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How to Solar Power Your Casita


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#31 k4fcp

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Posted 30 April 2009 - 04:48 AM

QUOTE (campnagle @ Apr 30 2009, 08:26 AM) <{POST_SNAPBACK}>
I find like most things, simple is best. Special wire, connectors and panel orientation are just not critical. After talking to old timers with solar in the field I found it's very easy.. A panel and controller is all that's needed. A three pronged extension cord is weather tight and can be plugged in only the correct way. Wiring is basic. Panel to controller, controller to battery. My 50 watt panel will charge my battery as fast as my genset and make my converter fans run. A volt meter plugged into 12 volt outlet shows my volts. I did not want a fixed roof mount as I try to set trailer in the shade when camping. Solar is just plain simple.


Simple solar

Perfect!
Rich Beamish, k4fcp@arrl.net
1994 13' Casita solar-powered
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#32 Art Davis

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Posted 30 April 2009 - 03:54 PM

QUOTE (campnagle @ Apr 30 2009, 05:26 AM) <{POST_SNAPBACK}>
I find like most things, simple is best. Special wire, connectors and panel orientation are just not critical. After talking to old timers with solar in the field I found it's very easy.. A panel and controller is all that's needed. A three pronged extension cord is weather tight and can be plugged in only the correct way. Wiring is basic. Panel to controller, controller to battery. My 50 watt panel will charge my battery as fast as my genset and make my converter fans run. A volt meter plugged into 12 volt outlet shows my volts. I did not want a fixed roof mount as I try to set trailer in the shade when camping. Solar is just plain simple.


Simple solar



Campnagle,

I like your setup a lot, but how about some more details? For instance, what gauge extension cord? My 50 watt panel says 10-14, so I assume you are somewhere in that range. Do you simply strip off the male plug end and attach crimp connectors to tie into the 12 V trailer system? And what type of exension cords do you use? I assume that you can plug them together to get an extension, right? I assume you are using some type of outdoor extension cord.

Thanks for any info.

Art


#33 campnagle

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Posted 30 April 2009 - 05:11 PM

Simple solar thread

I used a 16 gauge extension cord to the panel. All connections are soldered and heat shrink wrap. I mounted the controller far forward so putting back in the 30 amp cord would not disturb or hit it. I ran the female end of the cord from the controller to the power cord hatch with about 2' that you can pull out to connect to panel cord. I clamped it to a wood brace so you can't tug on it and pull the wires from the controller, just like the 30 amp cord. I ran 16 gauge water/oil proof cable from home depot from controller to battery. I zip tied all cables to the factory harness that runs back there. Using a 3 prong cord you can only plug it in correctly, just cut the third wire off.

Edited by campnagle, 30 April 2009 - 05:16 PM.

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#34 Art Davis

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Posted 01 May 2009 - 07:22 AM

Thanks for the additional info, CampNagle. Sounds like a nice setup.

No one ever responded to my earlier question: can I short circuit my panel to measure the shortcircuit current without damaging it? If I remember from my distant past as an EE the solar cells are basically diodes that run in the reverse-biased mode, so they look approximately like current sources. Hence, no damage. Am I right? Don't want theory to overwhelm practice here!

Another question---and I am being serious here---how do you keep the dogs off your panel?

Art

#35 JudyinWis

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Posted 02 May 2009 - 08:30 AM

I got the PT 12/24-10-TC charge controller from solarsellers.com, and the instructions say to attach the purple wire to the negative PV terminal if it is 24 volts, and not to connect it if the PV array is 12 volts. My PV panel is 17.4 volts, so do I use the purple wire or not?

Second question: The instructions say to connect the positive PV teminal to the red wire through a strain relief clamp. What is a strain relief clamp? Does anybody have a link with a picture of one? What other name might this device have?

Third question: The insturctions also say "The battery must be fused." What does that mean?

Thanks,
Judy

#36 Art Davis

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Posted 03 May 2009 - 08:02 AM

QUOTE (JudyinWis @ May 2 2009, 09:30 AM) <{POST_SNAPBACK}>
I got the PT 12/24-10-TC charge controller from solarsellers.com, and the instructions say to attach the purple wire to the negative PV terminal if it is 24 volts, and not to connect it if the PV array is 12 volts. My PV panel is 17.4 volts, so do I use the purple wire or not?

Second question: The instructions say to connect the positive PV teminal to the red wire through a strain relief clamp. What is a strain relief clamp? Does anybody have a link with a picture of one? What other name might this device have?

Third question: The insturctions also say "The battery must be fused." What does that mean?

Thanks,
Judy


Judy,

The voltage coming from the PV panel is going to be higher than the 12 V (or so) going to the battery. (Actually, a conventional battery charger puts out a bit more than 12V to overcome the internal resistance of the battery.) The charge controller "transforms" the voltage down to the appropriate level for the 12 V battery. That's the idea behind the MPPT controller: it selects the optimum voltage for maximum power into the battery depending upon the light level. The controller you bought has two modes: 12V and 24V. I suppose some folks charge 24 volt batteries for some reason. So you just follow the instruction sheet to set it up for 12V operation. (Ignore the purple wire.)

A strain relief is just mechanical---no electrical effect. It is to keep you from pulling the actual electrical connection apart when you tug on the cable going to your panel. Sorry, I don't have a picture. Maybe someone else can supply you with one.

When you are told to "fuse the battery," that doesn't mean use the phasor and reduce it to a slag heap! It means you should put a fuse in the line. I don't know exactly where the phrase is in the instructions (I will look and if I find something I will do a later post), but I suspect it means that you should put a fuse between the controller and the battery. However, I think it makes more sense to put a fuse between the controller and the line going to the panel---just in case you short the wires outside your trailer. Anyway, the idea of "fusing" something is simply to put a fuse between the device talked about and whatever it connects to so that neither battery nor device does "get phasored" due to an accidental short.

Art


#37 Art Davis

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Posted 03 May 2009 - 03:06 PM

QUOTE (Art Davis @ May 3 2009, 09:02 AM) <{POST_SNAPBACK}>
QUOTE (JudyinWis @ May 2 2009, 09:30 AM) <{POST_SNAPBACK}>
I got the PT 12/24-10-TC charge controller from solarsellers.com, and the instructions say to attach the purple wire to the negative PV terminal if it is 24 volts, and not to connect it if the PV array is 12 volts. My PV panel is 17.4 volts, so do I use the purple wire or not?

Second question: The instructions say to connect the positive PV teminal to the red wire through a strain relief clamp. What is a strain relief clamp? Does anybody have a link with a picture of one? What other name might this device have?

Third question: The insturctions also say "The battery must be fused." What does that mean?

Thanks,
Judy


Judy,

The voltage coming from the PV panel is going to be higher than the 12 V (or so) going to the battery. (Actually, a conventional battery charger puts out a bit more than 12V to overcome the internal resistance of the battery.) The charge controller "transforms" the voltage down to the appropriate level for the 12 V battery. That's the idea behind the MPPT controller: it selects the optimum voltage for maximum power into the battery depending upon the light level. The controller you bought has two modes: 12V and 24V. I suppose some folks charge 24 volt batteries for some reason. So you just follow the instruction sheet to set it up for 12V operation. (Ignore the purple wire.)

A strain relief is just mechanical---no electrical effect. It is to keep you from pulling the actual electrical connection apart when you tug on the cable going to your panel. Sorry, I don't have a picture. Maybe someone else can supply you with one.

When you are told to "fuse the battery," that doesn't mean use the phasor and reduce it to a slag heap! It means you should put a fuse in the line. I don't know exactly where the phrase is in the instructions (I will look and if I find something I will do a later post), but I suspect it means that you should put a fuse between the controller and the battery. However, I think it makes more sense to put a fuse between the controller and the line going to the panel---just in case you short the wires outside your trailer. Anyway, the idea of "fusing" something is simply to put a fuse between the device talked about and whatever it connects to so that neither battery nor device does "get phasored" due to an accidental short.

Art

P.S. (Note added later) Judy, I just finished looking at the printed material that comes with the controller. You connect the red lead to the solar panel positive terminal, the black lead to the solar panel minus terminal. You connect the white lead to a positive terminal on the trailer's 12 V system somewhere (I am going to tie in where the battery comes into the trailer) and the blue lead to ground (minus) of that system. Ignore all other leads, but make sure that they are insulated. (Tape the ends with electrical tape so that they can't inadvertently make contact with anything.)

Edited by Art Davis, 03 May 2009 - 03:07 PM.


#38 JudyinWis

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Posted 04 May 2009 - 05:32 AM

Thanks Art.

The instructions for the PT charge controller also say that you must always connect its red and black leads to the PV panel before connecting its blue and white leads to the battery. I had imagined using ring terminals to (semi)-permanently attach the charge controller to the battery, and securing the controller somewhere inside the battery cave, so this dictate is rather inconvenient. Further, I have disposed of the original Interstate battery and am about to have a 65# AGM battery installed, which I will be unable to move because of its weight.

John Drake at solarsellers.com has suggested attaching leads to the battery as I had planned, but then using a flat 2 pronged SAE connector to hook up the charge controller to those leads each time after establishing the connection between it and the PV panel. This probably means the charge controller would not be permanently attached to the trailer, and thus more susceptible to theft.

The instructions go on to say: "Ensure the battery is disconnected and/or safe operating procedures are follwed when making battery connections. Extreme care must be taken to ensure the battery is not shorted. BE SAFE....Qualified personnel only to connect and operate this unit."

I gather the concern here is that you could get an electrical shock if you touched any part of the circuitry once everything is hooked up, or more likely, in the process of hooking up the circuit. At this point I don't have a way to disconnect the battery, and I don't know what the standard safe operating procedures are. I can imagine that handling SAE connectors could even be somewhat risky, while screwing ring terminals onto the battery posts with the PV panel putting out voltage would be even moreso.

I gather some people have some sort of battery disconnect switch. Would that be installed inside the battery cave or near the converter? Neither location sounds particularly conveneint.

It occurs to me that possibly you could easily circumvent this entire issue by placing the PV panel face down on the ground before hooking things up, and the hooking up could then be done in no particular order. Am I right?

Judy

#39 Art Davis

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Posted 04 May 2009 - 07:43 AM

QUOTE (JudyinWis @ May 4 2009, 06:32 AM) <{POST_SNAPBACK}>
Thanks Art.

The instructions for the PT charge controller also say that you must always connect its red and black leads to the PV panel before connecting its blue and white leads to the battery. I had imagined using ring terminals to (semi)-permanently attach the charge controller to the battery, and securing the controller somewhere inside the battery cave, so this dictate is rather inconvenient. Further, I have disposed of the original Interstate battery and am about to have a 65# AGM battery installed, which I will be unable to move because of its weight.

John Drake at solarsellers.com has suggested attaching leads to the battery as I had planned, but then using a flat 2 pronged SAE connector to hook up the charge controller to those leads each time after establishing the connection between it and the PV panel. This probably means the charge controller would not be permanently attached to the trailer, and thus more susceptible to theft.

The instructions go on to say: "Ensure the battery is disconnected and/or safe operating procedures are follwed when making battery connections. Extreme care must be taken to ensure the battery is not shorted. BE SAFE....Qualified personnel only to connect and operate this unit."

I gather the concern here is that you could get an electrical shock if you touched any part of the circuitry once everything is hooked up, or more likely, in the process of hooking up the circuit. At this point I don't have a way to disconnect the battery, and I don't know what the standard safe operating procedures are. I can imagine that handling SAE connectors could even be somewhat risky, while screwing ring terminals onto the battery posts with the PV panel putting out voltage would be even moreso.

I gather some people have some sort of battery disconnect switch. Would that be installed inside the battery cave or near the converter? Neither location sounds particularly conveneint.

It occurs to me that possibly you could easily circumvent this entire issue by placing the PV panel face down on the ground before hooking things up, and the hooking up could then be done in no particular order. Am I right?

Judy


Judy,

Well, I'm glad you brought this up. I hadn't noticed the part of the instructions saying that you must connect the battery first. My intention was simply to unhook the panel without worrying about disconnecting the charge controller from the battery! We'll have to let the experts who have already done their hookups tell us about this one. That would be very inconvenient if we had to disconnect the charge controller each time we unhooked the panel. If we have to, we can install a switch, I suppose, that is accessible from the interior of the trailer.

On the issue of battery protection, you always get a lot of warnings about safety relative to batteries. The big thing is to not short the positive terminal to the negative terminal at any time. If you do, sparks will fly and things can be damaged (including you!). But I don't think you have to be too concerned when you are doing things like attaching ring terminals. A good procedure if you are attaching connections to any part of the dc circuit in your trailer is to simply remove the battery connectors while doing the work, do it, and then reattach them. I usually disconnect the negative terminal, then the positive terminal. After finishing the work, I connect them in the reverse order. This is because the negative post of the battery is connected to the frame of the trailer. This way, if you accidentally short the positive to the frame, no problem. If you accidently touch the negative to the frame, no harm done because you are going to connect it that way anyway.

I'll be monitoring to see what our experts have to say about your sequencing issue. Thanks for bringing it up.

Art
P.S. Don't worry too much about shock hazard. 12 volts is simply not enough to do any damage to human beings except in very, very rare circumstances. You can just put one finger on the positive terminal and another on the negative terminal if you like without any fear. (Unless, of course, you have gotten some battery acid on those terminals!) It akes maybe twenty or thirty volts before you will even begin to feel anything.

Later P.S. I just sent an e-mail to the guy at solarconverters.com asking him this question. I'll let you know what he says.

Edited by Art Davis, 04 May 2009 - 10:19 AM.


#40 Art Davis

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Posted 04 May 2009 - 07:49 PM

Okay, here is the e-mail I sent to Solar Converters, Inc.

Hi:

Just a question about wiring up your charge controller PT 12/24-5 to my rv battery from a nominally 12V Kyocera 50 watt solar panel.

I had intended to wire the output to the 12 V battery permanently in place (that is to a 12 V terminal strip coming from the battery via No. 10 stranded hookup wire, this strip feeding other parts of my 12 V circuit). My intent is to bring a flat molded connector out the "shore line" entrance normally used by my 110V AC power cord.

However, someone has pointed out that in your manual you specify that the panel must be connected before the battery is connected. I had been reading this merely as a general procedure for connecting the controller (that is, something has to come first). However, this person interpreted the sequencing as important: that damage might be done to the controller if the battery remains connected when we unplug the solar panel.

Would you please clear up my confusion on this issue?

Thanks in advance for your time and help.

Sincerely,

Art Davis



Here is Dave's response (I think he is the owner and the designer of our convertors):

It is a basic hook up procedure. You can hook up the battery first but always make sure you connect grounds first. For example, hook up blue then white then black and finally red.

Dave




So---it looks as though we are okay hooking up the controller to the battery and leaving it there.

Art


#41 JudyinWis

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Posted 05 May 2009 - 11:17 AM

I'm not sure I've got the niceties of pasting text in, but to keep the discussion in one piece, here goes:

From Campnagle: ".. A panel and controller is all that's needed. A three pronged extension cord is weather tight and can be plugged in only the correct way. Wiring is basic. Panel to controller, controller to battery..."

From Art: "...how about some more details?.. Do you simply strip off the male plug end and attach crimp connectors to tie into the 12 V trailer system? And what type of exension cords do you use? I assume that you can plug them together to get an extension, right?..."

From Campnagle: "...All connections are soldered and heat shrink wrap. I mounted the controller far forward so putting back in the 30 amp cord would not disturb or hit it. I ran the female end of the cord from the controller to the power cord hatch with about 2' that you can pull out to connect to panel cord. I clamped it to a wood brace so you can't tug on it and pull the wires from the controller, just like the 30 amp cord. I ran 16 gauge water/oil proof cable from home depot from controller to battery. I zip tied all cables to the factory harness that runs back there. Using a 3 prong cord you can only plug it in correctly, just cut the third wire off."

I think the recommendation for 10-12 guage wire makes sense if you are planning to use up to 50-75 feet of wiring from the trailer to the PV panel, given the expected drop in voltage over that distance. And especially in more northerly and wooded areas where sunlight is somewhat more limited. I also think using an extension cord with its better protection from the elements and abrasion than red and black wires purchased by the foot, together with flat 2 prong SAE connectors, makes sense.

However, a 50 foot 10 guage extension cord costs $55 at the local Lowe's. (Actually, using two or three 25 foot cords would probably make the most sense.) Before I purchase such an item and cut it, I'd like someone to reassure me that the wires inside are color-coded, and I thus will hook the two wires from each of the two cut ends to the correct terminals on the PV panel and charge controller, on the second try if not the first.

I am not equipped for or skilled in soldering and shrink-wrapping, and had imagined stripping wires, twisting them together, sliding a butt connector over the knot, and taping the butt connector in place. People here talk about 'crimping' the wires. I do have access to a wire crimper, and I'm wondering if crimping means just using the tool to sort of smash the wires together.

So I have 2 questions: Are the wires inside an extension cord encased in different colors? and what exactly is meant by crimping?

Also Art has not yet gotten a response to his questions about checking the voltage output of the PV panel without shorting it, and about preventing his dog from peeing on the panel.

Thanks to all,
Judy


#42 JudyinWis

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Posted 05 May 2009 - 11:33 AM

I'm not sure I've got the niceties of pasting text in, but to keep the discussion in one piece, here goes:

From Campnagle: ".. A panel and controller is all that's needed. A three pronged extension cord is weather tight and can be plugged in only the correct way. Wiring is basic. Panel to controller, controller to battery..."

From Art: "...how about some more details?.. Do you simply strip off the male plug end and attach crimp connectors to tie into the 12 V trailer system? And what type of exension cords do you use? I assume that you can plug them together to get an extension, right?..."

From Campnagle: "...All connections are soldered and heat shrink wrap. I mounted the controller far forward so putting back in the 30 amp cord would not disturb or hit it. I ran the female end of the cord from the controller to the power cord hatch with about 2' that you can pull out to connect to panel cord. I clamped it to a wood brace so you can't tug on it and pull the wires from the controller, just like the 30 amp cord. I ran 16 gauge water/oil proof cable from home depot from controller to battery. I zip tied all cables to the factory harness that runs back there. Using a 3 prong cord you can only plug it in correctly, just cut the third wire off."

I think the recommendation for 10-12 guage wire makes sense if you are planning to use up to 50-75 feet of wiring from the trailer to the PV panel, given the expected drop in voltage over that distance. And especially in more northerly and wooded areas where sunlight is somewhat more limited. I also think using an extension cord with its better protection from the elements and abrasion than red and black wires purchased by the foot, together with flat 2 prong SAE connectors, makes sense.

However, a 50 foot 10 guage extension cord costs $55 at the local Lowe's. (Actually, using two or three 25 foot cords would probably make the most sense.) Before I purchase such an item and cut it, I'd like someone to reassure me that the wires inside are color-coded, and I thus will hook the two wires from each of the two cut ends to the correct terminals on the PV panel and charge controller, on the second try if not the first.

I am not equipped for or skilled in soldering and shrink-wrapping, and had imagined stripping wires, twisting them together, sliding a butt connector over the knot, and taping the butt connector in place. People here talk about 'crimping' the wires. I do have access to a wire crimper, and I'm wondering if crimping means just using the tool to sort of smash the wires together.

So far I have 2 questions: Are the wires inside an extension cord encased in different colors? and what exactly is meant by crimping? Other questions: What is meant by zip-tying? Is the factory harness the bunch of wires coming from the pigtail, or something else? Why would would you want to tie wires coming from the charge controller to those? just as an anchor point? I thought that purpose was served by clamping them to a block of wood.

Also Art has not yet gotten a response to his questions about checking the voltage output of the PV panel without shorting it, and about preventing his dog from peeing on the panel. (Maybe spraying the panel with bitter apple would help. If that worked it would probably only do so for several hours, and then another application would be needed.)

Thanks to all,
Judy


#43 Art Davis

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Posted 06 May 2009 - 05:45 PM

Judy,

Well, maybe our experts have abandoned us. If so, we will just try to figure it out on our own.

I appreciate the tip about keeping dogs off, but I suspect it (as you say) will only be a temporary fix. Maybe dog pee doesn't really affect the panel. A washdown with a little water will probably put it back into shape for traveling.

I wound up just getting some No. 10 wire (red and black). I will use it, along with molded in line polarized connections I came up with at Batteries Plus (sorta' like the "flat four" trailer connector, but only two polarized contacts), and use nylon cable ties to keep them together. Thirty feet only cost me about 15 bucks at the local electical supply place.


Yes, crimping is just squashing the connectors down on the wire so that they make good contact, both electrically and mechanically. There is a slot in a crimping tool for each gauge wire (or range of gauges) that you use. Not hard to do at all.

Did you get the idea bout the strain relief? There is a "knock out" plug in the junction box on your panel that is a standard size. You get a gadget called a "strain relief" that is circular, but in two parts that form a clamp around the wires or cable coming in. There is a nut that goes around the thing that keeps it in the knockout hole, and a couple of scrwes that tighten down on the cable or wires. You can get them at any hardware or electrical supply place or at one of the big box stores such as Lowes or Home Depot.

Art

Edited by Art Davis, 06 May 2009 - 05:46 PM.


#44 Art Davis

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Posted 11 May 2009 - 08:01 AM

I just finished my solar installation.

Here is a link---just in case you want to see the pix:
http://www.lightweig...topic.php?t=432
Art

#45 campnagle

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Posted 11 May 2009 - 08:34 AM

Here is a video of my solar set up

Solar video

Edited by campnagle, 11 May 2009 - 10:32 AM.

Camp Nagle
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GREAT STATE OF ARIZONA