I Need a Rugged Outdoor Solar Bright Light

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George Stolz

George Stolz

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Windsor, CO NEC: 2017
Occupation
Hospital Master Electrician
...any suggestions? I am trying to illuminate a monument sign a good clip away from conventional power.

In my mind, I am picturing a decent sized solar panel, an ice chest buried 24" to 36" deep with a battery in it, and a 12V 50W flood on a post.

Thoughts?
 
You may find something that will work at a farm supply store. They make the solar panels for elect. fence chargers and gate openers. I installed a gate opener that was in the same situation as you. Too far for ac. The unit had a solar charger to keep the battery charged. Its been 3 years since the install and no problems that I know of. I think the brand was mighty mule.
 
Solar Lighting

Solar Lighting

George , first the run time on your Light ? dusk to dawn ? how many hours ?
Size of area trying to light up ?

Their are great lights available but for real lights they are pricey, we sell Solar Powered St. Lights and they start at 2,850.00 without the pole.
 
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LarryFine said:
How many watts for how many hours?
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I thought wattage would depend on the type of fixture.

According to one site...
Sun and Moon Data for One Day

The following information is provided for Fort Collins, Larimer County, Colorado (longitude W105.1, latitude N40.6):
Monday
21 December 2009 Mountain Standard Time

SUN
Begin civil twilight 6:50 a.m.
Sunrise 7:21 a.m.
Sun transit 11:59 a.m.
Sunset 4:37 p.m.
End civil twilight 5:08 p.m.

MOON
Moonset 8:44 p.m. on preceding day
Moonrise 10:25 a.m.
Moon transit 4:00 p.m.
Moonset 9:44 p.m.
Moonrise 10:47 a.m. on following day
Click to expand...

So from 4:30pm to 7:30am is fifteen hours, so it would be good to have the ability to have it run in the winter for fourteen or fifteen hours at around 20?F.
 
Okay, I see you mentioned a 50w light, which is about 4a at 12v, so you'd need a charging and storage capacity of at least 60ah. Of course, that's presuming full charging every day (not likely), 100% efficiency, etc., so double it.

Naturally, you'd want greater storage capacity for cloudy and rainy days, snow, eclipses, etc. Regardless of excess storage, you still have to replace the power used, so you need enough solar to replace 60ah in 8 hours or less.

That means at least 7.5a per hour of 8 sunny hours each and every day. Again, you probably have to double that for realistic conditions compared to theoretcial calculations. I'm just shooting at the hip here, so forgive me. :cool:
 
jumper said:
This site might give you a few ideas. I liked it because it gives the prices, none of the " contact us for pricing" run around.
http://www.siliconsolar.com/commercial-solar-lighting.html
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Well, we went with these folks. I imagine my boss ordered the light he wanted from them around the first week of April. After a lot of calls, changing the order once (because they were waiting on parts to build the first choice), we're still waiting to see it. Supposedly, we'll receive it on the 20th.

Is customer service so hard these days? :rolleyes:
 
What about getting a good solar panel, and putting a couple SLA batteries, a charge controller, and an inverter in a Nema 4 box and using that to supply a standard flourescent landscape light?
 
George Stolz said:
Well, we went with these folks. I imagine my boss ordered the light he wanted from them around the first week of April. After a lot of calls, changing the order once (because they were waiting on parts to build the first choice), we're still waiting to see it. Supposedly, we'll receive it on the 20th.

Is customer service so hard these days? :rolleyes:
Click to expand...

I also ordered from these people and was told my fixture was in stock and would ship the next day.After 1 week passed no fixture I started calling and could not get any one to return my calls.After 2 weeks I finally got someone on the phone and they told me it would be 6 weeks ,I canceled the order 4 weeks ago and they still have not credited my card.
 
George I can help you out, but I don't think you will like the cost.

Your first step is to determine how many watt-hours you need in a 24 hour period. So let's say you want to burn that 50 watt light for 8 hours. 8 hours x 50 watts = 400 watt hours. Now to account for system inefficiency multiply that by 1.5. 1.5 x 400 = 600 wh This is how much power you will need to generate every day on average.

Next piece of information you need is your solar insolation measured in sun hours on your shortest days in winter. You have to use worst case or shortest days of winter. Don't know where you are but the is usually around 2 or 3 hours. For our example let's say you are in Boston which has an insolation of 3 hours in December.

Ok to find the solar panel wattage is straight forward, take your daily wh / Sun Hour so 600 wh / 3 hours = 200 watts

Next step is the size of the battery. First determine the system voltage, we select 12 volts in your case. Next we need to multiply your daily adjusted usage by 5. The reaon is we never want to discharge a battery more than 20% in any given day to maximise the battery life of at least 5 years, and have reserve capacity to carry us through a cloudy day or two. So 5 x 600 wh = 3000 wh reserve capacity. From here is straight forward WH / V = AH, 6000 wh / 12 volts = 500 AH @ 12 volts


Lastly you will want a MPPT charge controller between the panel and battery. The minimum size is straight forward Panel wattage / system voltage, 200 watts / 12 volts = 17 amps, round up to 20 amps

Now for the fun part, cost estimation

Panel cost = $4 per watt = $4 x 200 = $800
Battery cost = $250 per Kwh = $250 x 3 Kwh = $750
20 Amp MPPT Charge Controller = $350
Misc hardware and wiring = rougly $200
Total equipment cost = $2100
Labor = ??????

If your electricity cost 14 cents per Kwh you are spending $2100 + labor to replace 6 cents worth of electricity per day. Those batteries have to be replaced about every 5 years, or less if kept in less than ideal conditions.
 
I would round the MPPT charge controller to 25 amps - you get a nice cold, clear winter day and most PV panels will exceed their ratings.

Edit: This is also an issue if you go above sea level. The thinner atmosphere allows for more sun and therefore PV output year-round. PV panels are rated at sea level, at 77F. Go higher or colder and you have to adjust wiring and charge controllers accordingly.
 
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