Solar The Solar Panel Thread

[Drover]

The only way you will get optimum angle all the time and get the most out of your MPPT controller and the panel is to fit a tracker really...............those figures look good compared to the stated figures, considering what they say is usually a mythical figure........
the panels on the roof of the ute, lay flat with a 10mm gap under them but I would like to be able to angle them but designing a mount that can hinge from 4 positions, with legs and doesn't mean a lot of ginning around to set up yet still be a firm mount when driving, to date the idea is scratched out on paper but easier to just plug a portable in to boost the system...................

 

[Boots in Action]

The only way you will get optimum angle all the time and get the most out of your MPPT controller and the panel is to fit a tracker really...............those figures look good compared to the stated figures, considering what they say is usually a mythical figure........
the panels on the roof of the ute, lay flat with a 10mm gap under them but I would like to be able to angle them but designing a mount that can hinge from 4 positions, with legs and doesn't mean a lot of ginning around to set up yet still be a firm mount when driving, to date the idea is scratched out on paper but easier to just plug a portable in to boost the system...................

I agree with you on most of those things @Drover, but each side of the "optimum" angle is a large area of best production as the sun moves across the sky. Of course, you cannot have it all the time. Don't forget, this test was done at home and not under field conditions. It was ONLY to confirm that the panel was at least close to specs and to reconfirm how heat affects output voltage, which is more critical with PWM controllers than MPPT type. The only sort of "tracker" is me and I will not be around the panel/s all day adjusting them every 15 minutes or so. I also agree that quoted "rating figures" are max at ideal laboratory conditions and rarely achievable in "real field" situations, but one has to try.
The idea of having a stable but adjustable mounting for a panel on the roof of your ute (or vans for that matter!) , that is simple to use, is yet to be invented, but I am sure your mind is already thinking of the engineering necessary to achieve this. Make sure you patent it.

 

[mikerezny]

I also agree that quoted "rating figures" are max at ideal laboratory conditions and rarely achievable in "real field" situations, but one has to try.

Hi @Boots in Action,
you may be pleased to know that your field results may be slightly better than the specifications for solar panels, especially up in sunny Queensland.

The output from a solar panel is indeed, as you said, measured under laboratory conditions, the so called 'Standard Test Conditions' (STC):

Standard Test Conditions (STC)

STC is the set of criteria that a solar panel is tested at. Since voltage and current change based on temperature and intensity of light, among other criteria, all solar panels are tested to the same standard test conditions. This includes the cells’ temperature of 25℃ (77℉), light intensity of 1000 watts per square meter, which is basically the sun at noon, and the atmospheric density of 1.5, or the sun’s angle directly perpendicular to the solar panel at 500 feet above sea level.

I suspect that in Queensland you may actually get a light intensity a little more than 1,000 W per square meter.

For instance, this website show data for a solar array at UQ in St Lucia. The peak was about 1,300 W per meter squared on the graph at the bottom of the page.

https://www.uq.edu.au/solarenergy/pv-array/sunlight

You can also click on the 'Live data Feed' to see current and past measurements.

cheers
Mike

 

[Drover]

I saw a fella at a camp who had a tri pod similar to a sat dish stand that had a gizmo on it which kept his 200w panel tracking the sun, I thought it was a snazzy bit of kit but he was a bit over the top as he had the van roof covered and I think 6 batteries, not including the panels and batteries in his tug, he had OD'd on solar I think, he went away to play with his panels, he could have powered about 10 vans so easy..........I couldn't work out why he needed so much power actually but he was fixated on it all...........................................My tracker is a bit clunky sets up 3 positions a day sometimes 4.........getting slower as it gets older though..............Doing it at home would be better than out bush, less distractions and the ability to experiment.........at least your figures are giving me a real world bench mark to work from compared to the stuff in mags.......

 

[Boots in Action]

I saw a fella at a camp who had a tri pod similar to a sat dish stand that had a gizmo on it which kept his 200w panel tracking the sun, I thought it was a snazzy bit of kit but he was a bit over the top as he had the van roof covered and I think 6 batteries, not including the panels and batteries in his tug, he had OD'd on solar I think, he went away to play with his panels, he could have powered about 10 vans so easy..........I couldn't work out why he needed so much power actually but he was fixated on it all...........................................My tracker is a bit clunky sets up 3 positions a day sometimes 4.........getting slower as it gets older though..............Doing it at home would be better than out bush, less distractions and the ability to experiment.........at least your figures are giving me a real world bench mark to work from compared to the stuff in mags.......

Hi @Drover, my "tracker" is the same as yours, 3 or 4 times a day if I am around the camp site and not out hiking or "bird watching" - the feathered type of course!! The number of times of "tracking" depends on weather and power demands on my single AGM 120ah house battery.
I trust that the figures I obtain are helpful to you and I thank you for putting up with all this "techo" stuff. Just catching up on a lot of the ideas you have supplied to me regarding fridge fans/thermostats , van load factors and many other suggestions too. Best wishes and kind regards.

 

[Boots in Action]

Hi @Boots in Action,
you may be pleased to know that your field results may be slightly better than the specifications for solar panels, especially up in sunny Queensland.

The output from a solar panel is indeed, as you said, measured under laboratory conditions, the so called 'Standard Test Conditions' (STC):

Standard Test Conditions (STC)

STC is the set of criteria that a solar panel is tested at. Since voltage and current change based on temperature and intensity of light, among other criteria, all solar panels are tested to the same standard test conditions. This includes the cells’ temperature of 25℃ (77℉), light intensity of 1000 watts per square meter, which is basically the sun at noon, and the atmospheric density of 1.5, or the sun’s angle directly perpendicular to the solar panel at 500 feet above sea level.

I suspect that in Queensland you may actually get a light intensity a little more than 1,000 W per square meter.

For instance, this website show data for a solar array at UQ in St Lucia. The peak was about 1,300 W per meter squared on the graph at the bottom of the page.

https://www.uq.edu.au/solarenergy/pv-array/sunlight

You can also click on the 'Live data Feed' to see current and past measurements.

cheers
Mike

Thanks @mikerezny , what a great site for info on solar generation on a LARGE scale. And here we are endeavoring to do the same thing and cover the same issues on a SMALLER scale. It explains and demonstrates just what factors affect solar generation for the University of Queensland and its various sites too. I would recommend that all members who have solar panels and are trying to get the best out of them should go to THAT site and hear it from the REAL EXPERTS. Thanks for referring me to it. It confirms ALL that both of us have been saying. Regards

 

[bigcol]

just to throw a spanner in the works

if I was given a small solar panel - like the ones you see for solar powered bug zappers and the like
and I wanted to hook it to my 2nd battery

do I need a fancy controller - or just red to + and black to -


like this

http://www.supercheapauto.com.au/Product/SCA-Solar-Maintenance-Charger-4-Watt/340106

 

[Bellbirdweb]

just to throw a spanner in the works

if I was given a small solar panel - like the ones you see for solar powered bug zappers and the like
and I wanted to hook it to my 2nd battery

do I need a fancy controller - or just red to + and black to -


like this

http://www.supercheapauto.com.au/Product/SCA-Solar-Maintenance-Charger-4-Watt/340106

I’ve got the same panel @bigcol.

Just connect straight to the battery, no controller required

 

[Drover]

I have one sitting on the cement mixer barrel, it keeps an old battery fully charged, has been keeping batteries charged continuously for about 6 yes now, best $19 spent....it should be on the shed roof... One day.

 

[Boots in Action]

I’ve got the same panel @bigcol.

Just connect straight to the battery, no controller required

Absolutely correct @Bellbirdweb. Insufficient current generated to cause any overcharging or overheating, hence no need for a controller for this small arrangement. Basically a very small trickle charger. Quite safe for battery @bigcol .

 

[Boots in Action]

Absolutely correct @Bellbirdweb. Insufficient current generated to cause any overcharging or overheating, hence no need for a controller for this small arrangement. Basically a very small trickle charger. Quite safe for battery @bigcol .

Sorry @bigcol , forgot to mention that if battery is down a fair bit, it will take a long, long time to fully charge up again. To give you some idea: If battery used for 1 hour at 5 amps (at 12 volts), that is 60 watts used. To recover 60 watts charged at the max of 4 watts (1/3 amp) but more likely 2 watts (1/6 amp) at say 13 volts is going to take somewhere between 15 and 30 hours of charging. Actually, that is the simple answer, because you need an additional 10% to cover charging losses, but that may be nullified to some extent by higher charging voltage required to overcome battery voltage. If battery is discharged down to say half capacity and needs 60 amps replaced (approx 720 watts), it will need more than 200 hours of charging at 4 watts or 400 hours at 2 watts. A bloody long time!!! Now that you are totally confused, just remember, it will take a long time to recharge right up again if you draw a lot out of it!!!

 

[bigcol]

I have an Optima Yellow top as my 2nd battery


the only thing running constantly on it is an analogue clock
car is only used every 2nd or 3rd day currently

when it sat for 2 months not being used, I had a battery charger on it, as the last time that happened - I flattened the N#2 battery

I just want something to help keep some charge in it, as they are awfully expensive to replace

 

[Drover]

When I moved house my old ute sat in mates yard for 4 mths with one of those panels on the dash hooked to the battery kept everything schmicko, used to have 2 of them on the shed roof and they kept the battery for the ride on and shed 12v system in good order, even kept the old vans battery topped up....................for storage best to charge the battery right up then these little panels will keep them there for a long time..

 

[Boots in Action]

When I moved house my old ute sat in mates yard for 4 mths with one of those panels on the dash hooked to the battery kept everything schmicko, used to have 2 of them on the shed roof and they kept the battery for the ride on and shed 12v system in good order, even kept the old vans battery topped up....................for storage best to charge the battery right up then these little panels will keep them there for a long time..

@Drover , right on - again!! Very good advice regarding storage for @bigcol .

 

[Drover]

@Drover , right on - again!! Very good advice regarding storage for @bigcol .

No need to quote each post you reply to @Boots in Action , on phones it does tend to take up a lot of screen area, sort of clogs things up.

 

[Eddii]

Hi @bigcol, I noticed you have a different brand second battery. I'm in a process of adding a second battery in our van. I have a Ritar RA12-100 DG (Blue top) and considering adding a different brand same Amp-hour battery. My concern is that it may not charge at an even rate when connected together due to the difference internal resistance. Do I need to worry about this?

After our first off grid camping on our new van, I found couple of things that "needs" to be addressed . First one is that we need another battery . Overcast weekend didn't help the solar to recharge our battery so on our second night we had 75% capacity. By morning it was down to 25%. Majority of our electrical consumption was from fans going all night and also we consumed 1 tank of water supply per night so that would be the 12v pump as well. So a second battery should solve this problem.

Next one (maybe) would be to upgrade PMW controller to MPPT type. After reading through this thread (I eventually finished reading all of this), Epever seems to be the go right?


Cheers
Eddii

 

[Drover]

A 2nd battery would be the go and an extra panel before the expense of a new controller, while a MPPT controller is better than a PWM it will not save you running out of power, I run a 200w on the roof but use a 120w portable and find the portable to actually provide more than the fixed one.........wired up correctly, 2 similar batteries should be okay, on paper the calculations may be less but in real life you wouldn't notice, same chemistry and size, it all should be good..........if the original is a few years old though it is better to replace as a pair .

Bigger power station and storage is a better spend of $$$ with a new controller if any left.

 

[Eddii]

Sounds like a great plan! thanks for the advice @Drover. My battery is only a month old so fairly new still .

 

[Drover]

Way to go then, no drama then.......................connect with 8 B&S like in this link ............https://caravanchronicles.com/guides/how-to-connect-two-batteries-in-parallel/

It explains how and most importantly why, with some good tips, nice and simple, the way I like..............read Part 2 also...............

 

[Eddii]

Ordered a new battery. Good read on how to connect them both, thanks @Drover.
I'd like to add an extra panel on the roof but afraid of drilling holes. I've seen people just sikaflex mounting brackets on the roof without screws. I've also seen comments here to not do it, might de-laminate the roof. Best bet is to screw them down with sikaflex but I need to find solid frames to screw it in . I have a 200w panel that I'll be mounting in the ute canopy, maybe upsize the van to this and put the 150w panel in the ute. Hmmm.