pictures of the panel after removal. It looks like the roof got very hot in points.
If you’re considering a permanent solar panel and are worried about removal you may like to read about using a Portable Folding Solar Panel
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very nice, great writeup too 😉
Cheers Phil 🙂
V interested to hear how it goes, I want to do the same thing!
The pedant in me wants to point out that Watts, Amps, Volts are instant state measurements and not “per hour”; you’re fridge takes about 1A. It does this in a millisecond, per hour, per day, it takes 1A current while it’s on. 🙂
Hi Rich, Indel B say that it is 60W installed power and runs an average of 13W per hour, obviously it only comes on to cool for a minute or two and then cuts off again. I’m not sure how to work out how long it would take to drain a 110Ah battery?
I took it away this weekend and the battery stayed at full charge, the fridge was pretty full and the temperature probe was reading 1°C, we also drove for about 2 hours in total. It was cloudy, but it seems that the panel is providing enough to keep the fridge running.
Hi Richard ,
Been reading your advice with interest. Got a similar van and roof .
Just ordered same solar panel fromsame company as well.
Was talking to a fitter and he had concerns over how the wiring was routed from the solar panel through the roof . He thought as the roof was put up and down the cable would be moved around. He thought there might be a risk of the cable failing and presenting a fire risk.
I was wondering how you routed your cable through the rear panel and into the control unit.
The other thing I was wondering was about how you fixed it to the roof.
I have a similar Reimo roof with the ridges.
What type of bolts and washers did you use?
Do you think the rubber strips will be ok with the heat generated by the panel?
Like you have ordered the glue to stick panel down but now don’t like the idea that it is so permanent .
Cheers in advance
Aidan
Hi Aidan, the cable provided to the panel is heavily over spec for the amps (thick) and I don’t think it will be a problem with the roof movement. It’s not a daily occurrence and the movement is minimal. I’ll always inspect it frequently. With a pop top I can’t see any other method of wiring it? Also the internal light cable already fitted follows the same path. I have seen some wired externally and then drop in through the door grommets which in theory would still wear with movement but may have less worry about an internal fire. Doesn’t look as good and I’ve seen plenty of internal installations from professional fitters.
The cable routes down with enough loose flex and drops through a gap into the rear wardrobe where the regulator is mounted. I might use some flexible plastic tubing to cover the cable in the future.
I used M5 20mm roofing bolts and A2 stainless steel M5 Penny Washers and SS Nylon Lock Nuts – all from Screwfix. On my roof 20mm was absolutely perfect. The silicone is stopping the wind from getting any lift so there’s not much force on the bolts. I think the panel holes would take M6 if you wanted thicker bolts (and larger holes in your roof).
I’m not sure what you mean by the rubber strips getting hot? But if you look on the website for the solar panel you’ll find the foam mounting tape that is designed for this purpose as you need the correct gap for the silicone (or glue) to set at the right thickness.
Oh, and the panel is keeping the fridge at 4°C in heavy cloud with the battery remaining at 100% 🙂
Let me know how you get on
Rich
Post updated after a two week tour with just solar power …
Hi rich,
Installed the panel , pretty much the same way you did. Fitted a mppt controller to improve efficiency of unit and a remote control panel link to the mppt . This gives a more detailed read out of the output of the panel.
Our fridge has a 40 w usage.
We are away at the moment on the south coast . The weather is a bit cloudy and the panel is struggling to meet the demands of the fridge. I think yours is 13w?
The output of. The solar panel seems to hover around 12v and 1 to 3amps. So you can see it will struggle with the fridges demand. Yet to monitor it on a really sunny day .
The remote also gives a read our of the leisure batteries status . A bit puzzled as to why the alternator isn’t topping it up better after a long run . Still shows only around 60% . The leisure battery is a 110a/h .
Any ideas ?
Thanks again for really useful blog.
Aidan
Hi Aidan, hope you’re enjoying your time away.
The manufacturers state it is a 60W fridge but runs on average 13W/h. During the night it probably comes on every 10 minutes for a few minutes at a time. It’s also dependent on ambient temperature of course and it’s better when I keep it full (even with bottled water). I also keep the freeze box section full of ice packs to help.
The panel is supposed to give 5A per hour in sunlight but it seemed to do really well in heavy cloud last week. I’ve not got a detailed read out like yours but the voltmeter shows 14v or 13.8v across the leisure battery when the sun is out and the LED on the PMS is 100%.
I wonder if you can check the panel for efficiency. I know that they are replaced if found to be under performing if some of the cells are not quite connected.
I take it you have a split charge relay and the leisure battery is getting a feed once the engine is running? the alternator should be providing at least 13.8v to your leisure battery – can you check this?
Is the leisure battery holding charge well? can you give it a charge on the mains and monitor it’s capacity?
Hope you get it sorted, let me know
Rich
Hi Richard,
Thanks for detailed reply.
The leisure battery seems to be holding up! Have turned the fridge down a bit. Haven’t driven the van for a couple of days so that’s pretty good. The remote read out seems to be showing a max at the moment of around 3 amps, often lower. Can get a bit into checking read out all the time. However the weather is very mixed.
Will test out the things you suggested when I get home.
Aidan
Nice writeup. I see you have an Austop roof like mine, I’ve been looking at a semi permanent solution and your way looks just the ticket! Did you remove the rood lining when you drilled your roof holes or did you drill through both the roof and lining and bold from underneath?
Thanks Matt, I think mine is a “poptoproofs.co.uk” but I think they are mostly the same?
Anyway, no, I(we) just drilled through both from the top. There was a little snagging once through to the carpet, but it worked fine.
Good luck!
Great writeup – just looking at the same 100W deal from Best Eco Shop, you have inspired me to place the order!
Thanks. Good luck! 🙂
Hey- Thanks for the write up, gave me confidence to follow suit. As you have previous experience of the PWM 10A controller i just wondered about the “light” output. I had planned to simply use the solar to aid the leisure battery and run a circuit for all my fridge/usb/lights etc from that but from what i understand this could also go directly from the PWM unit “light” connection. Do you know of any preference/reason for doing it either way. Cheers, Tim
Hi Tim, I use the “light” output to run a permanently on three socket cigarette lighter (with USB ports). You have to press the button on the PMW to turn this output on – but I personally wouldn’t want to use it to run the rest of the van. The PMS in the campervan handles all of the higher voltage stuff complete with individual fuses etc … https://flic.kr/p/uDCrgj
I think you could get away with the USB and LED lights being on the PMW but maybe put the fridge direct to the battery (through an inline fuse and maybe a 12v DC low voltage cut-out)
If the cheap PWM does blow, you’ll loose all of your electrics.
Hope this helps?
great blog thanks. I will be doing the same soon. i will go with the stick on panel as i’ve had leaks before when drilling holes in roof. Sealicon can brake down with temperature.
Just wondering have you used this in a hot country. Does the panel still work when the roof gets hot. I’ve read a little that the panel works up to 60 deg. So will full sun on a metal roof will this not be reached.
anyway great blog and will be doing the same soom
Hi Steve, thanks.
I didn’t feel comfortable with sticking the panel on for ease of replacement and am comfortable with replacing the silicone and rubber washers if required.
This isn’t mounted on a metal roof, it’s also raised with foam tape as per manufacturers instructions. Each panel has a STC figure which will tell you the reduction in efficiency over 25 degrees C. I don’t think they stop working completely. I mainly tour the UK so I don’t think I’ll have a problem 😉
Cheers.
P.S check out the benefits of a Portable Folding Solar Panel: http://richard.mackney.com/portable-folding-solar-panel-review/ 🙂
I’m doing mine but need to understand how you ran the cables inside the poptop. I’ve a reimo but struggling with the route and cable slack.
Hi Scott, my cable hole is close to the material on the inside, it then runs down with enough slack for it to open and close. However, I did like this external option running into rear light grommet http://i690.photobucket.com/albums/vv263/philipsmith1969/solar/file_zpswnvcijnb.jpg
I’ve read that solar panels fitted directly to the roof will suffer performance issues due to heat, have you had any problems with this? BTW, it looks very neat.
Hi Carl, a panel that heats up over the 25 ℃ STC rating suffers performance so in summer it would be better to have an air gap to help. If it was on a tin roof I think it would be even worse. However, I think the performance loss is about 10% and I’ve not noticed any problem personally. Of course it cools when driving and doesn’t suffer in the winter sun or cloudy conditions, which seem to be most of the time in the UK anyway 🙂
Take a look at my review of a Portable Folding Solar Panel because, to be honest I think it’s a better solution for me and replacing a failing panel is a real bind http://richard.mackney.com/portable-folding-solar-panel-review/
Cheers
Richard
Great article.
I arrived here as I’m looking to do something similar.
I have a PMS3 controller in my van – you mentioned you bypassed this?
Do you have a wiring diagram?
Hi Richard, I bypassed basically by running the solar controller directly onto the leisure battery (with an inline fuse). So it’s not part of the PMS but just looks after the battery on its own. Hope that helps.
Richard
Hi Richard, really good post thanks. Even if dated on 2015, it is still important. After a couple of year, do you think that your project is still valid or you would like to upgrade it? I mean, the panel is fixed to the roof by glue, tape and bolts, so you still suggest this approach ?
Thanks.
Michele
Hi Michele,
I think the project is still valid, a consideration would be if you can find a more powerful panel for a smaller budget these days. I’ve had a good experience with a portable panel and discuss the pros and cons of that here: http://richard.mackney.com/portable-folding-solar-panel-review/
The panel I fitted to my roof finally failed and I was sent a new panel F.O.C. This is great service from the company but still meant I had to remove the old panel. It came off easily with just the silicone being used – If I had glued it, it would of removed all of the roof paint. The silicone is still a pain to remove.
I’m investigating adding an air gap between the panel and roof by using strips of aluminium cross section that would allow bolts to be re-positioned along the bars. I found that the new panel had the holes in different places.
Cheers,
Richard
What’s your experience of the performance of the roof panel when the pop roof is up rather than down?
Hi Heathy, It’s all about the position and it’s worth getting the compass out when pitching up. When the roof is up and it’s facing the sun it does get a better charge. When the roof is up and it’s North facing it suffers.
Hi
I’m just about to start my Campervan conversion and i’d like it to be powered by solar only.
Can I mount a solar panel to a leisure battery without connecting it to my main battery? Or is this a stupid idea??
any help would be really appreciated.
Hi Brett,
Yes, mine is connected to the leisure battery only. It just needs to go through a solar charge controller. This is the (cheap) one I have http://amzn.to/2qipuO0 but you might want to get one with a LCD display that tells you a bit more about what’s going on.
Good luck.
Rich
UPDATE April 2017:
Well, the panel fitted failed. I contacted the company and they sent a new panel free of charge. This is great service from the company but it still meant I had to remove the old panel.
Pictures of the removal added to the post above.
Hi Rich,
Great article, it’s exactly same setup ( and roof) that I’ve got and same concerns, but appreciate if you could advise on the actual installation…
1. Airflow underneath? Therefore I assume no sealant placed under the panel at the front and rear ? Just on the sides? Is this ok when travelling on the motorway? Don’t want it flipping off…lol
2. What sealant did you use? Im also concerned using adhesive but would rather bolt the corners to aid security.
3. Looked on website but cannot find bars/foam mounting tape to place underneath so that the panel if flush going across the ridges. Where are these?
Look forward to your reply
Chris
Hi Rich,
Great article. Tips already and thanks for helping.
Chris
Hey Rich,
Awesome write up thanks! I’m doing something similar on my T4 this weekend. But I’ve got a couple of questions about your Bestek 12v adapter…
1. Does it give you a read out of amps being used by DC sockets or only the USB sockets?
2. Does it have an auto cut-off (for DC & USB) when the battery voltage drops below a certain point?
It would be great if you could help!
Many thanks, Mark.
Hi Mark, It does cycle through the different connections to show the amps but I don’t believe it has any cut out. I have seen some “cup” type adaptors on Amazon that have a cut out and quite a few more features that may be more beneficial to you over the basic on I have. Hope it goes well.
Rich
Cheers Rich. Thanks for getting back to me.
Unfortunately, mine looks the same, but doesn’t function quite the same as yours. It only gives amps for the USB sockets (volts for lighter sockets) and it’s cumulative (ie. totals it instead of scrolling through each port in use). Also means once you’ve plugged something in you can’t monitor the battery level without unplugging again.
Thanks for the tip off on the ‘cup’ style adapters. I’m going to find a 240v inverter that’ll allow me to monitor battery level and plug in USB at the same time. That should tick all the boxes, as I’ve now got all my other devices running through the charge controller to protect my battery from over-draining. 🙂
Thanks again, Mark.
Hi Mark, I must admit the LCD screen is a bit of a pain to use, but the adaptor does the job of splitting the outputs. I have a 12v cigarette female socket coming out of the solar controller so the Bestek can be plugged in to that and also retain the inline fuse that comes with the device (and benefit from the low voltage protection, as you say). Cheers. Rich
Hi, did you use the solar panel cable to connect the controller with the battery?
Hi, I used the solar extension cable to connect both the panel to the controller with the connectors (as the cable run supplied with the panel is short) and the rest of the extension to run from the controller to the battery (via another online fuse). Hope that helps. Rich.