BP Sx-3195 panels only putting out 80 watts in full sun???

quick2crawl

Hi,

I'm working on installing my second solar power system on my new rv and decided to use three BP-SX3195 panels wired in parallel to a Xantrex C40 charge controller. I got the panels installed today and they are only putting out about 80 watts per panel in full sun. These are supposed to be 195 watt panels. My last system used Kaneka 60 watt panels and they put out exactly 60 watts each in full sun.

The BP's are brand new and have never been installed. Open circuit voltage is around 27 but when hooked up to the charge controller and measured at the combiner box, they are outputting 12.83 volts at 6 amps. I'm using 12 gauge PV wire and the longest run is 12 feet so it's not voltage drop from the wire. This is strange.

Has anyone experienced a lower than expected output from their panels before?

boB

Re: BP Sx-3195 panels only putting out 80 watts in full sun???

Not a very good copy and paste from the spec sheet PDF, but
looks like that module (at 25 degrees C) is rated for 195 watts at
24 volts and you are loading it down to about half that
voltage. Without MPPT, you won't get near full power
out of them. I'd say it's most likely working OK even in
full sun.

boB


Electrical Characteristics2 SX3195
Maximum power (Pmax)3 195W
Voltage at Pmax (Vmp) 24.4V
Current at Pmax (Imp) 7.96A
Warranted minimum Pmax 177.5W
Short-circuit current (Isc) 8.6A
Open-circuit voltage (Voc) 30.7V

Temperature coefficient of Isc (0.065±0.015)%/ °C
Temperature coefficient of Voc -(111±10)mV/°C
Temperature coefficient of power -(0.5±0.05)%/ °C

NOCT (Air 20°C; Sun 0.8kW/m2 ; wind 1m/s) 47±2°C
Maximum series fuse rating 15A
Maximum system voltage 600V (US NEC rating)

Cariboocoot

Re: BP Sx-3195 panels only putting out 80 watts in full sun???

Welcome to the forum.

It is difficult to measure panel output even in full sun, because the panels will be feeding batteries. If the batteries don't need the current, the panels don't produce it.

These panels are "24 Volt" (Vmp 24.4) and will not work properly with a 12 Volt system and PWM type controller like the C40. The Imp on them is 7.96. If you want to check for proper output you need to measure the Isc (8.6 Amps) in full sun. You'll need a DMM capable of 10+ Amps or a clamp-on DC Ammeter. Check each one and see what you get.

But they still aren't going to work to full power with that C40 controller.

quick2crawl

Re: BP Sx-3195 panels only putting out 80 watts in full sun???

I have a nice klein DC clamp meter and that's where I got the 6 amp measurement.

I don't understand where I messed up on this one. My old system used 10- 67 volt Kaneka panels in parallel and an outback MPPT60 charge controller feeding a 12 volt battery pack. The charge controller had no problem stepping the 67 volts down to the 14 needed to charge the batteries and worked very efficiently. I'd regularly get 585 watts out of my 600 watt array after the loss from the charge controller and meter.

It seems like I need to get rid of that xantrex and get a better charge controller. It sucks that Xantrex doesn't mention this deficiency in any or their literature. I'm stuck with the panels and the 12 volt battery pack so I need a charge controller that will maximize the output of the panels. Any suggestions? I'd get another outback but I don't have that much money right now.

Cariboocoot

Re: BP Sx-3195 panels only putting out 80 watts in full sun???

quick2crawl wrote: »

I don't understand where I messed up on this one. My old system used 10- 67 volt Kaneka panels in parallel and an outback MPPT60 charge controller feeding a 12 volt battery pack. The charge controller had no problem stepping the 67 volts down to the 14 needed to charge the batteries and worked very efficiently. I'd regularly get 585 watts out of my 600 watt array after the loss from the charge controller and meter.

There's the big difference: the MPPT controller can take the higher Voltage and convert it to greater charge current. The C40 can not.

It seems like I need to get rid of that xantrex and get a better charge controller. It sucks that Xantrex doesn't mention this deficiency in any or their literature. I'm stuck with the panels and the 12 volt battery pack so I need a charge controller that will maximize the output of the panels. Any suggestions? I'd get another outback but I don't have that much money right now.

It isn't a deficiency, it's a different type of controller that functions differently. In it's own right it's fine.
You're going to need to handle less than 45 Amps (190 * 3 = 570 @ 77% = 439 effective Watts / 12 Volts = roughly 36 peak charging Amps). Probably the best choice here is the Morningstar MPPT 45: http://www.solar-electric.com/motr45ampmps.html

The Rogue is smaller, but can only handle 30 Amps and your panels will output more than that.

There might be others out there, but you'll have to determine for yourself if they're any good. Lots of poor quality controllers are available these days, including ones that say "MPPT" that aren't.

quick2crawl

Re: BP Sx-3195 panels only putting out 80 watts in full sun???

Thanks for the input! I didn't know that MPPT made such a big difference.

Looks like I'll either be sending the Xantrex back or trying to sell it and getting a Blue Sky 2512i instead.

Cariboocoot

Re: BP Sx-3195 panels only putting out 80 watts in full sun???

The Blue Sky is only 25 Amps maximum output. You'll be losing power.

quick2crawl

Re: BP Sx-3195 panels only putting out 80 watts in full sun???

Lol! I thought I had it figured out but another confusing little thing just happened.

In the spec sheet for the panels, it says that the maximum output is 7.96 Amps. So based on that, I thought I could get away with a 25 Amp controller. But I guess the charge controller ratings are for output amps, not input amps. They really need to be more specific in their specs!

Thanks again for all the help!

Cariboocoot

Re: BP Sx-3195 panels only putting out 80 watts in full sun???

Actually all controllers are rated for output current. The thing is with an MPPT controller the extra available Voltage turns into more current. So whereas a PWM controller puts out the panel current, the MPPT output is closer to the formula I used.

quick2crawl

Re: BP Sx-3195 panels only putting out 80 watts in full sun???

Makes perfect sense. If I ever get up to BC, I'm buying you a beer or something!

Cariboocoot

Re: BP Sx-3195 panels only putting out 80 watts in full sun???

quick2crawl wrote: »

Makes perfect sense. If I ever get up to BC, I'm buying you a beer or something!

If you ever get up to BC you'll probably be turning around and heading home as fast as you can! You'll have to walk 'cause you sure won't be able to afford gas ($5.47 per US gallon). Or beer ($1.30 per can and up). Or anything else (Vancouver: most expensive city in NA). That's why we call it Bring Cash, Canada!

CATraveler

Re: BP Sx-3195 panels only putting out 80 watts in full sun???

quick2crawl wrote: »

Thanks for the input! I didn't know that MPPT made such a big difference.

Looks like I'll either be sending the Xantrex back or trying to sell it and getting a Blue Sky 2512i instead.

Let's investigate: 195W*3 panels/12V = almost 50A. That would be overwhelming for a 25A CC.

I believe someone recommended the MS 60A MPPT CC.

Update: What's happening to my math skills? Like almost 60A, or a little less if you use about 14V for the battery.

CATraveler

Re: BP Sx-3195 panels only putting out 80 watts in full sun???

Cariboocoot wrote: »

If you ever get up to BC you'll probably be turning around and heading home as fast as you can! You'll have to walk 'cause you sure won't be able to afford gas ($5.47 per US gallon). Or beer ($1.30 per can and up). Or anything else (Vancouver: most expensive city in NA). That's why we call it Bring Cash, Canada!

I'll accept the chalenge as we might be in BC this summer. Are you close enough to the border that I can fill in the US and return? I'll pony up for local cool ones as we'll be legal crossing the border. We love BC! Don't know when we might return to Vancouver Island as the ferry cost for a RV are insane.

But with the Lady Rose calling and the Mars Bomber tour who knows?

Cariboocoot

Re: BP Sx-3195 panels only putting out 80 watts in full sun???

CATraveler;

I used to live a few blocks from the border. Now it's a long, long ways away.
You're confusing Van Island with Van City. The ferry rates are obscene now. So is the traffic throughout the GVRD. So glad I don't live there anymore!

Now if it would just stop dropping below freezing where I do live! Look up "100 Mile House".

CATraveler

Re: BP Sx-3195 panels only putting out 80 watts in full sun???

Well my post was as clear as mud. Most of the times we've used the ferry out of Pt Angeles but we have been to VC. Maybe just us but we really really like Vancouver Island!!!

Is 100 mile house like 7 mile house and we pub our way up??? Will look up.

mike95490

Re: BP Sx-3195 panels only putting out 80 watts in full sun???

While I currently have the MS TS MPPT 60, with the optional $90 meter, now that the Midnight Classic is out, that will be my next controller for phase II of my install. The MS MPPT -60 is great, no flaws, and the web interface and programming via serial port is working fine, the extra meter face and temperature sensor add on to the base price

(both are avaib at wind-sun)