Solar Panel Installation 13 Comments

Huge solar farms near Belchite.

The following article is all about the installation of a solar system onto our old motorhome a Hymer 694SL then retro fitting it to our current motorhome a Hymer B590.

Full Pictures too follow & it will be tidied up a little too soon.

I have mentioned this before in our tips section of Our Bumble a few issues ago but I thought I would go into more detail for those of you who have a motorhome or caravan and are considering a solar installation or those who are just curious.

Firstly why even bother with a solar system for a motorhome? Well our plan was to travel around Europe without the need to rely on using campsites that provided electricity in order to charge our batteries. This would allow us more freedom and also save us some money, even if we only used a site for one night a week and that site cost us just £10 a night then over one year we would spend £520 just in order to top up our batteries.

Why a solar system over perhaps wind energy or a generator? Well wind energy only works when it’s windy obviously, also the systems are not cheap and I don’t like the idea of having a propeller on the roof all the time or a system I would have to manually erect each time I wanted to charge the batteries. Generators all very good but equally they are not cheap if wish wish to buy a good one, they are also noisy, white heavy, require fuel to run and would also take up valuable space.

This left me with solar energy, they too have there downsides, systems can be quite expensive, the space needed to install them and they only work in the daytime and when it is sunny. I did some research on the internet looking at the different options available and having a system installed by a”professional” seemed ridiculous in terms of price. My money would go much further by doing it myself and I could also install a larger system for the same amount of money.

Firstly how much energy would I require? I calculated roughly how much energy is used by the equipment in the van, lights, tv, water pump etc and also what the Inverter (used to convert 12v into 240v) to power our 240v items like a hairdryer and chargers etc. Unfortunately I didn’t know how long I would use most items for as usage would change depending on whether it was summer or winter and hot or cold.

Solar panel output changes greatly depending on how many hours of sunshine they get and for how many hours. In summer somewhere like Spain I would get 100% for maybe ten to twelve hours compared to maybe only 10% in winter for only a few of hours in the UK. Add the fact that you would use more power in the winter on things like lights and heating but maybe use an electric fan in summer for eight hours a day to stay cool.

The best I could do would be “best guess” as we had never done this before or even had a motorhome. I wanted a system that would provide enough energy in the summer months with maybe requiring the odd charge in the winter months if we were conservative with our electrical usage. As you can see when you total everything up you could require a lot of energy I also had to be able to store this electricity into suitable batteries. Plus inverters are not 100% efficient at changing 12v to 240v so it’s usage would be higher than the sums indicate.

12v Electrical System



Hours of Use

Total Amps

10w halogen bulbs 0.8 3 2.40
5w LED bulbs 0.4 3 1.20
TV system 4 2 8.00
Water pump 2.5 1 2.50
Heating system 2 2 4.00
Extractor Fan 2 1 2.00

Total amps

20.10 amps


240v Electrical System

Item Amps Hours of Use Total Amps
1500w Hairdryer 125 0.12 15
Charge computers 7 2 14
AA/AAA battery charger 1.7 1 1.7
Electric toothbrush charger 2.5 1 2.5
Electric fan 2.5 2 5
Clothes Spinner 35 0.1 3.5

Total amps



41.7 amps

My “best guess” totalled over 60 amps of electricity, Most people seem to have a single 100w solar panel installed which gives about 5-6 amps per hour when operating at 100% so you could get as much as around 60-70 amps in summer per day, In winter however that output may be as little as just 5-10 amps for the day depending on the weather.

An average motorhomes leisure battery holds 100 amps, allowing them to get below 50% capacity is considered a no no. That gives me 50 amps to play with, I figured that if we don’t use the fan, keep the computer usage down, only use LED light bulbs, don’t watch too much TV and Joannes hairdryer usage kept to a minimum then we’d use around 30-40 amps per day. So after just 2 days I might run out of battery power with a 100 watt panel.

I needed more, much more in fact. I opted to get three times more than most people for both solar panel output and battery storage. This would give me the ability to last over a week in winter without needing a plug socket to charge the van up again. This was acceptable to us and in summer we would have more than enough electricity to keep us going. I would need 300 watts of solar power coupled with 300 amps of storage capacity.

Now that the maths side of things were covered I would have to decide what equipment would be needed. Solar panels and batteries come in all shapes, sizes and capacities, solar panels are basically available in 2 types, Poly and non poly, Poly panels are supposed to be more efficient for a given size but there output is easily lowered by even a small amount of the panel being blocked from light. The shadow from a leaf can supposedly affect their performance, Non Poly panels are slightly larger and are not affected the same as Poly ones coupled with the fact they are cheaper made this the obvious choice.

The next decision to make would be how many panels to make up that 300 watts, 1 single large panel or 2 or more panels connect together. 100 watt panels are very common so there price is the best bang for buck. I scoured the internet for more information, which brand was best, how much do they cost, what sizes are available. In the end I opted for the cheapest I could find that were suitable. No fancy names, after all they’re all made in China, I figured 300 watts is 300 watts, Just like a Phillips 60 watt light bulb is just as bright as an Osram 60 watt light bulb.

I placed my order for 3 100w panels, cabling, quick release connectors, regulator and some black brackets. The solar panels would be attached to the roof of the van via plastic mounts that enable air to circulate around the panels to help keep them cool, they are just injection moulded plastic and are complete rip off for what they are. The panels would be fixed to the brackets through their aluminium frame using stainless steel screws, the brackets are then bonded to the roof with special adhesive (Sikaflex). By screwing the panels to the brackets I can also easily access the underside if needed.

The wiring has to pass through the roof, down the vans interior and then to the vans electrical system near the batteries. I didn’t want any of the cabling to be visible inside the van and drilling a big hole into the roof to pass the cables through was not a pleasant experience. The hole needed to be close enough to the panels but also fall inside one of the interior cabinets, After a little careful measuring and marking on the outside I drilled a 12mm hole through the roof and into the rear of the cabinet that held the TV. A water tight gland is bonded to the roof of the van, the cables go through this and then into the cabinet, down some trunking and then the cabling runs behind the seating area, another hole is then also carefully measured before drilling through the floor to were the vans Electroblock (electrical system) is installed.

You cannot simply wire the panels to the batteries, the electrical output is too high and it’s not regulated and so would damage the batteries. I also wanted the installed system to charge the engine battery. I found out that if I used the same manufacturer of regulator than that of the Electroblock (Schaudt) that all of the vans electrical information could be displayed on the vans interior electrical panel, It would show voltages, Amps being produces and the actual battery capacity for both the vans batteries and also the engines.

I connected everything together and nothing, nothing was coming on the interiors panel. Volt meter in hand I checked the solar panels, they were producing electricity, 0.2 amps, that was it, 300 watts and all I was getting was 0.2 amps of electricity. I removed the panels and sent them back, Replacements arrived, I attached them to the roof but the same thing. Very little electricity was being produced. I wasn’t a happy chappy, I sat there, fag hanging out of my mouth regretting my great idea and promptly got drunk to drown my sorrows. The following day the sun came out, I’ll check em again I thought but not holding my hopes very high. 10 amps according to the volt meter, That will do me and a smile arrived on my face, I shouted Joanne again to show her the results. The first panels were not faulty after all, it just wasn’t a bright day and the sun was very low in the sky as it was December.

Now it was time to find out why the interiors displays didn’t display anything. I telephoned the regulator manufacture in Germany to find out how to get the display to work. No problem he said, you just need to press a particular button sequence on the panel and change the number that appears, it will then work correctly. What is the sequence and new numbers I asked? Sorry I cannot tell you and neither will Hymer (the vans manufacturer) unless the solar system was installed by them. Is that it then, is there no way I can get this information? I asked. Oh just look on the internet, it’s out there somewhere but sadly I am not allowed to say where. Two hours later and a little keyboard bashing trawling the internet i finally found the info. I reconnected everything together, entered the required codes and was rewarded with a display giving me more information than you could shake a stick at. Joanne was duly shouted over again and shown the results, somehow she wasn’t quite as pleased as me, there’s just no pleasing some people.

The following two weeks we where in Scotland for Xmas and New Year, The system would be put to the test. The results. Well put it this way, our old van was a pain in the arse, The solar system was the only thing that worked flawlessly.

We got rid of the old van (Homer) and bought our current one (Vin Diesel) but not before I removed all the solar stuff I had fitted. Vin already came with one 100w solar panel and 3 posh new 100 amp batteries already fitted and wired in but the solar system didn’t charge the engine battery. All I had to do was put 2 of the old panels on the roof and tap into the existing wiring. Fortunately I also kept the manual and spare wiring from the regulator I originally purchased, The new vans Electroblock was a different model but the regulator was the same. After carefully reading the manual and swapping a couple of wires the Electroblock would now charge both the vans leisure batteries and the engines too. So now I have a spare solar panel in the garage at home and a spare regulator to boot and three spare batteries .

Why new brackets? Well the adhesive I used wasn’t the cheapest, It’s £25 a tube at most places (I did finally find it for £12 on the Internet) It’s that strong it took me 3 hours with a hammer and chisel to get just one off. That and the fact the new vans white so I got 2 new sets in white to match.

The thoughts of installing a system may seem a little daunting, It is quite easy to do if you take your time, The hardest thing was reading through all the rubbish that’s on the Internet and comparing specifications of everything, Like a mentioned, I bought pretty much the cheapest solar panels and they work just like an expensive one. The total cost for everything was just over £500 for the solar stuff and £300 for the batteries, far cheaper than getting it installed by a “pro” and 3 times more powerful. In fact all of the systems I have seen since we started travelling around and those including those installed by “pro’s” are either badly fitted, not integrated into the existing vans electronics completely and still need to be plugged in from time to time to charge up properly.

Update: Our old van was traveling around for 12 months, the new van has been on the road for a couple of years now. Neither van needed a socket to get charged up except once (I forgot i was parked under a canopy in Italy so the sun didn’t get to the panels for a good few days). The system has paid for itself already and we never have to worry if we have enough juice to keep us bumbling. When you use an inverter the amount of electricity used is much higher than I originally thought. They are far less efficient than you think. We still have enough power but it’s a good idea to use it to charge computers etc when your actually driving from place to place. The vehicles alternator output offsets what is used by the inverter and it still charges your engine and leisure batteries at the same time.

New new van with the old panels transplanted onto it.

New new van with the old panels transplanted onto it.

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13 thoughts on “Solar Panel Installation

  • estatepipes

    Interesting read. I have a 230 watt single panel to install which I hope to link to 2 x 110Ah batteries. Hoping this will be sufficient. I want to move to 12 volt & usb as much as possible so have installed plenty of 12v/usb outlets around the van. I have managed to find online 12v chargers for the laptops – most phones, cameras and batteries will charge using usb and I even managed to find a 12v lead to recharge my electric razor! Hoping the 240v is hardly ever needed.

    • Bumble Crew Post author

      Most people use a single panel and 2 batteries like yourself, we just wanted a bit more so we could avoid campsites etc. Hope the system works well enough for you and enjoy you travels.

  • Mel Lewis

    Hi Craig, hope you’re having a great time! Just a quickie about solar panel installation. My Hymer has a panel fitted that charges the leisure battery via a Steka regulator, I want to replace this with a Schaudt LR1218 so that I get a readout on the onboard panel and also charge the starter battery,
    Now to my question, the number that you mentioned that you have to put in to register the solar panel, is it the same for all Hymers or is it model specific?
    Many Thanks and keep on trucking,

    • Bumble Crew Post author

      Hymers only use a couple of differnt elektrobloks, I think its the same but don’t quote me on it, the elektrobloks always prioritise the leisure batteries too, max output to the engine battery is usually 2amps. Anything else just ask.

  • Gerard

    Hi Craig

    This is great information. Any chance to can list the parts used. Haven’t bought the motorhome yet but in the planning stages and want to get the ducks in order


    • Bumble Crew Post author

      Hi Gerard glad the info is useful, the parts used were as follows:-
      3 X 100w solar panels (cheap ones seam just fine) = £330
      1 X 5m length of 2/4mm cable for connecting from panels to the solar regulator = £5
      1 X Schaudt LR 1218 Solar Charge Regulator as it contains all the necessary connectors for connecting to the electroblock = £65
      3 X connectors for the solar panels to connect to each other and then onto the regulator. = £10
      3 X Plastic bracket packs (2 in each pack) for the panels to mount on the roof = £75
      2 tubes of sikoflex adhesive/sealant to stick the brackets to the roof (can also get from most automotive paint shops at a good price) = £25
      1 X Cable gland for where the cables go through the roof. = £5
      1 X Box of 50mm stainless steel screws to screw the panels to the brackets. = £5

      The prices are approximate as I cannot remember them exactly but won’t be far off.

      It’s easy to do, just take your time and measure carefully, then enjoy the free electricity.

      • Gerard

        Hi Craig.

        Thx for that and sorry for late reply.

        One more question, the Schaudt LR 1218 is rated to take 275w and you have 300w connected. How did you get around that?


        • Bumble Crew Post author

          If i remember correctly it was something like total amps allowed was 18 but the panels fall just under at about 5.8amps each, i will check the manual if i can remember and let you know for sure, even if i made an error though we have never had any problems. 😀

  • Matt Bridges

    This article is so useful. Thanks for sharing.
    I notice it is 3 years old and wondered if you planned on reviewing and upgrading your solar panels? If so, what do you plan to do?

    • Bumble Crew Post author

      To be honest there are as good today as the day we fitted them, fingers crossed they stay that way. We also have a spare at home so i could always replace one if one went down.