SolarKing querie

Thank you Racey and RMD. The reason I ask is because while camping last week I met a guy who was asking me about the panel and he commented that it was wired in series which he said was unusual. From my memory of high school electrics, I agree with him. This is how it came out of the box.
Should I leave it or rewire it to parallel?

Thank you Racey and RMD. The reason I ask is because while camping last week I met a guy who was asking me about the panel and he commented that it was wired in series which he said was unusual. From my memory of high school electrics, I agree with him. This is how it came out of the box.
Should I leave it or rewire it to parallel?

AH, the dangers of the casual passer by.
How did he tell it was wired in series. Did he open the junction box while you weren't looking?
If he didn't open the junction box then he must be superman with Xray vision. Did he have his red undies over his trackie Daks.

If the wires going into the regulator have around 36+ volts on them when measured without any load, then it is in series.

If the voltage at that input to the regulator is around 18 and a bit volts, then it is wired in parallel. The internal connections of the junction box would also confirm the 18V level.
18V in parallel will give twice the amp flow into batteries and charge them quickerie, normal usage.

If wired in series, unusual but can be done, the regulator firstly has to be able to withstand 36 + V just to survive and is probably rated at 50V max on the input.
In series the panels will give lower output in amps but will still give some output at lower levels of light input.

If the spec sheet max voltage of the regulator is 25 v or 30V then it is in parallel and superman isn't so super. If it is rated much higher than 36V then SM maybe correct.

If you change it from parallel as it probably is and the reg is less rated, then goodbye regulator.

You have to do some checks to make sure.

Thanks RMD.
It all came about by him casually inquiring about my satisfaction or lack of, with the panels. He determined the wiring was series when he was looking at the wires coming out of the back of the panels. The regulator is at the other end of the lead, in the car beside the battery. The multimeter said there were 22.6v coming from the panels. Not to worry - I'll take it to a solar shop next week and get it checked out.
Thanks again.

"18V in parallel will give twice the amp flow into batteries and charge them quickerie, normal usage.

If wired in series, unusual but can be done, the regulator firstly has to be able to withstand 36 + V just to survive and is probably rated at 50V max on the input.
In series the panels will give lower output in amps but will still give some output at lower levels of light input."

I think this needs a bit of clarification.

It is true, the current coming out of a pair of similar panels in series and into a regulator will be about half the current coming out of a pair in parallel. The total power (wattage) remains the same. Eg A parallel pair at 18 volts producing 10 amps equals 180 watts. The same pair in series would be at 36 volts and would produce 5 amps, equals 180 watts.

Assuming the regulator can accept either voltage, and ignoring conversion discrepancies and cabling losses, the current delivered by the regulator TO THE BATTERY will be the same.

A parallel pair at 18 volts producing 10 amps equals 180 watts. The same pair in series would be at 36 volts and would produce 5 amps, equals 180 watts.

Assuming the regulator can accept either voltage, and ignoring conversion discrepancies and cabling losses, the current delivered by the regulator TO THE BATTERY will be the same.

Every reg I have used outputs nearly the same amps as is inputted, so could you explain how it could be different......this is assuming a PWM reg is used.

Solar King 120w. folding panels are connected in parallel and if the controller is marked MPPT it is actually a PWM
The problem with this unit is they use a panel with 44 cells (4x11) instead of the more usual 36 (4x9).
A cell has a voltage output of ~0.5+v. giving a panel output ~22+v. compared to ~18+v.for 36 cells. This voltage is much higher than required to charge a 12v. battery plus each cell amps output is reduced, being proportional to its size dimensions.
As delivered, the SK panel I bought with its inbuilt PWM controller gave a charge output of 4.8a. in full sun.
Changing to series connection and using an MPPT controller the charge output in full sun became 6.0a. (20% increase)
This is because an MPPT controller converts excess voltage into usable charging amps whilst a PWM controller has to dissipate higher voltage to protect the battery.
I gave this panel away and replaced with a 200w. panel, series connected with a MPPT controller closer to the battery bank. This provides a 12+a. charge rate at 14.1v. in full sun.
Another benefit of MPPT controlling is a 3 stage regime of bulk, absorbtion and float.
mike

"Every reg I have used outputs nearly the same amps as is inputted, so could you explain how it could be different......this is assuming a PWM reg is used."

Ah, there's the rub. Every reg I've used is MPPT.

Frank P
I love the example you showed with 18v and 10 amps = 180watts. Theoretically it sounds correct.
The poor bugger only has panels which state 120W output which is optimistic anyway.
I think he would be thrilled his 120watt panel setup is outputting 180 Watts. Whoopee.

The term Open Circuit voltage does have some meaning I believe. ie NO load at all.

OHMS law out the window now.

RMD,

In follow-up 4 above I was not intending to have a go at you. I just thought that there was something that could use clarification. If I caused offence, I apologise.

The numbers I used in my example were for easy maths. They were not meant to represent his panels. I would have though that was pretty obvious.

Perhaps confusion would have been avoided if I had said 18v and 6.66 recurring amps = 120 watts :-)

I'm not sure where open circuit voltage comes into our exchange. However the OP did mention in follow up 3 (889956) a panel voltage of 22.6. I assumed from the context of what he said and the figure he quoted that it would be open circuit as it's a typical Voc for nominal 12v panels. It follows, well to me anyway, that the 18v in the discussion would be the panel voltage under load, which is, again, fairly typical in an MPPT setup. That is why I used it in my example.

I'm aware that solar panels rarely if ever deliver their advertised wattage, but I don't think that was the point of the discussion, unless I've missed something.

Cheers

Thanks to all of you.
mike39. I'm now a little confused. I've taken the set up to a solar shop and it is definitely wired in series - that's out of the box. Also, why would the reg have MPPT printed on it if it was the other type - or is that the Chinese conning the customers?
Thanks, Deejay.

deejay.. was I correct in each panel having 44 cells? If not, what I have said maybe irrelevant.
I complained about the kit I purchased, the "MPPT" controller was replaced with an identical controller simply marked "Solar King".
There was no difference in the performance of the panel after changing controllers.
If you check the open circuit voltage at the input to the controller it will show whether the 2 panels are connected series or parallel. Also with open circuit amps.
If it is of any help, I still have access to this panel and could send email pics to show the setup
Regards..mike... bushyx2atbigponddotcom