Solar in winter months?

trevskoda

Full Member

Messages
1,858
I waited until both leisure batteries were showing fully charged by the solar controller and then disconnected the older one. I'll let it settle overnight and measure the voltage in the morning which I guess should indicate it's true capacity.
If you did not pull the fuse on the solar panel then removing a battery not good,i take it you left one connected. (y)
 

Phantom

Full Member

Messages
369
If you did not pull the fuse on the solar panel then removing a battery not good,i take it you left one connected. (y)
Yep, I just disconnected the older battery that came with the moho. About a year ago I added another as the connectors were already there. Not the best practice I know using old and new together but now seeing if the older one is too tired.
 

Pudsey Bear

Full Member

Messages
1,665
After looking at what we use these days, I'm not too concerned about what the panel can salvage from the sun in winter, we used to run a 240v TV and a 100w slow cooker, but last two times we went away, we didn't turn on the TV at all, mainly read or watch downloaded stuff from Netflix or iPlayer on tablets, so all we need now is to be able to charge tablets and phones and although I haven't worked out how much they use I don't think they'll bother the leisure batteries too much.
 

TR5

Full Member

Messages
36
If you have a 105ah battery and a 100w Solar Panel already. So if you fit another 100w panel, do you need a larger battery to cope with the extra charge in summer, or does the regulator deal with that.

The regulator will deal with that, but in summer you will be producing power that cannot be stored as the battery will be fully charged quickly - excess just going to waste, and in the winter you will have little reserve for cloudy days.

If not moving regularly, a wind turbine may be better for the winter months. More likely to get wind than sun, especially at night.
 

trevskoda

Full Member

Messages
1,858
The regulator will deal with that, but in summer you will be producing power that cannot be stored as the battery will be fully charged quickly - excess just going to waste, and in the winter you will have little reserve for cloudy days.

If not moving regularly, a wind turbine may be better for the winter months. More likely to get wind than sun, especially at night.
Wind turbines are very noisy and dont do much unless there mounted high and you are parked on a hill,what about some hamsters on a wheel dynamo.
 

Markd

Full Member

Messages
997
At the risk of starting everything off again I've got some fuel consumption results whilst stationary.
Not for a motorhome but from my 2004 Passat 1.9 PD engine.
I used VCDS to report fuel consumption in L/he.
With a not hot nor cold engine (62⁰) it uses 0.8L just ticking over. If I turn on rear screen heater, all lights and a.c. to max (runs 100w cooling fan) that rises to 1L per hr. This additional load is 30% of alternator capacity - at tickover probably amounts to 30-40 A
Might be less consumption if engine was up to temperature but that wouldn't be the case if running engine just to charge battery.
Presumably 2.8L Ducato engine would use more?
I hope this is useful to show that interpolation of mpg back to zero isn't necessary to get static consumption figures.
Maybe other have engine diagnostics to give accurate fuel consumption at tickover?
 

in h

Full Member

Messages
748
At the risk of starting everything off again I've got some fuel consumption results whilst stationary.
Not for a motorhome but from my 2004 Passat 1.9 PD engine.
I used VCDS to report fuel consumption in L/he.
With a not hot nor cold engine (62⁰) it uses 0.8L just ticking over. If I turn on rear screen heater, all lights and a.c. to max (runs 100w cooling fan) that rises to 1L per hr. This additional load is 30% of alternator capacity - at tickover probably amounts to 30-40 A
Might be less consumption if engine was up to temperature but that wouldn't be the case if running engine just to charge battery.
Presumably 2.8L Ducato engine would use more?
I hope this is useful to show that interpolation of mpg back to zero isn't necessary to get static consumption figures.
Maybe other have engine diagnostics to give accurate fuel consumption at tickover?
In post #86, I wrote "So your gallon ought to last five to ten hours. That's about £1.25 per hour.
A motorhome engine idling will probably use about two thirds of that much diesel. Say about £0.85 per hour."
Which is more or less what you're describing.
 

Markd

Full Member

Messages
997
If only that a litre of diesel cost 85p 😀
But an hour's tickover charging at 14V ought to put a decent lump of charge back into a depleted battery.
Personally I wouldn't do it every day but occasionally if there's no sun and I'm not going anywhere I'd do it to get enough power to see me through a night.
 

in h

Full Member

Messages
748
Well, my guess was 0.67 litres per hour.
Your estimate for a not-warmed-up engine was 0.8.
Not a lot different.
At 111.7p per litre, that's 75p or 89p per hour, respectively.
 
Last edited:

St3v3

Full Member

Messages
1,381
Well, my guess was 0.67 litres per hour.
Your estimate for a not-warmed-up engine was 0.8.
Not a lot different.
At £111.7 per litre, that's 75p or 89p per hour, respectively.

1ltr per hour when alternator loaded ;)

Where is diesel 111.7?
 

in h

Full Member

Messages
748
I think I said "about two thirds of that" referring to 1 litre per hour.
I filled up with diesel at Morrisons this lunchtime. It was £1.117 per litre. But not £111.70. I'd not pay that! Post corrected.
 

Markd

Full Member

Messages
997
Asda Gloucester - bought some yesterday!
It's impossible to predict just what consumption will be exactly on any particular engine - mine went up to 1L/hr with a heavy alternator load.
Whether you'd get the same load into leisure batteries would depend on cable size and for those who believe in them what sort of B2B you may have.
I don't think we should work on the basis of an idling engine being very warm - this discussion is based on charging on days with no sun and stationary vehicle.
I expect that larger motorhome engines (2.8L for many of us) will use more would it be 50%?
I don't know.
What I do know is that undersizing solar panels for regular use will need secondary charging and that carrying a separate generator and a container of petrol will eat into payload and storage space but using the vehicle engine doesn't.

I'd go for maximizing solar wattage and balance battery capacity against that.
Of course second and third batteries eat into payload and space - unless you've got lithium.

That should be good for another few pages of posts!! 😀😀
 

Ctcallow

Full Member

Messages
1
We will be living full-time in our moho over winter. We have a 120w solar panel and two leisure batteries but the only real demands are likely a few hours of TV a day and minor device charging. So guess this is quite borderline in winter?
There is scope to at least double solar capacity if needed, what would you suggest?
we have a solar panel on our van that dual charges the main and liesure battery. we were cocky last winter and left the van unattended for a couple of months, sadly main starting battery was flat. I suggest you would not be able to rely on solar.
 

Markd

Full Member

Messages
997
we have a solar panel on our van that dual charges the main and liesure battery. we were cocky last winter and left the van unattended for a couple of months, sadly main starting battery was flat. I suggest you would not be able to rely on solar.
You must have been somewhere very shaded if a dual charge controller couldn't keep a couple of batteries topped up with no load.
Perhaps its starter channel packed up or of course it is possible that the starter battery just died on you.

I've had a couple of dual regulators and they've both been reliable.
I suggest you check the controller before you lay the van up again as when using it normally the alternator masks any lack of solar to van battery.
 

in h

Full Member

Messages
748
It may be that the dual regulator isn't wired correctly and isn't charging the engine battery.
 

Users who viewed this discussion (Total:0)

Top