Portable Solar Panels

Hello everyone. Well I finally broke down and purchased solar power for my 2005 2619. I bought two 80w portable solar panel kits as shown here: http://rvsolarnow.com/80-watt-portab...-SLP80F-12.htm

A very nice feature is when folded and packed in the included padded storage bag, both panel kits fit under the dinette seat with room to spare.

You can use up to 4 of these portable kits totaling 320 watts. With two panels I will have 160watts. My hope is to have enough power to run a nice laptop computer I use for everything from HDTV, internet, emailing and gaming that uses 130 watts, leaving 30 watts for misc low power items like LED lighting, toilet and water pump. I won’t be using the laptop all day BUT I assumed I would in my power needs.

I am not sure how the furnace will impact this, but I know it will be very significant. I have a feeling without the furnace in the mix these panels will work pretty well, but with the furnace running I am not sure I will see my voltages remain healthy. Real world testing is needed.

I got the portable type solar panels because I travel with pets and park in the shade when possible, so having the flexibility to move them around will be nice...they will be cable locked to my RV to prevent them from being stolen.

I am going to camp in my backyard to see just what is realistically doable with 160 Watts of solar power feeding my dual 6v golf cart batteries, whether it will keep the battery voltages from dropping day after day or not. I have never used solar power before so I welcome any input on the matter. I know many here have installed panels, I remember seeing Wayne’s rooftop installation that was removable while towing, a great job and idea.

Mainly I am curious whether I will need to upgrade the converter or any other issues that others have worked with that may help me obtain the best results from these new panels.

Also the dealer sent me a very helpful RV appliance and utility power usage guide that helped me figure out how many panels I needed (see attached).

I will post back how well my backyard camping tests go.

Be interested in the results of your backyard experiment. When you figure in efficiency and losses in the line from solar panel to batteries and in the controller, I am guessing you will have about 100-120 wattsmax. Per their spec, 4.65 amps at 14V ( charging mode) is about 65 watts per panel at full efficiency .

Originally Posted by rumbleweed

Be interested in the results of your backyard experiment. When you figure in efficiency and losses in the line from solar panel to batteries and in the controller, I am guessing you will have about 100-120 wattsmax. Per their spec, 4.65 amps at 14V ( charging mode) is about 65 watts per panel at full efficiency .

Unless I am calculating this wrong the panels are 17.2 volts at 4.65 amps which calcs to 79.98 watts. I don't know about efficiency and what the real world results will be. It will be very interesting. I will definitely post back on what I found. I also am installing a Cobra 1500W inverter under the dinette seat on the forward bulkhead. When finished I am hoping to end up with an "ok" solar solution for dry camping as well as providing power when the big one hits . I live in So Cal and that is always a possibility. It's nice having the TM available with 40 gals of fresh water if such a scenario becomes reality.

You are correct, the panels generate 17.2V @4.65a, but what comes out of the charge controller is about 14V at max of 4.65a. ( 17.2V would damage the battery).A good way to check is to actually measure the current out of the charge controller under heavy load. Also keep in mind when connecting your inverter, you will need very heavy short cabling as it will require about 130+ amps from the battery if you ever use all 1500 watts.

[Bill]

Bob is right. The numbers associated with solar panels are a bit tricky to work with. If a panel is putting out 4.65 amps, then 4.65 amps is what will come out of the controller and into the battery. The purpose of the controller is simply to reduce the voltage to whatever the battery can accept. Sadly, the extra voltage is simply wasted.

However, there is way to beat this. The behavior Bob and I described applies to a simple PWM controller (which is what you and I both have). There is a magic controller called an MPPT controller that will convert the excess voltage to more current. It is considerably more expensive, and at the power levels being discussed, probably isn't worth the added cost. But we have had discussions of MPPT controllers on this board - you can look them up with the Search tool.

Your post describes consuming almost all of the 160 watts of solar power as soon as it is generated - laptop, etc. Realistically, the small amount of power that is left over - and then, only under optimum sun - won't do anything to recharge your battery from any discharge that it undergoes. You are right, the solar power will substitute for power that would otherwise come from the battery, and so the battery will last longer. But you are right again in saying that the furnace blower, as well as lights and other loads, will still come out of the battery. So don't expect magic results here.

Way back in the very early days of the Solar Power forum, Rocky Mountain Ray did a real nice installation. He dry-camped high in the Rockies (perfect sun every day!) on a regular basis, and he was an electronic gadget guy as you are. He installed, as I recall, about 300 watts of power, which allowed him to do what he wanted. You might consider digging up his story.

The owners of Northern Arizona Wind and Sun are technical guys, and their web site has a real nice technical section that is devoid of advertising hype or product-pushing. It is also technically accurate and honest, without the "wisdom" that comes from somebody's brother-in-law's cousin. It is located at www.windsun.com. Their goal is to make a smarter customer. I have learned more from this site than from anything else on the web.

They also have a store, separate from the tech site. It is located at store.solar-electric.com. (They also have a walk-in retail store.) I recommend them, having owned a bit of stuff from them. Their prices are quite a bit lower than other sources. Not to be a wet blanket, but you could have built the same system for about $350 less.

Meantime, welcome to the solar family. Since there aren't many of us, we will all be watching for your experiences and reports.

Bill

Originally Posted by rumbleweed

You are correct, the panels generate 17.2V @4.65a, but what comes out of the charge controller is about 14V at max of 4.65a. ( 17.2V would damage the battery).A good way to check is to actually measure the current out of the charge controller under heavy load. Also keep in mind when connecting your inverter, you will need very heavy short cabling as it will require about 130+ amps from the battery if you ever use all 1500 watts.

Thanks for the information. For wiring, I ordered the installation cabling they sell for this unit which uses 4 GA cabling. The lengths will be the shortest possible without mounting the inverter outside, which would only gain me 6" or so, being just on the otherside of the wall I will be mouting to. It will be located inside the RV under the curb side dinette seat mounted on the front bulkhead. I plan on adding some open framing around the inverter to make sure a clear air area is maintained to provide ample space for proper venting/cooling. If heat ends up being a problem I may mount it outside.

For battery monitoring I ordered the newer Clipper battery monitor shown here in the link below. After reading through the forum it sounds like this is an acceptable monitor that provides crucial information necessary to get the most out of this system:
http://www.amazon.com/gp/product/B00...ef=oss_product

Hopefully when this project is complete I will have a solar system in place that works well enough to allow fairly long, power conserving camping trips without too much pain and sacrifice.

Originally Posted by Bill

Bob is right. The numbers associated with solar panels are a bit tricky to work with. If a panel is putting out 4.65 amps, then 4.65 amps is what will come out of the controller and into the battery. The purpose of the controller is simply to reduce the voltage to whatever the battery can accept. Sadly, the extra voltage is simply wasted.

However, there is way to beat this. The behavior Bob and I described applies to a simple PWM controller (which is what you and I both have). There is a magic controller called MPPT that will convert the excess voltage to more current. It is considerably more expensive, and at the power levels being discussed, probably isn't worth the added cost. But we have had discsussions of MPPT controllers on this board - you can look them up with the Search tool.

Your post describes consuming almost all of the 160 watts of solar power as soon as it is generated - laptop, etc. Realistically, the small amount of power that is left over - and then, only under optimum sun - won't do anything to recharge your battery from any discharge that it undergoes. You are right, the solar power will substitute for power that would otherwise come from the battery, and so the battery will last longer. But you are right again in saying that the furnace blower, as well as lights and other loads, will still come out of the battery. So don't expect magic results here.

Way back in the very early days of the Solar Power forum, Rocky Mountain Ray did a real nice installation. He dry-camped high in the Rockies (perfect sun every day!) on a regular basis, and he was an electronic gadget guy as you are. He installed, as I recall, about 300 watts of power, which allowed him to do what he wanted. You might consider digging up his story.

The owners of Northern Arizona Wind and Sun are technical guys, and their web site has a real nice technical section that is devoid of advertising hype or product-pushing. It is also technically accurate and honest, without the "wisdom" that comes from somebody's brother-in-law's cousin. It is located at www.windsun.com. Their goal is to make a smarter customer. I have learned more from this site than from anything else on the web.

They also have a store, separate from the tech site. It is located at store.solar-electric.com. (They also have a walk0in retail store.) I recommend them, having owned a bit of stuff from them. Their prices are quite a bit lower than other sources. Not to be a wet blanket, but you could have built the same system for about $350 less.

Meantime, welcome to the solar family. Since there aren't many of us, we will all be watching for your experiences and reports.

Bill

Hi Bill, thanks for some great insight and the howdy, there are tons of great people on this site, it's a joy to plop down at my PC and spend quality time enjoying all things RVing and TM.

On expense, yes I realized upfront the option I chose was NOT the cheapest, not even close. I have read through the solar threads, saw the excellent job Wayne did with his two panels that have the same power mine do for about 1/3 the cost of what I am doing.

I really like the portable aspect of the panels I ordered and the ability to simply add more kits to get from 80w to 320w setup. I realize this isn't rocket science to do that with any solar setup, but it's just a bit easier with these turnkey kits.

The CEA Solar rep has been extremely helpful and I found he's well known in RV solar solutions. He even answered his phone at 7:30 PM on Saturday and was courteous and kind in taking whatever time it took to answer my questions. I was pleasantly surprised.

On the actual electron dynamics that occur once the solar panels are connected and supplying power is a bit of a mystery to me and I haven't asked about this yet, so I will now. Obviously I have lots to learn.

I wondered with these PWM type controllers, how is power allocated when the panels are active. Initially the main question that I have relates to what I believe you touched on in your previous post.

Assuming the panels are in full sun and connected, with a load being applied inside the RV that is LESS than the output capacity of the panels:

1 - Can the system both charge the batteries AND provide power as pass-through energy to devices/appliances?

2 - Does the power that's output out of the controller ONLY come from the batteries? (IE - It never can be directly output from the solar panels to any device OTHER than the batteries.)

Ok then if question 1 = NO and 2 = YES then it seems a simple analogy could be that my batteries are a water tank. The solar panels are like a hose flowing IN to the tank. My appliances are like a drain flowing OUT of the tank. IF I have more water coming IN throughout the daytime (active power state for panels) will my batteries remain and be fully charged at the end of that daytime period? Is it that simple?

I imagine it's much more complicated than this but this might get me on the right track for now.

Thanks!
Bob.

[Wavery]

We've had a 160W system on our TM for 14 camp-outs now (most were 4 days).

I have them permanently mounted on the roof because we mostly beach camp. However, even on camp-outs with partial shading or cloudy days we have almost always had full batteries by the end of the day (usually by 2:PM).

We do not have LED lights. We never monitor our usage (run around turning off lights) and we use our inverter on occasion. We use our furnace set @ 70*.

We have a PWM controller and I used 10G marine wire (16' run).

I think that you will be quite happy with your set-up. Th ability to move the panels to full Sun could give you up to double my output on any given day.

As to this question:
"Ok then if question 1 = NO and 2 = YES then it seems a simple analogy could be that my batteries are a water tank. The solar panels are like a hose flowing IN to the tank. My appliances are like a drain flowing OUT of the tank. IF I have more water coming IN throughout the daytime (active power state for panels) will my batteries remain and be fully charged at the end of that daytime period? Is it that simple?"

The answer is "Yes".....it is basically that simple.

The solar array is nothing more than a battery charger. Your 12V supply to your camper always comes from the battery (unless you are 110V hook-ups).

BTW.........unless you are using 100' of cable (from your panels to the battery) 4G wire is way over-kill and will be clumsy and difficult to work with. Someone is likely to steal your system for the wire more than for the panels.

Originally Posted by harveyrv

BTW.........unless you are using 100' of cable (from your panels to the battery) 4G wire is way over-kill and will be clumsy and difficult to work with. Someone is likely to steal your system for the wire more than for the panels.

Hi Wayne,

Thanks for the feedback, great job on your installation very clean, well done. You mention you have your panels permanently installed now. From what I remember initially you had them setup so you could remove them and store them on the bed inside the RV to avoid theft while park at your apartment complex. Either way, very clean job. I based much of my decision to go with 160 watt setup after reading your posts describing how well that panel configuration worked for you. Thanks again for the helpful posts.

The 4 GA wire I was referring to is included in the installation cabling kit Cobra sells for their 1500W inverter I am installing. It's for the short run from the batteries to the inverter. They provide both 4GA and 8GA in the kit. The wire from the panels to the battery is much smaller, more like you describe you are using.

Thanks,

Bob.

[Wavery]

Originally Posted by Mr Geek

Hi Wayne,

Thanks for the feedback, great job on your installation very clean, well done. You mention you have your panels permanently installed now. From what I remember initially you had them setup so you could remove them and store them on the bed inside the RV to avoid theft while park at your apartment complex. Either way, very clean job. I based much of my decision to go with 160 watt setup after reading your posts describing how well that panel configuration worked for you. Thanks again for the helpful posts.

The 4 GA wire I was referring to is included in the installation cabling kit Cobra sells for their 1500W inverter I am installing. It's for the short run from the batteries to the inverter. They provide both 4GA and 8GA in the kit. The wire from the panels to the battery is much smaller, more like you describe you are using.

Thanks,

Bob.

The removable installation that I did was on my previous TM. I recently bought a 2004 2720SL. The roof A/C made the removable panels impractical (my previous TM was a '98 with side mount A/C).

I understand now about the 4G wire for the inverter. I used 2G wire for my 2500W inverter. I may not install an inverter in this camper. We only used it for popping pop-corn, heating the occasional left-overs and once or twice (in 4 years) for the hair dryer.

I have a smaller (400-800W) inverter that we plug into the 12V receptacle inside the camper. I think that we may make due with that. I just can't justify spending another $300 for a new inverter for as little as we used it.

We bought a Coleman, propane coffee maker last year and that took care of our need to use the inverter (during quiet hours) to make coffee. In fact, we no longer bring the generator with us at all anymore.