Solar Panels - Information and Questions

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G'day All
I found the 80 watt didn't cut the mustard, battery went flat after 2 days and the 80 watter put out 20 volts but only 2.9 amps to the battery, the 200 watt panel I bought from outbax camping on ebay pumps out 18 volts but the amps is a good 8 amps, the controller is a mppt type 15 amp capacity I chose the 200 watt panel after reading the redarc info on how much you need for charging etc, the panel is folding panel, 1200 x 600 value $220 less for a single fixed about 170$,, 6 mm wiring from jcar thats the copper section not including the plastic
 
Rule of thumb in calculating a system size -

1. Work out what AH you use i.e. Lets say your fridge uses 25 AH per day (in Winter) and that's all you use.
2. If you are using this amount all day every day then it should be 25% of your battery capacity to maximise battery life - Therefore your battery should be a minimum of 100 AH. For Occasional use then up to 50%.
3. If solar is the only charging source and depending on your location and quality of panel/controller, you would need 2 to 3 times the AH of the battery in Watts output of the solar bank i.e. 200 to 300 W.

The same calculation needs to be done in Summer, as your fridge will use a lot more AH, but the panel should also produce more.

Once setup occasional extra load or reduced panel output is usually acceptable, but extended increases will mean an undercharged battery.

The best way of overcoming this is to have an optional second charging source i.e. 240V charger from a genny or from a vehicle. :)

My opinion is; When running a 12 VDC fridge, 100 AH is the minimum battery size to chose for a small 30 lt fridge. Bigger fridges, especially if duel zone with a freezer need bigger batteries.

Note; a 130 AH AGM battery has a similar footprint to a 100AH and is not much different in price, so why skimp.....
 
Sorry to tell you mate, but at that price, it won't be genuine mppt, it will most likely be pwm, which is still fine, they work perfectly well, they just don't produce quite as much power. It maybe only 10% difference, so for most people who rely on them for short periods they make great value and do the job just fine.

But many ebay sellers misrepresent their panel controllers.

A mate got one from 4wd super centre, which was falsely claimed as mppt, he emailed them and got a refund. They since changed their advertising, maybe they didn't know either and just went by the manufacturer's claims, at least they corrected the advertising.

Have a look here https://www.youtube.com/watch?v=la-gvy0DfJs&t=496s

If you have two multimeters you can test the controller to see if it is in fact mppt.
If the controller is mounted on the back of the panel you would be better off placing it near the battery to minimize voltage drop on the charge line and to prevent overheating of the controller.

Glad the extra power has sorted out the problem.
 
Hey all,need some help i think,just rewired and fitted a victron 75/10 reg to my chinese fold outs ive had for a few years,at home last week once was goin great tested in full sun hooked up a battery,straight into bulk charge etc,been out for a week plus now and just got them out today to top up 2 dual auxs in the cruza,in wa and cloudy at the moment,my trailer has a 120 panel and mppt charger and its pumping in what it can by the looks,volt meter sitting on 12.9 so i know a bits going in.
Now the fold outs this morn i setup and batts in cruza are sitting on 12.5,charger wont go into bulk,checked panel input voltage and in the cloudy weather it was about 13.7-8,im wondering if the reg wont kick off until panels are delivering over 14.4,thats the bulk charge rate,absorb is 13.8,gonna piss me off if controllers dodgy,i sikaflexed it to the panels....
PS: as i started typing wife was 150 yrds away with sdc,i could here it goin off,just walked back over with a 4.5grm bit :)
 
You may find as it's cloudy the panels are not putting out enough volts (or amps) to do the dc dc conversion on the mppt controller, that is where a pwm may in fact be better under those conditions.
Those camping type panels are normally closely matched in voltage to suit a pwm controller, when you fit an mppt and add cloudy conditions the voltage often just isn't enough.
That controller will accept 75v in, perhaps since you have the folding panels wire them in series to raise the voltage.
Have a look on the back of the panels and give us the specs, or post a pic of the label, it will most likely be 21v or so open circuit per panel, if so definately wire them in series.
Keep in mind if you do that it can only be used on a mppt controller efficiently, if you wanted to use it with a pwm you'de have to parallel the outputs again.
Also, do an open circuit test on each panel to see if each one is ok.
 
Thanks OP that was my thoughts also,put em in series to up the voltage maybe,there 120's with open circuit volts 17.5,overcast here again today and there the same as yesty,not charging,i forgot to mention we shifted camp 4 days ago,last spot i had them out and same scenario in full sun,i ended up disconnecting panel wires,left it for 10 mins to maybe reset itself and hooked panels and battery back up and bingo,off and running.
Tinned panel wires togethor when i fixed them up at home so i cant try them in series until back from bush.....
 
Occasional_panner said:
open circuit 17.5 youll need total full sun for it to have the slightest chance to run. series should fix your issue.
Click to expand...

thought id disconnect panels again OP and was having a sqizz,wired it all up with anderson plugs,as im fiddling the positive wire to batt supply just fell out of the screw clamp doo dad on the regulator,mmmmm,so fixed that reconnected it all and both leds flashing(bulk charge),another ******* moment bought to you by me :)
Ya still reckon wire it up in series? Can do it while out here,just tin wires when i get home,gonna check panel voltage in a minute.....
 
Still do it in series mate, that mppt will get more power out of it in a day with the higher voltage.
That's a good controller BTW.
Tinned wires often come loose, you need to check them regularly with anything mobile.
 
Yeah got some sidecutters in the toolbox so i'll prob put them in series in the morning,yeah should be a good regulator the only thing im not fussed on is to adjust any settings now i have to buy a $50+ lead and download an app i think.....
On our trailer we have a ching chong mppt 20 amp on a 200w panel that im quite impressed with,display screen and program it with ease,to large to fit on fold outs though i think,little victron is compact....
If link works the chinese one on our trailer: https://www.ebay.com.au/itm/201529067943
 
You'll probably find the default settings will work just fine, don't waste money on the extra crap unless you really feel the need to, the small amount of time the batteries will be exposed to that fold out system you have will have negligible effect even if the bulk/absorbtion/float levels aren't quite right for the batt chemistry.

A really good MPPT controller that is available here is the epever tracer controller also on ebay. A 30A unit can be had for a tad over $100 They are releasing a new better model in a couple of months. That is a good company that make very good inverters too.
Edit, their inverters are very pricey but their controllers aren't, the controllers are worth more than what they sell them for.
 
Yeah OP when i was decking out our trailer i researched quite a few but i thought they where all pricey except the eco worthy one,heard of tracers,must of missed the pricetag on them maybe,or maybe theyve all dropped back a bit lately in price,bit like panels,so cheap thesedays......
 
Hello Everyone. I have a 2016 BT50 with a "smart alternator". I have set up a second battery in the back which has a solar regulator connected. I want to connect a solar panel which is also regulated. My question is "can I disconnect the regulator on the panel and just join corresponding wires and run that through to the second battery"? The second battery has a "Kickass" regulator which I know is a little down on quality but seems to be working ok. Thank you, Rick
 
As long as your running thru a regulator before the battery should be fine. In fact if your running thru a solar regulator before battery then certainly remove reg that's on panel. MPPT ................... genuine MPPT type regulator is the go not the re badged PWM that many are flogging as MPPT on fleabay. Some of the better dual battery regs have solar MPPT built in to them. Redarc, Projecta etc
Condor has done his homework on this type of stuff and will be able to give you much more detail regards this :Y:
 
You can tell if it's MPPT if the input panel voltage (measured with multimeter) is much higher than the battery voltage, PWM just drags it down to just a tad above battery voltage.
Have you got a link to the regulator you have for the Aux battery?
 
Yeah Bogger has the tips right down pat, no doubt.
Rick, ya lunatic, I'm about 200 mtrs from you as the crow flies! Come down and we'll chuck the meter on it!
 
It is a Projector regulator. The Kickass mob do a battery box which has usb, Anderson plugs etc all built in. I have been to a battery joint who wanted me to spend $700 on a new Redarc set up. But I can't afford to go down that road hence hooking up the solar as well. Cheers
 

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