Evaluating a used solar panel & controller?
Hello folks - Thete's a 100 watt panel plus controller, local to me asking price $100. I emailed the seller and asked for details and what make/model of controller. (No reply yet.) I'm pretty s...
Forum Discussion
Hi,
It should have it's factory rating stamped on the back of the panel, and recently panels started to come with factory production dates, more for warranty reasons than any other. I have a pair of 45 watt panels that cost $600 back in 1994, but are only worth about $100 today. I have not checked the amperage output, but most warranties state that they should have 80% of their normal rated output when 20 years old, or they can be replaced as defective.
I don't think that the solar panel should degrade that much over time. The normal 12 volt panel will have a 19 - 22 volt 'open circuit' rating, and you should measure that voltage when it is in full sun and no wires attached.
If you hook up a headlight to it, then you will get the voltage under load. Most car lights are in the 55 watt range, so it might still produce 14 volts with a 4 amp load on it, and make that headlight shine bright! Or two headlights and it should load up the panel to the max wattage, you might get anything from 10 volts to 14 volts (depending on the headlight wattage rating, and how bright the sun is, and how many amps are going into the light bulbs).
Clamp on meters that read DC amperage are very rare, but Sears used to sell one for about $100. IT will clamp around a DC wire and measure it's amperage. Most clamp on meters only measure AC amperage, as it is easy to pick up the influx of power going through a AC line.
You can print out the prices at this website (for panels without a frame cost is around $1 per rated watt new) and give them the print out, and perhaps get this panel (with a frame or it will be practically useless to install on a RV) for around $75.
SunElec.com
If you do not buy this panel, you can look for 12 volt 'nominal' panels at this website, and look for ones with a frame. Normally aluminum frame that you can bolt to brackets mounted to your roof.
I made my brackets out of 2" aluminum angle that have 3 holes 3/16" into the roof and 5/16" hole for a 1/4-20 bolt into the aluminum frame of the panel.
Good luck with your project!
Fred.
It should have it's factory rating stamped on the back of the panel, and recently panels started to come with factory production dates, more for warranty reasons than any other. I have a pair of 45 watt panels that cost $600 back in 1994, but are only worth about $100 today. I have not checked the amperage output, but most warranties state that they should have 80% of their normal rated output when 20 years old, or they can be replaced as defective.
I don't think that the solar panel should degrade that much over time. The normal 12 volt panel will have a 19 - 22 volt 'open circuit' rating, and you should measure that voltage when it is in full sun and no wires attached.
If you hook up a headlight to it, then you will get the voltage under load. Most car lights are in the 55 watt range, so it might still produce 14 volts with a 4 amp load on it, and make that headlight shine bright! Or two headlights and it should load up the panel to the max wattage, you might get anything from 10 volts to 14 volts (depending on the headlight wattage rating, and how bright the sun is, and how many amps are going into the light bulbs).
Clamp on meters that read DC amperage are very rare, but Sears used to sell one for about $100. IT will clamp around a DC wire and measure it's amperage. Most clamp on meters only measure AC amperage, as it is easy to pick up the influx of power going through a AC line.
You can print out the prices at this website (for panels without a frame cost is around $1 per rated watt new) and give them the print out, and perhaps get this panel (with a frame or it will be practically useless to install on a RV) for around $75.
SunElec.com
If you do not buy this panel, you can look for 12 volt 'nominal' panels at this website, and look for ones with a frame. Normally aluminum frame that you can bolt to brackets mounted to your roof.
I made my brackets out of 2" aluminum angle that have 3 holes 3/16" into the roof and 5/16" hole for a 1/4-20 bolt into the aluminum frame of the panel.
Good luck with your project!
Fred.
