jimindenver
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I mentioned one of my odd ball series vs parallel and mixed panel test, a few said they were interested so here is one. The results are just my observations and may only apply to the few using grid tie panels. I don't have multiple 12v panels to run test on. On with the test.
When I first got my original panels I talked to quite a few people including Mark at Rogue saying to run them on his 30a MPPT controller. I had told him they were different wattage as well as type but that didn't concern him at all. With all of my driveway test I realized that they never matched up in any way in any light. The 220w mono will gain a higher Voc in bright light than the 230w poly, but in low light it crashes while the poly still produces. Reading that somehow the controller tweaks the array made me think that the different voltages would have a adverse affect. I have never tried them together but I did know that I would have matching panels to mount.
Move forward to this spring when I got the Morningstar TS-MPPT-60 and did test adding the 230w poly into the three 250w polys as a mixed panel test. The 230w wasn't a match but it was of the same type and reacted to different light like the rest. What I saw was less output than I would have expected from the 970w total or even four 230w meaning that the whole array was being controlled by the low panel. Either should have easily maxed out the controller but the best I saw was 58 amps, close but no cigar. Looking at the grafts I saw that the array was providing over 800w at times but the controller was only using a portion of it and not much more than the three 250w panels could produce themselves.
In parallel vs series testing on the three 250w polys I found the peak of each panel in parallel to be 18.5a for a possible 55.5a, in series they ran at 48a. The conversion from 100+ volts to charging voltage is less efficient than the 35v the panels normally run at. Running at a higher voltage in low light conditions wasn't a advantage either because the amps out dropped. Lower voltage and combining the amps works better.
Back to my original mixed panels.
Since my MegaWatt died I took advantage of needing to hook up something at home and ran the 230w schott poly and the 220w Canadiansolar mono together in series on the TS-MPPT-60 for the first time. I set them out around 10 am in bright sun with a decent tilt/angle. The 220w had a Voc of 23.8v, the 230w 24.5v. When I hooked them in series I got 68v which would follow the concept of the lower panel controlling the voltage.
Now I know in parallel the 220w puts out 12a and the 230w puts out 15a here in Denver. In series they were maxing out at 23.8a which again would follow the concept of the 220w limiting the 230w.
What was interesting is the display on the controller was jumping up and down by a watt and a bit of a amp. It was doing it when the batteries were in absorb and close to what the 230w could do on its own so I unhooked the 220w and ran the 230w alone. As soon as I did that the watts and amps production settled to a solid amount.
I put the 220w back in and ran a log. The Voc, Vmp and watts/amp input from the two panels remained steady. What the controller accepted changed constantly. Array voltage, wattage, current all bounced up and down slightly in steps and then start over again. An example is the array voltage starting at 63.23v and in seconds dropping 63.11, 62.95, 62.66, 62.26v and then back up to 63.23v to start it over.
So as for why or how, I do not know but the mixed voltage and amps of the two panels didn't set well with the controller. I'll go through the logs of the mixed polys and see if it was happening there too. Then I would see wattage from the array of 750-800 but the controller only use 660w of it.
The next test will be running the two mixed panels in parallel to see if the controller can settle on a set of values. I did run the mixed polys in parallel but wasn't looking for bouncing values.
Hope I didn't bore you all.
When I first got my original panels I talked to quite a few people including Mark at Rogue saying to run them on his 30a MPPT controller. I had told him they were different wattage as well as type but that didn't concern him at all. With all of my driveway test I realized that they never matched up in any way in any light. The 220w mono will gain a higher Voc in bright light than the 230w poly, but in low light it crashes while the poly still produces. Reading that somehow the controller tweaks the array made me think that the different voltages would have a adverse affect. I have never tried them together but I did know that I would have matching panels to mount.
Move forward to this spring when I got the Morningstar TS-MPPT-60 and did test adding the 230w poly into the three 250w polys as a mixed panel test. The 230w wasn't a match but it was of the same type and reacted to different light like the rest. What I saw was less output than I would have expected from the 970w total or even four 230w meaning that the whole array was being controlled by the low panel. Either should have easily maxed out the controller but the best I saw was 58 amps, close but no cigar. Looking at the grafts I saw that the array was providing over 800w at times but the controller was only using a portion of it and not much more than the three 250w panels could produce themselves.
In parallel vs series testing on the three 250w polys I found the peak of each panel in parallel to be 18.5a for a possible 55.5a, in series they ran at 48a. The conversion from 100+ volts to charging voltage is less efficient than the 35v the panels normally run at. Running at a higher voltage in low light conditions wasn't a advantage either because the amps out dropped. Lower voltage and combining the amps works better.
Back to my original mixed panels.
Since my MegaWatt died I took advantage of needing to hook up something at home and ran the 230w schott poly and the 220w Canadiansolar mono together in series on the TS-MPPT-60 for the first time. I set them out around 10 am in bright sun with a decent tilt/angle. The 220w had a Voc of 23.8v, the 230w 24.5v. When I hooked them in series I got 68v which would follow the concept of the lower panel controlling the voltage.
Now I know in parallel the 220w puts out 12a and the 230w puts out 15a here in Denver. In series they were maxing out at 23.8a which again would follow the concept of the 220w limiting the 230w.
What was interesting is the display on the controller was jumping up and down by a watt and a bit of a amp. It was doing it when the batteries were in absorb and close to what the 230w could do on its own so I unhooked the 220w and ran the 230w alone. As soon as I did that the watts and amps production settled to a solid amount.
I put the 220w back in and ran a log. The Voc, Vmp and watts/amp input from the two panels remained steady. What the controller accepted changed constantly. Array voltage, wattage, current all bounced up and down slightly in steps and then start over again. An example is the array voltage starting at 63.23v and in seconds dropping 63.11, 62.95, 62.66, 62.26v and then back up to 63.23v to start it over.
So as for why or how, I do not know but the mixed voltage and amps of the two panels didn't set well with the controller. I'll go through the logs of the mixed polys and see if it was happening there too. Then I would see wattage from the array of 750-800 but the controller only use 660w of it.
The next test will be running the two mixed panels in parallel to see if the controller can settle on a set of values. I did run the mixed polys in parallel but wasn't looking for bouncing values.
Hope I didn't bore you all.
