Solar panel charging in U.K. - what to expect in December?

[Moped]

We have been having solar charging issues and have been back and forwards to the Swift dealer several times to get this sorted.

Both the Truma solar charging regulator and the Sargent power box have been replaced and the dealer assures us the solar panel is now charging. The Truma regulator is set for 70/30 and for a sealed battery. The only thing that has not been replaced is the 100w solar panel on the roof.

We have our motorhome in storage in the midlands and since the last dealer visit the battery voltages have dropped from 12.7v to 12.2v and the solar panel display is showing that it is not charging. Admittedly this time of the year the sun does not rise above the warehouse behind so the van is in the shade for the entire day. I do have the power box turned on to enable the Swift Command app to monitor things remotely.

Even though on blue sky sunny winter days the panel is showing 0.0 charge. Not even 0.1.

It’s currently 10am, sunny blue skies and display showing 0.0 charge.

Is this normal for a U.K. winter day or is there still a charging issue?

We are off to Spain in January and don’t really want to go back to the dealer again on this until it has had a proper test in sunny Spain.

Any guidance would be appreciated.

 

[Petes]

On a bright sunny day my 160w of solar can manage around 30W, 2.5A if I'm lucky, on overcast days its around 7W 0.6A.
If your van is in the shade then you will have no benefit from the panels, I would find somewhere else to store the van or turn everything off.

 

[colinm]

You need to put a volt meter across the inputs into regulator, this will tell you if panel is actually producing anything.
It won't be much, but there should be some voltage showing.

 

[Moped]

Just to clear this up then to avoid any doubt on my part.

The solar panel does require the sun to be directly in its line of sight for the panel to generate any power at all whether clear or cloudy. If the panel is in the shade no power will be generated summer or winter.

True or false?

 

[trevskoda]

I have 200w and no charging at this time of year.

 

[Victor]

Just to clear this up then to avoid any doubt on my part.

The solar panel does require the sun to be directly in its line of sight for the panel to generate any power at all whether clear or cloudy. If the panel is in the shade no power will be generated summer or winter.

True or false?

Ive got a 120w ecoworthy portable solar panel which is placed on the dashboard inside the vehicle. Even on dull & dank days I get 0.5 - 1.5 , so there should be something going into your battery ...

Is your roof panel clean ? Its amazing the difference a simple wipe can make .
Apologies I dont want to sound patronising but a lot of people seem to overlook this as usually its difficult to get up on the roof of the van.

Best of Luck Victor

 

[winks]

Full shade will do nothing for the solar harvesting. Partially shading a panel drastically reduces output. I have some pictures of an 80W panel giving 2.5A in full sun and 1.1A with only a hand sized area of the surface covered.

Just to clear this up then to avoid any doubt on my part.

The solar panel does require the sun to be directly in its line of sight for the panel to generate any power at all whether clear or cloudy. If the panel is in the shade no power will be generated summer or winter.

True or false?

That's it in a nutshell. Here's some pictures to illustrate the effect of shading only a hand sized area of an 80W panel.

The values are in Amperes and ,I hope, pretty much self explanatory.

Cheers

H

 

[colinm]

Ah the thorny subject of panel shading, I have done extensive tests on two different panels and can report that the output drops due to shading depends on the 'quality' of shading (i.e. a full block as in post above, or a shadow cast across) and the way the cells are 'wired'. This can mean that on two different panels a small amount of shading might almost totally stop them working, or it might just reduce power by the amount of panel shaded.
Now down to practicalities, our van is stored under a 'tin' roof with open sides, so it gets zero direct sun on the panel, and as the roof is only a foot or so above panel the shading is extensive. I was intrigued that during daylight our regulator input LED was lit, on investigation (on a very sunny day) it showed 5v, not enough to produce any charge to the batteries, but showed that pretty much any stray photons will make the panel work.

 

[Alshymer]

200watts of panel and 1 x 100ah lithium. Todays reading in Devon.

 

[r4dent]

Couple of years ago I was in Spain in August.

The site owner had erected the fine mesh screens above all the pitches to provide shade.

Too much shade, no solar.

Clever!

Everyone had to pay for EHU.

 

[wildebus]

Just to clear this up then to avoid any doubt on my part.

The solar panel does require the sun to be directly in its line of sight for the panel to generate any power at all whether clear or cloudy. If the panel is in the shade no power will be generated summer or winter.

True or false?

Well, if you want a True/False reply, the answer is FALSE.
You for sure get better harvesting when the panel is in direct view of the sun but it is not correct to say you don't get ANY harvesting if it is not.

Solar Harvesting in Winter is extremely limited compared to Summer for a number of reasons - height of the sun, strength of the sunlight, generally more overcast and much shorter daylight period.

I had a look at the last two days from my 270W of flat roof-mounted panels ....
Yesterday I got a total of 60Wh of Solar, a peak of 21W (7% of the Summer Peak) on a theoretical harvesting duration of under 7 hours/
Today was better with 100Wh and a peak of 49W - still less than a 5th of Summer Maximum
(note: location is south Scotland)

With my 270W, in the summertime I would expect to hit the full 270W for short periods and a daily harvest of over 1000Wh day after day.

 

[trevskoda]

Ive got a 120w ecoworthy portable solar panel which is placed on the dashboard inside the vehicle. Even on dull & dank days I get 0.5 - 1.5 , so there should be something going into your battery ...

Is your roof panel clean ? Its amazing the difference a simple wipe can make .
Apologies I dont want to sound patronising but a lot of people seem to overlook this as usually its difficult to get up on the roof of the van.

Best of Luck Victor

Yours in the dash may be pointing to the sun, one laying flat on a roof is doing almost nout.

 

[Victor]

You are quite right... I am lucky that my van is parked up facing south so at the angle the panel is positioned, it makes the most of any sun that is available.

Its was weeks of trial & error before I settled on what works for me ...

 

[jagmanx]

With the vehicle in a poor situation I would expect almost zero from say nov 21 to jan 21.
As has been pointed out
Low sun
No sun
Low angle
Shading from warehouse
Shortage of daylight hours
Clouds
We have solar panels on our house in full sun.
We get minimal/trivial harvesting on the winter quarter (3 months)
You will do well if your batteries suffer from minor loss only for the 2 months either side of the winter solstice.
Also how far north are you ?
Simple "Earth science" and geometry !
I noted today at noon the sun was only 15 degrees above the horizon
This on itself causes 100 % to go to 25% and that is only for midday.
Yes solar in winter is indeed "Doom & Gloom"

 

[trevskoda]

Just sorting out the garden for an amp or two over winter.

 

[Geek]

Admittedly this time of the year the sun does not rise above the warehouse behind so the van is in the shade for the entire day. I do have the power box turned on to enable the Swift Command app to monitor things remotely.

Even though on blue sky sunny winter days the panel is showing 0.0 charge. Not even 0.1.

Sounds to me as if it is working correctly. If it was in 'full' sun at this time of year you might get enough charge to maintain the batteries, if not charge them.

If it is in shade, the panels won't get enough voltage to put anything at all into the batteries. Indeed, the small load from the solar controller will be running the batteries down a little.

Unless you can park it in sun, perhaps the best plan is to take one battery home at a time and charge it up.

 

[Debs]

My solar panel is on the roof, but I can tilt it for those days when the sun shows up, and I can put a decent charge into the batts. Today Sun, went to the van at 11.00am and took photo 1. Then put cdh on which normally pulls about 10amps on start-up. Photo 2 is when the heater throttled back cos it was toasty. It's quite bright today, but my van slopes a little away from the sun and the panel is flat to the roof.

my panel is 200w running through C-tek

 

[Debs]

Don't know why the photos have repeated. Hoping to get out during the end of the week, and panel goes up at every opportunity Winter harvesting is do-able, but it helps if you can tilt your panel, and you get some sunny days

 

[Admin]

Any guidance would be appreciated.

Have a look here:

Comparing Solar Power In Summer And Winter ..........

.........A Theoretical Approach. Everyone in the UK who has solar panels finds that significantly more solar energy is harvested in the summer than in the winter. And those who live at more northerly latitudes expect to harvest less solar energy than those living in the south. To put this...

motorhomer.com

 

[xsilvergs]

We have been having solar charging issues and have been back and forwards to the Swift dealer several times to get this sorted.

Both the Truma solar charging regulator and the Sargent power box have been replaced and the dealer assures us the solar panel is now charging. The Truma regulator is set for 70/30 and for a sealed battery. The only thing that has not been replaced is the 100w solar panel on the roof.

We have our motorhome in storage in the midlands and since the last dealer visit the battery voltages have dropped from 12.7v to 12.2v and the solar panel display is showing that it is not charging. Admittedly this time of the year the sun does not rise above the warehouse behind so the van is in the shade for the entire day. I do have the power box turned on to enable the Swift Command app to monitor things remotely.

Even though on blue sky sunny winter days the panel is showing 0.0 charge. Not even 0.1.

It’s currently 10am, sunny blue skies and display showing 0.0 charge.

Is this normal for a U.K. winter day or is there still a charging issue?

We are off to Spain in January and don’t really want to go back to the dealer again on this until it has had a proper test in sunny Spain.

Any guidance would be appreciated.

At the time you mention (10 AM), here in Dorset my 450 watts of clean, un-shaded and horizontal solar panels were managing 50 watts of solar yield! This was into lithium's that would have accepted everything the panels and charger could have thrown at them and more!

The sooner Boris open the mines the sooner this country will be back on its feet, coal is our future, or the two tides a day in the Solent.