Small Solar System

Posted by 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.

Posted by Tom Mayrand on September 08, 2008, 10:13:32 AM

Re: Small Solar System (Reply #11)

Patrick, take a look at the "Learn" section here. It has a wire chart that will help you determine the gage wire you need and how far you can run it base on the amount of amps you are drawing or you can find one easily online.
You mention you will grow your system. You may also consider using smaller dedicated systems, somewhat like what you have now, to operate specific loads. That way there if you purchase panels in the future, and they are not compatable, you can hook the two systems up separately and reliablity goes up.
As far as the 230 pump goes, it is 3/4 HP, so 750 Watt/HP x .75 HP = 570 Watt and 570 Watt/ 230 V =2.5 amp. Or 570/12 V = 47 amp. Look for a metal tag on the pump itself. It should have the specs there. There may be a surge or startup current that is a little higher than this. This would translate into approximately 1/2 hr to 45 min max that you can operate this pump without degrading the battery.
Then it would take your current setup of 10 amps at 12 volts approximately 8-10 hrs to recharge the loss on the battery.
Hooking up your batteries in parallel is the same deal as the panels, all the negatives and all the positives connected. There may be some battery diagrams here in the learn section. Start with the ground connection then neg then pos. This way here there is alway a connection to ground while wiring and hopefully and current will go that way first.

« Last Edit: September 08, 2008, 10:44:13 AM by Tom Mayrand »

Posted by Patrick Guenette on September 08, 2008, 11:38:12 AM

Re: Small Solar System (Reply #12)

Uhoh..now you just scared me!

You have to ground the batteries??

The only ground anywhere in the whole system is on the inverter. The solar panels are plastic everywhere except for the glass and the 2 wires coming out (1pos and 1 neg). - No ground wire and no metal pieces to attach a ground wire to.

Plastic charge controller also has no ground. - Only has 4 receptacles. (1pos and 1neg for solar array and 1pos and 1neg for battery connection).

When I read the instructions in the book that came with solar panels, it never mentions any grounding...

Batteries have 2 connectors each (1pos and 1neg)... So where/how do I ground them?? If I connect neg to neg and then pos to pos, will I get electrocuted? (sorry if this sounds stupid)

Thanks,
Patrick

Posted by Tom Mayrand on September 08, 2008, 11:56:11 AM

Re: Small Solar System (Reply #13)

Patrick, in the grand scheme of things, your system is small so major damage from a lot of power is not to big a deal. If the inverter has a ground then just use that. All other component are connected so they too are somewhat grounded. The gound is an emergency negative so you would probably hook up any grounding lines to the neg. If you cannot find information here, Home Power Magazine has a lot of schematics you can look at.
You can also/should install circuit breakers or fuses in line anywhere you think a surge may occur to protect any equipment. Shut offs or disconnects are something to consider also, especially in larger systems.

Posted by Romeo Archie on September 08, 2008, 11:12:23 PM

Re: Small Solar System (Reply #14)

Hello Patrick, you need to install your equipment according to code rules. This would provide the safety necessary for your installation. Your concern about the high current drawn on the batteries is valid. You have to do a little math in balancing your system so it works propperly.

Where will the system be installed? Fixed residential? Portable remote locations?

Does your inverter have a floating NEUTRAL?

Your inverter (3000 watts) cannot be loaded to its maximum rating for a prolong time. I would suggest you limit your maximum load to 80 percent capacity (2400 watts).

Your calculation regarding currend drawn is correct and is not a problem once you install the devices in the propper enclosure and use the propper size of conductors required to handle the amperage drawn. Visit your local electrical supply store for the propper equipment required. Correct fuse sizes for circuit protection is required. Locate the inverter as close as possible to the battery bank. Extreme care should be exercised in connecting batteries to the inverter. A shorted battery can deliver very high currents (1000 amps).

The 24.4 volts DC you measured is the open circuit voltage of the panel (no load connected)check panel specifications.

I realize you are embarking on a project with limited knowledge. I would suggest you do some reading on the subject to expand your knowledge base. Take your time and do it right. Be cautious in your approach, electricity KILLS! Install acccording to electrical code rules.

Regards, Romeo

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