DIY Solar Panels

[91cavgt]

It would be for watering the yard, and it would probably run for about 1 1/2 to 2 hours at a time.

It depends on the power consumption of the motor as to how large of a setup you would need. Do you have any idea how much power it consumes?

[91cavgt]

David, you don't have a 30A+ charge controller to part with do you? I am just about to have a 145w panel (I'm building) in service on the shop!

Is it a 12 volt panel or a 24 volt panel?



I've got a 30 amp PWM charge controller at the cabin but it is designed for 12 volt panels. Right now it is connected to a single 18 watt panel on the shed that is charging a 14 amp/hr battery bank. Basically it is just setup to run all of the 12 volt stuff in the cabin. If you have a smaller charge controller you could swap the big one out for then you could use my 30 amp one.

[Brazos Hunter]

Is it a 12 volt panel or a 24 volt panel?



I've got a 30 amp PWM charge controller at the cabin but it is designed for 12 volt panels. Right now it is connected to a single 18 watt panel on the shed that is charging a 14 amp/hr battery bank. Basically it is just setup to run all of the 12 volt stuff in the cabin. If you have a smaller charge controller you could swap the big one out for then you could use my 30 amp one.

It is 12 volt. I don't have a smaller one not being used right now. I could pick up one from HF and switch it out when I can get over there. I have the other three panels, controler, single red battery, and the 350 watt inverter kepping my radios going and a fan. I plan to connect the 145 watt panel to the two grey batteries and the 1k watt inverter. Thanks Dave! The next time you are down or we are your way we will shop for me one to order.

[Brazos Hunter]

Is this one yours? If so, I'll just order it.

http://www.ebay.com/itm/30A-AMP-Solar-Charge-Controller-PWM-For-12V-Volt-24V-Solar-Panel-Battery-PV-/201031261922?pt=LH_DefaultDomain_0&hash=item2ece659ee2

[91cavgt]

Is this one yours? If so, I'll just order it.

http://www.ebay.com/itm/30A-AMP-Sola...item2ece659ee2

Nope, this is the one that is at the cabin now;

http://www.ebay.com/itm/Sunforce-600...item233a28428b

[Brazos Hunter]

Nope, this is the one that is at the cabin now;

http://www.ebay.com/itm/Sunforce-600...item233a28428b

[clffrdfdge]

subscribed

[91cavgt]

I realized I didn't cover the amp/hr ratings very much on the batteries so let me explain a bit more.

To refresh, the most common battery rating is the AMP-HOUR RATING. This is a unit of measurement for battery capacity, obtained by multiplying a current flow in amperes by the time in hours of discharge. (Example: A battery which delivers 5 amps for 20 hours delivers 5 amps times 20 hours, or 100 amp/hr. So a 100 amp/hr battery can only supply 5 amps of current over a 20 hour period before the battery voltage gets down to 10.6 volts which is the maximum discharge a battery should ever be brought down to.)

But what happens if my 100 amp/hr battery is used in a system where more than 5 amps is drawn from it? If 10 amps are drawn from it, will it last for 10 hours? No. When a load is put on a battery that is greater than it's standard then a battery will discharge quicker. If 10 amps are drawn from a 100 amp/hr battery then it will only last about 8 hours before dropping to the minimum 10.6 volts.

So what happens if I draw less than 5 amps from a 100 amp/hr battery? How long will the battery last if it only has a 2.5 amp draw? Will the battery last for 40 hours? No, it will last for longer than 40 hours!! It should last for 45-50 hours before dropping to the 10.6 volt minimum.

So this is why it is always better to go with a larger battery bank then what you think you may need. A slightly over sized battery bank will last for MANY hours longer than a slightly under sized battery bank.


It is also a good idea to keep a battery charger on hand in case the battery voltage does drop, unexpectedly(like if a tropical storm blocks out the sun for a week). It is always a good idea to have a backup plan for recharging a battery bank. If you have grid power close by then a battery charger will do fine for a backup charger. However, like at the lease where there may not be any power you can always use the 12 volt outlet on a generator, or you can use a set of jumper cables connected to a running vehicle to quickly recharge a battery bank. For the ultimate in charging a battery bank in cloudy conditions would be a small wind turbine. Rarely ever is it cloudy AND there not be any wind.

[91cavgt]

I'm too tired to type out the next discussion topic, but if I don't put it down here then I'll forget about it. So, the next topic I'll be discussing is how your electrical connections effect your solar panel setup, and how to do a proper electrical connection. Here's a hint, it's not wire nuts!!

[Brazos Hunter]

I'm too tired to type out the next discussion topic, but if I don't put it down here then I'll forget about it. So, the next topic I'll be discussing is how your electrical connections effect your solar panel setup, and how to do a proper electrical connection. Here's a hint, it's not wire nuts!!

Good writeup and points brother!

[Tilladaddy]

I'm too tired to type out the next discussion topic, but if I don't put it down here then I'll forget about it. So, the next topic I'll be discussing is how your electrical connections effect your solar panel setup, and how to do a proper electrical connection. Here's a hint, it's not wire nuts!!

Is soldering the best method?

[91cavgt]

Is soldering the best method?

Yes it is.




So why can't I use wire nuts to connect the electrical on a solar setup? It works just fine for home electrical use.


In home electrical wiring, all the wiring is protected from the elements by being inside of walls, and this wiring is not subjected to vibration or movement so wire nuts work just fine.

However, when you are dealing with wiring that is outside, in the elements, and is subjected to vibrations and movement, wire nuts can not do an effective job. The vibration alone could cause the wire nuts to come loose over time, but the biggest concern is for corrosion caused by the elements. Corrosion to bare wire causes an increase in the resistance of the wire. This means that the power you are trying to pass through the wire will be diminished because the corrosion is resisting the flow of electricity through the wire. If you have ever seen copper wire turn a greenish brown on the ends where the insulation has been stripped back then you have seen wire corrosion.

So how do you stop wire corrosion from happening? Well, you have to effectively shield the wire connections from the elements.

I can wrap a whole bunch of electrical tape around twisted wires and it'll work just as good as any kind of soldering, right? Wrong.


Wrapping electrical tape does keep the water out, but not the air out(which has moisture in it) and so, your wire will still fall victim to corrosion. The only true way to prevent corrosion in your connections is to solder them, then wrap the soldered wires in heat shrink tubing, or worst case scenario wrap the soldered wires good in electrical tape.


But I don't know how to solder.


Relax, it is easier than it sounds. Here is the best way to solder wires together. First thing to do is to strip about 3/8" of insulation off of the ends of the wires. DOUBLE CHECK YOUR POLARITY OF THE WIRES!!! Bad things can happen when DC polarity is crossed. Take a piece of 2" heat shrink and slide it down one of the wires. We will need it later, but it has to be put on the wire right now. Now take the 2 wires to be soldered together and twist the wires together. There is an art to this which is very difficult for me to explain (maybe someone else who is not on pain meds can jump in and help to explain how to twist wires together before soldering?).

So, after you have the wires twisted together you need to get your soldering iron and solder. Make sure to let your soldering iron get fully up to temp before trying to solder. So once the soldering iron is up to temp, touch the iron to the bare wires that have been twisted together. You want to get the wires hot to allow the solder to flow through and around the wires. Now, begin touching the solder to the wires, NOT THE SOLDERING IRON!!!! Once the wires are hot enough, the solder will instantly melt into the wires and get deep in to the twisted strands of wire which will provide a good electrical connection.

If you put the solder on the iron and then touch the iron to the wires, you will end up with what is called a cold solder joint. This will not protect the wires from corrosion and it will not help in transferring power from one wire to the other.

After the wires are soldered together, take the heat shrink that we put on one of the wires earlier and slide it over the soldered wires. You may have to let the solder and wires cool for a few minutes before sliding the heat shrink as it might prematurely start to shrink due to the heat. So after you have the heat shrink in position, use a heat source to cause the heat shrink to shrink around the wires. Stop applying heat when you start to see a bit of plastic melting out of the ends of the heat shrink. This to takes some practice to get it right.

[91cavgt]

I forgot to discuss how a bad electrical connection effects your solar setup.


So, let's say that the electrical connection at the solar panel is out in the elements, and when it was installed, the installer just wrapped the wires together and wrapped it all up in electrical tape. For arguments sake, we will say that you are using a single 50 watt solar panel to recharge your RV batteries. A 50 watt panel will put out around 2.8 amps in direct sunlight.

Corrosion in the wiring will act like using wiring that is too small for the job. So, if you have a bad connection, it will work perfectly fine for a short period of time, but once corrosion sets in, your 2.8 amps in direct sunlight will start to decrease. Before long, that 2.8 amps will have dropped off to only 2 amps. As time goes by, that 2 amps will keep dropping as corrosion gets worse. Eventually, you may only get 0.5 amps out of the solar panel, and that is not enough to keep 2 batteries charged even if you only use your RV once a month.

This is why a proper electrical connection is imperative. If you skimp out in this area, it doesn't matter if you have 5,000 watts of solar panels, the power those panels put out will be dramatically decreased to the point where it either won't be producing enough power to be worth it, or if you have a LOT of solar panel power, it is possible that the wiring could catch on fire.

[91cavgt]

Does anyone have any questions?

[Texas Grown]

Good info so far!

As for battery life, I have heard that if a battery is partially drained without immediate recharging, it looses some recharge capacity, such as in a car battery. And batteries of such should be recharged every thirty days to maintain capacity. Is this true?