Flexible Solar Panel - Will This Wire Cause Problems

mitch5252 wrote:
OP HERE:

I found this description of the charge controller I purchased (shown above; waiting for delivery). Did I waste my money?

This is a compatible MPPT charge controller PWM intelligent / efficient / energy saving, he not only has efficient MPPT controller charging function to automatically track the maximum power point, 10% -30% higher than the ordinary controller charging efficiency, also has standby energy saving, more than 30% energy than ordinary controller, the standby power consumption of only 10mA-15mA.

Here's the link: http://www.chinasolarregulator.com/solar-controller-cm50-cm60-cm6048-cm5048-cm3048-mppt-10-20-30.html

Note in that link where they show the one with the coil (true MPPT)and one without.(PWM only) Some without the coil nevertheless have MPPT written on them and are advertised as such. Usually the true MPPT ones are more expensive.

You didn't waste your money since the PWM us all you need for 12v panels. (You must have true MPPT to run a 24v panel though since it also has a way to deliver 12v to the battery from the 24v panel.)

If you are curious, you can unscrew the cover and the circuit board on yours and see if it has that coil or not.

i think you got a good deal
you will know for sure, after a few months of steady use
its listed as reverse polarity protection for both solar input and battery connection

and that is good

BTW always connect the battery to the controller first, then connect the solar panel

the controller needs to sense the system voltage, before receiving solar input

OP HERE:

I found this description of the charge controller I purchased (shown above; waiting for delivery). Did I waste my money?

This is a compatible MPPT charge controller PWM intelligent / efficient / energy saving, he not only has efficient MPPT controller charging function to automatically track the maximum power point, 10% -30% higher than the ordinary controller charging efficiency, also has standby energy saving, more than 30% energy than ordinary controller, the standby power consumption of only 10mA-15mA.

Here's the link: http://www.chinasolarregulator.com/solar-controller-cm50-cm60-cm6048-cm5048-cm3048-mppt-10-20-30.html

mitch5252 wrote:
OP HERE.

I am waiting on delivery for this charge controller:



I'll use the panel to keep my Group 27 trailer battery charged. I'm quite frugal with usage; however, I understand that in my new Fun Finder trailer, that the fridge in the slide, because it's in the slide, has a fan for whatever reason (Atwood Helium fridge (been nothing but trouble)). I imagine that could suck a battery fast?

I can't make out which controller that is, but it might not be a "true" MPPT. Some advertised as such are really just PWM. However it does not matter since you have a 12v panel and it only needs PWM.

Here's what I would want if I were to add solar power to our RV - three or four or more of these. For the price you have to pay you get the ultimate non-roof-mounted-solution ... panels you can fold up and store in a drawer when you aren't parked with the RV in the shade and these panels in the hot sun:

http://www.google.com/shopping/product/8198109488693641221?hl=en

P.S. Use them to keep lithium RV batteries topped up and then you'd really have, IMHO, a great boondocking electricity setup ... assuming you also have a generator along for as-needed air conditioning.

greenrvgreen wrote:
Yeah, that looks like the specks. Here's some splaining on what I was talking about:

With my cheap PWM controller, no matter what voltage comes out of the panel, I'm only ever going to get the nominal 12v, at whatever amperage it's sending. So although a hundred watts come out of the panels (19v x5.7a), my PWM controller is going to take the first 60 or so watts (12v x 5.7a) and throw the rest away.

You have linked to a nice-looking MPPT controller. This controler can take a wide range of voltage (19v at 5.7a is easy), and turn it into more amps at lower volts (12v at 8a, say). There is still a lot of inefficiency, but at least it's not throwing as much power away.

With a single panel, you will probably not notice the difference. With multiple panels, MPPT can allow you to link the panels in series so that 38v (19v x 2 panels) comes at the controller and 12 v comes out, at three times the amps. That's the theory, anyway. There have been discussions here on whether it ever really works that well.

The fact is I am an incredibly lazy human being, and if my panels are giving me enough power at 12v with a cheap PWM controller, I'm really not inclined to stress out over where the rest of the power has gone.

Your charge controller is likely to take the first 14.4V or 14.8V @ 5.7 amps, and throw the rest away... about 85 watts at 14.8V.

mena661 wrote:
BTW, Isc is the Short Circuit Current.

Indeed it is, and there will be times with a PWM controller, if you keep logs, that you do see that level of current flowing from panel to batteries. Not often, but it should be kept in mind when doing calculations for how much amperage your solar panel combination can put out, to prevent Charge controller surge failures.

BTW, Isc is the Short Circuit Current.

The rule of thumb for PWM charge controllers and 12V solar panesl is that we are not interested in watts of output from a panel... when you run with a PWM charge controller, you should always be comparing AMPS output from your 12V style solar panel at "Isc" reading. Since watts is Volts x Amps... getting more amperage at 17.0V is more important than getting less amps at 18.5V, since the wattage is the same, giving up a little bit of voltage for more amps results in more amps output, and less volts being thrown away by the charge controller. Amp rate is important in recharging batteries, a bigger number of amps, in marginal systems, is better, provided you can get 14.8V at the battery for flooded lead acid batteries, or 14.4V for AGM batteries.

Yeah, that looks like the specks. Here's some splaining on what I was talking about:

With my cheap PWM controller, no matter what voltage comes out of the panel, I'm only ever going to get the nominal 12v, at whatever amperage it's sending. So although a hundred watts come out of the panels (19v x5.7a), my PWM controller is going to take the first 60 or so watts (12v x 5.7a) and throw the rest away.

You have linked to a nice-looking MPPT controller. This controler can take a wide range of voltage (19v at 5.7a is easy), and turn it into more amps at lower volts (12v at 8a, say). There is still a lot of inefficiency, but at least it's not throwing as much power away.

With a single panel, you will probably not notice the difference. With multiple panels, MPPT can allow you to link the panels in series so that 38v (19v x 2 panels) comes at the controller and 12 v comes out, at three times the amps. That's the theory, anyway. There have been discussions here on whether it ever really works that well.

The fact is I am an incredibly lazy human being, and if my panels are giving me enough power at 12v with a cheap PWM controller, I'm really not inclined to stress out over where the rest of the power has gone.