Solar 'Pauper' panels

GroundHog · December 29, 2019

Costco sells a kit with a 100 watt solar panel and controller. You connect the + and - as the instructions tell you to do with the controller. The Solar Panel is full sized glass and aluminum framed. Cost $120. They are on sale again, my wife said this morning. They ship it to your doorstep.

I also use AGM sealed batteries on our latest trailer. Before... any battery will do and when they need to be replaced, go to AGM sealed batteries. Our last trailer did 8 years with AGM batteries and were fine when we sold it with the small 40watt solar in 2006.

I take an extension cord. Cut about a foot off the 'plug side' and wire it to the Solar Panel Controller, which the controller is secured inside with the batteries. (More if you use a separate female plug and mount to the battery box area.) Run the power cord out of the battery box and figure out how to secure the 'female plug'. Mark which is + and -.

The cord with the cut end is now wired to the Solar Panel's + and -. Just keep track of the + and -. The wiring inside the power cord are colored, so you cannot confuse the polarity. Otherwise, have your wife help you. Women know more than they lead on. OK?

Now you have the Solar Panel wired + and -. You have the female plug end wired + and - to the batteries. (I took one end, either will do, to one battery and the other end to the second battery. So one + and the other on the - battery connection.)

Lean the Solar Panel onto a milk crate towards the sunlight. Plug the male plug from the Solar Panel into the Female plug on your battery box. If the panel is charging... you will see the yellow diode glow. When green, your battery is fully charged. Just follow the directions that come with the panel. You can get yellow and green mixed up if you know what I mean...

I will stand in between the Sun and Panel and watch my shadow on the solar panel... to get the best angle for maximum charge. You move the panel and adjust as the Sun moves. It can be set for Sunrise, once you figure out where sunrise will clear the trees, etc. You sleep in and the Solar Panel is working at sunrise! Whooo Weeee! Even doubling the crates and add some weight into the crates. Get heavy milk crates from a junk yard that were used for milk deliveries. You can also make brackets or anything that will support the panel. (Only leave out overnight, when Boondocking Off the Grid where no thieves are wandering around at night. Campgrounds... secure your panel in tow vehicle or trailer. I take a magic marker and write our name on the back and edges for... recognizing your panel on someone else's trailer.)

If you like this after one panel. Go for a second panel and repeat. Separate panel, controller and wiring. Less than $250 for 200 watts or more. The extension cord I use is probably 25 feet long. I can be camped in the shade and the solar panel in the sun. After awhile you will think you are some kind of genius, saved a $1,000 for a professional system on the trailer's roof... and it works just as well.

When traveling, we put our one panel on our bed and wrap in a blanket. It does not slide off on rough roads and our batteries are happy. We are happy... and most of all, you did it yourself. I am not an experienced electrical minded individual and did it twice! If you keep your + and - connected from the Solar Panel to the Controller to the Batteries... you will sit back and your batteries will be getting a FREE Solar Charge all day.

Edited December 29, 2019 by GroundHog

Darryl&Rita · December 30, 2019

Don't use a regular AC extension cord. Use the right equipment.

oldjohnt · December 30, 2019

Ground Hog, the last few (Not any kit) 305 watt solar panels I bought were around 75 cents per watt and they keep coming down each time I buy more. However, the price you quoted (subject to quality) is fair and reasonable, I've seen higher. One advantage of portable set out panels versus flat roof mounted is the ability to aim and tilt them toward the sun during the day which increases energy harvest.

A 100 watt panel, depending on the intensity and angle of the sun and efficiency of the panel and solar charge controller (a kit likely has PWM versus MPPT) might pump 5 to 7 or so charging amps into a 12 volt battery (subject to its condition and SOC) and if that much ??? were present for six hours, that would be 30 to 42 Amp Hours of energy capture which can help charge your batteries enough for small electronics, charging, lighting etc. While it depends on the suns angle (geographical location plus time of year) and intensity, about 5 charging amps (subject to battery and its SOC) is the most I typically got from a 100 amp panel.

I prefer the use of cables and connectors other then home or extension type cords myself, but to each their own. I also upgraded from flooded lead acid to AGM batteries my last upgrade based on my age, how much longer I might RV, and my or the RV's life expectancy lol

CONGRATULATIONS you're on your way, thanks for sharing

John T Long retired n rusty Electrical Engineer

Edited December 30, 2019 by oldjohnt

fratermus · December 31, 2019

Like oldjohn, I found higher-voltage pauper panels to be inexpensive locally. The overall point, I think, is that solar power doesn't have to be expensive. My 570w:220Ah system (with voltage-sensing isolator) was less than $800 and makes copious power. I boondock fulltime with it.

For onlookers interested into small/inexpensive solar installs, a couple thoughts

kits with pwm or shunt/on-off controllers will typically make a bit more power with poly panels than with mono panels and do it at a slightly lower cost. MPPT controllers don't care about panel type unless one plans to be in very hot conditions where mono can be preferable.
pwm controller setpoints can be tweaked a bit to squeeze out a couple more watts from the panel while remaining in the realm of battery manufacturer recommendation sanity
I do not consider AGM an "upgrade" in any normal sense: they cost 2x as much and have higher charge rate minimums (typically C/5) that solar-only charging struggles to meet. Yes, there are valid reasons to go AGM, and folks who boondock periodically between stays on shore power charging will probably be able to keep AGM healthy. Of course, used AGM are often found being sold after telco backup duties which takes the money issue out of the equation.

Randyretired · December 31, 2019

Solar can be very beneficial for boon dockers but sizing the array to ones expectations is important. Knowing how much solar is needed for the power requirements is necessary to avoid spending to much or being disappointed. In the past I have helped install solar on a couple of RV's only to have the owners disappointed because they expected more. It also seems wise to consider using larger than minimum for things like wire size and maybe even controllers so that simple additions are possible. We started out years ago with a 50 watt panel when solar was rare. It was expensive but it was good for our weekend fishing trips. Now we have 1060 watts and we are considering adding a little more.

oldjohnt · January 1, 2020

19 hours ago, Randyretired said:

We started out years ago with a 50 watt panel when solar was rare. It was expensive but it was good for our weekend fishing trips. Now we have 1060 watts and we are considering adding a little more

Randy, might it be said "great minds think alike" orrrrrrrr "even a blind squirrel finds a nut now n then" lol

I ask because that's almost the same thing I did. Yearssssssss ago before solar was considered by most folks I too started with a 50 Watt panel and a PWM controller and now years later I'm running 1080 Watts and an MPPT controller. I don't need more now because (for one my roof is full) in our small 29 Ft Class C with moderate energy requirements I can run all BUT AC , seldom discharge over 30% overnight, and often reach 100% SOC by mid morning. While my solar may be considered by some as excessive, as you well know if its rainy and cloudy for a few days and/or you're parked under full shade canopy, YOU NEED EXTRA SOLAR !!!!!!!!!!!

As said, any solar is good solar and more solar is better

Happy New Year

John T

Jack Mayer · January 1, 2020

John, what I usually advise people to do these days - on any but the most conservative, small systems - is to maximize the solar panels right from the start. Given the cost per watt of panels, and especially if you are DIY, you may as well cover your roof with panels and upgrade your controller(s) to handle the array size. Given the cost of the total job it in not much more, and you rarely find someone complaining they have too much power generation capacity. Of course, there are legit reasons not to do this - but for most people, it is something to be considered if you are going to the trouble of doing solar and actually intend to boondock.

Randyretired · January 1, 2020

Solar provides so much more while boon docking I find myself coming up with new things. We recently added a small freezer and now I am looking at a small mini split. Solar has come down in cost so much that it opens up things I never would have considered before. Jack's suggestion of maximizing panels from the start is good advise.

oldjohnt · January 2, 2020

8 hours ago, Randyretired said:

Jack's suggestion of maximizing panels from the start is good advise.

AMEN to that. Its how I have done myself and as I said MY LIMITED 29 FT OF ROOF SPACE IS FULL so I'm maxed out regardless lol. I've seen and read all about energy audits and that's all well and good and a necessity in good design HOWEVER its often one may encounter rain or clouds or shade cover for days on end (plus flat roof mounts cant be tilted to improve harvest) so maxing out the solar as Jack advised is a good plan and more battery energy storage and controllers, inverters etc. can be increased as needed.

9 hours ago, Jack Mayer said:

John, what I usually advise people to do these days - on any but the most conservative, small systems - is to maximize the solar panels right from the start.

Jack, you have much more experience then I do in this area (thanks for your past help) and FWIW I LIKE THAT advice.... especially as prices continue to drop.

John T In Avon Park currently not dry camped but will be in the future although with only modest energy requirements.

Edited January 2, 2020 by oldjohnt

jcussen · January 2, 2020

https://www.ebay.com/itm/10pcs-Solar-Panels-SunPower-327-Watts-High-Efficiency-Mono-Panels-327W/283633517947?epid=27022588460&hash=item4209e0057b:g:6ToAAOSw4xJdl6~B

$130 for a 327 watt high efficiency [20 %] delivered to your house. Back in the day, remember paying almost $2 a watt.

oldjohnt · January 2, 2020

jc, that's a good price for anyone needing ten used panels and 3270 watts of solar wooooo hooooooooo. In our area new ones with warranty are trending downward getting near 75 cents per watt, hey that ain't shabby. Believe it or not I buy mine from a nearby Amish supplier. Many of them are installing 4000 to 5000 watts on their roofs....

John T

jcussen · January 2, 2020

The guy I buy my solar equipment from, has 65 THOUSAND watts on his roof and arrays in his yard. He is grid tied, but his electric supplier will not buy his power, he only gets credits. But he does have rental properties and he can apply the credits to them.