Solar panels....

[scimdiesel]

For several years I had a 80w panel i'd attached to a "Westy" style luggage well (pop top) above the cab. This year I wanted to be able to use this well for carrying things and a touch of upgradeitus saw me buying a 120w semi flexible panel, This went on the "pop" top and is very neat. I felt it did not keep up with demands as well as before! but i had nothing tangible to base this on. I also though the leisure battery may not be as fresh as it was so replaced it. I bought a better charge controller which gives an amperage reading. I was amazed by how little the panel produced in anything less than direct full sun. A few weekends ago I placed the old panel on the roof next to the new and was able to compare the two. 80w vs 120w... Guess what! they produced almost the same in the same conditions. The sun was in and out of the clouds and they simply produced within 0.1 amps of each other usually the rigid panel producing 0.1 more.

Now i'm pondering putting the original panel on the front again with some sort of a hinged mechanism to able to stow stuff under the panel, that in addition to the semi flexible panel .... 200watts potential! Looking at the info online about connecting these together i can do this parallel or series. Both appear to be less than ideal if the panels are not identical. Has anyone got any views on this. Another thought I have is what about running 2 charge controllers so each charge the leisure battery independently. Again has anyone got any views on this.

My main power consumption is based on a Waeco compressor fridge. The marketing lies suggest 80w while running and an approx 50% running time at a certain temp i can't remember. My estimate is really at night its probably on 1/4 of the time but when the van is out in the sun and all locked up its on most the time. I've not worried about this as my beer is still cold and in my head the solar panel is hopefully offsetting the extra use. Its nolonger my belief.... If my wife would allow us to be hooked up all night at the camp site i think i'd just find a space for an extra leisure battery but this is not the case.

[kevtherev]

Some reading.
https://club8090.co.uk/forum/viewtopic.php?f=39&t=127964" onclick="window.open(this.href);return false;

[kevtherev]

More from a user

Hi Kev
Got a 100Ah leisure so should run a compressor fridge quite happily (latest waeco draws about 1.2Ah/h on a warmish day if you believe the literature) for a day or so, which is what I want. With regard to old fridge, no gurgling when on and I haven't noticed any ammonia stink so a bit perplexed to be honest, I am also a bit pee'd off as this could put a big dent in the alloy wheel fund! Think I'll have a scan to check my options, memsahib wants me to go new route as she doesn't trust second hand and runny butter was the last straw

[BOXY]

I've got panels that I can connect on flying leads with two pin plugs. I've got one charge controller for leisure battery and one on the starter. Being able to move the panels around means I can position them where they're going to get the most sun. Normally I sit them on the gutter against the high-top or on the bike rack.



Since I fitted a watt meter it's been an eye-opener just how little power gets produced except is direct sunlight.

[CovKid]

I adopted the redundancy method which seems to have paid off. Fitted way more flexis than I needed, after all they're cheap enough. Currently 300 watts which keeps my batteries in tip-top fettle even in Winter (the reason I fitted solar) and copious power in Summer. You can't see them either which is a bonus.

Prior to that, the starter battery would be well down after a couple of weeks sitting there. I don't get that anymore.

[CovKid]

Just thinking about this a little more. I have not charged the leisure battery from the alternator or any kind of external charger since March this year. It is, and continues to be, charged wholly by the panels. Its been dull for weeks but the leisure is up to full charge and trickle charged to keep it up to spec. The same for the starter battery although once the engine is running, the starter battery does then get charged via the alternator, but the leisure only gets solar power. It was more an experiment but since it works, I've not bothered to refit the split charge relay.

Food for thought anyway. Most see 150 watts to 200 watts as a good size in solar, and I'd agree, but with flexible panels on a curved roof (mines a tintop), 300 watts is a better bet to allow for the reduction in sunlight at this time of year. Pros and cons of the different types but on a curved roof, in particular tintops, flexibles shed water/dew quickly and the panels are at least getting something being curved, even when the sun is just starting to come up. In summer, I'm up to full charge before 8am. In the end, you either spend time pointing the panels for maximum efficiency or just opt for the overkill redundancy method and basically forget about them.

[Ianinpoole]

Solar is cool it goes well beyond " tree hugging" not that I have an issue with it ! Honest !
Have a look at this handy pic we use as a guide, it's basic but that's a good thing.

https://www.flickr.com/gp/148469178@N08/8s8317" onclick="window.open(this.href);return false;

[Ianinpoole]

Ps
Still can't get the hang of this photo upload thing

[kevtherev]

Ps
Still can't get the hang of this photo upload thing

[Ianinpoole]

Pmsl

Ta !

[Ianinpoole]

So
My point is
For the gains available I would "Keep It Stupid Simply". (Kiss) and put the panels flat on the roof, unless you have a pop !

[CovKid]

Seconded. Solar tracking is for those with OCD

[kevtherev]

OK I'll start.
The flat panel pointing at the sky, when is that at 93?
Is it at the zenith on a summers day?
I recently attended the 80-90 werks do up on the Staffs hills.
We thankfully had a bright clear morning after the battery sapping cold night whereby the webasto was on constantly.
With the sun at this time of year tracking a very low angle across the sky
My panel was flat and showing 0.5A
I get out and deploy my solar array at the winter angle, meter now reads 3.9A.
Right up until the sun dropped below the horizon, I was still on 3A
I believe that at this time of year it makes sense to collect the maximum amount of photons as possible when the situation arises.
With cloud cover or in the summer, I can agree there's no point in pointing.

[CovKid]

If you've got the one, it makes a lot of sense to point, particularly if you rely on it for TV etc etc. Mine just keep batteries up for propex and starting, plus a constant trickle charge in Winter so the redundancy approach works brilliantly for me. Thats all I ask of it.

Was frankly staggered that in May this year, both my batteries were up to maximimum charge by 8am and I'd used the Propex all night as it was very cold. I just never wanted to mess with bolted on panels that I'd have to move throughout the day. In fact I may just fit the third one in the Spring. 300watts way more than I'd need but it'll charge regardless of whether they're orientated or not, and even when sunlight is minimal. Price of them continues to fall, all to the good.