The best photovoltaic solar panels
Thought I would share some information on what are rated as the best/most efficient panels available. Sanyo HIT Power N Series. The cells are hybrids of monocrystalline silicone, surrounded by ultr...
Forum Discussion
You must of made an exhaustive search to see if any panel's temp coefficient nears -1.1%. None were found, what a surprise! I now see you agree that -0.5% is the norm.
You can find any "fact" you want on the internet. Hell, I'm sure you'll find someone claiming the moon is made of Swiss cheese. As mentioned before critical thinking is required. For you to keep arguing the -1.1% claim is not a good sign. Technology is no pissing match.
As to your question, what temp increase will reduce power by 1.1%.
The temperature coefficient of silicon is -2.2 mV/C. A 12V panel that contains 36 cells, has a voltage temperature coefficient of:
V_tc = 36 * -2.2 mV/C = -79.2 mV/C.
If Vmp = 17.7V, then -1.1% of 17.7V is -195 mV. The temperature increase that reduces power by 1.1% is:
Temp rise = -195 mV/-79.2 mV/C = 2.4 C.
We can check our answer by using the typical -0.5%/C power temperature coefficient:
Temp rise = 1.1% / 0.5%/C = 2.2 C
I would say we got this nailed!
Sal
You can find any "fact" you want on the internet. Hell, I'm sure you'll find someone claiming the moon is made of Swiss cheese. As mentioned before critical thinking is required. For you to keep arguing the -1.1% claim is not a good sign. Technology is no pissing match.
As to your question, what temp increase will reduce power by 1.1%.
The temperature coefficient of silicon is -2.2 mV/C. A 12V panel that contains 36 cells, has a voltage temperature coefficient of:
V_tc = 36 * -2.2 mV/C = -79.2 mV/C.
If Vmp = 17.7V, then -1.1% of 17.7V is -195 mV. The temperature increase that reduces power by 1.1% is:
Temp rise = -195 mV/-79.2 mV/C = 2.4 C.
We can check our answer by using the typical -0.5%/C power temperature coefficient:
Temp rise = 1.1% / 0.5%/C = 2.2 C
I would say we got this nailed!
Sal
harold1946 wrote:Salvo wrote:
Virtually all solar panels specify either voltage or power temperature coefficient (or both). If you can't show me a panel with -1.1%/C then that claim is pure nonsense.
I can't believe you're that gullible. Some critical thinking is in order.
Sal
The 1.1%/C was not intended to represent any panel PTC or voltage.
How many degrees of temperature increase over 25C-77F would it take to reduce PTC to 1.1 %?
The rule of thumb is that the efficiency of a cell decreases 0.5% for every 1 degree C (1.8 degrees F) above 25C (77F). This means the efficiency of a cell could easily drop by 25%.
