Help needed with 12v solar & inverter

d_generate · Post by **d_generate** » Tue Jan 07, 2014 2:39 am

As above, I've recently fitted two 12v solar panels to the roof of my Transit van, one 200w & one 100w running in parallel, I should be getting around 15 - 17v but I'm lucky to get 11.8v at the batteries and low 12's at the panels, I've used 10mm sq cable which is more than big enough and it's about 2.5m from the batteries (2 x 130ah gel) to the panels.

My son in law is a sparky and he came over today and it's got him bamboozled also, everything I've done seems right but it's either the eBay panels which are the same brand but from different suppliers or ?????, all suppliers have good feedback and I sent off a question to them today.

I'm also having problems with my inverter, it's a 2000/4000w unit but it's somehow getting negative whatever the voltage in the battery is showing on a multimeter & it'll spark on contact with anything that's earthed to the body if the body of the unit touches earth though it works fine( I.E. if I put the multimeter between one of the body screws and the vehicle body it'll show something like -12.4v)......... well it did until we connected the control box today, now the control box beeps and shuts down the inverter which means I can't run my 240v fridge off it any more so I have to be plugged into mains, run the car for a couple of hours a day or run the generator so if anyone knows about this stuff or knows someone who does please let me know..............I'm supposed to take off on Sat.

On it's first trial run last week up at Lanno & Cervanties.

Couldn't do without a Subaru part or two so it's got a Foz seat with a swivel base and a couple of lap belts on the lounge in the back.

Cervanties.

Gannon · Post by **Gannon** » Tue Jan 07, 2014 11:39 am

Have you tried measuring the voltage of the solar panels individually? (i.e. disconnected from each other)

As for the inverter, is it a cheap chinese one? Could be that the chassis is actually grounded to the positive terminal somehow. Maybe if you mount it so there is no metal connection between the body of the inverter and the chassis of the vehicle

Might pay to make sure there is no lethal voltages between the earth pin of the 230v outlet and the chassis of the vehicle.
Ive seen this with a cheap inverter and there was 120 volts between a metal bodied drill and the ute body that had the inverter in it. The earth pin was connected between to the centre tap of the output transformer and so was the input negative. Very dangerout situation
Good inverters are properly isolated and have a floating output
Get your son in law to check it out

Subydoug · Post by **Subydoug** » Tue Jan 07, 2014 12:52 pm

Might have to look into solar panels and running them in parallel, especially two different panels. With batteries, if you hook up a flat battery and a charged battery in parallel, the charged battery will charge the flat one until they are at the same voltage. You might need to run the panels in series, then step it down.

Try using the inverter out of the car with just a battery and measure with your multimeter between the case and both terminals. I would expect next to nothing. Do the same with the ac output, just don't fry yourself

.

Regards

Doug

tambox · Post by **tambox** » Tue Jan 07, 2014 6:39 pm

As per the previous comments.
1. Check each solar panel, without connecting to anything else, ie Open/Circuit, see what it gives in full sunlight.
2. Check the inverter, by removing it and connecting it to a good battery.
3. Some inverters have links on them to ground the earth, check that.
If all seems ok, then
a. Connect the inverter to a fully charged battery in your vehicle and check what you get on output.
b. Connect one of your vehicle solar panel wiring and check to see if charges.
c. Connect the other panel and make sure it charges.
What sort of regulators/diodes (maybe inbuilt) are you running on your solar panels?
Is your van a positive earth on the normal (not solar) battery?

d_generate · Post by **d_generate** » Tue Jan 07, 2014 6:44 pm

Thanks for your replies, both battery's are brand new as is everything else, the inverter is only earthed to the battery, it sits on a wooden shelf and has no screws attached, just held on by a nylon belt, if you know about this stuff I'm quite happy to drive over to Carlisle for you to have a look & pay for your time.

Tom o422317ooo

ktmtragic · Post by **ktmtragic** » Tue Jan 07, 2014 7:45 pm

What happens if you touch the inverter case to the vehicle with both + and - connected? Is there an earth stud on the inverter case? What voltage are you getting out from each panel separately? ( not connected to anything?)

d_generate · Post by **d_generate** » Tue Jan 07, 2014 8:05 pm

They are both the same brand, one is 100w the other 200w, at the panels when I installed them to the roof before wiring to the car I was getting 13.4v from the 200w and 12.6v from the 100w panel which is why I wired them direct to the battery's.

Once wired in parallel the voltage dropped to about 12.6 but I'm pretty sure they were partially shaded by then but now the 100w is disconnected, I think I just need someone who knows their stuff to have a look, the son in law is more an industrial sparky, bit like asking a diesel fitter to change the points on an FJ Holden.

If I disconnect the earth on the inverter I'm still getting the negative 12.whatever is in the batteries when I go from the face plate or body on the inverter to an earth point in the car.....weird thing is if I disconnect the positive I get the same result, if both disconnected obviously no voltage to the body.

Both battery's are earthed to body individually

Subydoug · Post by **Subydoug** » Tue Jan 07, 2014 8:10 pm

Im no longer in Carlisle, moved to Rocko a month or so ago, your welcome to bring it around if you want though.

Can you put up the brand names and part numbers for the panels and inverter? or even links to websites? Would help to know as much about the panels as possible, see if there is any internal circuitry or if it is just a raw output.

This is a pretty good read, relevent to your situation I think.

http://www.thenakedscientists.com/forum ... ic=30954.0

Hooking up the panels in series and a stepdown reg to 13.8v may be your best option.

Regards

Doug

Subydoug · Post by **Subydoug** » Tue Jan 07, 2014 8:21 pm

Ok, with the inverter, a quick test to try. On your multimeter, is there a setting for continuity? will beep when you short out the probes. If there is, with the battery completely disconnected, try touching one end to the case of the inverter and the other to the +12v lead and GND lead (separately of course). If it beeps, post up which wire it beeps on. If no beep then the voltage is getting in some other way internally and without pulling it apart Its hard to speculate. If your multimeter doesnt have a continuity mode, do the test in OHM's mode and note down the values. Symbol for ohms is a small bell outline thingy.

Regards

Doug

d_generate · Post by **d_generate** » Tue Jan 07, 2014 9:04 pm

How about I pay you to look at it, I'm only 10min up the road, fitting stereo's when I was 18 I understood, this stuff is beyond me, like my daughter teaching me how to use an Iphone yesterday..........aghhhhhhhh, I'll try to get the son in law to read it but when he did yesterday he said it was not much good.

Some pics of the set up

Subydoug · Post by **Subydoug** » Tue Jan 07, 2014 10:50 pm

Yeah mate, you can swing around. Weekend suits me best but can do after work. No need to pay me to have a look, Will be nice to check out your rig

. Il give you a ring tomorrow after work.

Arh so there is a controller for the batteries and panels. A quick search online pulls up the specs on that solar 60 controller. Can handle up to 48v input from the solar panels so switching from parallel to series should be a piece o cake.

http://www.chinasolarregulator.com/sola ... r60solar80

Regards

Doug

d_generate · Post by **d_generate** » Wed Jan 08, 2014 12:32 am

Sweet as, I'm supposed to be gone by Sat so during the week would be great, thx a million, I guess it's going to be harder to check the solar but they are monocrystaline so supposedly the better of the two and seem to be ok in shade.

This is the panel I bought, the other is the same but 100w http://www.ebay.com.au/itm/370833154734

Subydoug · Post by **Subydoug** » Wed Jan 08, 2014 7:10 am

Ok. I Dont really know what time Il get home tonight, gotta go up to inglwood till about 5pm. Thursday should be fine though. Il give you a call tonight anyway.

Regards

Doug

d_generate · Post by **d_generate** » Wed Jan 08, 2014 1:32 pm

Thanks again.

Tom.

ktmtragic · Post by **ktmtragic** » Wed Jan 08, 2014 2:38 pm

What comes to mind is that possibly the case is used as a heat sink. I would suggest connecting the inverter directly to the battery. What happens then?

d_generate · Post by **d_generate** » Thu Jan 09, 2014 12:12 am

That's how I had it set up for the first week, panels directly to battery and inverter also direct to battery, when it was set up like this everything was fine as far as the inverter working but the solar panels were not charging enough to run the fridge by the second day from a full charge from driving, the inverter has an internal heat soak and an external one but it was still showing negative whatever was in the battery if it touched the body, now that we have installed the solar regulator I can't even run the inverter for some reason, SubyDoug is going to have a look tomoz after work so hopefully something can be sorted or maybe a reason as to why it's like it is.

tambox · Post by **tambox** » Thu Jan 09, 2014 5:23 pm

Often regulators cannot take the load of an inverter on their load connection, it only designed for a light load, like lights.
The simple way is to connect the inverter straight to the battery.
The panels through the regulator.
Then do your maths, how much does the fridge need, how much can the batteries store, how much can the panels provide (these are usually rated with the panel facing directly at the sun, if the panel is not facing the sun its output is reduced)

d_generate · Post by **d_generate** » Thu Jan 09, 2014 11:54 pm

Thanks Tambox, you are 100% on the money that's pretty much what SubyDoug did today, we put the inverter back on the battery's after he stripped the guts out of the inverter and found one of the screws was put literally fraction of mm's in the wrong position causing a short in the heat soak chassis, a plastic screw fixed it, I can't thank Doug enough for his time and patients........and his boss to a lesser extent for sorting part of my problem.

Here are the solar specs, the most voltage I've seen out of it was 13.4 at the panel in ideal conditions, the same brand 100w one at the sametime was 12.6 from memory. Certainly not enough to charge over 300ah of battery's.

High Performance Solar Panel
Monocrystalline Cells
Low Reflectin of Sunlight
High Light Absorption
Functions perfectly under low light or panel being partly shaded
Top Range Alloys Anodized Frame with Corner Protectors

Max Power: 200W
Max Power Voltage: 18V
Max Power Current: 11.1A
Open-Circuit Voltage: 22.5V
Short-Circuit Current: 11.78A
Cell Efficiency: 17.5%
FF: >75%
Maximum System Voltage: 1000V
Temperature Range: -40～C - 85～C
Power Tolerance:± 5%
Standard Test Conditions: 1000W/m2, AM1.5, 25°C
Solar Cell: Mono
Front Glass: 3.2mm Tempered Glass
Maximum Hail Load: steel ball fall down from 1m high
Frame: Anodized Aluminium Alloy
Dimension: 158 x 80.8 x 3.5cm
Weight: 15.5kg
***Please ensure your regulator is able to handle the voltage of this item***

tambox · Post by **tambox** » Fri Jan 10, 2014 5:17 pm

Thats great hear.
Relax and enjoy the trip.
And hope for sunshine.