I thought I was beyond beginner level.... but apparently not!
Background, I had 1500 watts rooftop solar, feeding my Schneider 60/150 SCC, 48 volt lithium system. This is 250 watt panels, 3sx3p. Being on the roof we found that during the winter problems arose when 2"-3" of snow covered them and even if the sun came out later/next day it could take a full day or more if it was really cold for the snow to slide (45* angle) and we commence charging again. The solution was to add a 3rd string attached to the front deck that could be reached to sweep the snow off. Identical panels.
Here are the stats:
Power250Watts
VOC37.6Volts
VMP30.3Volts
ISC8.85Amps
IMP8.27Amps
Nominal Battery Volts 48Volt lithium (Chevy Volt Modules, 12kw)
PV Array Number Of Modules In Series3 Number Of Parallel Strings3 Total Modules9
Rated PV Array Power2250Watts
Anticipated Array Power @ 93 F2160Watts
Rated PV Array Current24.81Amps
Battery Charging Current @ 57.6V39.1Amps
VMP (Maximum Power Point Voltage90.9Volts
VOC (Open Circuit Voltage)112.8Volts
VMP @ -33 F115.8Volts
VOC @ -33 F135.6Volts
The two strings on the roof are combined up there using MC4 wyee connectors and the +/- then come off the roof to a Midnite Solar combiner box with one 30a breaker. Got the new string wired yesterday and brought their +/- leads to the combiner box where I added another 30a breaker on the bus bar. From there the lines run to another breaker box and through another 30a breaker before feeding the SCC. Output from the SCC returns to that breaker box then through a 60a breaker before the connection to the battery bank positive bus bar.
When I kicked on the breaker yesterday to bring the new string online all seemed to go well. It was about mid day and the panels were supplying about 1600 -1700 watts... maybe a bit of shade, plus panel tilt is fixed and not optimum for this time of year. That said, 1600 - 1700 watts is pretty good. The battery level was at 46.5v when I energised the system and within an hour we floated. I noticed then that the input wattage had dropped to 2 watts... should have alerted me as all loads will run off the panels first when Floating, then pull from the battery bank. Our average load during the day is around 40 watts... fridge, freezer, satellite internet.
That evening I looked at the SCP and noticed the SCC was not showing connected! I went into the room the equipment is in and sure enough the SCC screen was blacked out... nothing, no power. I quickly scanned the manual and saw a note about the ground fault fuse. So I kicked both breakers - 60a/30a, to and from the SCC - and popped out the fuse to check continuity... it was good. I put it back in then flipped the breakers back on and the SCC came back to life. It was dark so no input from the panels, just from the battery bank. Unfortunately I had not noticed when I shut the breakers off if one or both were tripped.... I assume both though as the SCC was off...?
Is my math bad? What am I missing.... I don't see how I overload the SCC, breakers? When I wired the new string into the combiner box... did this increase the voltage... I thought it would increase the amps, but not enough to matter? Any thoughts?
Thanks for the help!
Background, I had 1500 watts rooftop solar, feeding my Schneider 60/150 SCC, 48 volt lithium system. This is 250 watt panels, 3sx3p. Being on the roof we found that during the winter problems arose when 2"-3" of snow covered them and even if the sun came out later/next day it could take a full day or more if it was really cold for the snow to slide (45* angle) and we commence charging again. The solution was to add a 3rd string attached to the front deck that could be reached to sweep the snow off. Identical panels.
Here are the stats:
Power250Watts
VOC37.6Volts
VMP30.3Volts
ISC8.85Amps
IMP8.27Amps
Nominal Battery Volts 48Volt lithium (Chevy Volt Modules, 12kw)
PV Array Number Of Modules In Series3 Number Of Parallel Strings3 Total Modules9
Rated PV Array Power2250Watts
Anticipated Array Power @ 93 F2160Watts
Rated PV Array Current24.81Amps
Battery Charging Current @ 57.6V39.1Amps
VMP (Maximum Power Point Voltage90.9Volts
VOC (Open Circuit Voltage)112.8Volts
VMP @ -33 F115.8Volts
VOC @ -33 F135.6Volts
The two strings on the roof are combined up there using MC4 wyee connectors and the +/- then come off the roof to a Midnite Solar combiner box with one 30a breaker. Got the new string wired yesterday and brought their +/- leads to the combiner box where I added another 30a breaker on the bus bar. From there the lines run to another breaker box and through another 30a breaker before feeding the SCC. Output from the SCC returns to that breaker box then through a 60a breaker before the connection to the battery bank positive bus bar.
When I kicked on the breaker yesterday to bring the new string online all seemed to go well. It was about mid day and the panels were supplying about 1600 -1700 watts... maybe a bit of shade, plus panel tilt is fixed and not optimum for this time of year. That said, 1600 - 1700 watts is pretty good. The battery level was at 46.5v when I energised the system and within an hour we floated. I noticed then that the input wattage had dropped to 2 watts... should have alerted me as all loads will run off the panels first when Floating, then pull from the battery bank. Our average load during the day is around 40 watts... fridge, freezer, satellite internet.
That evening I looked at the SCP and noticed the SCC was not showing connected! I went into the room the equipment is in and sure enough the SCC screen was blacked out... nothing, no power. I quickly scanned the manual and saw a note about the ground fault fuse. So I kicked both breakers - 60a/30a, to and from the SCC - and popped out the fuse to check continuity... it was good. I put it back in then flipped the breakers back on and the SCC came back to life. It was dark so no input from the panels, just from the battery bank. Unfortunately I had not noticed when I shut the breakers off if one or both were tripped.... I assume both though as the SCC was off...?
Is my math bad? What am I missing.... I don't see how I overload the SCC, breakers? When I wired the new string into the combiner box... did this increase the voltage... I thought it would increase the amps, but not enough to matter? Any thoughts?
Thanks for the help!
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