Charge controller / panel / inverter

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Clyde
Clyde Registered Users Posts: 8 ✭
in Solar Beginners Corner #1
hello, love the site, there is plenty of information here thats for sure.

I have lots of problems, but ONE problem I have that I have solved is remote area lighting. I don't want to run a power wire to every shed/barn/building that I have so i purchased some 15 watt LED area lighting like this http://www.ebay.com/itm/like/111292800165?lpid=82. As a proof of concept I had a duracell 400 watt modified sine wave inverter and I pulled the trolling motor battery out of the boat. I know I know I know cheap inverters/"fishing" batteries etc ….. as a PROOF OF CONCEPT. It works! yay! My first battery powed lighting and I did it!

Ok, so I knew going into this that the trolling motor battery is not the best choice and the little duracell inverter may or may not have to be replaced. So thats what I am here to find out. Please consider the following:

I have a golf cart that I am about to replace all the batteries because one of them is dead, the set is over three years old and did not want to mix and match.

I am powering 4 of the 15 watt lights (they are 110v)

I currently do not own a kill a watt.

MAX use on the lights should be around 2 hours a day 3-4 days a week. I get (per map) about 4 good hours of sunshine a day. I would like to have 3-4 days reserve.

All that being said I need to purchase a panel, charge controller and do you think that I can use two of the old golf cart batteries (they are 6 volt 100 amp/hr I believe)? AND, should I consider using a better inverter?

I have no idea how to size the panel I tried to figure it out but the loads are throwing me off with draw of the inverter (<.5w), any and all help will be greatly appreciated and thanks and appreciation will be heaped upon any and all that respond:)

thanks

clyde
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #2
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    Re: Charge controller / panel / inverter

    forget the inverter - there are many 12VDC LED lights in the marketplace, and many charge controllers have a Dusk-Dawn lighting relay output.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

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  • SolInvictus
    SolInvictus Solar Expert Posts: 138 ✭
    #3
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    Re: Charge controller / panel / inverter

    With the inverter and all power for the load coming from the batteries:

    4 bulbs * 15 W/bulbs * 2 (h/day running bulbs) / .75 (efficiency of wiring, charge controller, inverter) / .75 (efficiency of batteries) / 4 h/day of sunlight) = 54 W of PV

    4 days of reserve before the lead-acid battery gets to 50% state of charge:

    4 bulbs * 15 W/bulb * 2(h/day running bulbs) / .80 (efficiency of inverting, wiring) / .5 (depth of discharge) * 4 days / 12 V = 100 Ah of battery @ 12 VDC

    The moderators here think the battery should be charged at a fairly high rate of 5% to 10% of the battery capacity, which means the PV panel should output between 5A and 10A for the 100 Ah battery. According to this rule the PV panel should be between 88 W and 177 W. Without a generator, you probably should not reduce the days of reserve in the battery. Because you plan to run the lights 3 or 4 days/week, the battery could last 4 to 8 days with constant clouds. If you pick a PV panel whose power is at the higher end of the range, then it will recharge the battery faster after several days of clouds which will help to prolong its life. Also some of the low wattage 12 V PV panels are more expensive than the higher wattage ones, so you will need to compare prices.

    As mike95490 wrote, for lighting you should probably skip the inverter and use 12 VDC LED lamps which would improve your efficiency reducing the sizes of the PV panels and battery. Unfortunately you already purchased the 110 VAC lamps.
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  • Brewgonia
    Brewgonia Solar Expert Posts: 31 ✭
    #4
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    Re: Charge controller / panel / inverter
    SolInvictus wrote: »
    With the inverter and all power for the load coming from the batteries:

    4 bulbs * 15 W/bulbs * 2 (h/day running bulbs) / .75 (efficiency of wiring, charge controller, inverter) / .75 (efficiency of batteries) / 4 h/day of sunlight) = 54 W of PV

    With efficiency being a 'bad' thing, shouldn't theses calcs be written as *1.25 instead of /.75? Of course math isn't my strong suit so pardon my ignorance if wrong...
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,457 admin
    #5
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    Re: Charge controller / panel / inverter

    Mathmatically, 1/0.75 = 1.333

    But, for me, it is just trying to use the same factors... A panel+controller is ~0.77 "efficient" (really a combination of efficiency and panel deratings due to temperature/controller options).

    So if I have a panel:

    100 watt panel * 0.77 = 77 Watt to battery/loads

    But if I have a known load and want to figure out the panel:

    77 watts * 1/0.77 = 77 Watts / 0.77 = 100 watts
    77 watts * 1.299 = 100 Watts

    Same results, but I don't have to "confuse" folks by using 0.77 in some equations vs 1.299 in other calculations for panel+controller deratings.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Clyde
    Clyde Registered Users Posts: 8 ✭
    #6
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    Re: Charge controller / panel / inverter
    SolInvictus wrote: »
    With the inverter and all power for the load coming from the batteries:

    4 bulbs * 15 W/bulbs * 2 (h/day running bulbs) / .75 (efficiency of wiring, charge controller, inverter) / .75 (efficiency of batteries) / 4 h/day of sunlight) = 54 W of PV

    4 days of reserve before the lead-acid battery gets to 50% state of charge:

    4 bulbs * 15 W/bulb * 2(h/day running bulbs) / .80 (efficiency of inverting, wiring) / .5 (depth of discharge) * 4 days / 12 V = 100 Ah of battery @ 12 VDC

    The moderators here think the battery should be charged at a fairly high rate of 5% to 10% of the battery capacity, which means the PV panel should output between 5A and 10A for the 100 Ah battery. According to this rule the PV panel should be between 88 W and 177 W. Without a generator, you probably should not reduce the days of reserve in the battery. Because you plan to run the lights 3 or 4 days/week, the battery could last 4 to 8 days with constant clouds. If you pick a PV panel whose power is at the higher end of the range, then it will recharge the battery faster after several days of clouds which will help to prolong its life. Also some of the low wattage 12 V PV panels are more expensive than the higher wattage ones, so you will need to compare prices.

    As mike95490 wrote, for lighting you should probably skip the inverter and use 12 VDC LED lamps which would improve your efficiency reducing the sizes of the PV panels and battery. Unfortunately you already purchased the 110 VAC lamps.

    ok so 150 watt panel will work for my setup as it is. Im good with that, now, what charge controller?

    AND, another question….. If I go with 12v lights, can I use the 12/2 wire that I have installed? the run to the furtherest light is probably 60', with a total of 100' run to get all lights power. As for already purchasing the lights, I have lots of places I can use these lights, they really are amazing!

    You guys are great and I really appreciate your input.

    Clyde
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #7
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    Re: Charge controller / panel / inverter
    Clyde wrote: »
    ok so 150 watt panel will work for my setup as it is. Im good with that, now, what charge controller?

    A 150 Watt 12 Volt panel will produce about 8.5 Amps of current, so you'd need a 10 Amp PWM type charge controller. It should work fine for a 100 Amp hour battery, especially used for lights only (no draw during charging).
    AND, another question….. If I go with 12v lights, can I use the 12/2 wire that I have installed? the run to the furtherest light is probably 60', with a total of 100' run to get all lights power. As for already purchasing the lights, I have lots of places I can use these lights, they really are amazing!

    You guys are great and I really appreciate your input.

    Clyde

    Wire sizing is a matter of two things: the current expected and the Voltage drop over distance (which also depends on current). Across 60 feet 12 AWG on a 12 Volt system will handle about 2 Amps before the V drop gets above 3%. 2 Amps @ 12 Volts is all of 24 Watts. If you want to power four 15 Watt bulbs that's 5 Amps @ 12 Volts and you'd need 8 AWG to keep the V-drop down.

    Still think low Voltage DC lighting is a good idea?
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  • vtmaps
    vtmaps Solar Expert Posts: 3,741 ✭✭✭✭
    #8
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    Re: Charge controller / panel / inverter
    Clyde wrote: »
    AND, another question….. If I go with 12v lights, can I use the 12/2 wire that I have installed?

    Avoid 12 volt lighting if you can. In addition to the voltage drop issues that Cariboocoot mentioned there are other reasons to avoid 12 volt lighting. You will have a better and cheaper selection of lights and appliances at 120 volts. Another consideration is the variation in voltage... a 12 volt system may be anywhere from 11 to 15.5 volts, depending on where you are in the charge/discharge cycle. This wreaks havoc on SOME 12 volt lights and appliances. With a decent inverter, your 120 volts will be better than what you get from the grid.

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
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  • Clyde
    Clyde Registered Users Posts: 8 ✭
    #9
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    Re: Charge controller / panel / inverter
    vtmaps wrote: »
    Avoid 12 volt lighting if you can. In addition to the voltage drop issues that Cariboocoot mentioned there are other reasons to avoid 12 volt lighting. You will have a better and cheaper selection of lights and appliances at 120 volts. Another consideration is the variation in voltage... a 12 volt system may be anywhere from 11 to 15.5 volts, depending on where you are in the charge/discharge cycle. This wreaks havoc on SOME 12 volt lights and appliances. With a decent inverter, your 120 volts will be better than what you get from the grid.

    --vtMaps

    kinda what I was thinking (now) but was just using what I had lying around. Guys this is really cool! Got the panel and charger and have programed my phone to make sure I go and check the water levels twice a month. So far I am making a lot more power than I am using, thinking about putting the lights on some sort of timer, but worried the pigs may not like it:D

    thanks sooooooo much for the input, advice and help. Going to start a new thread about a different idea soon.

    thanks again

    Clyde
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