Solar Panels - Series or Parallel ?

[colemj]

We installed a new Morningstar MPPT controller three months ago which allowed me to do some experimentation with our 4 Kyocera 120W panels. They are mounted on the bimini 2 on each side. These panels see random partial shading at certain times of day due to the SSB antenna, the mast and the radome. I move the boom out of the way to prevent shading from that.

Wired in parallel they average 125Ahr/day. Wired in series/parallel (2 panels in series, 2 banks in parallel) they average 150Ahr/day.

So Nick is wrong - we are only seeing a 20% improvement and not 25%.

I have not wired all 4 of them in series yet because of the PITA of doing so coupled with the fact I had other fish to fry over the past few months, but I plan on doing that experiment now that we are back out cruising with wide open days.

Mark

[s/v Jedi]

Originally Posted by colemj

So Nick is wrong - we are only seeing a 20% improvement and not 25%.

I have not wired all 4 of them in series yet because of the PITA of doing so coupled with the fact I had other fish to fry over the past few months, but I plan on doing that experiment now that we are back out cruising with wide open days.

Well, we all know where that 5% is hiding then

But you must be wrong because I have lost all perspective of reality with my claims that series connection works more efficient than parallel

p.s. Did you discover the thread I started about your "reckless behavior"?

p.p.s. Don't forget to disengage the integrated autopilot while at anchor. It might start your engines and power you right onto the rocks where the Sirens are singing their song of complacency!

ciao!
Nick.

[prroots]

Originally Posted by colemj

We installed a new Morningstar MPPT controller three months ago which allowed me to do some experimentation with our 4 Kyocera 120W panels. They are mounted on the bimini 2 on each side. These panels see random partial shading at certain times of day due to the SSB antenna, the mast and the radome. I move the boom out of the way to prevent shading from that.

Wired in parallel they average 125Ahr/day. Wired in series/parallel (2 panels in series, 2 banks in parallel) they average 150Ahr/day.

So Nick is wrong - we are only seeing a 20% improvement and not 25%.

I have not wired all 4 of them in series yet because of the PITA of doing so coupled with the fact I had other fish to fry over the past few months, but I plan on doing that experiment now that we are back out cruising with wide open days.

Mark

Your setup is quite similar to mine except that I have only two panels and my total is 420 watts vs your 480 watts. I also get random shading at different times of day from wind generator and radar radome.

Do you have the 45 or 60 Amp version of the controller? Are you using MSView to monitor daily output from the panels? How have you come up with the parallel vs parallel/series results given the variable effects of weather? The only way I can imagine it is that you average the results of several days to, hopefully, filter out the weather variable. That would seem to be a very difficult thing to do given the variability of weather ie, cloud cover. An alternative is to wait for a cloudless day and then switch back and forth between series and parallel. That would give the percent difference, but not the average daily output. This is what I plan to do as soon as that illusive day arrives
Pete

[colemj]

Originally Posted by prroots

Your setup is quite similar to mine except that I have only two panels and my total is 420 watts vs your 480 watts. I also get random shading at different times of day from wind generator and radar radome.

Do you have the 45 or 60 Amp version of the controller? Are you using MSView to monitor daily output from the panels? How have you come up with the parallel vs parallel/series results given the variable effects of weather? The only way I can imagine it is that you average the results of several days to, hopefully, filter out the weather variable. That would seem to be a very difficult thing to do given the variability of weather ie, cloud cover. An alternative is to wait for a cloudless day and then switch back and forth between series and parallel. That would give the percent difference, but not the average daily output. This is what I plan to do as soon as that illusive day arrives
Pete

We have the 60A version. I use MSView to monitor the output. The weather and sun here in San Blas Panama is very consistent this time of year. One day looks just like the next - sunny and windy with scarce high white clouds. I first averaged measurements for a month wired as parallel, then wired them as series/parallel and averaged the measurements for another month. This morning, I wired all 4 panels in series and will now measure the output from that for a couple of weeks.

Note that my panels are 17V ones, so I did not get any benefit from the MPPT when they were wired in parallel. Essentially, the controller simply directly connected them to the battery bank every day without doing any conversion or regulation until late in the day when the batteries would get near full.

Yours are already higher voltage panels, so will see a benefit from the MPPT even in parallel mode.

Mark

[prroots]

Originally Posted by colemj

We have the 60A version. I use MSView to monitor the output. The weather and sun here in San Blas Panama is very consistent this time of year. One day looks just like the next - sunny and windy with scarce high white clouds. I first averaged measurements for a month wired as parallel, then wired them as series/parallel and averaged the measurements for another month. This morning, I wired all 4 panels in series and will now measure the output from that for a couple of weeks.

Note that my panels are 17V ones, so I did not get any benefit from the MPPT when they were wired in parallel. Essentially, the controller simply directly connected them to the battery bank every day without doing any conversion or regulation until late in the day when the batteries would get near full.

Yours are already higher voltage panels, so will see a benefit from the MPPT even in parallel mode.

Mark

Sounds good. We've also spent time in San Blas and the rest of Panama as well. They were great. Yes, my panels give me some Voltage overhead even in parallel mode for low light conditions. Hopefully, we'll get a relatively cloudless day soon.
Pete

[prroots]

I just received a schematic of the bypass diodes on my Photowatt PW2050-210 panels. I posted it here:

Best Solar Panels for the Buck

Can anyone figure it out?
Pete

[prroots]

Originally Posted by ChuckSK

Hi Pete

I checked the other products produced by Photowatt and all other panels had 1 bypass diode for each 18 cells. I suggest that your panel of 54 cells has 3 bypass diodes and that the documentation has a misprint.

If that is the case then 2 Photowatt 210 watt panels in series would be equal to 3 Kyocera 130 watt panels in series. Both configurations would have 6 sub-panels.

Chuck

Good point. I finally received the schematic from Photowatt showing placement of bypass diodes. There are actually 4 bypass diodes. The panel is divided into 3 substrings of 18 cells each. Each of these substrings has its own bypass diode. The 4th bypass diode covers 2 substrings. In this manner if the panel were in series with other panels, one would never encounter more than a two diode drop.
Pete