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| Testing solar panel output http://solar-guppy.com/forum/viewtopic.php?f=3&t=599 |
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| Author: | Michael_C [ Fri Dec 14, 2007 12:30 pm GMT EthGMT ] |
| Post subject: | Testing solar panel output |
I received the Wattsun trackers on Monday, and will be finishing the mounting of the last few panels this morning. I bought the Evergreen ES-180-SL seconds from Sun Electronics, and saw some odd looking sections on some of the panels while mounting to the tracker. It may be cosmetic, but I wanted to test the panel output under load before connecting them in series. What's a good load for a 180 watt panel - I was thinking of using either light bulbs, or heaters - any suggestions/cautions. I could wait until I wired everything together and checked the combined production, to determine if there is even a a problem, but the logistics doesn't make that attractive. I'm electing to go with a rebate program based on production, so once I connect to the grid, the 5 year rebate period starts - I want the system "tuned" and ready to go once I connect to the grid to maximize the rebates. Any thoughts would be appreciated. A side note - I was impressed with how smoothly the installation went with the Wattsun trackers - The AZ 225's are well thought out, and a beefy design Michael |
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| Author: | BB [ Fri Dec 14, 2007 12:42 pm GMT EthGMT ] |
| Post subject: | |
The simplest is to use a DVM set to 10 amp scale (assuming the panels have less than 10 amps Isc) and measure the short circuit current and also measure the open circuit voltage... Between the two--you will be 99% sure the panel is good. Remember the current is pretty much proportional to the amount of sun (less sun on panel, less current). The open circuit voltage, once you have "enough sun" is pretty much proportional to the temperature of the panel (above 77F, the voltage will drop a little bit, below 77F the voltage will increase a bit). -Bill |
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| Author: | Solar Guppy [ Fri Dec 14, 2007 1:05 pm GMT EthGMT ] |
| Post subject: | |
I have 30 of the same panels... its purely cosmetic, my panels are working quite well |
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| Author: | Michael_C [ Fri Dec 14, 2007 1:09 pm GMT EthGMT ] |
| Post subject: | |
BB wrote: The simplest is to use a DVM set to 10 amp scale (assuming the panels have less than 10 amps Isc) and measure the short circuit current and also measure the open circuit voltage... Between the two--you will be 99% sure the panel is good.
Remember the current is pretty much proportional to the amount of sun (less sun on panel, less current). The open circuit voltage, once you have "enough sun" is pretty much proportional to the temperature of the panel (above 77F, the voltage will drop a little bit, below 77F the voltage will increase a bit). -Bill Bill, I had planned on checking all of the panels, and looking for relative differences between the panels. If all were close, then I wouldn't worry about the "oddities" I had seen. The short circuit currents are spec'd at 7.78 amp, so it's under the 10 amps you mentioned. I don't have a feel for how the more common panel manufacturing problems "show" themselves, and if the Voc and Isc would catch them. I'm guessing by your answer, that most of the common problems would be caught. Thanks for the suggestion - Definitely an easier solution than the thoughts I had. Michael |
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| Author: | Michael_C [ Fri Dec 14, 2007 1:12 pm GMT EthGMT ] |
| Post subject: | |
Solar Guppy wrote: I have 30 of the same panels... its purely cosmetic, my panels are working quite well
Some of the traces look like they don't go through. Michael |
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| Author: | Solar Guppy [ Fri Dec 14, 2007 9:19 pm GMT EthGMT ] |
| Post subject: | |
I have the exact same thing on about 10 of the panels, its makes no difference The panels are verifiy +2%/-4% and are tested exactly as you receive them |
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| Author: | Michael_C [ Fri Dec 14, 2007 10:43 pm GMT EthGMT ] |
| Post subject: | |
Solar Guppy wrote: I have the exact same thing on about 10 of the panels, its makes no difference
The panels are verifiy +2%/-4% and are tested exactly as you receive them I'm open to the idea that it is cosmetic - just want to verify for myself before I start the "rebate clock" Thanks for the reassurance. Michael |
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