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Topic: Solar panel working or not? (Read 1070 times) previous topic - next topic

Solar panel working or not?

There ia a solar panel on the roof of our GV and the wires (I think they are the solar panel wires) come into the battery compartment under the steps. One wire (the white one) goes to the negative post on the coach battery. The other wire (red) goes to where the positive battery cables are connected by a solenoid or switch block--not really sure about function.

How do I ascertain if things are kosher from the solar panel?? If I am getting anything from the solar panel? Should there be any type of meter/regulator/control/gauge on this? Seems quite simplistic in design.  Sun is out=panel producing. Sun is not out= panel not producing. Could panel overcharge that great big old boat anchor of a battery? What happens when hooked up to shore power or generator?
Nitehawk,  Demolition Lady, & our NEW master, Zippy the speeding BB cat.
1989 Grand Villa 36' ORED
Oshkosh chassis, 8.2 DD V8
2006 Saturn Vue AWD

Re: Solar panel working or not?

Reply #1 –
On my '94 U300 the solar panel feeds into the 12 volt electrical system at the rear of the refrigerator. There is a block connector that  supplies house battery 12 volts to the refrigerator system and the solar panel is piggy backed on to that block. I can remove the solar panel feed wires and check for voltage coming from the roof panel (usually 14 to 18 volts) . All access is from the outside refrigerator access door....
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Gerry & Brenda
CHARLOTTE HARBOR, FL
1994 Grand Villa - # 4466
U300 Unihome - 6V92 Detroit
4 speed Allison - Jake Brake

Re: Solar panel working or not?

Reply #2 –
Norm, there are others far more knowledgeable that will probably respond but it is my understanding that you should have a solar charge controller somewhere in line between the solar panel and the battery if the solar panel is over 15 watts. It may be anywhere but the refrigerator bay is a good place to start looking.

You might want to post the dimensions of the panel and any markings on it.
The selected media item is not currently available.Kent Speers
Locust Grove, OK
1993 U300 SSE 40' (Restored at FOT 2009) Build 4323
720 watts Solar
6V92TA DDEC Silver Engine
2014 Subaru Outback

Re: Solar panel working or not?

Reply #3 –
This is strictly a layman's answer. We have 3 solar panels on our roof. We have a small yellow charge controller (smaller and thinner than a pack of cigarettes) in line and above the 3 house batteries. We were told by MOT that the solar panels are designed to help keep the batteries topped of. If that is accurate, it seems as though there is no danger of over charging.

Whenever I am on the roof I wipe the dust and road grime off the solar panels so that they get more light.
George Stoltz.  Retired from full-time living in a great Foretravel and now are back to living in a traditional sticks and bricks in Florida.

Re: Solar panel working or not?

Reply #4 –
Disconnect both white and red wires and at night, check voltage between wires, it will be zero if from solar panels.
This test is to be sure these wires are from solar panels and not from your batteries.
 
When the sun is shining, disconnect both wires and check voltage between them. If "self regulating" solar panels, voltage will be circa 18 volts, if regular panels, voltage will be circa 21. This is called the "voltage open circuit" or VOC. You will now also have confirmed that  red is positive and white is negative.

Check for voltage between the red wire and a good ground which should be zero (same with white wire). Neither wire (positive or negative) from solar panels should be grounded.

Now check for current flow. Short the white and red wires through a 30 amp fuse, then a 20 amp fuse, then a 10 amp fuse. If none of the fuses blows then you have solar panels which produce less than 10 amps. Measure the "short circuit amperage"  between the red and white wires with an ammeter. Based on your description, this will be 2 or 3 amps and it would be "OK" to leave connected to your batteries (about 50 watts of solar) if you have 300 amp hours of batteries. If short circuit amperage is more than 3 amps you need to obtain a solar controller or risk overcharging you batteries.

This is a simplified explanation because the type/condition of your batteries and your 12 volt phantom loads will effect how many solar watts can safetly be left on your batteries. 

Note:
 You may find shorting these wires a little frightening because there can be arching and sparking - this is normal and will not harm your solar panels. I have 750 watts of solar panels which are paired so that my VOC on wires from the roof is 41 volts and the "short circuit amps" is 21. If my batteries are low, the charge current is often more than 35 amps. When I disconnect the solar panel wires from the controller a quite noticable welding arc buzz is heard.

Note also that producing sparks near a wet cell battery could ignite the gas coming from a charging or discharging battery.


 
Wyatt
96 U320 40 WTFE, build 4943
84 Toyota Supra towd
2015 Jeep Wrangler towd
Victoria, BC, Canada

Re: Solar panel working or not?

Reply #5 –
Wyatt pretty much hits it on the head. I have had a voltage regulator on mine go bad. They reduce the voltage to approx. 13.8V and taper the charge so the batteries don't cook. Also, prevent battery voltage from feeding back into the panels when the sun is down. The regulators are inexpensive and should you need a new one, or want to price them, check ebay at: solar panel regulator | eBay

A local automotive electric shop will be able to check out your system for loose connections or a bad regulator for a nominal fee and may also be able to supply you with a replacement if yours is bad. Home solar electric businesses can also do it but may be more expensive. I have found the mom and pop auto-electrics are usually a good deal. Ask if you can watch the electrician work as they will have a lot of good tips.

Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: Solar panel working or not?

Reply #6 –
Solar panels have come down in price.

We just bought two Kyocera 135 watt panels for $332 each to add to our other two four-year old Kyocera 130 watt panels. Our solar panels are all 12-volt nominal. Shipping was $112 FedEx-ground from New Mexico to Nacogdoches.

Re: Solar panel working or not?

Reply #7 –
What company is in New Mexico? I'm usually eyeballing Northern Az Wind and Sun's prices...
The selected media item is not currently available. Dave Head & Megan Westbrook
Titusville, FL - The Great Outdoors
'98 270 buying this month
Toad is a 2018 F150 XLT

Re: Solar panel working or not?

Reply #8 –
Short answer...  If your solar panels ae small compared to your battery bank, it is like a trickle charger. It will keep your batteries charged and you won't hurt them. If they are a large array, you will need to regulate them to prevent overcharging the batteries.  ANYTHING  that you put between your solar panels and your battery WILL reduce the charging. 
Michael Baldacchino
'97 40' U320

Re: Solar panel working or not?

Reply #9 –
Quote
RE what company is in New Mexico? I'm usually eyeballing Northern Az Wind and Sun's prices...

Not many 12-volt panels to choose from anymore.

Affordable Solar, using:
Kyocera KD135SX-UPU, 135W Solar Panel