House grade solar panel - any use? (1 Viewer)

treeman

Free Member
Nov 22, 2011
112
13
poole
Funster No
18,985
MH
'86 Classical Designs
Exp
relative newbie
I've been given a large solar panel that was destined for installation on a house roof but the glass has cracked on it so was being discarded. I've taped over the crack to hold glass and it works fine so was wondering if I could use it on my MH. Unfortunately it outputs 24v and is rated at 218w so plenty of power but too many volts.
Is it easy to regulate the output to 12v is I suppose my question?
Are there other problems using a panel designed for a house?
 
Jan 24, 2012
50
19
St Andrews
Funster No
19,566
MH
C class
Exp
Since 2010 All Year Round!!
Well, My tv has a voltage regulator which gives 12v with an input of between 11.5 & 25.5 (I think?)
Some thing like that would do? Have a look at good old RS uk.rs-online.com

:Smile:
 
Apr 27, 2008
11,788
13,940
Eastbourne East Sussex
Funster No
2,327
MH
Hymer low profile
Exp
Since 1972
Although the panel is nominally 24v it could in use go as high as 50v. In the same way a 12v panel on a motorhome may well produce 25v in 'ideal' conditions. This is why you need a regulator.
You can get 24v regulators that would work with your panel and then reduce the 24v regulated output to 12v, however as you say the glass is cracked and so it probably wouldn't last long out in the weather.
You may find it cheaper in the long run just to buy a 12v panel.

Subscribers  do not see these advertisements

 

niggle

Banned - Rule 1
Banned
Aug 5, 2010
804
601
SOUTH AND FRANCE
Funster No
13,042
MH
A CLASS
Exp
30
one of the m/h er's near me has done a dodgy deal and got two from the installers and fitted them to his m/h and they work better the the standard 12 volt ones it only cost him i think £39.00 for the box in maplins ??:ROFLMAO::ROFLMAO:
 
OP
OP
T

treeman

Free Member
Nov 22, 2011
112
13
poole
Funster No
18,985
MH
'86 Classical Designs
Exp
relative newbie
Thanks for the replies. Looked at RS Components and they sell regulators down to 12v but prices are around the £100 to handle the wattage so as mentioned it may not be financially worthwhile.

Niggle - do you know what product the m/homer bought from Maplin?
Looked on Maplins but the only solar regulators I see are for 12v (max 20v) inputs. They do sell a handy 16A 12v regulator on there for £22 and has 2 battery output connections.

I've been told if I cover half the panel up it will output only 12v - just going out to try that now (bit overkill but if it makes panel useable then possibly worth a try).
 

niggle

Banned - Rule 1
Banned
Aug 5, 2010
804
601
SOUTH AND FRANCE
Funster No
13,042
MH
A CLASS
Exp
30
not a clue as all i did was help him lift them on the roof, sorry ::bigsmile: if i see him at yard i will ask but we only pass from time to time,, i know he got the sparky to do the wiring for him as it was diff for him ...

Subscribers  do not see these advertisements

 
OP
OP
T

treeman

Free Member
Nov 22, 2011
112
13
poole
Funster No
18,985
MH
'86 Classical Designs
Exp
relative newbie
Well that works - covered half the panel and got 12.2v out on this cloudy day.

Could this be the answer, permanently cover 1/3 (so 2/3rds for use on cloudy days) then have a removable cover to take it down to 1/2 cover for sunny days. Then buy the 16a solar charge regulator from Maplins with dual charging outputs to leisure and vehicle battery for £22.

£22 for in effect a 109w charging panel?

Does that make sense or am I looking at it too simplistically?
 

hilldweller

LIFE MEMBER
Dec 5, 2008
605
36,108
Macclesfield
Funster No
5,089
MH
Zilch Mk1
Exp
From Aug 2007
Could this be the answer

Possibly the worst idea ever floated on FUN.

Get on ebay and find a Solar Charge Controller with the right input voltage and 12V out. Sorted.

Apart from it being damaged and will probably fail the first time you go over a bump or if not when water gets in.
 
OP
OP
T

treeman

Free Member
Nov 22, 2011
112
13
poole
Funster No
18,985
MH
'86 Classical Designs
Exp
relative newbie
As a new member I apologise if I've offered the" worst idea ever floated on FUN", only trying to find an affordable power source for my MH.

Is this the type of eBay item product you are talking about - 10A solar panel charge controller / regulator 12/24V for camper / caravan / boat

http://www.ebay.co.uk/itm/10A-solar-panel-charge-controller-regulator-12-24V-camper-caravan-boat-/110805574281?pt=UK_Gadgets&hash=item19cc86e289

I appreciate the panel is weak and leaky so the plan was to re-seal the whole unit if it was viable to use. No point in replacing glass then find out it's no use to me.

Subscribers  do not see these advertisements

 
Apr 27, 2008
11,788
13,940
Eastbourne East Sussex
Funster No
2,327
MH
Hymer low profile
Exp
Since 1972
The 12-24v regulators are not your whole answer as they are designed to output 24v from a 24v panel and 12v from a 12v one. The voltage is normally set automatically once you connect to your batteries (which you must always do first otherwise you can zap the controller.
If you look at the spec for the controller you will normally see a figure for input overvoltage which is usually about 28v fora 12v setup. In other words it will probably work in weak sun but in bright sunlight will either cook the regulator or cause it to automaticaly shut down to protect the circuits.
This may work if you cover part of the panel in bright sun, but a bit of a faff. It probably only needs a small part covering as partial shading rapidly brings down the output. As an example, on a bright January day my single 85w panel gave 0.6A but after cleaning off a modest deposit of seagull crap it gave 1.1A.
As an aside I had 3 more panels fitted on Sunday and since then it has been uniformly overcast and wet. The maximum I had was 2.2A, but I am waiting for sunshine.:thumb:
 

stcyr

Free Member
Apr 11, 2011
1,765
1,160
Normandie
Funster No
16,005
MH
A class
Exp
On & off, since 1966 - fulltime since 2005
I had a cracked panel on a previous MH - I put a sheet of perspex over it, trimmed to size and sealed - new owner reports it still works fine. :thumb:
 

hilldweller

LIFE MEMBER
Dec 5, 2008
605
36,108
Macclesfield
Funster No
5,089
MH
Zilch Mk1
Exp
From Aug 2007
As a new member I apologise if I've offered the" worst idea ever floated on FUN", only trying to find an affordable power source for my MH.

Is this the type of eBay item product you are talking about - 10A solar panel charge controller / regulator 12/24V for camper / caravan / boat

http://www.ebay.co.uk/itm/10A-solar-panel-charge-controller-regulator-12-24V-camper-caravan-boat-/110805574281?pt=UK_Gadgets&hash=item19cc86e289

I appreciate the panel is weak and leaky so the plan was to re-seal the whole unit if it was viable to use. No point in replacing glass then find out it's no use to me.

Well, electrically that was like taking 4 plugs out of a V8 because you want a 4 cylinder.

That controller is very close 50V in 12V out but only 170W. The chances of getting more than 170W is slim because the rated output is for best possible conditions. You can take a cheap gamble or go for a bit bigger regulator.

But if that cracked glass flexes and splits one of the cells you've had it because they are wired like "fairy lights" and probably half would go down with just one cell.

Subscribers  do not see these advertisements

 

hilldweller

LIFE MEMBER
Dec 5, 2008
605
36,108
Macclesfield
Funster No
5,089
MH
Zilch Mk1
Exp
From Aug 2007
The 12-24v regulators are not your whole answer as they are designed to output 24v from a 24v panel and 12v from a 12v one.

Don't confuse him even more.

The regulator he has chosen will take any input up to 50V.

The regulator will determine if it is charging a 12V or 24V battery and switch automatically.

That is it, simple.
 
Apr 27, 2008
11,788
13,940
Eastbourne East Sussex
Funster No
2,327
MH
Hymer low profile
Exp
Since 1972
Don't worry about comments about the 'worst idea' floated on the forum. Hildweller is exaggerating, there have been many worse. I'm sure some of mine have been .

BTW how heavy is your panel, I assume as it is for a house the manufacturers may have not bothered much about keeping the weight down.

Subscribers  do not see these advertisements

 
OP
OP
T

treeman

Free Member
Nov 22, 2011
112
13
poole
Funster No
18,985
MH
'86 Classical Designs
Exp
relative newbie
Panel is rather heavy, could cause a few issues in mounting and directing at the sun.

Panel spec has max open circuit voltage (Voc) of 33.6v at 8.4amp so if a controller could handle 50v and 20amp I'd hope that would cope. It is all a tad confusing regarding all the electrical technology but seems a shame to waste a powerful panel so I'll pursue it.

It would be nice to have some sun so I could check max voltage before spending on a controller.
 

hilldweller

LIFE MEMBER
Dec 5, 2008
605
36,108
Macclesfield
Funster No
5,089
MH
Zilch Mk1
Exp
From Aug 2007
Panel is rather heavy, could cause a few issues in mounting and directing at the sun.

That is the downside of the way panels are mounted on a MH, usually flat. The panel spec is for it face the sun, here at 50 deg a flat panel loses 25% ( sin(50) = 0.75 ). But if you angle it at 50 deg you have to arrange for it to track the sun.

We came to the conclusion a while ago that it's simpler to throw on another panel than have a tracking system.
 

stcyr

Free Member
Apr 11, 2011
1,765
1,160
Normandie
Funster No
16,005
MH
A class
Exp
On & off, since 1966 - fulltime since 2005
Is this any help? : "Almost any charge controller will work as long as the input voltage is rated to handle the open circuit voltage of the panel which may be in the 40v range. The panel's voltage will drop to match the load during charging, it just won't be as efficient as it could be unless you get a controller with 'maximum power point tracking' (MPPT). Mppt will get the most power from the panel and convert it to the proper charging voltage for the battery bank"


:thumb:

Subscribers  do not see these advertisements

 

Wildman

Free Member
May 30, 2008
0
8,470
Ilfracombe, Devon
Funster No
2,913
MH
Amazon Ambassador
Exp
since 1967
you could always add a second battery in series and charge as 24V then tap power for the van across one battery at 12V, however those glas panels are rather heavy and as already said very likely to fail due to flexing damage. I could use it as I have 24v system on my generator at the smallholding should you decide not to use it. Good luck.
 

chrisgreen

Funster
Jul 26, 2009
5,980
12,332
england
Funster No
7,663
MH
c class
Exp
since 2004
get the charge controler,and get it on the roof of the motorhome,welldone on getting it free of charge:thumb:value with cracked glass about £200 fix the glass and the value goes up:thumb:
 
Jul 28, 2010
1,710
617
The world
Funster No
12,902
MH
Small car
Exp
1
Glue another pane of glass over the panel it should then work ok

wish i could be given one it worth a fortune :cry:

Subscribers  do not see these advertisements

 
OP
OP
T

treeman

Free Member
Nov 22, 2011
112
13
poole
Funster No
18,985
MH
'86 Classical Designs
Exp
relative newbie
Thanks for all the tips. Full sunny day today so got it sitting at 90' to the bright sun and max open circuit voltage measured 34v as stated on the panel so hopefully a max 40v controller will work although I'll look for a 50v. As 8.4amp rated max current I guess a 10amp would work but again I'll look for a 15 or 20amp controller.

Anyone got any recommendations for a controller? Is there things I should look for or avoid? I like the idea of 2 battery connections as can charge both car and leisure - or make the second circuit open to charge my boat battery etc.

Regarding the structural integrity, all the glass is still in place I will look to either replace the glass or put a sheet of perspex over it. For the time being though I've stuck clear carpet protector film over it to ensure no water gets in.

Looking forward to free(ish) power!!!

n.b. found this article had some useful explanations for the layman like me........

http://www.altestore.com/howto/Sola...-Components/Solar-Panels-PV-and-Voltages/a98/
 

hilldweller

LIFE MEMBER
Dec 5, 2008
605
36,108
Macclesfield
Funster No
5,089
MH
Zilch Mk1
Exp
From Aug 2007
either replace the glass or put a sheet of perspex over it.

Minefield again. In all probabilty the cells are bonded to the glass.

One member made a DIY panel and it went tits up when it came to making it watertight. Bonding to the glass came into the conversation.
 

Wildman

Free Member
May 30, 2008
0
8,470
Ilfracombe, Devon
Funster No
2,913
MH
Amazon Ambassador
Exp
since 1967
do remember the sun is low in the sky at the moment so not at its best, also the rated current is for 24V that will double if you cut down to 12V so at least a 20amp controller required. a crack sealer on the glass might do it backed up by translucent tape.

Subscribers  do not see these advertisements

 

hilldweller

LIFE MEMBER
Dec 5, 2008
605
36,108
Macclesfield
Funster No
5,089
MH
Zilch Mk1
Exp
From Aug 2007
also the rated current is for 24V that will double if you cut down to 12V so at least a 20amp controller required.


Spot on with one slight problem, is the 10A rate input or output ? I can't make my mind up. I guess the best thing is to go for worst case and buy a 20A controller.

Oh boy have I gone this route before, "hey this is great, what a bargain" soon followed by "oh well, at least there's room in the bin".

But if he pulls it off a 200W panel is a huge asset.
 
OP
OP
T

treeman

Free Member
Nov 22, 2011
112
13
poole
Funster No
18,985
MH
'86 Classical Designs
Exp
relative newbie
UPDATE..........

Well after consulting some guys in the know ( particularly Igor at www.photonicuniverse.com) and also considering all the comments on here I purchased a 20A PWM controller that can handle up to 50v input so can take the large on-grid type panel such as mine.

It's now connected up and charges my 90ah battery very well and has a switchable load output that is regulated to switch off below a certain voltage so no more dead batteries.

All for £32.99

Now all I need is the panel to stay in 1 piece!!!!!!!
 
OP
OP
T

treeman

Free Member
Nov 22, 2011
112
13
poole
Funster No
18,985
MH
'86 Classical Designs
Exp
relative newbie
To be honest it was all effort well spent even if the panel fails. The guys at www.photonicuniverse.com helped my understanding and with what I've learnt by trialing the panel I think I would just go and get another on-grid panel as price per watt they are good value as there are so many of them around now they are just a commodity - like Sky sat dishes - everywhere!

Among the things I've learnt is that you'd struggle to have too much power with PV panels. Users often talking about adding panels or upgrading panels but no-one ever even mentions buying a lesser panel. 218w and 8 amp I think is ideal for me.

Also if my efforts help someone else get some affordable power into their motorhome then all is worthwhile.
 
Apr 27, 2008
11,788
13,940
Eastbourne East Sussex
Funster No
2,327
MH
Hymer low profile
Exp
Since 1972
Pleased for you that it worked:Smile:

You certainly can't have too much solar on a van, on a grey February day my 4 panels (325w total) struggle to produce a couple of amps. I have got room for one more but its always a matter of getting huge amounts of leccy in the summer when you need less and hardly anything in the winter when you need it most:Sad:
 
OP
OP
T

treeman

Free Member
Nov 22, 2011
112
13
poole
Funster No
18,985
MH
'86 Classical Designs
Exp
relative newbie
ANOTHER UPDATE.................

Fiddle sooner and fiddle more is my new motto.......

After deciding to rewire the panel-to-controller cabling, I found by removing the back cover on the PV panel that it looks like it is in fact 2 x 12v circuits wired in series - making in 24v - see pic...

DSCF52173.jpg


Not certain but if I change the wiring in that panel box to create 2 circuits in parallel I'll have a 109w 12v 8Amp panel? (or will it be a 218w 12v 16Amp) my physics is not good - anyone advise me of what I'll end up with?

Having said that I'm not sure if it's worth it for me know, my controller works fine and on very overcast days like today the panel only outputs about 13v anyway. So do the electrical minds out there think best left alone now?

But for anyone else with the chance to pick up a house-grade panel cheap - an easy conversion to a high power 12v panel is looking feasible and free!

Subscribers  do not see these advertisements

 
Last edited:

Join us or log in to post a reply.

To join in you must be a member of MotorhomeFun

Join MotorhomeFun

Join us, it quick and easy!

Log in

Already a member? Log in here.

Latest journal entries

Funsters who are viewing this thread

Back
Top