Barn and Stable lighting

System · September 2007

My barn is way too far from existing power, and I'd like to put in some lights. What kind of 12 volt lights should I consider? If I put in compact flourescents in two stalls and my tack room, how many batteries will I need for a couple of hours a day?

What kind of charging system do I need to set up? How big, etc.

Please help me out!

mike95490 · September 2007

Re: Barn and Stable lighting

How long will lights be on? So I'll assume a couple of things and 13w CFL's

Porch light - dusk - dawn 14 hrs winter.
tack room 4 hrs
stall 1 2 hrs
stall 2 2 hrs

so for a wild guess, I have 22 hours at about 15 watts ( I round consumption up, you get less odd surprises that way. ) That comes to 330 watt hours. Off a 12V battery that is 28 amp hours.
A standard Costco or Kragen Deep Cycle, flooded cell battery holds about 80AH, so you are well below the 50% depth of discharge limit (batteries age MUCH faster when discharged below 50% )
To charge it, you have about 4 or 5 good hours of solar in the winter (average, you didn't say what city you are in, that will fine tune the calculations) I'll say 4 hours winter. So you will need to generate in that 4 hours of usable sun, about 35Ahr of power. Batteries have losses when charging, about 20% (28x1.2=33 round up to 35)
Recharging at 15V x 35A = 525 watts spread that over 4 hours, and you have 135W for 4 hours.
Wait, there's more. A 135W panel, will only give you about 110W when outside the laboratory they are tested in. In real life, you will need a single, well aimed 160 watt panel.
In summer you will charge more, and will need some sort of charge controller to prevent overcharging the battery.
In actuality, you don't always charge at full rate, the last 80% of charge goes slower, and maybe 2, 100W panels will be better to keep the batteries topped off. Or use the lights less.
Less lights = smaller panel = less $
Hope this helps.

possible parts list:

Battery $90 Kragen
Charge controller C12 $90 http://store.solar-electric.com/c12.html
(add battery temp sensor if in extreme climate, or buy batteries more often)
12Vdc 13W CFL by Glenergy $15ea http://tinyurl.com/23h7bm an eBay Store
Blemished Modules with a 25 Yr. Warranty 190W $560 http://www.sunelec.com/
PV panel mount ?? $$
Wire & switches (can use household switches, the CFL will not burn them out.)
8A DC fuse & holder (automotive parts store $5)

lamplight · September 2007

Re: Barn and Stable lighting

the c12 is a very cool little charger and cheap, i have one for a mini night light system and the lighting controller functions are very neat.

base don mikes specs this kit might interest you though is SLIGHTLY bigger than you need (assuming mikes guesses are in line w/reality) see kit#2. (220w)
http://newenglandsolar.com/catalog_pages/catalog28.htm

its not cheapest route especially if you are enterprising, patient shopper and/or cheap or into DIY, but the nice thing about his kits is that the components come on a nice prewired board and all components chosen by an expert.

also: consider a 12vdc motion light for the porch as an option to dramatically reduce usage if thats acceptable for the location/need
edit: if the assumptions on usage are accurate then ths would give you a litte extra power to play with (radio?, plasma tv? disco ball?)

System2 · September 2007

Re: Barn and Stable lighting

I appreciate the replies. following your logic, would the following work?
If so, can you direct me to a dusk to dawn sensor???

2 Porch lights, dusk til dawn, led from Glenergy, each using app. 1 Watt (just need a little glow…)
Tack Room, 2 hours 15 w cfl
Stall 1 2 Hours 15 w cfl
Stall 2 2 hours 15 w cfl

6 hours @ 15 watts = 90 watt hours + 28 Watt hours = 118 watt hours
Should equal about 10 Watt hours?

10 x 1.2 = 12, round up to 15 for good measure.

Recharging at 15v x 15A= 225 spread over more than 4 hours, but assuming 4 =56.25
2 30 watt panels? One 60 Watt?

lamplight · September 2007

Re: Barn and Stable lighting

Hi we already did

: the c12 is a light sensor/controller as well as charge controller: instead of a light sensor it senses night by the lack of power of the PV, it works really well

note these calculations arent my strong point id reread the other post carefully its probably accurate as to the math, but here goes as I do see some probs with what you're saying:

1wx 14 hrs (night light)= 14whrs
other 15w cfls: 90whs
= 104 watt hours total
104wh / 12v = 8.7 Amp hours per day needed

so a 60w 12v panel could give you a good 40w for 4 hours (~50w if going with 80% of rating but lets be safe and/or consider your tilt isn't perfect or that dirt is on your panels, it's really hot, etc etc.. ) , shortest day scenario= 13.2 amp hours in a SUNNY day. so while its enough, youd have no light after 2 days of rain. my advise: get ONE of the largest panels (and appropriately sized battery) you can afford so you have some more stored power -
see mikes battery calc's. note ALSO that not only is that only about 1 night of power but discharging the battery halfway every day and it wont last that long. one compromise: get a large panel and only 2 days of batt. capacity.

mike95490 · September 2007

Re: Barn and Stable lighting

LED lights are a grand idea, saves a lot of power. There are also some Cold Cathode lights at the Glenergy site, but I have no idea what their light is like, maybe try one of their 4w bulbs.
Use the C12's dusk-dawn feature
don't go lower than 100W panel.
If you kill a battery from low charge, it's only a $90 item, and you will know you are using too much power, and need another panel to keep the charge up.

"" Recharging at 15v x 15A= 225 spread over more than 4 hours ""
15A /4 hours = 3.75A @ 15V = 60W of panel output, which will require at least a 80W panel

The charge controller will prevent overcharging. Under charging will kill the storage battery.

crewzer · September 2007

Re: Barn and Stable lighting

ljones,

We need to know more about where you're located. If possible, please select a location from this list: http://rredc.nrel.gov/solar/old_data/nsrdb/1961-1990/redbook/mon2/state.html

More later,
Jim / crewzer

System2 · September 2007

Re: Barn and Stable lighting

crewzer wrote: »

ljones,

We need to know more about where you're located. If possible, please select a location from this list: http://rredc.nrel.gov/solar/old_data/nsrdb/1961-1990/redbook/mon2/state.html

More later,
Jim / crewzer

My closest location is Memphis, TN

You guys are great. The links and answers are fantastic. I do appreciate it.

crewzer · September 2007

Re: Barn and Stable lighting

2 Porch lights, dusk til dawn, led from Glenergy, each using app. 1 Watt (just need a little glow…)
Tack Room, 2 hours 15 w cfl
Stall 1 2 Hours 15 w cfl
Stall 2 2 hours 15 w cfl

6 hours @ 15 watts = 90 watt hours + 28 Watt hours = 118 watt hours

My closest location is Memphis, TN

Ljones,

118 Wh/day / 12 V = 10 Ah/day net energy requirement. Allowing for three days of autonomy (no Sun), limiting discharge to 50% SOC, and allowing an extra 20% for cold temperature operation, you’ll need a 12 V deep-cycle battery rated at (10 Ah/day x 3 days) / (50% x 80%) = 75 Ah.

The top-of-charge coulombic efficiency of flooded-cell batteries is ~80%. In order to supply a net of 10 Ah/day, the PV array will need to generate ~12.5 Ah/day.

Worst case average insolation in Memphis for a south-facing panel tilted up at latitude + 15 degrees = 3.6 hrs/day in December. This suggests that you’ll need a PV module rated at 12.5 Ah/day / 3.6 hrs/day = 3.5 A. Assuming a minimum 17 Vmp STC spec, you’ll need a PV module rated for at least 60 W STC.

Something in the 65 W to 85 W range would provide an adequate cushion. The PV module should not be shaded during the day, and must not be shaded from 9 AM to 3 PM local standard time.

See: http://store.solar-electric.com/kykc65wasomo.html
And: http://store.solar-electric.com/kysokc85wa12.html

The Morningstar SunLight charge controller includes a built-in timer. Its dusk-to-dawn feature could automatically control the porch lights.

See: http://store.solar-electric.com/sunsolligcon.html
And: http://www.morningstarcorp.com/products/SunLight/info/SL_DataSheet.pdf

My experience with this type of setup is that the battery requires watering maintenance every two- to three months.

HTH,
Jim / crewzer

machineman · September 2007

Re: Barn and Stable lighting

How big is your barn? Maybe you can use a hand full of battery operated LED lanterns. Most will run 10days straiaght on D cells. They sell them in camping stores for <$30.

Barn and Stable lighting

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