How to tie solar into system with normal converter for battery charging.

TucsonAZ
TucsonAZ Solar Expert Posts: 139 ✭✭
in Caravan, Recreational Vehicle, and Marine Power Systems #1
I have a lot of experience with solar at this point thanks to all the help of the forum and diving in on a 1,400 watt install with my DIY RV two years ago.  This year I will be traveling in a class a with a generator and while I would like to go full solar I'm going to hold off until I know it's a good fit for my needs.  I picked up a small system with two 75w grid tie panels and a Flexmax 60 charge controller I've been thinking about tossing on it.  I figure if it doesn't fit my needs somebody will like having it on there and it's a spare system for me anyway.  So how would I tie it in as I have no experience with a system that isn't fully independent.  Can I just run it to the coach batteries and be all set and good to go or does it need to be further isolated from being charged by the generator and converter?

Thanks a lot!
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,626 admin
    #2
    I am not quite sure I understand your question... The simple answer is to wire the panels to the solar charge controller, and then wire the charge controller directly to the battery bank/battery bus (short heavy cables, through a fuse/circuit breaker on the positive lead).

    150 Watt array on an Outback Flexmate 60 charge controller is bit overkill (small array on a large MPPT type charge controller). Is this your final configuration--Or are you planning on a larger array later?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • littleharbor2
    littleharbor2 Solar Expert Posts: 2,113 ✭✭✭✭✭
    #3
    Please explain, "  two 75w grid tie panels " Are these Thin film high voltage, low amperage panels?

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric,  460 Ah. 24 volt LiFePo4 battery bank. Plenty of Baja Sea of Cortez sunshine.

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  • TucsonAZ
    TucsonAZ Solar Expert Posts: 139 ✭✭
    #4
    Yeah, 150 watts on the Flexmax 60 is a little overkill but it's the spare controller I have floating around.  So it's either install my main 1,840 watt system with 6,500 watt AGM battery bank or this.  Given the time, roof space, and uncertainty if it will fit my needs before this trip I'm going to install this one as I don't have any real use for it.  

    These are Solar Frontier SC75-EX-B panels, they're 40.5V and 1.85amp max panels.  

    I guess my question is I'm going to add to AGM batteries to the front of the coach where they had the old house batteries.  As things sit I would assume they would get charged by the coaches converter/charger when plugged into shore power or running off the generator and by the vehicle alternator when driving down the road.  If I'm running the generator while driving are they being charged by both?  Is it okay for me to just run straight from the charge controller to the batteries in addition to those other two charging methods?  If I'm driving after the solar install are they being charged by all three?
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,626 admin
    #5
    Yes, all three sources will be charging your coach's converter+vehicle batteries. The device with the highest set point for charging will "win". But 150 Watt array (~10 amps charging) is not a lot (assuming you have a 200-400 AH+ @ 12 volt battery bank in the coach). Just set the charging points for the FM 60 you need, and let it go.

    If this bank is also the vehicle battery (engine, engine computer, vehicle radio, etc.)--I would suggest that you set 14.4 volts as the maximum. The vehicle electronics may not like 15-16+ volts when charging "cold" and/or equalizing the battery bank. Also, if AGM battery bank, usually 14.4 volts (at 75F) is about the maximum typically.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • TucsonAZ
    TucsonAZ Solar Expert Posts: 139 ✭✭
    #6
    Thank you VERY much for the help!  The battery bank is going to be about 150 amp hours so I figure 150 watts is just fine for what I need this trip.  Last adventure I was running a toaster over, micro, chest freezer, fans, device chargers and more but I was all solar and didn't have a generator.  If I stay with this rig I will do full solar with all 1,800 watts but I'm not going to take that step until I know I will have this thing for years to come.  The 150 watts will just help me be certain the batteries are getting topped off.  The house batteries are separate so no worry there.  I'm guessing I could even disconnect them so they aren't tied into the vehicles alternator.  
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  • oil pan 4
    oil pan 4 Solar Expert Posts: 767 ✭✭✭✭
    #7
    Usually vehicle electronics will tolerate 15 to 16 volts. That way if the alternator fails in a way that produces too much voltage usually 16 to 18 volts it doesn't fry every thing.

    Solar hybrid gasoline generator, 7kw gas, 180 watts of solar, Morningstar 15 amp MPPT, group 31 AGM, 900 watt kisae inverter.

    Solar roof top GMC suburban, a normal 3/4 ton suburban with 180 watts of panels on the roof and 10 amp genasun MPPT, 2000w samlex pure sine wave inverter, 12v gast and ARB air compressors.

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