Weight of solar panel

MartinL replied on 10/04/2016 21:09

Posted on 10/04/2016 21:09

I have given a lot of thought to adding a solar panel to my Sterling Eccles Moonstone (2007) caravan to provide battery top up on 2-3 long weekend breaks per year where we do not have hook-up.  Initially I thought about a lightweight 100Watt Semi flexible panel. These are designed to be glued down on the roof - which dont like as they are a nightmare to remove if they go faulty.  I considered fixing it to the roof temporarily with suckers or ties (not mobile) but they are not designed to be portable -  and when regularly flexed  apparently the metal strips between the cells can fracture. 

It is not practical to use a suitcase style panel at ground level as this needs turning into the sun from time to time and Security at some event sites I use is not particularly good. (I am away from the van most of the day)

I then looked at a permanent installation, between my front large roof vent and the roof extractor fan, using a ridged solar panel supported by 4 corner  and 2 side UPVC blocks.  A 100W panel weights about 9Kg.  This would raise the centre of gravity of the van slightly.  Does anyone know if the roof will adequately support such a weight in a mobile situation without weakening the roof stucture over time please?

ocsid replied on 11/04/2016 07:18

Posted on 11/04/2016 07:18

IMO it depends on the roof construction and I don't know what is used in a Sterling Eccles Moonstone (2007) caravan.

I would have full confidence if it is a fully bonded sandwich but far from enough confidence if it was a floating skin type. In the latter the skin can't transfer the loading anywhere directly so must be induced to potentialy excessive flexing.

There is another permutation using free standing panels,  to lay them on the roof when in untrustworthy locations or simply on the ground where it is safe; in the latter case do as I do and have them secured by a security cable. You don't need to track a freestanding panel, it optimises performance doing so but just like a fixed panel it only suffers the same level of loss if left flat. In summer that should be of little importance. A 100 Watt is a bit big to manhandle onto a roof but two 60s say are not; simply couple their cables with plugs to work as one. A friend puts an 80 Watt lose panel on his roof, because he will not make a cable hole. In summer using just a single 60 could well be enough.

cyberyacht replied on 11/04/2016 08:55

Posted on 11/04/2016 08:55

I bonded a semi-flexible panel to my 'floating skin' roof. There is, after three years, an intermittent fault caused, I beleive, by the continued expansion and contraction. Rippling of the roof during travel is also a possible factor. With the benefit of hindsight, I would only fit this type of panel to a fully bonded roof. Otherwise take the weight 'hit' and fit a framed panel.

JohnDH replied on 11/04/2016 09:48

Posted on 11/04/2016 09:48

It could be, because of your particular circumstances, that solar is not for you. Try a second battery, maybe. If your out in the car, you could charge it going along.

Freestanding panels imho are the more efficient than roof mounts. Its a myth they need turning during the day. Just point the south and let them get on with it. The down side, as you have already said, they're not thief proof.

Surfer replied on 11/04/2016 14:03

Posted on 11/04/2016 14:03

I have given a lot of thought to adding a solar panel to my Sterling Eccles Moonstone (2007) caravan to provide battery top up on 2-3 long weekend breaks per year where we do not have hook-up.  Initially I thought about a lightweight 100Watt Semi flexible panel. These are designed to be glued down on the roof - which dont like as they are a nightmare to remove if they go faulty.  I considered fixing it to the roof temporarily with suckers or ties (not mobile) but they are not designed to be portable -  and when regularly flexed  apparently the metal strips between the cells can fracture. 

It is not practical to use a suitcase style panel at ground level as this needs turning into the sun from time to time and Security at some event sites I use is not particularly good. (I am away from the van most of the day)

I then looked at a permanent installation, between my front large roof vent and the roof extractor fan, using a ridged solar panel supported by 4 corner  and 2 side UPVC blocks.  A 100W panel weights about 9Kg.  This would raise the centre of gravity of the van slightly.  Does anyone know if the roof will adequately support such a weight in a mobile situation without weakening the roof stucture over time please?

We had a 120w solar panel fitted onto the roof of our 2011 Lunar Delta TI .  We also paid a bit extra to have a MPPT controller and monitor fitted. Weight on roof is about 9kg but it is spread out over a large area so i woudl guess at about 2kg on each corner.

The whole job was done by an AWS technician and with materials and labour cost us about £350.  The panel has a very long warranty and was purchased from Sunstore as a complete kit.

MartinL replied on 13/04/2016 13:35

Posted on 13/04/2016 13:35

Thanks to all of you for the feedback.   Having thought about this further I have decided to go for a riged frame panel. The weight is only a very small percentage of the van weight.  I talked to swift customer services who said the roof can easily take this weight.  Considering whether to use an additional 2 supports half way down the long side which would mean each supports 1.5Kg.   I quite like the spec of the panels from sunstore .  The panel would be just to the rear of the main vent window which is around 3" above the roof.  So additional drag, when mobile, should be minimal.

Surfer replied on 13/04/2016 13:50

Posted on 13/04/2016 13:50

Thanks to all of you for the feedback.   Having thought about this further I have decided to go for a riged frame panel. The weight is only a very small percentage of the van weight.  I talked to swift customer services who said the roof can easily take this weight.  Considering whether to use an additional 2 supports half way down the long side which would mean each supports 1.5Kg.   I quite like the spec of the panels from sunstore .  The panel would be just to the rear of the main vent window which is around 3" above the roof.  So additional drag, when mobile, should be minimal.

I think that with the Sunstore package deal you get 4 feet one for each corner however we opted to buy two additional long ones that will hold down the long sides to make it more secure when travelling.  This is not necessary but we had them fitted for peace of mind.