Small Solar System For Sign

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Ravenvalor

Ravenvalor

Senior Member
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Piedmont region of NC
Hello,

I need to illuminate a ground sign with 2 - 600 lumen lights at the entrance to a subdivision. The lights need to stay on for 8 - hours during the darker months from 5pm until 1am. The sign has 2 - columns with 30" x 30" tops. I was thinking about putting a 30" x 30" solar panel on each column top (facing straight up and not angled). Installing a battery or two behind the sign and running a cable about 20' to the 2 - 600 lumen, 5 watt lamps. Are there any high quality systems on the market that will last a good 20 - years?

Thank you
 
I would expect any battery that is going to be recharged everyday will not last anywhere near 20 years. I think you will also find that these kind of systems often don't recharge very well on overcast and rainy days, so the amount of battery you need is a lot more than the numbers you might think.
 
My thoughts, in no particular order: You should angle the panels to minimize snow and debris build-up.

You'll need the light the most on the days with the least sun. I think you need more than 8 hours of capacity.

To make the math easier, let's call your lights 6w each, for a 1a load. So, 1a times X hours of desired runtime.

Perhaps at least 100 amp-hours. I'm thinking a deep-cycle marine battery in a locked, chained battery case.
 
I haven't looked at them in a while, but Morningstar used to make packaged systems that would do what you are trying to do. Solar module, battery, charge controller, and photocell activated lighting relay. You'd want LED lighting, of course.

There are others. I googled "dusk to dawn solar lighting" and a bunch of them came up. I don't think you need to reinvent the wheel.
 
Ravenvalor said:
Hello,

I need to illuminate a ground sign with 2 - 600 lumen lights at the entrance to a subdivision. The lights need to stay on for 8 - hours during the darker months from 5pm until 1am. The sign has 2 - columns with 30" x 30" tops. I was thinking about putting a 30" x 30" solar panel on each column top (facing straight up and not angled). Installing a battery or two behind the sign and running a cable about 20' to the 2 - 600 lumen, 5 watt lamps. Are there any high quality systems on the market that will last a good 20 - years?

Thank you
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I developed software (PVCAD) over 30 years ago to design reliable PV systems for applications such as communications, using weather and sunshine data for specific locations. Battery sizing is important if you need to survive major storms such as hurricanes.
Assumptions: 1-amp load at 12V, resistive (not constant power), 6 hours/night, Raleigh NC

Very reliable, long period w/o bright sunshine, works with battery at end of its life (80% of new capacity), etc.:
40W Module (Vmp 16-19V) (higher voltage means lower current for same power) mounted at 60° tilt facing South with a 55 AH (or higher) battery. Use a Morningstar Sunlight 10A regulator (provides timing in addition to regulation).

Lower cost system, may operate only 5 hr once or twice a year:
30W Module (Vmp 16-19V) mounted at 60° tilt facing South with a 40 AH (or higher) battery. Use a Morningstar Sunlight 10A regulator

For best results bury the battery in a non-metallic NEMA-4 enclosure to minimize temperature extremes, regulator with the battery. Battery cost will be a major consideration, consider Deka solar batteries, 6-7 years if kept clean and avoiding temperature extremes.

Consider using Holly Solar Products Brick Style LED Vandal Resistant Lights.
 
BillK-AZ said:
I developed software (PVCAD) over 30 years ago to design reliable PV systems for applications such as communications, using weather and sunshine data for specific locations. Battery sizing is important if you need to survive major storms such as hurricanes.
Assumptions: 1-amp load at 12V, resistive (not constant power), 6 hours/night, Raleigh NC

Very reliable, long period w/o bright sunshine, works with battery at end of its life (80% of new capacity), etc.:
40W Module (Vmp 16-19V) (higher voltage means lower current for same power) mounted at 60° tilt facing South with a 55 AH (or higher) battery. Use a Morningstar Sunlight 10A regulator (provides timing in addition to regulation).

Lower cost system, may operate only 5 hr once or twice a year:
30W Module (Vmp 16-19V) mounted at 60° tilt facing South with a 40 AH (or higher) battery. Use a Morningstar Sunlight 10A regulator

For best results bury the battery in a non-metallic NEMA-4 enclosure to minimize temperature extremes, regulator with the battery. Battery cost will be a major consideration, consider Deka solar batteries, 6-7 years if kept clean and avoiding temperature extremes.

Consider using Holly Solar Products Brick Style LED Vandal Resistant Lights.
Click to expand...
Those Brick Style lights look great. The regulator looks good also. Those Deka batteries do look expensive but for 6 years it seems worth it.

Thanks for the help. If I get this little project I will post a picture.
 
BillK-AZ said:
Very reliable, long period w/o bright sunshine, works with battery at end of its life (80% of new capacity), etc.:
40W Module (Vmp 16-19V) (higher voltage means lower current for same power) mounted at 60° tilt facing South with a 55 AH (or higher) battery. Use a Morningstar Sunlight 10A regulator (provides timing in addition to regulation).
Click to expand...
Hello,
I am looking for 2 - small panels 30" x 30" in the rv marketplace. Hoping to find something with a 25 year warranty. Can you recommend a good small panel? Also, the only option that I have for panels location is 2 - columns that are about 48" above the ground. These 2 - stone columns make up the sign that I am illuminating. Would it be unwise to point these 2 - panels facing straight up? The customer won't accept anything other than facing straight up.
They will be near a small tree that is thankfully a couple of feet north of the proposed panel locations. I would anticipate a lot of sap, and leaf debris build-up on the 2 - panels so I would have to stipulate that the customer should contract with the landscaper to clean those panels weekly.
Thanks,
 
Ravenvalor said:
Hello,
I am looking for 2 - small panels 30" x 30" in the rv marketplace. Hoping to find something with a 25 year warranty. Can you recommend a good small panel? Also, the only option that I have for panels location is 2 - columns that are about 48" above the ground. These 2 - stone columns make up the sign that I am illuminating. Would it be unwise to point these 2 - panels facing straight up? The customer won't accept anything other than facing straight up.
They will be near a small tree that is thankfully a couple of feet north of the proposed panel locations. I would anticipate a lot of sap, and leaf debris build-up on the 2 - panels so I would have to stipulate that the customer should contract with the landscaper to clean those panels weekly.
Thanks,
Click to expand...
I think you will find that pointing the panels straight up will mean you get virtually no electricity during some parts of the year when the sun is low in the sky during the day. is there some reason you cannot just run power out to the sign?
 
petersonra said:
I think you will find that pointing the panels straight up will mean you get virtually no electricity during some parts of the year when the sun is low in the sky during the day.
Click to expand...
Per PVWatts, for a random point in NC (35.5 degrees Latitude), a panel straight up will see an average of 2.4 kWh/m2/day of incoming sunlight in December, vs 7.0 in June. So that's a big ratio, but December is not 0.

Tilting it just 10 degrees to the South changes the December number to 3.0 with no change in June, so is a significant improvement. (20 degrees is even better, 3.5 and 6.9.) Maximizing the minimum monthly average irradiation requires jumping up to a 55 degree tilt, for which December is 4.6 and July is 4.8 (and the peaks are in the spring and fall).

Obviously a crude analysis, looking just at monthly averages of incoming sunlight.

Cheers, Wayne
 
wwhitney said:
Per PVWatts, for a random point in NC (35.5 degrees Latitude), a panel straight up will see an average of 2.4 kWh/m2/day of incoming sunlight in December, vs 7.0 in June. So that's a big ratio, but December is not 0.

Tilting it just 10 degrees to the South changes the December number to 3.0 with no change in June, so is a significant improvement. (20 degrees is even better, 3.5 and 6.9.) Maximizing the minimum monthly average irradiation requires jumping up to a 55 degree tilt, for which December is 4.6 and July is 4.8 (and the peaks are in the spring and fall).

Obviously a crude analysis, looking just at monthly averages of incoming sunlight.

Cheers, Wayne
Click to expand...
For the OP's case where the lights would go off at 1AM all year, I assume that optimizing it for the end of December would be more than adequate for June?
 
If you optimize the panel orientation for December the rest of the year should take care of itself. In case that wasn't clear from Wayne's post.
 
jaggedben said:
If you optimize the panel orientation for December the rest of the year should take care of itself. In case that wasn't clear from Wayne's post.
Click to expand...
Didn't the OP say that his customer insisted that the PV module be pointed straight up? That seems silly to me, but the customer is who signs the check.
 
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