Solar panels + cold = A potential problem
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Solar panels + cold = A potential problem
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Re: Solar panels + cold = A potential problem
#2Why would lower temperatures lower the maximum voltage?
Sure, diode forward voltages change a little but seems like something else is going on…
Re: Solar panels + cold = A potential problem
#3Why does the Delta Pro not have a fuse on the input, with the MPPT limiting the max voltage to 150v (by upping the current until the voltage sags and/or the fuse blows, or even a straight crowbar circuit). This is a premium consumer brand selling a mostly complete product, and protecting the input from overvoltage would be straightforward. The frustration at the warranty weaseling isn't surprising.
Re: Solar panels + cold = A potential problem
#4I am sure many are familiar but I found it amusing when someone explained to me why it is called magic smoke.
It is because electronics work through magic so when you let the magic smoke out, they stop working.
Re: Solar panels + cold = A potential problem
#5Why would lower temperatures lower the maximum voltage? Sure, diode forward voltages change a little but seems like something else is going on…
It’s not that it lowers the maximum voltage that the charge controller/inverter can handle. It’s actually that the panels become MORE efficient in the cold temperatures, resulting in a (potentially unconsidered by end-user) increase in voltage, overwhelming the downstream BoS components.
Re: Solar panels + cold = A potential problem
#6Why would lower temperatures lower the maximum voltage? Sure, diode forward voltages change a little but seems like something else is going on…
Solar panel voltage goes up as temperature decreases. The chart is misleading, it's stating something like an equivalent max voltage if you think of the solar cell voltage as staying the same (and presuming your temperature coefficient matches)
Re: Solar panels + cold = A potential problem
#7I was going to comment on the manufacturer's safety margins, but then I found a graph [1] on the variability of voltage vs temperature and it seems to be a lot steeper than I thought/expected, to the point that I'm wondering how these do not require either training or a voltage regulator to install and operate properly:
https://www.researchgate.net/figure/Module-voltage-current-v...
Re: Solar panels + cold = A potential problem
#8I was going to comment on the manufacturer's safety margins, but then I found a graph [1] on the variability of voltage vs temperature and it seems to be a lot steeper than I thought/expected, to the point that I'm wondering how these do not require either training or a voltage regulator to install and operate properly: https://www.researchgate.net/figure/Module-voltage-current-v...
They do!
Basically anything that consumes solar power incorporates what's called a "MPPT", or maximum power point tracker.
Basically, it's a smart DC-DC converter that continually tracks the voltage/current output of a solar panel and adjusts the load to extract the maximum available power from the panel.
It's not uncommon to have issues with extremely high panel voltages in snowy climates, when they're first illuminated in the morning. If you are close to the maximum voltage your MPPT charger can handle in normal circumstances, extreme cold can even damage things during the initial morning transient. You then have to do oddball things like use a crowbar system to prevent blowing up your MPPT system.
(see https://en.wikipedia.org/wiki/Maximum_power_point_tracking )
Re: Solar panels + cold = A potential problem
#9I am sure many are familiar but I found it amusing when someone explained to me why it is called magic smoke. It is because electronics work through magic so when you let the magic smoke out, they stop working.
It's the soul leaving the IC.
Re: Solar panels + cold = A potential problem
#10Why does the Delta Pro not have a fuse on the input, with the MPPT limiting the max voltage to 150v (by upping the current until the voltage sags and/or the fuse blows, or even a straight crowbar circuit). This is a premium consumer brand selling a mostly complete product, and protecting the input from overvoltage would be straightforward. The frustration at the warranty weaseling isn't surprising.
You might think that the voltage rise could be too fast for most protective technologies to save the downstream electronics, but the general case is that the temperature slowly drops and the sun slowly rises. So the voltage should slowly approach the limit.
Adding a normally-open relay and a voltmeter and a microcontroller should fix this. Relay won't close on startup unless the voltage is safe. Microcontroller will open the relay if the voltage gradually nears the limit. Should be solvable for Dark start (when the batteries are flat w/o grid power) will be challenging. There will need to be a small battery to power the voltmeter and relay, or a high-voltage tolerant supply to power the microcontroller and relay temporarily. A 9V should likely be sufficient.