New Solar Panel

[TroutBum]

Howdy all...  DW and I just got back from a week long trip to Bothe-Napa Valley State Park (with stops at DW's Aunt and Uncle's place in Reno both ways).  More details on the trip later.

DW's Uncle recently picked up a bunch of 55W Solar panels from the State of Nevada.  He gave me one of them.  They had been for road sign lights, and had been replaced by newer models.  He says he tested it and it still works fine.

So I need to know what I should do from here.  I heard there is a regulator box that prevents overcharging/back-charging at night but I can't remember anything about it.  Also, what are recommendations in hooking it up (how long should wires be?  Permenant/semi-permenant mounting/on or off the PUP)

Any help would be appreciated.

[fritz_monroe]

I hate to point you to another forum group, but over at PopUpExplorer , there are a few people that use solar panels.  I haven't been around this forum long enough to know who uses them.  You will need a charge controller.  The majority of the solar hook ups are permanent mounts, but I've also seen some that are temporary mounts.  Good luck with your connections, and congrats on the awesome score.

[wavery]

Howdy all...  DW and I just got back from a week long trip to Bothe-Napa Valley State Park (with stops at DW's Aunt and Uncle's place in Reno both ways).  More details on the trip later.

DW's Uncle recently picked up a bunch of 55W Solar panels from the State of Nevada.  He gave me one of them.  They had been for road sign lights, and had been replaced by newer models.  He says he tested it and it still works fine.

So I need to know what I should do from here.  I heard there is a regulator box that prevents overcharging/back-charging at night but I can't remember anything about it.  Also, what are recommendations in hooking it up (how long should wires be?  Permenant/semi-permenant mounting/on or off the PUP)

Any help would be appreciated.

A 55w panel is pretty minimal. I wouldn't worry about any type of controller. That would just be a waste of $ IMHO. All you have to do is remember to disconnect it at sundown. That panel will put out the same as a 4amp battery charger at peak sunlight. That means  around 4A from 11:AM to about 2:PM IF the panel is pointed directly at the sun. It will be something less (down to zero) before and after that time frame. If you have 11 hrs of sun, you may get 25 amps of charge on a good day.

Wiring it would depend on your camping style and needs. If I were to put a 55w panel on my PU, I would get a 50' 14g extension cord from Home Depot and cut the ends off. I'd wire the white as pos and the black as neg to the solar panel. I'd put alligator clamps on the other end to put on the battery. I would also use 2 batteries, to avoid over-charging and make sure that I could capture every juicy amp that I could.

I wouldn't mount the panel on the PU. I'd have it so that I could move it out into the sun or even put it up in a tree, if need be. Sometimes, I try to put my PU in a shady spot to avoid the sun. In that case, the solar panel would have to be put elsewhere to work.

There is very little chance that you would over charge your battery with a 55w panel. You would have to go for a couple of days without turning on lights or running water. In that case, just check the voltage on the battery and make sure that it doesn't exceed 15v. Trust me......it won't.

If he wants to sell some, let me know. I might be interested in buying 4 of them. I still wouldn't waste my money on a controller though. I'm pretty used to living with solar panels and I know how to manage them. I had 4 - 50w panels on my yacht and didn't use a controller. Although, I used a lot of electricity and spent most of my time in the tropics (lots of sun).

[TroutBum]

It is kind of funny.  I was wanting a solar panel (cheap option) or Honda generator ($$$ option), and after this latest trip, I found I didn't need it.

We added a 2nd Battery before we left, and they are connected somehow (I honestly didn't look at the cables that carefully).  We were hardly miserly in our power use, and had plenty of juice for 4 nights.

Consequently, I had dropped a power source down to the bottom of the wish list.  And then a solar panel lands in my lap.

So tell me Wave...

The panel has 2 little black boxes with 2 wires each coming out of them.  One of the boxes is marked positive.  Does this sound right...  3 clips.  1 positive, 1 neg. and 1 consisting of both grounds.  I connect the clips to the appropriate terminals of one battery and the ground clip goes where?  Are both batteries getting a charge?  You really think that a controller is unnecessary?  I think I can definately handle making the clips myself.

[wavery]

It is kind of funny.  I was wanting a solar panel (cheap option) or Honda generator ($$$ option), and after this latest trip, I found I didn't need it.

We added a 2nd Battery before we left, and they are connected somehow (I honestly didn't look at the cables that carefully).  We were hardly miserly in our power use, and had plenty of juice for 4 nights.

Consequently, I had dropped a power source down to the bottom of the wish list.  And then a solar panel lands in my lap.

So tell me Wave...

The panel has 2 little black boxes with 2 wires each coming out of them.  One of the boxes is marked positive.  Does this sound right...  3 clips.  1 positive, 1 neg. and 1 consisting of both grounds.  I connect the clips to the appropriate terminals of one battery and the ground clip goes where?  Are both batteries getting a charge?  You really think that a controller is unnecessary?  I think I can definately handle making the clips myself.

I'm A little puzzled by the set-up. It should have two wires coming out of one box. One wire being pos and one wire being neg.

You do not need a controller unless you are going to leave the panel hooked up while stored or you use very little electricity. Even then, I doubt that you could over-charge two batteries with that panel, even on the sunniest days. To double check me, just put a multimeter on the batteries, twice a day, during the sunniest part of the day.

Just remember to unhook the panel at sundown. It tends to act as a "heater" after the sun goes down and will draw about 1 amp to "warm" the panel, in the absence of sunlight.

[ForestCreature]

I will disagree with Wavery about not getting a charge controller. With 55 watts you don't need a fancy expensive one . You can get a $40 controller, it's worth it just to not have to mess with remembering to disconnect every night and reconnecting again in the morning and cheap insurance for your 2 batteries.

[wavery]

I will disagree with Wavery about not getting a charge controller. With 55 watts you don't need a fancy expensive one . You can get a $40 controller, it's worth it just to not have to mess with remembering to disconnect every night and reconnecting again in the morning and cheap insurance for your 2 batteries.

I see your point and would agree with you if he had a 200w array. A controller consumes a certain amount of power just by the very nature of the fact that it is wired into the system. It also has a built in diode that will keep the panel disconnected until it reaches a certain wattage (during low light times). When the diode closes the connection (allowing the panel to charge) it has about .5amp resistance. Some say that it is lower but I have done extensive research comparing 2 identical sets of panels, mounted side by side with amp meters attached to each. One set had a controller, the other set didn't. Then I switched panels. The panels with the controller consistently put out .5amps less than the set that was wired direct. With a small array like that (55w), .5amps is significant IMO. It may make a difference of 5 amps (about 20%) over the course of the day. In other words, instead of have a 55w array, he would effectively have a 44w (or less) array. I say "or less" because the panel will put out "0" until it overcomes the diode. There are a lot of hours that the panel could be putting out .2 - .4amps during low light but it won't with the diode. After the diode switches over, it continues with that .5amp shortage throughout the day.

With a 200w array, that .5amps would only be about a 5% loss throughout the charging cycle. The larger arrays would have the capacity of possibly putting out 18amps (4 times as much as the 55w panel) and lends itself to the remote possibility of over-charging a small battery bank in times of high output and low consumption. Even then IMHO, the better solution would be to add more battery capacity instead of having the controller disconnect when the batteries are full.

As you can tell, I am very miserly, when it comes to storing every precious amp that a solar panel has the capacity of putting out. The idea of turning the panels off at full sunlight is foreign to me. It's just my background. On my yacht, I had 4 - 50w panels and a wind generator that was capable of putting out 20amps in a 20mph breeze. I also had 3 - 8D batteries with a storage capacity of over 600amps so I never worried about over-charging unless I was away from the boat for 2 or more days at a time. Then, I switched over to a controller. I had mine wired so that all I had to do is flip a switch to put the controller into the line.

It sure wouldn't hurt to start out with no controller and see if you are capable of self-managing the system. In the unlikely event that you find that taking the alligator clip off of the positive battery post at sun-down too labor intensive, you can always add a controller. It is far more likely that you will find that a 55w array will not keep up with your demand. It is extremely unlikely that you will find that panel putting 2 batteries into an over-charged state, unless you leave it hooked up for a couple of days with zero power usage. Although, you will be able to go longer periods of time without needing to charge your batteries (if there is any sun at all), that's for certain.

[mike4947]

Not to mention there are controllers and controllers. The cheapo controlers definitely do degrade the output from panels. Since they simply clip the voltage rather than transform it you lose apx 15-25% of the panels rating versus an MPPT controller (more expensive) that transforms the "extra" voltage in amperage.

[Fleetwood Max]

Wow, Some of you all are way over my head on all this stuff. I also have a solar trickle charger that i use to keep the battery up. Got this idea from a vintage VW camp out we went to. Seems that when they ship the VW's over the "big pond" they all have a solar charger in the windows of the vehicle. Plugged in to the cig. lighters to keep batterys up. Suction cups are attached to the charger to keep them in the windows. When they reach the dealers, some  just throw them away. I got mine from a fellow that works at one of the dealers. Anyway i went to radio shack and picked up a 12V DC Adapter, it already has the battery clamps on it and just plugged in the charger and clamped it to the battery. and there i go.

[wavery]

Wow, Some of you all are way over my head on all this stuff. I also have a solar trickle charger that i use to keep the battery up. Got this idea from a vintage VW camp out we went to. Seems that when they ship the VW's over the "big pond" they all have a solar charger in the windows of the vehicle. Plugged in to the cig. lighters to keep batterys up. Suction cups are attached to the charger to keep them in the windows. When they reach the dealers, some  just throw them away. I got mine from a fellow that works at one of the dealers. Anyway i went to radio shack and picked up a 12V DC Adapter, it already has the battery clamps on it and just plugged in the charger and clamped it to the battery. and there i go.

If you are talking about something like this:
http://cgi.ebay.com/2-SOLAR-PANEL-12-VOLT-BATTERY-CHARGER-CAR-TRUCK-BOAT-RV_W0QQitemZ9518257827QQcategoryZ14951QQrdZ1QQcmdZViewItem
They are all but useless for charging batteries. They are designed to keep a fully charged battery from discharging during non-use periods. They are called "Float chargers". The manufacturer realized that a lot of car batteries go dead while the car is sitting in storage. They spend a lot of man-hours jump-starting cars, just to move them then the battery goes dead again. When the buyer finally gets the car, the battery is shot and must be replaced under warranty. That's another expense plus a loss of confidence from the customer.

[chasd60]

My research has found that a panel less than 10W per battery will not need a charge controller. Anything larger than that should have one. The panel is capable of putting out in excess of 17V and that isn't too good for a fully charged battery.
If you have a charge controller, the system becomes hands-free with the exception of checking battery electrolyte level.
 
http://www.discountpv.com/chargecontrollers/MPPT-250.htm

[wavery]

My research has found that a panel less than 10W per battery will not need a charge controller. Anything larger than that should have one. The panel is capable of putting out in excess of 17V and that isn't too good for a fully charged battery.
If you have a charge controller, the system becomes hands-free with the exception of checking battery electrolyte level.
 
http://www.discountpv.com/chargecontrollers/MPPT-250.htm

I believe that the recommendation may be based on a battery and solar panel combo that is disconnected from service and left for charging only, over a long period of time. If a battery is being used, that changes everything because a 50w solar panel will rarely keep up with a battery in even minimal use. Just try putting a 4amp trickle charger up to your battery for 5 hours a day and see if it will keep up with the demand that you put on it while camping. I put my 25amp battery charger on my batteries for 4 hours a day just to keep them up with the demand that I put on them while camping. All you have to do is a little math to figure out that a 10w solar panel puts out less that 1amp at full sunlight and will deliver less than 6 amps a day (probably more like 3-4). That won't even keep up with the normal use of 2 - 12v light bulbs.

Most solar panels are actually capable of putting out 22v in direct sunlight. The instant that you put resistance on it, it drops in accordance with the amount of resistance (the voltage of the battery). There is NO WAY that a 10w or even a 50w solar panel would ever get up to 17v while connected to a battery (except maybe a watch battery :p ). If they make that statement in the article, I can only say that the article was written by someone that is dealing in deception in order to sell controllers. That is so far out in left field that it isn't worth discussion and the writer has zero credibility in my books. I hate it when people write outrageous stuff like that to try to intimidate the reader into buying a product :swear: .

[chasd60]

Mine puts out in excess of 22V open circuit and 17.3V at maximum power point. This is why my panels are rated at 4.63A. At a reduced voltage of 13.5V the actual wattage would only be about 62.5W with a PWM charge controller. An MPPT charge controller increases the current output and gives me about 75W after the panel diode losses.
 
An unregulated 50W panel will probably put out 2.9A without a charge controller. If you don't want to deal with tracking the consumption and monitoring the charge state, i.e in storage...after towing. Then a charge controller is a good thing to have.
 
I agree that a switch to bypass the charge controller when you need a larger charge could be helpful if you have a smaller panel. Most people want the system to be hands free though.
 
My camper is in my driveway right now and the output from the controller is probably about 14.4V (temp compensated) and 0.4A right now. My LINK10 system monitor probably shows a charge rate of

[chasd60]

The more I think about it the more it makes sense not to use a controller if you are only using the panel while camping. Wavery is right about the panel output VS usage during camping. If your panel is not permanently mounted and you are going to pull it out when you go camping, you will most likely need full blast charging and no charge controller would work fine if you monitor it.
 
If you are going to permanent mount it I would go for the controller.