Questions about solar

[Paulinwales]

i have 160 watts on my system 100w semi flexible on roof and 60w folding panel that can track.
Problem with roof panel is that when up it don't get that much light if not positioned right (i use drive away awning so don't move)
consequently i leave the roof down in day till dusk to get more charge. the portable unit (briefcase type) tracks the sun great

This setup runs compressor fridge cdf18 under 5'c full of beer and meats
I use evaporation principles to cool the bread and fruit (wet towel over foldable hole filled box
kids watch a film at night while adults chat, runs little disco balls, charges 2 phones and 3 tablets a day also

runs pretty well even if a little overcast most of time. if a fall below 11v i turn the engine on for 20 mins but that has only happened once.
rest of time usually battery is over 12.7v if there's any sun at all till 9pm

If i was to do it again i would chose 50w on roof and 100w tracking mobile unit as I think thats optimal 50 w for charging when touring and the 100w extra to boost having the kids misus using all the power and lots beer kept cold

that's how I solve the probs running 110ah leisure battery

[Dodgey]

If you park at the right angle (along the north-south line) and pointing so the sun is behind your van, then you actually get the best sun coverage possible throughout the day.

The panel is pointing perpendicular to the sun, which makes a huge difference in performance, and then the sun passes over your roof, from behind, from one side to the other - so you get the best possible exposure. The same as domestic installations.

Having the panel flat means it spends all of it's time not pointing (perpendicular) to the sun which means you get less than optimal performance. This is unless the sun passes directly over the roof of your van, which is uncommon in Europe ? (never seen it so can't be sure).

The key is to point the van in the right direction. If you have the sun passing over the front of the van then you'll get next to no solar performance.

[Paulinwales]

Good point dogey. I often forget about compass direction. Too busy thinking about view. Flatness and wind direction. Good to remind all about optimal sun location, although I tend to go for view first. Flatness pretty close second, and then sun positioning last. Roof flat does not give bad results. Must get a little compass to put in the van to remind me.

Cheers paul

[Dodgey]

My other half is thoroughly fed up with me moving the van when we pitch up. Generally, I get out my compass, which you have to hold out of the window or the car interferes, then I choose my angle, get out, while she patiently waits for me to get back in and start all over again lol

We use a gazebo as an awning so the direction of the van has little bearing on the view unless it's actually on the other side of the van. I wouldn't do that!

Flat mounted panels work well enough. They have to, they are on nearly all campers. Angled panels just add a good whack. I did some rough tests one day and was getting 4amps flat and around 4.5 - 5 angled. Saying that, when the sun is above you the difference is far less, and you can't easily track the sun with a panel on a small van so flat can be a good compromise.

[briwy]

Dodgey, you need one of these, Bongo and awning should fit on OK.

https://www.youtube.com/watch?v=ZdpgNZHDUXY

Might even be possible to automate it so that it turns to the sun by itself.

[mikexgough]

I have an android phone and use the free app.... Solar Finder....so when on site and setting up...we try to find a place with maximum sun...if we can of course...although to be fair our set up is great...... and stay with roof down from 12:00 book in until almost dusk...if really low on power(not usually) and then roof up over night....... I must say our set up with a 100w solar panel...Compressor Fridge and 110Ah battery....is brilliant....especially with the LED lighting....and we use TV/Sat decoder too if we see fit....and charge phones etc....

[Dodgey]

My uncle in Arizona has a mountain cabin (Arizona has skiing as well as desert) which is powered entirely by solar - two very large arrays mounted on auto trackers. p.s. when I say "cabin" - think huge wooden house - Americans hey!

The panels follow the sun using no energy at all. They have a special gas in tubes. Each side of the panel arrays has the gas in black pipes with silver reflectors. When the sun is to one side, the other side gets hotter, the liquid expands into gas and shitfs to the other side, and then there is an imbalance, so the panel array rotates. Very clever stuff.



They are a little out of sync there as one has just swung around. They are kept in balance with shock absorbers and weights. When they turn they turn in quite large "chunks". You adjust the angle of them on the vertical axis each sping and Autumn by moving a bolt to different holes so they point at the different height sun better.