Solar Panel - what power ?

[Badgerdad]

Hi
Looking to fit a solar panel to a small van conversion.(Vauxhall Vivaro)
Has a new leisure battery that is connected to split charger.
Will run 4 small-lights, water pump and most importantly a compressor fridge.
Should be ok for weekend trips , but looking for a solar panel to keep me
going for maybe a week off grid.(in summer UK / France.)
Any thoughts / experiences ?? (need a panel that is up to the job otherwise fitting
one would be a waste of time/ money)

Thanks in advance
Bob

 

[Jev88]

More knowledgeable people will answer shortly but the bigger the better with a MPPT controller rather than PWM if you can.
Typically 200 watts and 200ah of batteries seems to be good for a week off grid but does depend on usage - fan heaters, diesel heater, etc....

 

[Richard n Ann]

What is the running amps of your compressor fridge? Just been looking at one online and it's 5.6a which is quite high.

 

[Richard n Ann]

 

[Eggs]

Hi, fit the biggest panel that you can fit on the roof. And add another leisure battery, decent controller.

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[Spriddler]

Approx. how often and for how long will you be driving (which will put some charge in the battery)...…...every day? ...every few days?

 

[autorouter]

There's some discussion of compressor fridge power calculations near the end of this thread, from post #37. That's the long answer, the short answer is what Jev88 said.

Running a 3-way fridge

Hi, can I have basic run down of how to run a fridge for a full timer with good solar panels and propane please? I was thinking 12v all the time, step to gas if I’m low on battery juice, and the odd 220v got rare plug ins. But I think the previous owner of my a Hymer said that 12v won’t run when...

www.motorhomefun.co.uk

 

[Badgerdad]

Thanks for responses.
A second leisure battery is a good idea, but takes up a lot of room.
Was thinking of installing an 80 watt panel, with a charge controller .
Sunstore do a complete kit for under £200.
Anyone used Sunstore - or can recommend a brand
( have heard some horror stories about shoddy panels )
Thanks
Bob

 

[Lenny HB]

Thanks for responses.
A second leisure battery is a good idea, but takes up a lot of room.
Was thinking of installing an 80 watt panel, with a charge controller .
Sunstore do a complete kit for under £200.
Anyone used Sunstore - or can recommend a brand
( have heard some horror stories about shoddy panels )
Thanks
Bob

80watts will be nowhere near enough I would have thought 200 Watts minimum and a decent MPPT regulator either a Votronic or Victron. And a second battery is essential, need to store the power you generate. Even then you might struggle in the UK.

 

[Badgerdad]

Thanks Lenny
You have confirmed what I have feared - mainly a huge panel required !
A portable panel might be an option- but then it has to be stored somewhere ( avoiding damage) and then security issue if unattended.
Taking van for a quick spin to recharge leisure battery every few days might be the more practical solution for what is likely to be a couple of one week trips a year.

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[Eggs]

Thanks Lenny
You have confirmed what I have feared - mainly a huge panel required !
A portable panel might be an option- but then it has to be stored somewhere ( avoiding damage) and then security issue if unattended.
Taking van for a quick spin to recharge leisure battery every few days might be the more practical solution for what is likely to be a couple of one week trips a year.

You are still going to need solar and another battery to run your fridge.

 

[autorouter]

The fridge will probably use about .5kWh in 24 hours, That's about 40 amp-hours from a 12V battery. A 100Ah battery will provide that in one day, but note that for standard lead-acid batteries you shouldn't discharge much less than 50%. You don't say what type of battery you have, but a Gel type can be discharged more, down to the 20% level.

For solar panels flat on the roof, the maximum power you will get is about 70% of the nominal power in Europe. You need it to produce 40 amp-hours per day, and that is very season-dependent. A 100 watt panel will very likely produce that in Spain/Italy in midsummer, but if you want to allow for a couple of grey days then 200 watts is a more solid choice. In the winter there are days when the 4000 watt array on my house doesn't produce 40Ah.

It's probably a bit late to say this, but if you're very restricted on battery size/weight then Lithium batteries are half the size and weight of lead-acid for the same capacity. But rather more expensive.

 

[Badgerdad]

Thanks for replies.
I have decided to increase battery capacity.(solar panel maybe later).
My research suggests that AGM batteries are good for wild camping for 3 reasons
1.Can discharge more of their capacity ( claimed) - so if can discharge say down to an theoretical 40% compared to 50 % for conventional lead/acid.
If my theory/ logic holds then that would ( for a like for like capacity) an extra 20 %
of available charge before depletion.
2. Claimed that AGM batteries recharge more rapidly - useful if I need to take van
for a quick spin to recharge battery after a few days of grid.
3. Leak less current when not in use.
4.Also more robust -good for UK roads.

My rudimentary maths would then suggest a 180 ah AGM battery would give close
to double the juice from a conventional 110ah lead/acid.

Is my logic sound ?
Would appreciate any advice.

Also suggests I should check that my current charging is suitable for AGM battery.
Using a conventional set up - split charger from van alternator with
a relay. Any thoughts ?

Many thanks in advance.

Bob

 

[Emmit]

Some funsters on here are m when it comes to AGM batteries.
I can only tell you what we have found.
At the mo we have a 20amp mppt charge regulator which has improved our charging régime in the past 12mths (we did have a cheap Chinese 20amp pwm before that)
We have 2 x AGM 100 amp batteries and only 80watts solar on the roof.
We have just come back from Spain/Portugal slowly with usually less than 100miles a day.
We used the blown air heater cos it was parky but, every day we had sufficient electricity to run everything.
We don't have a compressor fridge. That would have made a huge difference had we had one (to a detrimental effect)
I go with everyone else on here.
You need another battery. Think of it as a bucket. You cannot store your Lecky if you only have one bucket/battery and it is full.
You also need more than us as far as solar is concerned.
We have plans to increase our array this year ready for next winter.

 

[Stealaway]

Would it be cheaper and easier to buy a gas fridge?

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[Cal54]

I too have a compressor fridge and found to my expense that they can be a bit greedy when off grid. I started out by fitting a second 100 amp Leisure battery (when the van was new) and 12 months later had a 100 wt solar panel installed. Another year on and I had a second 100 amp solar panel fitted and a decent MPPT controller. After that I had a BM1 battery monitor fitted and I can see at a glance how much ‘juice’ I have left - displayed as a % cos that’s what I understand!!!
I’m now managing ok but do switch the fridge off overnight at times (depending on what’s in it!). I can now manage quite nicely off grid in summer and long weekends away in winter are no longer an issue.

 

[Lenny HB]

Thanks for replies.
I have decided to increase battery capacity.(solar panel maybe later).
My research suggests that AGM batteries are good for wild camping for 3 reasons
1.Can discharge more of their capacity ( claimed) - so if can discharge say down to an theoretical 40% compared to 50 % for conventional lead/acid.
If my theory/ logic holds then that would ( for a like for like capacity) an extra 20 %
of available charge before depletion.
2. Claimed that AGM batteries recharge more rapidly - useful if I need to take van
for a quick spin to recharge battery after a few days of grid.
3. Leak less current when not in use.
4.Also more robust -good for UK roads.

My rudimentary maths would then suggest a 180 ah AGM battery would give close
to double the juice from a conventional 110ah lead/acid.

Is my logic sound ?
Would appreciate any advice.

Also suggests I should check that my current charging is suitable for AGM battery.
Using a conventional set up - split charger from van alternator with
a relay. Any thoughts ?

Many thanks in advance.

Bob

Noooooooo don't buy AGM's total useless crap had then in the last van both batteries failed at 18 months old. The only time AGM's might work is if you have very good professional AGM charger and professional AGM batteries which will cost hundreds of pounds.
I replaced mine with Gel batteries. Current van I have 3 Gel batteries and 300 Watts of solar with a Votronic MPPT regulator we hardly ever use EHU I don't even bother plugging in at home.

Gels you can discharge to 80% DOD but to fully charge they do take longer as they need an absorption phase of a few hours. You also so need a charger capable of charging Gels.

If you are only doing one week trips probably better to fit one or two extra batteries and a B2B.

 

[Lenny HB]

Would it be cheaper and easier to buy a gas fridge?

I can't believe a Yorkshire man is suggesting that.
Have you seen the price of 3 way fridges?

 

[The Wino]

Would it be cheaper and easier to buy a gas fridge?

Yes I think that's going to be your problem also remember unless you have a b2b charger when you drive around the hab battery will take ages to charge up.
Without the fridge it would be a very low battery use but I think if you like to stay off grid it's going to be expensive to solve

 

[DBK]

A member of my family has an East Neuk Campervan with a compressor fridge, 200W of solar and a 230Ah battery. It is fine for a weekend in Scotland, even in winter and more or less indefinitely in summer.

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[Richard n Ann]

Gel are tolerant of 80% discharge and last years. Our 80ah gel has 64ah useable.
I think exide do a 140ah one too ?

 

[autorouter]

The downside of gels is they are not tolerant of high currents, such as an inverter load. But that's not a problem for you, as you say in post #1. With gels it's best to limit the current in/out to C/5, where C is the battery capacity - eg 100/5 = 20 amps for a 100Ah battery.

They won't charge to completely full from the engine alternator with a standard split charge relay, but they will with a good solar controller that has a gel charging option.

 

[TheBig1]

as a rule of thumb, you need at least 100w of solar panels to charge 100ah of battery. So I would double up on the leisure battery bank and fit 200w of solar. A 100w kit should be around £100

As for AGM, after suffering early failure of supposed quality AGM batteries, I will only fit wet lead acids or Gel. The jury is still out on whether Lithium batteries are cost effective. If a £100 lead acid battery lasts 4 years (usually more) that is £25 per year. If a £1000 lithium battery (prices slowly dropping) lasts 10 years, that is still £100 per year. A £200 Gel will last 6 years and maybe more so that would £33 per year

Before anyone starts querying the figures, they are ballpark approximations not absolute

 

[Emmit]

Noooooooo don't buy AGM's total useless crap had then in the last van both batteries failed at 18 months old. The only time AGM's might work is if you have very good professional AGM charger and professional AGM batteries which will cost hundreds of pounds.
I replaced mine with Gel batteries. Current van I have 3 Gel batteries and 300 Watts of solar with a Votronic MPPT regulator we hardly ever use EHU I don't even bother plugging in at home.

Gels you can discharge to 80% DOD but to fully charge they do take longer as they need an absorption phase of a few hours. You also so need a charger capable of charging Gels.

If you are only doing one week trips probably better to fit one or two extra batteries and a B2B.

I did tell you that folk would be along to neighsay AGM batteries.

On the flipside to Lenny, ours have been in for Three years and are still going strong.
I do agree with Lenny re Chargers. Ours was given a serious looking at and fixing about 42 mths ago and the guy who did the work specifically recommended AGM's. Maybe we were either lucky or our charger suits AGM's.

 

[Lenny HB]

I did tell you that folk would be along to neighsay AGM batteries.

On the flipside to Lenny, ours have been in for Three years and are still going strong.
I do agree with Lenny re Chargers. Ours was given a serious looking at and fixing about 42 mths ago and the guy who did the work specifically recommended AGM's. Maybe we were either lucky or our charger suits AGM's.

I think you have been lucky, you only need to look on the German Motorhome forums to see how bad AGM's are.

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[Badgerdad]

Once again many thanks for advise,
so ......
1.My existing split charger with relay may not be up to the
job for recharging AGM batteries .
I don’t at this stage want to change this conventional set up.
2. Looks like the safest option would be to fit a sealed lead/ acid battery with a
greater capacity.
Bosch do a 230 ah -

12V 230AH Bosch Silver Powerframe Leisure Battery (L5080) (N/A) - Alpha Batteries

230AH 12V Leisure battery by Bosch For extremely high power requirements and frequent discharge – e.g. ideal for caravans, boats […]

www.alpha-batteries.co.uk

Looks like this might be a decent option.
( going to be using van mainly for weekend trips in UK)
again views much appreciated

(Think trick of placing everything pre chilled into fridge- with some
Cooler packs will help .As will maybe switching* off at night.
Have done this before with a rental van with an inadequate battery and compressor fridge - (not a good combination!)

Once again thanks for views/advise.

Bob

 

[Badgerdad]

A member of my family has an East Neuk Campervan with a compressor fridge, 200W of solar and a 230Ah battery. It is fine for a weekend in Scotland, even in winter and more or less indefinitely in summer.

Thanks - answer I was hoping for - mainly for weekend use in UK.
For future summer trips abroad a portable solar panel may be a good option.
Probably going to go with 230ah sealed lead/acid, which should charge ok with my split charger.

 

[DBK]

Probably going to go with 230ah sealed lead/acid, which should charge ok with my split charger.

It depends how far you are going to drive, a split charge system could take over 4 hours driving to put a meaningful charge back into the battery. A Battery to Battery charger might do it an hour or so but they aren't cheap.
Give the larger battery a try on its own and see how you get on with it, obviously giving it a good charge before you leave for the weekend. And keep a close eye on the voltage and don't let it go below 12 volts if at all possible. In winter you will probably find you can turn the fridge off when you go to bed and turn it on in the morning. A cheap fridge thermometer will tell you what's happening inside the fridge.

 

[Garratt]

Thanks for responses.
A second leisure battery is a good idea, but takes up a lot of room.
Was thinking of installing an 80 watt panel, with a charge controller .
Sunstore do a complete kit for under £200.
Anyone used Sunstore - or can recommend a brand
( have heard some horror stories about shoddy panels )
Thanks
Bob

I’ve used Sunstore and been very happy with the kit. I bought a rigid panel, aluminium mounting brackets that were recommended by sunstore for fixing the panel to my Ducato van conversion and a Victron MPPT controller with Bluetooth. I rang them to discuss options before ordering, and they gave me a 10% discount because I asked.

 

[Garratt]