How are my solar panels doing?

[Vach]

First time extended camping with my new panels and I would like to know what others think of their performance. I have two 140 watt panels and a Morningstar sunsaver duo charge controller. Highest amperage has been 12.25 which I think is pretty good. Most days peak is 7-8 amps. Highest voltage has been 14.2 volts, mostly in the mid 13's though. Controller is Programed for 14.8 volts max charge. Most mornings the batteries "rested" voltage is 14.3 to 14.4. 8 gauge wire from panels to charger and short run to bats. I read extensively and believe the install is good.

Should I be getting more than 8 amps with full sun under these conditions? Plugged in back home I did see 15.0 volts at one time. Bats are watered, no shade, connections tight. Thanks for the input.

[scrubjaysnest]

Bend wrote:
See the Install & Operations manual:

http://www.morningstarcorp.com/wp-content/uploads/2014/02/MS-ZMAN-SSD01-D1.pdf

Check pages 9 & 26 for flooded settings.

Seems bulk goes to 14.4v then absorb at that voltage for 1 hour before changing to float at 13.7v.

The "boost" is every 28 days at 14.8v for 2 hours.

Might want to turn the controller off for a few minutes after float to see if you can cycle the absorb time again.

Bulk and boost are the same thing, the every 28 day cycle is equalize.
Bulk or boost charge is where you get the first ~80%, absorb is the next 20%. Float for most wet lead acid batteries is~13.2 to 13.4 volts.
Each battery maker has slightly different values so one should check with the battery manufacture for proper settings.

[ewarnerusa]

I also have 2 x 140 watt 12V panels (Cynergy, max current rating = 8A each), Morningstar Tristar 45 PWM, and 2 x 6V GC batteries. Panels are mounted fixed and flat on the roof, although neither is actually parallel with the ground due to the slope of the slightly rounded roof. During summer, I regularly see over 15A max current. I use MSVIEW software on my laptop linked to the charge controller via RS-232 cable to monitor panel performance.

During the winter here in Montana, when the panels aren't buried under snow, I'm lucky to get upwards of 7A max charging current due to the reasons that many have mentioned (low sun angle). I have been watching it closely lately though because I've been worried that maybe only one panel is working since I wouldn't ever see more than 8A. As we get further into spring, max amp ratings have moved upwards as well and now I regularly see it over 10A. So I think your observations sound normal for winter harvest with flat mounted panels.

[Bend]

See the Install & Operations manual:

http://www.morningstarcorp.com/wp-content/uploads/2014/02/MS-ZMAN-SSD01-D1.pdf

Check pages 9 & 26 for flooded settings.

Seems bulk goes to 14.4v then absorb at that voltage for 1 hour before changing to float at 13.7v.

The "boost" is every 28 days at 14.8v for 2 hours.

Might want to turn the controller off for a few minutes after float to see if you can cycle the absorb time again.

[EsoxLucius]

Those that give up their freedoms in the name of security deserve neither Thomas Jefferson

http://techcrunch.com/2014/02/14/how-the-world-butchered-benjamin-franklins-quote-on-liberty-vs-secu...

Come over to the Study Butte RV Park and we can cogitate this.

[scrubjaysnest]

You didn't say what battery(s) you have but the sunsaver should put out around 14.4 Vdc during boost or Bulk mode once the sun is up good, say 10 am. With the panels angled about 30 degrees and faced slightly east of south expect about 20% less current in winter time full sun. Once the sunsave switches to absorb you should see 14.8Vdc, current should taper down to about 1% of c/20. For a 100aH battery that's about 1 amp at which time the sunsaver should switch to float or about 13.4Vdc. This depends the battery(s) getting enough charge during the boost and absorb cycles. With two 80 watt panels feeding a pair of Exide stowaways through a Morning star TS-45 PWM CC in Dec in AZ I was measuring between 9.5 to 10 amps during boost. During Jan and Feb it ran between 8 and 9 amps.
If the panels are flat on the roof expect less.

[Vach]

Finally had a chance to do a better test of the system and peaked at 13.45 amps which I think is pretty good. Thanks for helping me understand this system better. My thoughts now are looking toward adding one more 120 watt panel and a battery upgrade. Thanks again for all your input and help.

[pianotuna]

Hi,

If you want to know max output find out when solar noon is. If it is a bright sunny day with perfect solar conditions, 5 minutes before that power a 1000 watt load from the inverter. Now measure the amperage coming into the controller.

[MrWizard]

your are right to a point
that point being that is all that is needed, WHILE solar conditions could deliver more, IF needed

which is very possibly the case in point here

which is why i suggested the TV-DVD load test.
a better test would be a 20" box fan plugged into the inverter

[camperkilgore]

Been following the topic, but I'm pretty ignorant in all things solar. The thing I am confused about is that the current flow in amps usually is related to whatever the load requires(the load will draw whatever amps it needs to function).

So when 8 amps is being delivered by the panels, isn't that the amount that the load is requiring, and so the panels only put out that much?

Like I said, there's a lot about solar that I don't understand, and maybe there's a part of the system that does not act like a normal electrical circuit.

[MrWizard]

What has not been mentioned
Batteries are at the lowest in the morning, so is the sun
By the time the sun is in position to give max power, the batteries have been accepting a charge for at least 4 hours, and are no longer needing what they might have accepted IF full rate had been available hours earlier
As they charge internal resistance goes up, and it takes a higher voltage just to maintain that 8 amps, into the batteries
On a day with moving clouds, connect inverter turn tv and DVD, watch a movie, then go check the meter, you will see much higher Peak outputs recorded, and higher avg output reading

[Vach]

15 degrees cooler today and peak amps reached almost 11, nearly 20% higher than warmer days. I know temperature makes a difference but didn't think it was this much. Anyone know what the recommended distance between panels and the RV roof clearance should be?

[2oldman]

Vach wrote:
Just thought 8 amps typical max was on the low side.

It is low, probably because your panels are not catching rays at 90°. In summer with the sun overhead, or tilted panels now, you should see upwards of 15.

[Vach]

The charge controller is showing 50 amps hours harvested on a sunny day. Just thought 8 amps typical max was on the low side.

[westend]

I'd say your panel output is in the ballpark of acceptable. There are a lot of variables that effect output: sun angle to panel. time of year, atmospheric clarity, etc. Doesn't the Sunsaver Duo monitor have an AH counter? That is the best indication of daily harvest.