Small Solar System

Posted by Patrick Guenette on September 09, 2008, 11:15:33 AM

So I went ahead and did the installation (very carefully!).

Have the 2 batteries connected in parallel, connected to the inverter and connected to the charge controller. Charge controller is connected to 8 of the panels via junction box.

I'm using 6 gauge "solid" wire to and from the solar panels to the charge controller, and the same wire to the batteries.

Using 4 gauge "battery cable" to connect the batteries in parallel and to the inverter. The 4 gauge wires are 12 inches long from battery to batter and 24 inches long from battery to inverter.

No fuse or breaker on the positive cable from the battery to the inverter yet. - Any suggestions as to where I could get one? Went to various hardware stores (home depot etc) and none of them had a 250 amp fuse/breaker for 4 gauge wire.

The 6 gauge wire (it's actually "Heater" wire apparently, and it's rated for 20amps at 110v) is about 25 feet long and the wires coming out of the solar panels are 12 feet long. So that makes the total length from the panel to the inverter about 37 feet. - With this gauge wire, am I losing very much efficiency?

It's raining here today (no sun), but I put 4 of the 8 panels outside, just flat, not pointing in any particular direction (did this at 9am), and the charge controller is displaying 00.3 amps. So each of the panels is generating 0.075amps lol. Hope that is due to the rain and not the cable lenght. They are rated at 15watts - 1amp @ 12v.

Charge controller indicates the batteries are fully charged and is indicating "trickle charge". So that seems to be working.

Also tried the inverter. Plugged in a laptop power supply into the inverter, turned it on, and then turned on the laptop (took battery out of laptop). - Laptop booted up fine. So that seems to be working!

Won't use heavier loads until I get a breaker/fuse and more panels, figured testing a 50w laptop (4.1amps at 12v) would not pose too much of a risk with the 4 gauge cable.

Now if I make my system 30 times bigger, I can get off the grid!! lol

Thanks to all those who replied with help.
Patrick

Posted by John B on September 09, 2008, 11:19:42 AM

Re: Small Solar System (Reply #16)

Quote from: ken hall on September 08, 2008, 02:15:42 AM

230V ac is two phases of 115V that are 180 degrees out of phase to each other. A transformer will not solve the problem.
You could do it with two piggy backed inverters.
But you might find it cheaper to change the motor/pump.

Actually a 120/240 step-up transformer will work just fine. I have one (Outback X-240) running my 1HP well pump and 1HP pool pump.

If he opens the connection to the pump it is very likely that it has an option inside to be wired either for 240V or 120V. Note that 230V and 240V is within the same tolerance and can be used interchangeably.

My 1HP pumps use about 1200 watts when running (10 amps at 120V or 5 amps at 240V) with about one-and-a-half times that at start-up, so I would estimate that his 3/4HP pump would probably draw around 8 amps continuous at 120V or 80amps at 12V from the batteries.

As for the rest of the advice, I'm inclined to advise Patrick to go back to the drawing board. Perhaps he can get Canadian Tire to exchange those ten 15watt panels for a single 150watt panel or two 75watt panels. Those 15 watt panels were designed for trickle charging batteries and he will only give himself a headache trying to build a system 15 watts at a time.

Posted by Patrick Guenette on September 09, 2008, 11:35:55 AM

Re: Small Solar System (Reply #17)

Hey John, thanks. I will see about getting a step up transformer.

The reason for the small panels to start was cost;

Canadian tire had these panels on sale at $69 each. They also had a 30W panel for $329!! And an 80w panel (biggest one they had) for $999!!

So I figured I could get 150w for $690, instead of paying $658 for 60 watts, or $999 for 80w.

Posted by John B on September 09, 2008, 12:09:45 PM

Re: Small Solar System (Reply #18)

$4.60 per watt is not a bad price for less than 200 watts, but as your system expands you want to be sure that the panels you add on will have the same specs as the original panels otherwise you will need to add a new charge controller for each new type of panel that you add on to your system.

A 15 watt ungrounded panel is not much of a hazard when it is the only source of power, but when it is included into a system where power may be fed back to that panel in a fault situation then you have a problem because you are violating electrical codes that are in place for your own safety.

Posted by Patrick Guenette on September 09, 2008, 02:57:59 PM

Re: Small Solar System (Reply #19)

How do I ground the solar panel(s)? They are made of plastic....only thing coming out of them is a neg and pos wire... Do I connect a ground to the neg wire?

I called Motomaster (maker of the Eliminator panels I bought) and they just said "you don't need to ground them"

Also - This grounding issue got me thinking, when my batteries are full, and the charge controller stops them from being charged, where does the electricity go? It has what looks like a heat sink on it, so imagine it dissipates it through that in the form of heat, but what if it becomes too hot? Panels are generating it, it's going into the charge controller, but then what happens to it if it's not being fed to the batteries?

« Last Edit: September 09, 2008, 03:03:47 PM by Patrick Guenette »

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