MrM1
I'm Here, But I'm Not All There
I designed my system 4 years ago and it has been up and running well since. I recently upgraded to a 24v 8s 230Ah LFP x 2 in parallel ~ 8s2p battery bank and I am finding I only have enough power coming in from the array for a full charge IF the conditions are optimal. Getting another Charge Controller is over my pay grade at the moment. But Over-Paneling is an option. I have not ordered anything yet, so wanting to run this by the group before I do
When I designed the system 4 years ago I used the Midnite Solar Classic Sizing Tool and built to the max number of panels (285w 3s3p) that the tool said I could use for a 24v system. I did not know about over-paneling at that time.
My array is built for 2565w but I generally see about a 15% derating on the best of days. I am in NE Florida.
Current setup
- Midnite Classic 150 set to 24v system
- 460Ah LFP ~ Eve 230Ah cells 8s2p 25.6v nominal
- Array = 2565w 3s3p: REC Twinpeak 2 285w 3s3p ~ VOC 38.6v (115.8 per string)
- Input Current ISC: 28.98 amps
Over-Panel Upgrade ??
- Array will = 4305w 3s5p: adding 6 New panels REC Twinpeak 2 290 ~ VOC 38.8v
- So I would have 3 old strings at 115.8v VOC and 2 new strings at 116.4v VOC
- The 2 new strings would have 0.6v more voltage per string
- New Input Current ISC would be: 48.4 amps from the 5p stings (3 at 28.98 and 2 new at 19.42)
I have reached out to Midnite and they say it is not problem as long as I stay within VOC (which I would be at with the new 3s5p array at 115.8v +/- VOC for the 5 strings). Midnite tells me the Classic 150 will simply not use the extra power beyond it's design and that it will not dispurse the extra as heat ... it simply will not use the over-panel wattage if it exceeds what the Classic 150 can use.
My Goal is simply to produce the max amount of current the Classic can out put during peak times, But more specifically to harvest more power on cloudy days, and in the morning / afternoon. I currently seen about a 11kwh - 12kwh Max daily production from the array over the past 4 years. Those 11 and 12kwh days are few and far between. My average is somewhere around 5-8kwh per day. Worse on really bad days. If I could get those numbers up say, 2-3kwhs per day I would be happy...er.
I realize on peak days/times this will cause the Classic 150 to be running and outputting at or near full capacity for maybe a few hours a day ~ 94 amps. I would keep an eye on my FETs and PCB temps, but again, Midnite says this would not be a problem
So, before I do anything, just checking one more time ... Is Over-Paneling a Midnite Classic 150 24v to an array of this size going to be a problem for the Classic 150 ??
Is that 0.6v VOC difference between strings 1-3 and the new strings 4-5 going to be a problem? Anything else I should know?
Thanks
Mike ~
When I designed the system 4 years ago I used the Midnite Solar Classic Sizing Tool and built to the max number of panels (285w 3s3p) that the tool said I could use for a 24v system. I did not know about over-paneling at that time.
My array is built for 2565w but I generally see about a 15% derating on the best of days. I am in NE Florida.
Current setup
- Midnite Classic 150 set to 24v system
- 460Ah LFP ~ Eve 230Ah cells 8s2p 25.6v nominal
- Array = 2565w 3s3p: REC Twinpeak 2 285w 3s3p ~ VOC 38.6v (115.8 per string)
- Input Current ISC: 28.98 amps
Over-Panel Upgrade ??
- Array will = 4305w 3s5p: adding 6 New panels REC Twinpeak 2 290 ~ VOC 38.8v
- So I would have 3 old strings at 115.8v VOC and 2 new strings at 116.4v VOC
- The 2 new strings would have 0.6v more voltage per string
- New Input Current ISC would be: 48.4 amps from the 5p stings (3 at 28.98 and 2 new at 19.42)
I have reached out to Midnite and they say it is not problem as long as I stay within VOC (which I would be at with the new 3s5p array at 115.8v +/- VOC for the 5 strings). Midnite tells me the Classic 150 will simply not use the extra power beyond it's design and that it will not dispurse the extra as heat ... it simply will not use the over-panel wattage if it exceeds what the Classic 150 can use.
My Goal is simply to produce the max amount of current the Classic can out put during peak times, But more specifically to harvest more power on cloudy days, and in the morning / afternoon. I currently seen about a 11kwh - 12kwh Max daily production from the array over the past 4 years. Those 11 and 12kwh days are few and far between. My average is somewhere around 5-8kwh per day. Worse on really bad days. If I could get those numbers up say, 2-3kwhs per day I would be happy...er.
I realize on peak days/times this will cause the Classic 150 to be running and outputting at or near full capacity for maybe a few hours a day ~ 94 amps. I would keep an eye on my FETs and PCB temps, but again, Midnite says this would not be a problem
So, before I do anything, just checking one more time ... Is Over-Paneling a Midnite Classic 150 24v to an array of this size going to be a problem for the Classic 150 ??
Is that 0.6v VOC difference between strings 1-3 and the new strings 4-5 going to be a problem? Anything else I should know?
Thanks
Mike ~