Introduction: Portable Low Cost DIY Solar Panel Setup

Intro:

This $150 - $200 solar project is a great addition to the camping and road trip arsenal. Parts are readily available at your local hardware store or Canadian Tire. It takes an hour or two to build and the electrical is very simple so even the least handyman person can build one with ease. Let's get started!

Step 1: Gather Materials

Note most of the materials I bought were on sale at Canadian tire, the store has frequent sales so don't rush to buy everything at once.

1 - Solar panel (I went with a 20 watt RV panel because it came with an aluminum frame that was easy to drill into and keeps the panel from bending)

1 - Sheet of wood cut down to the size of your panel yet thick enough to drive screws into

1 - PWM Solar Charge controller (I bought this off ebay for ~$10, I chose PWM because it is the cheaper option)

1 - Lead acid battery (I went with a 7.5 Ah battery but you could use any lead acid battery, even a car battery, I chose this one because of its weight and slim build)

1 - Power Inverter (I used a 400 Watt inverter so I can run appliances that can draw more current without going overkill and breaking the bank)

1 - Voltmeter (This measures how much electricity your solar panel is generating, it is wired in parallel with the panel)

10ft - 1/2 inch Steel strapping (Used to hold the battery and power inverter securely to the board)

10ft - 10-14 AWG stranded electrical wire (I had some lying around but when you buy some I would not go below 14AWG, you don't wanna cause a fire)

2 - Small Steel or Aluminum L brackets (size doesn't really matter but go with the width of your panel so it does not stick out too much)

2-4 - Hinges (go with a size that will fit nicely on your piece of wood and does not stick out)

Mounting hardware - so screws shorter than the width of your peice of wood.

Screwdriver, Drill, and that's about it!

Step 2: Mount Components

This is an easy step and all it requires is to screw in all the components into your sheet of wood. Align them level and screw in. Keep in mind that you will need room to run a wire from the Solar Charge Controller to the battery, voltmeter, and power inverter. Whatever you can't screw in bend the steel strapping tightly around the component and screw that in place.

Step 3: Attach Hinges and L Brackets

These may be screwed into the top of the sheet of wood anywhere, use a measuring tape to offset them the same amount from each side of the board. Make sure the hinges are straight. The hinges must be screwed into both the metal and the aluminum frame of the solar panel. Because it is aluminum you can use regular screws to secure it or use a machine screw and a nut on the other end for extra reliability. The L brackets must be bent to the angle you want your solar panel to sit at. Use a pair of pliers and experiment with this until you are satisfied.

Step 4: Electrical

Caution: Electricity can be dangerous, but since you're working at 12 volts it shouldn't be life threatening to the average healthy person with no metal implants or heart irregularities. Just make sure you connect red(+) to red(+) and black(-) to black(-) and you'll be fine. At no point in this, you should be connecting them together.

The charge controller has symbols that show you where to connect the solar panel, battery, and power inverter. I crimped on connectors to make the connections but all you have to do is twist the wire around the screw then screw it in.

Red and Black of Solar panel ==> + and - on charge controller solar panel section respectively

Red and Black of Battery ==> + and - on charge controller battery section

Red and Black of Power Inverter ==> + and - on charge controller load section

Red and Yellow of Voltmeter ==> + on charge controller solar panel section

Black of Voltmeter ==> - on charge controller solar panel section

Make sure there are no cuts in the wire insulation or wrong connections before plugging your panel in.

Comments

author
stadek (author)2017-07-11

CMP12 no PWM !!!!

author
DonnH1 (author)stadek2017-07-11

Hahahaha, interesting side note - no PWM. A few years ago I was camping up near Terrace BC and thought I'd go on the air with my ham radio gear to chat with local radio guys. I had never had my radio on in the day time before. At night there is no charging and so the charge controller wasn't doing anything. In the day the PWM pulses of the charge controller made it impossible to use my ham gear without disconnecting the solar panel. That was an interesting lesson learned. Not sure what to do about that. Maybe put a big capacitor bank across the feed to my radio and some sort of big iron choke in series with the power. Has anyone got any experience with that? Any good solutions to the whyne problem on the power?

author
stadek (author)DonnH12017-07-22

problem jest znany- konstrukcja większości regulatorow polega na odcinaniu ladowania w dość wąskim zakresie co powoduje zakłócenia. Osobiście stosuje regulator MPPT i po naładowaniu akumulatora przechodzę na układ ze zwyklym stabilizatorem liniowy L200 plus tranzystor mocy. Oczywiście działa to automatycznie . Regulator PWM taki prawdziwy reguluje ładownie szerokością impulsu natomiast ten MC to taka prowizorka wręcz niebezpieczna bo zabezpieczona 15A bezpiecznikiem. Pisz na stadek@poczta.fm to podeślę Ci trochę więcej informacji

author
MikeD11 (author)2017-07-11

7.5 amp hour battery means it will supply 12V at 7.5 amp for an hour. Volts times Amps is power in watts so that is 12 x 7.5 = 90 watts(W). So with a 20W solar panel the battery will take roughly 90/20 = 4.5 hours of full sun to charge. Your 400W inverter if fully loaded will totally drain the battery in 90/400 = 0.22 hours or 13.5 minutes. I just want people to know that this system would be good to charge their cel phone but won't run any electrical appliance for long.

author

Thanks for the insight Mike, could this simply be solved by adding more batteries to increase Amp Hours? I have access to about 1000 12v7ah batteries and was thinking of placing clusters of them around my farm that I could hook this sort of unit up to (except I was imagining 250w panels).

author

Are these UPS batteries? I'm not up on my batteries but everything I've read so far has put those batteries as not the most desirable batteries for solar as they are quick discharge batteries and not deep cycle batteries. Please don't quote me on that, I have about a dozen or so UPS batteries that I haven't bothered with due to this. I opted for deep cycle marine batteries in my project. (still in pieces and not running completely yet).

author

Yes, You have 70,000W of batterys. Say you get 6 hours of sun a day. That's 70,000/6 = 11,666W per hour of solar cells needed to fully charge the batteries. Using 250W panels means you need 47 panels. To buy this much electricity from the power company is 70KW x 11 cents per KWH or $7.70 per day (yes everyone thinks they'll save their whole electric bill!). If you live up north you won't get as much power out and if it's cloudy you'll get 10%.

author
hyjynx (author)MikeD112017-07-11

MikeD11, I agree with your figures....Kwh is much higher here in the Desert, and we get much more sunlight year around. I'm planning on using Harbor Freights 45 watt panels (3 in a panel) and charge manager with a 750 amp hour deep cycle battery to run security lights on my 1/2 acre. The batteries are about $100 apiece but will last 3 yrs, and with LED security lights will save a lot considering we pay a penalty for use of AC during summer months.

author
chingada (author)2017-07-12

Nice cool project but need some accurate calculations for better performance instead of a CMP-12 for a little bit more you can get a programmable one for settings to play with .

author
maewert (author)2017-07-11

Very nice!
Is your Charge Controller too small for your inverter? The CMP12 has a 10 amp maximum current and a 400 watt inverter would draw as much as 33 amps, wouldn't it? I think you'll be fine if you keep the inverter draw less than 120 watts.

Best Wishes!

author

Thanks Maewert, how can you tell how much an inverter draws in amps?

author

I just used math to estimate that at best if your inverter is supplying its maximum 400 watts, then the draw on your 12v battery should be 33.3 amps (P=IV). Usually the inverter is maybe 90% efficient (or less) so the real current would be even higher. If you try to draw more current than 10 amps, hopefully the charge controller won't fry but will simply limit to 10 amps... and the inverter maybe will beep a warning or at least indicate on its LEDs that the source is insufficient.

You can measure the current draw on the battery with a multimeter but most can only measure up to 10 Amps or less. Here is one link on how you can measure higher currents using a shunt: https://mycontraption.com/measuring-current-withou...

(On my system on my van (https://www.instructables.com/id/Mobile-Solar-Powe..., I wired my inverter directly to the battery but doing this you lose the nice battery protection functions that the controller provides like disconnecting the load if the battery gets too low.)

Best Wishes

author

400 watts divided by 12 volts is 33.33 amps.
You can check this chart to see what size wire you need for 33 amps.
http://www.allfordmustangs.com/forums/attachments/...

Then on the output side, 400 watts divided by 120 volts is 3.33 amps.

The other thing to consider is that no inverter is 100% efficient, so if it's putting out 92% to 96% of what it takes in from the battery, you are doing good. So keep that in mind and oversize the input wires a bit to give yourself a safety margin.

Also, you should have a fuse somewhere inline on both the input and the output, in case of an accidental short circuit. Many inverters have an automatic circuit breaker built in, but make sure yours does. If not, you can get an inline fuse at any autoparts store.

author
FelixR2 (author)2017-07-11

You should consider using a bigger battery. You won't get more power from the solar panel, but you could run the inverter at full load for more than 10 minutes at a time.

author

: { In the Nineties I designed one of the first Solar System and let me tel you that your idea is good, but does not have enough power to deliver to the load. Simple Mat Calculation: 400W inverter 90/400 = .225 hours almost 15 minutes. If you lower the power of the inverter you could get more time, but less power. But if you increase the power of the inverter, then you have less time to runs full power to deliver at load and keep running electrical appliances....

In other words, your invention is good to solve with a pair of led bulbs, charge phones and do some solar experiments. You should consider the battery charge since in the past my first solar system that I myself design was of little power panel but the battery bank was fantastic and I worked for days, of course this, I myself design all the circuits, wirings and the inverters.

Sometimes I think that many Technological things of the past were better and had better performance, better functioning and duration; even I think that many of Electronic components and Electrical pieces from before were so much better in function and long duration that all these modern ones that are made to last a short time...

YOU DO NOT BELIEVE IT???
YOU DO NOT BELIEVE IT ALSO???
author

Inverters are rated at MAXIMUM load. If you are not using the full 400 watts, the inverter is not drawing 400 watts from the battery. and figuring you are only getting about 240 watt hours from the solar panel per day, you probably won't use 400 watts very often.

author
BP7 (author)2017-07-11

Solar wiring tip:

Keep all the low voltage wires short as possible, reduces losses.

Especially from battery to inverter.

author
GeraldM40 (author)2017-07-11

Don't forget sinewave clipping. That can ruin your day depending on what you run from the inverter

author
thatguyer (author)2017-07-11

Just a minor comment on the wording: saying "don't go below 14awg" might be misleading to people who don't realize that higher numbers are actually thinner wires

author
Radd28 (author)thatguyer2017-07-11

You are so right and I noticed right how that could be mistakend by someone that doesn't know.

author
stribout (author)2017-07-11

Just curious, hows the charging? What type of run time are you getting?

author
Augustny (author)2017-07-11

Nice! Thank you for sharing

author
Patel Darshil (author)2017-07-07

Excellent!!!!!!!!

author
BeachsideHank (author)2017-06-30

Drop in the local big box store, go to the lumber section and pull the plastic strapping from the trash, they're happy to see it gone and it's incredibly tough and strong too- and free! ☺

author
Swansong (author)2017-06-29

That's a neat build :)

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