Helping another off-gridder

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  • stephendv
    stephendv Solar Expert Posts: 1,571 ✭✭
    #32
    Re: Helping another off-gridder
    BB. wrote: »
    I would stick with the MPPT type controller. Vmp 30 volt panels are just too low of voltage for charging a 24 volt battery bank.

    Yeah, but bear in mind he has a whole other 1.7kW of PV power on the western roof to complete absorb and EQ. These 3 panels on the eastern roof are just to boost bulk and get some power in earlier in the day.
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  • Surfpath
    Surfpath Solar Expert Posts: 468 ✭✭✭
    #33
    Re: Helping another off-gridder
    stephendv wrote: »
    Yeah, but bear in mind he has a whole other 1.7kW of PV power on the western roof to complete absorb and EQ. These 3 panels on the eastern roof are just to boost bulk and get some power in earlier in the day.

    Stephen,
    I thought about this as well and have prepared him a 'PWM' quote, just in case. See below.

    But equipment is hard to get here quickly and I see the MPPT Kid controller as a back up in case the SB goes kaput. The Kid can handle the old (12v) panels if the bank had to be temporarily charged, while a PWM would struggle a bit.

    Plus I think the the Kid is an easier bit of kit for him to "read." A lot of the PWM controllers have poor or no LCD readouts (IMO). But yes, they are cheaper.

    One other factor which I did not mention before is that he is purchasing a lot of GT panels for another GT project. So for him to add 3 more of the same panels is a bit of a convenience. But you would have not known this. By the way, Your Sunny experience has been really useful. I am sure that I will have a few more questions before his refit is over.:roll:

    SP


    *PWM Quote:

    Here is a reliable PWM controller as a comparison ($170) Doesn’t have a meter/readout – has LED lights:
    http://www.solar-electric.com/trts12vochco.html

    Another one (same company). This one has a digital meter, but less amps:
    http://www.solar-electric.com/inverters-controllers-accessories/chco/mochco/stpwmchco/ps-30m.html

    If you went with the PWM Controller you would need 2 or 3 of these 72 cell panels (VMP=35.76v) in one series (ie 570 or 855 watts for 2 or 3 panels depending on the controller).
    Outback Flexpower 1 (FM80, VFX3048E-230v, Mate, FlexNetDC) 2,730watts of "Grid-type" PV, 370 AmpHrs Trojan RE-B's, Honda 2000 watt genny, 100% off grid.
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  • Surfpath
    Surfpath Solar Expert Posts: 468 ✭✭✭
    #34
    Re: Helping another off-gridder
    BB. wrote: »
    You might want to put a switch/circuit breaker on the PV wiring if the owner ever wants to turn off the array to service/reboot the MPPT charge controller. One of those "nice to have options".-Bill

    Good suggestion Bill
    Something like this will do?
    http://www.solar-electric.com/blseabaswon3.html
    Outback Flexpower 1 (FM80, VFX3048E-230v, Mate, FlexNetDC) 2,730watts of "Grid-type" PV, 370 AmpHrs Trojan RE-B's, Honda 2000 watt genny, 100% off grid.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #35
    Re: Helping another off-gridder

    Would be fine... You can also get DIN Rail breakers for much less money:

    http://www.solar-electric.com/midnite-solar-mnepv-20-amps-circuit-breaker.html

    Or just get a good quality marine switch (over rated for current--Many "cheap" switches/fuses/etc. will fail if operated near rated current for long periods of time).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Surfpath
    Surfpath Solar Expert Posts: 468 ✭✭✭
    #36
    Re: Helping another off-gridder

    An update regarding my friend's system:

    He received a build estimate from the proposed installer. Here is the main gear:

    "Sixteen rolls S-530 batteries, twelve 12 LG 300W nano panels (these I think - specs here), and two 80/600 MPPT Conex charge controllers."

    Basically it seems like a completely new system. Big bucks. What on earth does he do with his old Sunny system now? He has reasonable loads Maybe 3.5 to 4.5 kwh/day.

    I see no mention of an inverter. Does any of this gear play with his Sunny Island.

    Anyway, this seems over the top. For the price of just one of those charge controllers ($1,000 us) he could meet his needs by adding 600-800 watts of PV on his Eastern roof and the midnite kid to his existing 3-5 year old Sunny system. An 8 battery L-16 bank would also suffice.

    One has to expect a bit of equipment "add-on" from an installer though, but come on.
    Outback Flexpower 1 (FM80, VFX3048E-230v, Mate, FlexNetDC) 2,730watts of "Grid-type" PV, 370 AmpHrs Trojan RE-B's, Honda 2000 watt genny, 100% off grid.
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  • Surfpath
    Surfpath Solar Expert Posts: 468 ✭✭✭
    #37
    Re: Helping another off-gridder

    four of those 554 amp hr 6volt Surrette batteries x 4 series = 2216 amp hrs of bank on a 24v system- that's nuts.
    Outback Flexpower 1 (FM80, VFX3048E-230v, Mate, FlexNetDC) 2,730watts of "Grid-type" PV, 370 AmpHrs Trojan RE-B's, Honda 2000 watt genny, 100% off grid.
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  • Aguarancher
    Aguarancher Solar Expert Posts: 315 ✭✭✭
    #38
    Re: Helping another off-gridder

    It seems they are set for 48v by default. Couldn't read the specs on your link so I found them in a round about way here.

    http://webcache.googleusercontent.com/search?q=cache:I3hJNw-gwDUJ:solar.schneider-electric.com/wp-content/uploads/2014/08/Conext-MPPT80600-Datasheet-DS20140811_ENG.pdf+&cd=1&hl=en&ct=clnk&gl=us
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  • Surfpath
    Surfpath Solar Expert Posts: 468 ✭✭✭
    #39
    Re: Helping another off-gridder
    Aguarancher wrote: »
    It seems they are set for 48v by default. Couldn't read the specs on your link so I found them in a round about way here.

    http://webcache.googleusercontent.com/search?q=cache:I3hJNw-gwDUJ:solar.schneider-electric.com/wp-content/uploads/2014/08/Conext-MPPT80600-Datasheet-DS20140811_ENG.pdf+&cd=1&hl=en&ct=clnk&gl=us

    Hi Aguarancher,
    The link you have above is for the Conex controller. If you are referring to the panels, appears the installer quoted grid tied type panels (32 Vmp, 10.5 Isc) - which would work for any bank with an mppt controller. Nonetheless, I agree that 48v would be the better way to go with a 3200watt array.

    However my instinct tells me that 3200w wont meet the 10% charge rate for those 16 Surrettes in any configuration.

    Here's my stab for the 10% charge rate:

    24 volts * 1712 AH * 1/0.77 panel+controller derate * 0.10 rate of charge = 5,336 watt watts array for a 10% rate of charge
    48 volts * 856 AH * 1/0.77 derate * 0.10 rate of charge = same 5,336 watts
    Outback Flexpower 1 (FM80, VFX3048E-230v, Mate, FlexNetDC) 2,730watts of "Grid-type" PV, 370 AmpHrs Trojan RE-B's, Honda 2000 watt genny, 100% off grid.
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  • Aguarancher
    Aguarancher Solar Expert Posts: 315 ✭✭✭
    #40
    Re: Helping another off-gridder

    It seems as though that controller can handle 4800 watts of panel input @ 48v battery bank, so only one controller is req. for that amount of panel? It can only take 2560watts of panel on a 24v bank according to the spec sheet.
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  • stephendv
    stephendv Solar Expert Posts: 1,571 ✭✭
    #41
    Re: Helping another off-gridder
    Surfpath wrote: »
    I see no mention of an inverter. Does any of this gear play with his Sunny Island.

    Anyway, this seems over the top. For the price of just one of those charge controllers ($1,000 us) he could meet his needs by adding 600-800 watts of PV on his Eastern roof and the midnite kid to his existing 3-5 year old Sunny system.

    He can install those conex charge controller and new panels with the "old" sunny island system, no problem. What's he going to do with the existing panels and sunny boy inverter?
    Agree that the Conex are not the right choice, he could go with the midnite classic's for a cheaper and IMO better system.
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  • Surfpath
    Surfpath Solar Expert Posts: 468 ✭✭✭
    #42
    Re: Helping another off-gridder
    stephendv wrote: »
    He can install those conex charge controller and new panels with the "old" sunny island system, no problem. What's he going to do with the existing panels and sunny boy inverter?
    Agree that the Conex are not the right choice, he could go with the midnite classic's for a cheaper and IMO better system.

    Stephendv,
    I slept on it and this morning realized that the 2 conex controllers & the additional 3200 watts of PV could charge the proposed new bank along with the 1800 existing watts and the Sunny Boy. Total of 5000 watts. I think he lists two inverters because he is leaving the Sunny Island to do the inverting, and that is fixed at 24v.

    Still, very expensive.

    If he halved his battery bank (8 Surrette's) and kept one Controller and added just 1200 watts of PV to his existing 1800 watt array (a total of 3000 watts), that would be more reasonable.

    24 volts * 856 AH * 1/0.77 panel+controller derate * 0.10 rate of charge = 2,668 watt watts array for a 10% rate of charge

    3000 watts would give him roughly a 12 -12.5% rate of charge.
    Outback Flexpower 1 (FM80, VFX3048E-230v, Mate, FlexNetDC) 2,730watts of "Grid-type" PV, 370 AmpHrs Trojan RE-B's, Honda 2000 watt genny, 100% off grid.
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