new guy to solar PV here in south florida, going "Off Grid"

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Logan5
Logan5 Solar Expert Posts: 32 ✭
in Solar Beginners Corner #1
hello to all. new here but not new to solar:
I inherited an old 75 watt solar panel nearly a decade ago. I have used it and 3X12amp hr SLA battery's for outside security lighting ever since. 2012 is the year I decided to create a solar battery backup system for my security cameras and DVR, that was done easily and relativity low cost, for the convenience of having 99.99% up time and some extra power for my laptop. at this point I concluded since I already bought an Outback FX80 as my charge controller, and I can purchase $1 a watt solar panels TAX FREE locally, including the fact I needed an awning over my outdoor work bench. I might as well continue to migrate my whole home off grid. My signature includes my basic system configuration. I plan to double the size of the system by spring, and I plan to run inverter-less for the long haul. I have spent weeks reading over the forum. I still have many questions about the OB FX80, Battery maintenance and ventilation, the benefits of running 24-48 volt system with step down converters. What to replace my 32"LED tv with that runs on DC or how to change the internal power supply on 110AC electronics. is the split cool DC18 still available and what are the other DC air conditioning options. I look forward to hearing from good people who care to talk.

Thanks, Logan...
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
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    Re: new guy to solar PV here in south florida, going "Off Grid"

    Welcome to the forum, Logan.

    What can we do to help?

    Well there's this bit about why you might pick one system Voltage over another: http://forum.solar-electric.com/showthread.php?15989-Battery-System-Voltages-and-equivalent-power

    There's the warning that going all DC may not be such a good idea as the lower Voltages involved will make V-drop a bigger issue the longer the wire runs have to be for any given current. The house is probably already wired for 240 VAC split phase, so why not use it? An inverter could possibly consume less power than you'd lose in the wiring.

    Trying to increase system size in stages is problematic but can be eased if you have an ultimate target (reduces the amount of redundant buying).

    The Outback FM80 is a fine charge controller indeed. Quite dependable and flexible with lots of neat features. :D

    Your 980 Watt array should be good for your 225 Amp hour 36 Volt batteries. Although 36 Volts is a bit odd (charging a golf cart are you? :p ).
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #3
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    Re: new guy to solar PV here in south florida, going "Off Grid"

    i'm a bit confused by coot's last 2 sentences as i did not see a reference to a 36v battery bank. those 3x12ah batteries are most likely parallel to act as a 36ah battery bank at 12v.

    edit to add-
    logan,
    the power requirements of the cameras may be fine with the small ah battery bank and pv, but you will not meet the needs of a dvr with your present arrangement. these often require 50-75w and running these 24/7 will kill a small battery bank quickly.

    logan,
    you should probably vie for a battery backed gt system rather than the effort to go off the grid entirely. this way you could sell to the utilities and still have power for an outage. i would make this new arrangement separate from the security arrangement. if the fm80 is currently being used for the security them i suggest putting the fm80 to use in the battery backed gt system and opt for a smaller controller for the security setup with the 80w pv. you can still use an mppt cc if you like and something like this could fit the bill and even have some room to expand upon it should you decide for more autonomy time.
    http://www.solar-electric.com/mosumpsochco.html

    i should mention that in order to size up a system, be it off grid or backup, is to know what the power requirements will be in either watt hours or kilowatt hours over a 24hr day.
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  • Logan5
    Logan5 Solar Expert Posts: 32 ✭
    #4
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    Re: new guy to solar PV here in south florida, going "Off Grid"
    Cariboocoot wrote: »
    Welcome to the forum, Logan.

    There's the warning that going all DC may not be such a good idea as the lower Voltages involved will make V-drop a bigger issue the longer the wire runs have to be for any given current. The house is probably already wired for 240 VAC split phase, so why not use it? An inverter could possibly consume less power than you'd lose in the wiring.

    *I am prepared to buy an inverter if I have to. but my plan it to run a 48 volt system so as to incorporate the Split cool DC18 by summer. my longest run is 60 feet of 10 awg @36v stepped down to 12v for kitchen lights and a variable PWM reversible controller for a window fan.

    Trying to increase system size in stages is problematic but can be eased if you have an ultimate target (reduces the amount of redundant buying).

    *I selected the components of my system for scalability. I already have incremental upgrades planned and foresee little redundant buying)

    The Outback FM80 is a fine charge controller indeed. Quite dependable and flexible with lots of neat features. :D

    *I am a bit baffled by the FX80 as I draw a constant load day and night, but I find in the middle of the day when I reach a fully charged state, the controller goes cold and stops providing power from the panels. meanwhile my entire load is drawn off the battery's and the solar is wasted. I find myself reengaging the controller. it goes into a quick tracking state and then continues to charge for the rest of the day.

    Your 980 Watt array should be good for your 225 Amp hour 36 Volt batteries. Although 36 Volts is a bit odd (charging a golf cart are you? :p ).

    *I purchased the panels one at a time and the battery's in pairs. 4 panels is max on a single string so my next purchase will have to be 2 panels for a total of 6 as there is no way to have 5 panels on this charger. when I add the next pair of battery's I will wire them as 2 banks of 24 volts since my current "bargain" step down regulators work from 20 to 40 volts. these will be replaced by summer with higher quality much more expensive isolated step down converters with an input range of 20 to 72 volts.

    If I do buy an inverter, I assume the units that work at higher input voltages are more efficient?
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  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    #5
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    Re: new guy to solar PV here in south florida, going "Off Grid"

    Niel, it's in his sig line...
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
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  • Logan5
    Logan5 Solar Expert Posts: 32 ✭
    #6
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    Re: new guy to solar PV here in south florida, going "Off Grid"

    Notice my previous post includes my reply in the quotes field. sorry.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #7
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    Re: new guy to solar PV here in south florida, going "Off Grid"

    oops, thanks for pointing that out.:roll:

    yes, that is an odd voltage. why the use of 36v?
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  • Logan5
    Logan5 Solar Expert Posts: 32 ✭
    #8
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    Re: new guy to solar PV here in south florida, going "Off Grid"

    I used a VDC watt meter to find the DVR and all the cameras, 2 channel Plus quad modulators and combiner amplifiers only use 23 watt's. The 19" TV that claims 36 watt's of power consumption on the back panel, actually only draws about 13 watt's
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #9
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    Re: new guy to solar PV here in south florida, going "Off Grid"
    Logan5 wrote: »
    *I purchased the panels one at a time and the battery's in pairs. 4 panels is max on a single string so my next purchase will have to be 2 panels for a total of 6 as there is no way to have 5 panels on this charger. when I add the next pair of battery's I will wire them as 2 banks of 24 volts since my current "bargain" step down regulators work from 20 to 40 volts. these will be replaced by summer with higher quality much more expensive isolated step down converters with an input range of 20 to 72 volts.

    If I do buy an inverter, I assume the units that work at higher input voltages are more efficient?

    Yes; in the short form as you go up in Voltage you can get the same Watts for less Amps, and Amps = power going to heat rather than work.

    Niel is perfectly correct that off-grid power comes with a steep price tag. Whatever your reasons for going off grid when you have utility power available economics isn't one of them. The grid-tie solar with battery back-up for emergency power makes more sense, but again none of it is cheap.
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  • Logan5
    Logan5 Solar Expert Posts: 32 ✭
    #10
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    Re: new guy to solar PV here in south florida, going "Off Grid"

    36v because I have 6X6 volt battery's when I get the next two I could go 48 volts but the step down regulators I am useing for this phase would need to be changed out otherwise I will back down to 24volt for the interim
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  • Logan5
    Logan5 Solar Expert Posts: 32 ✭
    #11
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    Re: new guy to solar PV here in south florida, going "Off Grid"

    I am on grid till I take incremental measures to eliminate it. but will always be there as an option for emergency charging, to prevent from losing my occupancy permit. to run the super pump on the Jacuzzi, or even running the compressor in the garage. I just don't want to be dependent on the power grid and cost is much less of a concern than energy independence.
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  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    #12
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    Re: new guy to solar PV here in south florida, going "Off Grid"
    Logan5 wrote: »
    The 19" TV that claims 36 watt's of power consumption on the back panel, actually only draws about 13 watt's

    yes without that conversion from 110 to 12 or ??Volts there are power savings to be had. Our Toshiba 19" uses 23w on 110 but with a PFC of .49 so it is really sucking out ~ 45w from the batteries! Once off warranty I'll hack it to give it DC straight.
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #13
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    Re: new guy to solar PV here in south florida, going "Off Grid"
    westbranch wrote: »
    Our Toshiba 19" uses 23w on 110 but with a PFC of .49 so it is really sucking out ~ 45w from the batteries!

    Excluding whatever the inverter is using to run its electronics--Your batteries should be supplying:

    23 watts * 1/0.85 inverter eff = ~27 watts (+ whatever the inverter Tier losses are--usually around 6-30 watts, depending on inverter)

    Poor Power factor should not up the DC Power=V*I requirements.

    If you have inverter losses and no other AC requirements but the TV at times--Then going to a small DC:DC converter (or smaller AC inverter) may be worth the power savings.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #14
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    Re: new guy to solar PV here in south florida, going "Off Grid"

    dvrs are small computers and to my knowledge they haven't taken on the custom of keeping power usages down because of a need of portability such as is the case in laptops. typical power consumption on these may be around 50w by themselves. do confirm the draw from your dvr and if it is as low as you claim then good.
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