Barcelona BETA Testing in Montana

[Weldman]

This is about the dirtiest hack I have done in emergency to keep lights on. Be nice to have emergency phone number for when these systems go down in emergency situations. When frostbite can set in, in 5 minutes to exposed skin you aren't taking gloves off to make this pretty.

[Weldman]

Rosie is back online. After pulling covers off I took a torpedo heater and put some heat to it, it fired up in 10 minutes. WARNING, DO NOT SHUT THESE UNITS OFF IN SUB ZERO TEMPERATURES, THEY WILL NOT I REPEAT NOT TURN BACK ON!!!

[boB]

Well, -35 degrees is pretty darn cold !

I don't suppose you have an idea of what temperature it was when it turned back on again ?

What kind of batteries do you have again ?

boB

[Weldman]

Well, -35 degrees is pretty darn cold !

I don't suppose you have an idea of what temperature it was when it turned back on again ?

What kind of batteries do you have again ?

boB

I can say even at -12°F it wasn't coming back online, I believe around 0 to 10°F it came back online based on how long I put the heater on it. I have a FLA forklift battery, I'm just going to take the whole unit and put it in a bunker with the battery in a separate compartment so it doesn't off gas onto the electronics soon as we get above 30°F.

[Weldman]

Want me to test all of Midnite's products down to -50°F and up to 115°F just send them here and I can do just that in a year. If they can survive here, then they can survive anywhere in the US!

[boB]

I guess we spec the Rosie down to -20 F or is that -20 C ?  I will have to look.

But once you get to -35 to -40 they are about the same.   -40 I think is the crossover where they are equal.

When you heat those units up with your radar heater, the temperature you measure on the outside of the unit is probably still going to be a bit warmer than the inside and whatever component is keeping it from turning back on.   Low temperature operation is a good thing.   But we have lately been more concerned with and spending more time on operational characteristics than lower temperatures.

What you have shown here is very good to know as our temperature chamber is being used for another product right now.   We'll get to this sooner than later I hope.
Really all we have to do is to spray some freeze-mist into various areas of the Rosie or whatever unit to see what makes it not turn on at cold temperatures.

Stay tuned !   I'm sure we can use your help.

boB

[Weldman]

I guess we spec the Rosie down to -20 F or is that -20 C ?  I will have to look.

But once you get to -35 to -40 they are about the same.  -40 I think is the crossover where they are equal.

When you heat those units up with your radar heater, the temperature you measure on the outside of the unit is probably still going to be a bit warmer than the inside and whatever component is keeping it from turning back on.  Low temperature operation is a good thing.  But we have lately been more concerned with and spending more time on operational characteristics than lower temperatures. I can do color too.

What you have shown here is very good to know as our temperature chamber is being used for another product right now.  We'll get to this sooner than later I hope.
Really all we have to do is to spray some freeze-mist into various areas of the Rosie or whatever unit to see what makes it not turn on at cold temperatures.

Stay tuned !  I'm sure we can use your help.

boB

It's spec down to -4°F which would be -20°C and the unit will stay on, but if you turn it off even for a second which is what I did, it didn't come back on. All I did was flip the panels off on Barcelona, disconnected two solar panes, turned battery input off, turned battery input off Rosie and flipped the main shutdown that shuts whole system down in one throw. Turned it back on and Rosie wasn't having it. We got down to -40°F after all was said and done with -65°F windchill. When you hit -40° is when it evens out.

What I can do is if y'all really want to in the name of science as this will suck for me to do, but in the name of science I can shut the unit down again and this time crank up the FLIR and record the results. This was yesterdays picture of surface temperature.

[FNG]

Welp I have pushed Barcelona to her breaking point, she should come back when temperatures increase or I take a panel offline I hope. At -35°F it was barely manageable to read the display, but she was resting when sunlight is out. Popped cover off and said 690VDC on initial contact a few times when testing, but idled down to 560VDC after a second. So I guess the unit is in self preservation mode?
Don't see how it got so high when the VOC is 49.7VDC per panel, there is only 11 panels in series and there is 300' of cable for it to send down 10AWG sized wire.

49.7v x 11 is 546.7, With a 50-60 degree C drop from STC you are looking at 1.25 times the voltage or 684 volts

[Weldman]

Welp I have pushed Barcelona to her breaking point, she should come back when temperatures increase or I take a panel offline I hope. At -35°F it was barely manageable to read the display, but she was resting when sunlight is out. Popped cover off and said 690VDC on initial contact a few times when testing, but idled down to 560VDC after a second. So I guess the unit is in self preservation mode?
Don't see how it got so high when the VOC is 49.7VDC per panel, there is only 11 panels in series and there is 300' of cable for it to send down 10AWG sized wire.

49.7v x 11 is 546.7, With a 50-60 degree C drop from STC you are looking at 1.25 times the voltage or 684 volts

Well that should show the hardiness of these units or sophistication to shut down and able to protect itself. So the inrush wasn't lying on 690VDC, wow nice to know.
Looks to be best for where I live at to put all 11 panels back on in series, but have breakers to shut down 2 on each leg when it hits 0°F, and turn back on the 4 panels when harsh of winter is gone. I was looking at other panel brands in the 400W range and they put out even less amps than these on bifacials. That might have a factor in the high voltage too.

[Highflyer]

A lot of learning! 

Also, I am glad I do not see -20C here.  Been there, done that in another life.

[Weldman]

A lot of learning! 

Also, I am glad I do not see -20C here.  Been there, done that in another life.

I remember those days of never seeing these temperatures, born and raised in SE Texas. More freedom here so I will take it and smile.

[Weldman]

Well we all learned how well Barcelona can take voltage, now lets see what happens with amperage/wattage. It's 2°F with -35°F windchill we just had 6 inches of snow dumped on the panels, sun is out and I'm pushing snow off with push broom and got this brilliant idea. Get bigger cable and go 6S 2P per a channel instead of trying to push 11S per a channel as we seen how that went. Going to have to buy two more panels, but I'm not afraid of the loss they will be dragged down to run with older ones.
Keep in mind I am running bifacial panels so that's why I have 500 down for max wattage, so I can't try 7 or 8S and 2P per a channel, unless y'all want me to push it to the limits one more time.

[Weldman]

Alright here is something interesting. After observation of the system without changing anything with my current panels online of 9 in series on each channel (18 panels) I am getting 120+ amps which is more than enough for my 48VDC 1010Ah battery and I am seeing over 4kW watts coming in per channel. What I am getting at is I never seen these numbers this high with 11 panels in series per a channel, so even though I wasn't over voltage till it -35°F or thereabouts, it was clipping with over wattage as in trimming off a lot of wattage.

[boB]

Yes, CoLd weather can increase PV output by quite a bit !

As long as the sun is out.

boB

[Weldman]

Yes, CoLd weather can increase PV output by quite a bit !

As long as the sun is out.

boB

Even in the dead of summer I never seen this much wattage coming in with the 11 panels. We are currently at 40°F on the plus side of 0° right now and we were when I had 11 panels hooked up back in December and still didn't see this much wattage come in till I went to 9 panels.