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Hairyloon

Joined: 20 Nov 2008
Posts: 15425
Location: Today I are mostly being in Yorkshire.

Posted: Mon Apr 15, 19 8:37 pm Post subject: Solar panels.
I'm wanting to get a solar panel for the motorhome. I'm thinking to get one of the flexible type, not least because they seem to be a fair bit lighter. Any comments or recommendations? Brands or dealers to avoid?

sean
Downsizer Moderator

Joined: 28 Oct 2004
Posts: 42219
Location: North Devon

Posted: Mon Apr 15, 19 9:26 pm Post subject:
No idea. Might be worth a look/ask on the forum at www.ukcampsite.co.uk

buzzy

Joined: 04 Jan 2011
Posts: 3708
Location: In a small wood on the edge of the Huntingdonshire Wolds

Posted: Mon Apr 15, 19 9:36 pm Post subject:
Do take care. I have seen several articles on MSN news along the lines of "Solar Panels are Blowing Up In Wiltshire". Haven't read the articles, but sounds pretty scary. Henry

Hairyloon

Joined: 20 Nov 2008
Posts: 15425
Location: Today I are mostly being in Yorkshire.

Posted: Mon Apr 15, 19 10:45 pm Post subject:

buzzy wrote:

Do take care. I have seen several articles on MSN news along the lines of "Solar Panels are Blowing Up In Wiltshire". Haven't read the articles, but sounds pretty scary.

I'm only thinking of about 100W. It shouldn't blow with a very big bang.

dpack

Joined: 02 Jul 2005
Posts: 46209
Location: yes

Posted: Mon Apr 15, 19 10:53 pm Post subject:
the panel bit is fairly simple getting the right kit between the panel and the appliances is the trickier bit. what do you need to run is the first question .

Hairyloon

Joined: 20 Nov 2008
Posts: 15425
Location: Today I are mostly being in Yorkshire.

Posted: Tue Apr 16, 19 2:13 am Post subject:

dpack wrote:

the panel bit is fairly simple

getting the right kit between the panel and the appliances is the trickier bit.

I've actually got kit to go between: it came with the van, is just the panel was shot. Of course it might not be the right kit...

Quote:

what do you need to run is the first question .

All I need is lights and a recharge for the tools when they need it, but it would be handy to have a computer and might be nice to have a TV now and again.
I don't necessarily expect to get it all from the solar panel: if the tools want a lot of charging then that probably means I've got a job on and most such jobs have electricity available with them.

dpack

Joined: 02 Jul 2005
Posts: 46209
Location: yes

Posted: Wed Apr 17, 19 12:15 pm Post subject:

lights no prob

tools ,depends what they are , if they are like mine they need a fair bit of feeding at 18v or 28 v which means inverter and dedicated charger

pooter, my decent laptop ate a `12v 80ah gel cell via an inverter in about 10 hours so for a rough guide 1 hr of pooting = about 10 ah from 12 v storage

small low energy telly no prob especially if it has a "portable" design with a low voltage power input to avoid using the inverter.

a fairly major point is input voltages if they are under the voltage of the storage system there is a smallish power loss between panel and use, however if the input voltage is above that of the storage you lose at least 30 % at the inversion to 230v stage as well as a smaller loss dropping 2vo to a suitable input voltage and current suitable for that battery or appliance.

you also need to allow for panel out put which can vary quite a lot depending on how sunny it is, orientation ( a bit limited with a panel bolted flat on a van roof ), temperature and have you recently cleaned it ( road muck can cover a panel quite effectively )

a rough guide is you need more panel than the numbers on the adverts might suggest but you do not need too much for the system to cope with on a cold ,sunny , perfectly orientated day.

at a guess you need a couple of meters square of panel but chatting with boaters and motor home folk will probably be a good guide to the real world value of pv and power from the engine when it is running

iirc most folk seem to have bulk power generated from the engine to the storage batteries and the pv keeps that topped up while parked up for a while

full pv for tools pooter etc etc would probably need the sort of panel area you see on a house roof and a rather neat storage and control rig to be a practical option.

all the usual caveats regarding leccy with a couple of special ones such as:

pv has a variable output from the panels and you need varied inputs for a range of appliances .

you say you have everything but the panel but is it up to having a new panel system put on top?
are the storage bank batteries in good condition ? what is the total capacity?
are the wires and control gear up to providing the power you need?

huge subject

ps i have enough bits and meters to start working out what my new usb/5.5v super low voltage rig can do .
i decided large power use was impractical for a mobile kit (so far all the parts are under 5kg inc lots of li rechargeable aa/aaa batteries for assorted equipment such as night vis, cb's, gps, camera, decent radio etc etc etc )
phones etc are not very power hungry but they need a rather smooth power supply provided by the li power bank rather than direct which is possible but a bit risky

imho the way to go is to work out how little power you need and work from that rather than start from how much power can i harvest.
ie reduce demand to a minimum and it is easier to provide it

and

the engine [ or a genny if static ( or the grid with a hook up ) ] is your best bet for enough power to charge tool batteries or run a half decent pooter

mousjoos

Joined: 05 Jun 2006
Posts: 1986
Location: VERY Sunny SW France

Posted: Thu Apr 18, 19 8:29 am Post subject:
Hopefully a photo is attached. With 4 of these panels, what could I reasonably expect to run at home ?

dpack

Joined: 02 Jul 2005
Posts: 46209
Location: yes

Posted: Thu Apr 18, 19 10:46 am Post subject:

led lights take almost nothing.

from the numbers on the label a fair guess would be that they might give 200 to 300 w at about 20 v during daylight.

again a guess without knowing battery and control gear rig or if you have low energy appliances and if my maths is about right but things such as :
fridge freezer, vacuum cleaner, kitchen mixers and small appliances etc etc, telly, domestic pooter and maybe washing machine ( with hot water feed so as leccy just makes it move ). perhaps dishwasher.

it seems unlikely to be able to run a leccy cooker as a regular thing although on a good day you might just get a roast dinners worth of energy.

do you have any actual real world performance data for those panels and control gear? it would be interesting to compare that to my guestimate

Hairyloon

Joined: 20 Nov 2008
Posts: 15425
Location: Today I are mostly being in Yorkshire.

Posted: Thu Apr 18, 19 11:09 am Post subject:

dpack wrote:

a fairly major point is input voltages if they are under the voltage of the storage system there is a smallish power loss between panel and use, however if the input voltage is above that of the storage you lose at least 30 % at the inversion to 230v stage as well as a smaller loss dropping 2vo to a suitable input voltage and current suitable for that battery or appliance.

The tools are 20V and we could quite easily get 24V by putting two 12V batteries in series...
Whether that is worth the faff for the energy saving from avoiding the need for an inverter seems rather doubtful though.

Quote:

at a guess you need a couple of meters square of panel but chatting with boaters and motor home folk will probably be a good guide to the real world value of pv and power from the engine when it is running

My thinking was to get a panel and see how it goes. I can always add another panel at a later date if I feel the need.

dpack

Joined: 02 Jul 2005
Posts: 46209
Location: yes

Posted: Thu Apr 18, 19 11:58 am Post subject:

24 is ok for those tool batteries, you do need to endure the correct current is supplied as too much is out of service or on fire.

with an inverter and smart charger you would lose around 40% of what comes out of the battery bank.

if your battery bank is 12 or 24v wet/gel cells tis but a few clips and wires to have 24v dc at battery strength, a current control box uses next to no power.

it really depends how much charging while static you might need to do .

re one or two panels i would go for two and a good battery bank with proper deep discharge leisure batteries.

iirc i got good gel deep slow discharge batteries from a working ship's chandler rather than caravaner's/canal boater's shops .
online shop around for decent batteries as there are good bargains to be had and if the ones you have are old chances are they are more brick than battery.

they are heavy to drive around so having a good energy storage to wt ratio matters .not much point going pv if it takes more energy to shift it than it can store and provide .
ps car batteries are very unsuitable as they are built for high current short duration then recharge rather than charge and discharge leisurely:wink:

dpack

Joined: 02 Jul 2005
Posts: 46209
Location: yes

Posted: Thu Apr 18, 19 12:05 pm Post subject:
80 or 120 Ah gel are probably what will fit in the battery bank space but it is worth measuring and checking sizes before you order em. li storage is far better but it still aint cheap ( once electric vehicle batteries are replaced at around 30% capacity drop they will be cheap and perfect for leisure or home pv rigs )

mousjoos

Joined: 05 Jun 2006
Posts: 1986
Location: VERY Sunny SW France

Posted: Thu Apr 18, 19 1:13 pm Post subject:

dpack wrote:

led lights take almost nothing.

from the numbers on the label a fair guess would be that they might give 200 to 300 w at about 20 v during daylight.

do you have any actual real world performance data for those panels and control gear? it would be interesting to compare that to my guestimate

TBH I have no idea about these panels or what's needed to connect them to anything.
They were a windfall at the weekend, from a client that owns a factory where 100's of them are installed to feed the grid.
He told me they were 1000w but clearly he has less understanding of the figures than I do. If I've calculated correctly, I can expect 560w from the 4 of them, either to connect to the house to supplement the EDF supply ; or provide lighting & maybe a little power to the workshop via inverter / batteries.....but again, I have no idea what any of this means

dpack

Joined: 02 Jul 2005
Posts: 46209
Location: yes

Posted: Thu Apr 18, 19 3:37 pm Post subject:
bench test at 560 is very likely to be half of that most of the time but it could be twice that on a cold sunny day the more i learn about this kit the more complex it gets. if they are oldish they should still work if clean etc iirc a 25 yr life span is designed into decent panels the panel bit is fairly easy , getting the output into a usable form is a bit trickier.

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