Low wattage output; Panel problem or MPPT controller problem (Solved)

[2BZ2Ranch]

I am spending a week in northeast Missouri this Memorial Day visiting family.
My truck camper system is 2S2P Rich Solar 80W CIGS (320W total) running through a Victron 100/30 MPPT controller charging a home built 200AH LiFePO4. I currently have the SCC on the default LFP setting. I monitor the system with a Victron SmartShunt.

During the trip from Flagstaff I was getting PANEL OUTPUT of 280 watts or more on sunny days. While in Missouri during overcast skies w/light rain the Victron SCC app was showing 80 to 120 watts with 180-220 watts during occasional breaks in cloud cover. Even during some heavy rains it had 60+ watts at high noon. After 3 days of rain I had a 45AH deficit with a promise of bright sunshiny days for a few days. The first sunny day the SCC app was showing panel output of only 20-30 watts (+/-). When there was a DC load (running the water pump) the panel output jumped to 70 watts and dropped to 20-30 watts with the load removed. I reconfigured my panels (swapping leads) several ways @ 2S among the four panels. The SCC always showed a panel output of 30 watts or less. I reset the SCC, tried different absorption and float voltage, but panel output is never greater than 30 watts.

Is there a problem with the solar charge controller? I wouldn’t think there could be a problem with the panels because I tried isolating the panels.

Dave

 

[Bobert]

I am spending a week in northeast Missouri this Memorial Day visiting family.
My truck camper system is 2S2P Rich Solar 80W CIGS (320W total) running through a Victron 100/30 MPPT controller charging a home built 200AH LiFePO4. I currently have the SCC on the default LFP setting. I monitor the system with a Victron SmartShunt.

During the trip from Flagstaff I was getting PANEL OUTPUT of 280 watts or more on sunny days. While in Missouri during overcast skies w/light rain the Victron SCC app was showing 80 to 120 watts with 180-220 watts during occasional breaks in cloud cover. Even during some heavy rains it had 60+ watts at high noon. After 3 days of rain I had a 45AH deficit with a promise of bright sunshiny days for a few days. The first sunny day the SCC app was showing panel output of only 20-30 watts (+/-). When there was a DC load (running the water pump) the panel output jumped to 70 watts and dropped to 20-30 watts with the load removed. I reconfigured my panels (swapping leads) several ways @ 2S among the four panels. The SCC always showed a panel output of 30 watts or less. I reset the SCC, tried different absorption and float voltage, but panel output is never greater than 30 watts.

Is there a problem with the solar charge controller? I wouldn’t think there could be a problem with the panels because I tried isolating the panels.

Dave

If your batteries are full (or bad) the charge controller will only provide what the system is using. Best to have your batteries less than %75 state of charge before testing the output of your panels and charger. Then you will be sure your battery will be able pull your full output. Or place enough load on your system to exceed your potential charge output by a good margin.

 

[2BZ2Ranch]

Thank you for your reply.
I understand the SCC battery output would depend upon battery charge, however, SCC panel output has (had) always been 250+ watts in full sun when charging regardless of battery SOC unless battery voltage was above the absorption setting then the SCC would change to floating. The camper’s onboard converter brought the battery up w/out a problem of course.

Dave

 

[Bobert]

The fact that the output of your scc went up when using the water pump indicates an issue on the battery side. The most common is a truly full battery. Most likely the batteries were still charging when you got your earlier readings or you would not have gotten those numbers. The charge controller does not harvest the energy captured by the solar panel unless it has a place to put it. ( the batteries or loads on the system)

 

[2BZ2Ranch]

Thank you for your reply.
? That’s what I thought too (considering the load from the pump). This was just the first time in almost a year this “issue” has shown up. I almost always dry camp w/o hookups and we do consume a bit of power especially when we run the furnace. I keep a close eye on the battery.
I was down 45+AH (after a full charge three days earlier) and when the sun came out yesterday all I could get out of the panels was the 30 watts. Don’t be misled by the battery voltage on this screenshot. I had just changed the absorption voltage from 14.5 volts. Panel output was the same yesterday when battery voltage was 13.3 volts. In other words, regardless of SOC (AH consumption), SCC battery voltage shown, or the absorption voltage setting, panel output is always low.

Thanks again for your help.
Dave

 

[dmkjr]

Thank you for your reply.
? That’s what I thought too (considering the load from the pump). This was just the first time in almost a year this “issue” has shown up. I almost always dry camp w/o hookups and we do consume a bit of power especially when we run the furnace. I keep a close eye on the battery.
I was down 45+AH (after a full charge three days earlier) and when the sun came out yesterday all I could get out of the panels was the 30 watts. Don’t be misled by the battery voltage on this screenshot. I had just changed the absorption voltage from 14.5 volts. Panel output was the same yesterday when battery voltage was 13.3 volts. In other words, regardless of SOC (AH consumption), SCC battery voltage shown, or the absorption voltage setting, panel output is always low.

Thanks again for your help.
Dave

View attachment 96300

I have the exact same issue right now, with almost the exact same readings. What did you figure out to be the problem?

 

[2BZ2Ranch]

I have the exact same issue right now, with almost the exact same readings. What did you figure out to be the problem?

My sincere apologies for the late response.
It was as @Bobert suspected as being a problem on the battery side. In my case it was the cheap ($12) 40A inline circuit breaker between the SCC and the battery that had poor continuity/bad contacts. I rapped on the CB with a small hammer and the output jumped to 250+ Watts.
I replaced it with a much more expensive ($40) heavier duty “marine” breaker and have had no problem since.
Dave