Need some help. Small solar system.

Solar_lj
Solar_lj Registered Users Posts: 2
in Solar Beginners Corner #1
I got a hodge podge of stuff from a guy moving. The guy didn't have time to put everything together, so Now I am trying to make sure it all works together correctly and if not, what else do I need? I know it's not the best way to put together a system but I took a chance and I got a pretty good deal component wise so here is what I have.

2 solar panels rated at 280 watts/ 34.9 volts/7.8 amps
2 agm batteries, 12 volts, 100amp hours
Blue sky solar boost 2000e
Power inverter.

This is for a small solar generator that will power a tv and some other small things for a tailgate. So, 6 to 8 hours of runtime, maybe some small led lights, all powered off the batteries using the inverter.

So I am thinking I would keep the battery bank at 12 volts. (Unless someone has a good reason not too.). I want to connect the 2 panels in parallel. Which I am ok with.. Now these panels came with the bizlink junction box.
http://www.sunbolts.com/jb_std4.html#4P

I am not familiar with these connectors. Can someone tell me after I connect the panels in parallel, what types of wires/connectors to connect to the charge controller with this type of junction box? Has anyone used these before?

As for the charge controller, is it ok for the panels and system I am planning? If not, then do you have a suggestions?

Does anyone have any other recommendations or suggestions? At the very least I got a 2 nice batteries and a good inverter for emergency power even if I have to charge it every so often from a wall socket...

Thanks for the help !!!
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Comments

  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
    Re: Need some help. Small solar system.

    Welcome to he forum.

    Got aspirin? :p

    Those panels would work fine for 12 Volts using an MPPT type controller. They would also work on a 24 Volt system using either PWM controller or MPPT controller.

    Unfortunately the Blue Sky controller will not work with them because its maximum input Voltage is 30 Voc and the panels' Vmp is 34.9.

    So you will have to get a different controller, no matter what.

    Your junction box image doesn't show any connectors, just squeeze-tight fittings for wires to go through and connect inside. Probably solder-type connectors inside, maybe screw terminals. You could buy some standard MC4 cables to fit to them: http://www.solar-electric.com/incaforsoelp.html One 'jumper cable' per panel, cut in half, attach the cut ends inside the junction boxes. Then you have the industry standard PV wiring connectors.

    Now about that battery you haven't got. The two 280 Watt panels could support 360 Amp hours @ 12 Volts using MPPT controller or about 150 Amp hours @ 24 Volts using a PWM controller. You have some options.

    What sort of inverter do you have or have you not purchased one yet?
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  • Solar_lj
    Solar_lj Registered Users Posts: 2
    #3
    Re: Need some help. Small solar system.

    Thank you for the information!! I'll start looking for a charge controller that will work. Any suggestions on one would be appreciated.

    As for the inverter, one came with it and its a cobra, 1500 watt continuous, 3000 watt peak. I looked it up on amazon and its this one.

    http://www.amazon.com/Cobra-CPI-1575-Power-Inverter/dp/B00126IDDC/ref=sr_1_1?ie=UTF8&qid=1359855975&sr=8-1&keywords=Cobra+15000+watt+3000+inverter

    As for batteries, it looks like I can add to the ones I got, but would I need to right away?

    Thanks again for the help!
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #4
    Re: Need some help. Small solar system.

    The Cobra inverter is an MSW type, meaning its output waveform is not suitable for everything. It may throw up some interference in your TV.

    Now from 200 Amp hours of battery you could expect a maximum of about 1kW hour AC run time, at which point the batteries would be 50% discharged (assuming no charging while in use). You can run your TV (and anything else you were thinking of powering with the inverter) through a Kill-A-Watt meter and get a real idea of how much power it will use over time. That will tell you how long the batteries alone can support your loads.

    You do not have to increase the battery capacity now, as the 30 to 36 Amps of charge current can be regulated to less to prevent too much current to the batteries. One problem you have here is that the best charge controller for this particular application is no longer in production. Rogue is promising a new 30 Amp MPPT controller soon, so is MidNite. At the moment the smallest one is a 15 Amp Morningstar unit which is a bit small but one panel could power it to the max and 15 Amps on 200 Amp hours would work, especially for an occasional use system. The next size up is the Morningstar 45 Amp MPPT. You can look over the specs for both here: http://www.solar-electric.com/admpchco.html

    So you could use one panel with the 15 Amp controller and keep the 200 Amp hours @ 12 Volts charged, or you could plan for further expansion and buy a bigger charge controller. It will help a lot to figure out how much load you're needing to supply and under what conditions.
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