Panel v leisure battery sizing. (1 Viewer)

[NickB]

Help please I'm getting more and more confused.
Senario. .....
Medium wheelbase well insulated Ducato single berth, with 200Ah conventional alternator and 110Ah starter battery.
Rarely on hookup ... travelling 50 - 150 miles every other day.
A. 4x 10 watts Led lights 3hrs day.
B. Wallas xc duo hob. (maximum winter use with the heater on 11 watts 10hrs a day)
C. Shurflo pump. (Negligible 5-10mins a day)
D. Compressor fridge 40 watts.
E. TV 18 watts 4hr/day.
Now the question???
What are your thoughts regarding panel wattage versus leisure battery (ies) capacities.
It's pointless in my opinion to have a panel producing more than can be stored and simultaneously used. But the batteries must have enough capacity to get through the night Etc.
What sizes would you choose?
Suggestions

 

[andy63]

It's pointless in my opinion to have a panel producing more than can be stored and simultaneously used.

You cant have it all ways... if you want enough solar to even come close to keeping your batteries charged in winter then chances are you may well have more than you need in summer...a good controller/ regulator will help get the best from whatever you end up fitting...
You do have a couple of heavy use items listed... your compressor fridge and the diesel hob/heater... id suggest that in winter even with 300w of solar you would struggle to keep your batteries fully charged with solar alone in the winter months..
What about charging laptops and phones on a daily basis... it all adds up...
Andy.

 

[NickB]

That's the precise conundrum, panel size versus battery capacity that I'm looking for opinions / suggestions on.
I didn't want to confuse the question with the relative efficiencies of the controler, regulator, panels, batteries, wiring lengths and chargers Etc and you're 100% correct everything adds up.
Regarding phone and gadgets in the past I've always used the starter battery dash sockets, cafes and the like when traveling.
This van will be my first LPG free van so going and on my past experiance I know I'm going to take a financial hit to get it right.
(BTW I'm a 'compulsive' energy saver so my usage estimates are worst case.)

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[andy63]

That's the precise conundrum

And thats what im trying to say... or am i missing the point ...there is no definitive answer to your question... we are talking about a source that is not a constant guaranteed source... as much solar as your roof will take is often quoted...but if your set up is new it might be better to run it for a while and see how your batteries cope before deciding on solar capacity..
Ive got 280w of solar... similar battery capacity ie 200ah's...
The diesel air heater would be the biggest user in my van...your hob would be similar or even hungrier and you have a compressor fridge...
In winter months im often in deficit...the solar can be doing next to nothing ... certainly not keeping my batteries fully charged...but i take your point about been careful...
So using me as an example as i said above 300w wouldnt be enough at times but more than enough at others..
Andy..

 

[NickB]

Yes it's subjective that's the difficulty.
280w with 200Ah
Let's see who has a another opinion.
BTW I'm of the habit that when I'm away I don't want to sit in my van so obviously .... Winter I'll be out all day most days, so the van will be colder (fridge works less hard) heating will be off during the day and the panels will be contributing nothing substantial.)
Summer I'll be out all day most days fridge will work harder but there will be a solar contribution.
No wonder the balance is SO difficult.
Thanks for your view

 

[Lenny HB]

If it was me I would fit biggest and most solar panels and batteries you can get on/in the van. The fact you have more than you need in summer is illrelavant. It's the worst days in winter you need to cope with.
We have 3 x 78a/h Gel batteries and 300 watts of solar with a Votronic MPPT regulator, just about does for us.

When fitting your solar do spend the extra on a decent regulator a Votronic or Victron MPPT, with low sun angles & cloudy days you get a lot more output.

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[NickB]

Thanks thinking of CTEK myself

300w with 234 Ah
.. what are your big loads?

 

[two]

Fit a battery monitor to see what's actually going on, then you can remove some of the guesswork. A B2B charger may be worth consideration. Solar is free but unreliable and even non-existent in Winter. I'd get enough solar to run the fridge but look at B2B for the rest.

 

[Richard n Ann]

If you can tilt the panels up in winter they will make a lot more power, awkward if you're on the move a lot though.

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[pappajohn]

100watt panel will be fine with your usage in summer......

Then see how long you last in winter.

You can't have it both ways....you either have too much some of the time or not enough some of the time.

 

[NickB]

Yes... I specified the enhanced 200Ah alternator and the upgraded 110Ah starter battery when I ordered the van.
I "think" the Ctek has B2B I'll have to check?

The problem isn't really having it both ways it's having the solar capacity / battery capacity ratio just right with regard to load.

 

[pappajohn]

Thanks thinking of CTEK myself

300w with 234 Ah
.. what are your big loads?

You don't have to have big loads but capacity is useful and a reasonably fast recharge.
What happens if you only have 110ah of battery and 4 or 5 days with no sun in winter.

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[NickB]

Exactly right ... here and elsewhere I've read solarWatts to match leisureAh but that I think is for vans with LPG fridge/heating.
I put 200w and 210Ah on my last van 17 years ago and that was fine because I had 3 way fridge and gas heating.
I'm on a new adventure going diesel cooker/heating and compresser fridge.
That's why I'm looking for opinions.

 

[andy63]

The problem isn't really having it both ways it's having the solar capacity / battery capacity ratio just right with regard to load.

And that can never be.... as one of them is so variable..
But with other options as mentioned you can get a system that suits your usage and needs...
Andy.

 

[two]

Your battery capacity will determine the minimum time you can 'hold your breath without coming up for air'. It will be longer when you're lucky enough to gain some solar input (or access to EHU). At other times you will need to use the alternator to redress the deficit and B2B would greatly assist with that. I suggested matching your fridge requirements to the solar output because they might balance better.
If you want a big battery reserve, consider Lithium to reduce weight and space. If i wanted to survive Winter in the Northern hemisphere, though, I wouldn't rely on solar.

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[Pausim]

With moving on regularly I think @two s suggestion of a b2b is worth considering. Just make sure you have a big enough battery for 2 days. Difficult to estimate how many amp hours you need. How much does a compressor fridge use, presumably it doesn’t run continuously at 40w.

 

[Driventemple]

Our 'van came with two 90Ahr AGMs and no solar panel. I installed a Victron battery meter to find out how much we were using (diesel heating, compressor fridge). I found that capacity was down about 10% on an overnight stop and that was replaced by a short 30 mile run next day. I have come to the conclusion that I don't need solar... I think the battery meter is a good idea.

 

[NickB]

That is really interesting, which compressor fridge do you have?
Thanks

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[andy63]

On a self build camper i have a 65l waeco compressor fridge... ...it draws between 3 and 4 amps when running ... id say it takes a 100w panel to run that alone..and thats with good ammount of light..
Andy.

 

[NickB]

I spoke to two leisure electric suppliers this afternoon who both picked up on the size of my starter battery and upgraded alternator.
Ctek d250sa Etc. was my initial route but it was explained that when driving I'll get a better charging feed from this 200Ah alternator so maybe a Merlin ABSO B2B either the 30A or 50A (e.g. scope for larger leisure battery capacity ) and its native inbuilt solar panel input (up to 500w) might be a better choice.
So I'm still open to ideas.

 

[NickB]

I spoke to two leisure electric suppliers this afternoon who both picked up on the size of my starter battery and upgraded alternator.
Ctek d250sa Etc. was my initial route but it was explained that when driving I'll get a better charging feed from this 200Ah alternator so maybe a Merlin ABSO B2B either the 30A or 50A (e.g. scope for larger leisure battery capacity ) and its native inbuilt solar panel input (up to 500w) might be a better choice.
So I'm still open to ideas.

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[Driventemple]

That is really interesting, which compressor fridge do you have?
Thanks

It's a 95L Vitrifrigo - at least that's what the spec says. It's too cold to go out and look at the 'van!

 

[NickB]

@andy63 that's interesting as well do you have the CRX65 model?
What size leisure batteries?
Thanks

 

[NickB]

Thanks @Driventemple cold here in South Wales as well.

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[NickB]

Duplicate removed

 

[andy63]

@andy63 that's interesting as well do you have the CRX65 model?
What size leisure batteries?
Thanks

I'm sorry I can't remember what the model number is and not at home to check it.. the details I posted are all I can remember... bought the fridge new at the end of 2010 I think..
lovely fridges , but with that and a hydronic diesel heater for heating and hot water the van is power hungry
it has two 100ah leisure batteries... and a 100w solar (no room for more ) with an mppt controller... and I carry a little Honda generator if im away for more than a couple days
Andy

 

[NickB]

Thanks @andy63 I've got an insulated calorifier piped into the engine cooling system to give me 20l hot water... so NO electric needed there.
And similarly a 1kw sine wave generator.

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