Solar in winter months?

Phantom

Full Member

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369
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?
 

jagmanx

Full Member

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2,054
Yes I suggest more solar.
I have solar on my house roof and no shade (apart from cloud).
The energy harvested in the winrer quarter is about 20 % of the summer quarter.
"Official figures" suggest December is about 12% of the summer. Then you migt have trees or buildings.
I realise you appreciate the "concept" and with 2x LBs that should do you.
I have fitted a cheap and cheerful voltmeter as well. Albeit not a proper monitoring system but is works for us !
The fan on your gas heating system takes some energy when first put on (Well it does on our Truma system).
Once venhicle is up to temp then gas on tickover is ok
 

Mr and Mrs Tupcox

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Messages
512
If your in the uk you will need more solar for sure .
If runing tv and heating and chargeing phones .
Our set up .
350 w solar with good mppt solar charger regulator& 2x125 batts .this runs the hab side of things.

I then fitted another solar panel 150w x2x110 batts mppt solar charger regulator connected to inverter 2000w which charges phones and gives us 240 w for hair stuff microwave and Hoover. These are not connected to the hab side of things
We get all the power we need in summer and winter .
Total investment about £1000
 

St3v3

Full Member

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1,381
Put as much up as you can. Solar gives nowhere near the quoted power in the summer, let alone winter. I have 350W, and the peak power generated has been around 320W on the odd occasion. However, what is important is the total yield. Most ever was 1500Wh. This means (approx) I could run something 150W for 10 hours, on those odd couple of days when everything was perfect. Mostly sunny near Paris 5 days ago was just 930Wh...

You didn't mention heating or fridge, how is this done in your van?
 

silverweed

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Messages
185
Don’t forget lightning too. You may not use much for this but it all adds up. So unless you are moving daily and then a good distance you can quickly empty your batteries
 

nabsim

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2,448
Where are going to be parking up? The reason I ask is if it is on a site where you can put a panel outside I would do that (if you can store inside at other times). I have 300W on the roof and 2x100ah Lifepo4 battery’s and I have to use a genny to charge if I am not moving every couple of days. I may use more power than you though
 

in h

Full Member

Messages
748
On average, in winter you will get the equivalent of one hours sun per day.

So if you need 8Ah per day, you'd need a 100 solar panel - if it was aligned to the sun.

With the panel flat on the roof, you probably need 200 watts of panel.

The average isn't what you get each day, so you will need several days' power stored to get you through a stretch of overcast weather.

I'd suggest fitting a good b2b charger and run the engine for an hour each day in winter, whether you are travelling or not.

The biggest power use for me is the fans for the heating. I have a feeling that averages at about 1.1A, which is 26Ah per day.
 

Mr Torchy

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176
Can you replace a 100w solar panel for a say 300w fairly easy? Can I keep the same 105ah battery or would I need to upgrade it. I haven't the space to carry an additional battery, which I guess would help.
 

wildebus

Full Member

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3,130
Can you replace a 100w solar panel for a say 300w fairly easy? Can I keep the same 105ah battery or would I need to upgrade it. I haven't the space to carry an additional battery, which I guess would help.
you'd almost certainly have to change the solar controller. You would also need to get an MPPT controller rather than PWM as a 300W will have a 40V voltage output rather than 20V. And finally ... you will need the roof space (300W will be nearly 3 times the size).
 

in h

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748
Depends how much unshaded space there is on your roof. Every 100 watts of panel has to be half a square metre.
 

trevskoda

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1,858
Im running 180ah batts with 200w panels through a mppt regulator rated at 250w max.
I have a 230v fridge working through a smart soft start inverter 600w nikkai,it will run the fridge for 2 days,if i used a tv and a light you will only get one night in good lightish days.solar duel a.pngroof van.jpgfridge a.jpg
 

in h

Full Member

Messages
748
The battery is just an electricity bucket. You can probably charge it to 95% full, discharge to 50% full, so the effective capacity is 45% of 105Ah, which is around 47Ah.
In turn, that's about 564 watt hours, the equivalent of 40 grammes of LPG (costing about 5p). Sadly, gas won't run your TV!
 

davef

Full Member

Messages
21
I have kept figures of solar production of the 16 large solar panels on my workshop roof. Up here in Scotland there is a huge difference in output summer to winter. May to July output is about 400 to 600 Kw hrs per month depending on cloud cover, but output in December and January is only 45 to 50 units per month, so only one eighth to one twelfth of summer output. Add to that on a van roof the panel will be lying flat while the sun will be low in the sky in winter, so even less efficient. Having said that - every little helps....
 

in h

Full Member

Messages
748
I have kept figures of solar production of the 16 large solar panels on my workshop roof. Up here in Scotland there is a huge difference in output summer to winter. May to July output is about 400 to 600 Kw hrs per month depending on cloud cover, but output in December and January is only 45 to 50 units per month, so only one eighth to one twelfth of summer output. Add to that on a van roof the panel will be lying flat while the sun will be low in the sky in winter, so even less efficient. Having said that - every little helps....
Yes, as I said in #9 it's only the equivalent of one hour of sunlight each day, and flat on the roof, effectively only half that.
Adding extra panels makes a difference in spring and autumn, changing the date it becomes sufficient each year. In summer you have too much, in winter too little.
 

Exwindsurfer

Full Member

Messages
1,142
You can get good solar in the winter if you can tilt your panels. I’ve never had a problem in winter but I can tilt my panel up to 90deg,and yes it make a really big difference.I can’t understand why more people don’t do it it’s not expensive to do it.912CDB4C-ECA6-4FEE-94E6-C53254D50242.jpeg
 

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