Driveway columns with Solar LEDs.

[BigBand]

Hi everyone!
I'm new to this forum, and I need to start off with a request for some help.

I'm relatively new to solar power (although I have an technical background), and
I'm looking for a solution to a lighting need in my home.

I'm planning to build some driveway columns and I would like them to have
built in lighting, which would be behind some glass blocks.

Brightness would be in the neighbourhood of a 75 watt standard incandescent
bulb, and I like the idea of LED light fixtures. I would probably put two
lights into each column so I can somewhat direct the light.

There is no power available anywhere nearby, so I'm looking at solar power.
As if this wasn't enough, I do not want a motion sensor, I would like them
to be 'on' at their full brightness all night (a light sensor would be desirable).

I'm guessing I would be looking at a substantial battery, and a solar charger
to charge the battery each day.

Can anyone direct me to where I could get 'schooled' in this technology?
Or, has anyone already done something similar?

[littleharbor]

There's a huge variety of them on eBay and Amazon. The ones with 3.6 volt lithium ion batteries seem to be better and brighter than the AA battery types.

Solar post light.jpg

[BigBand]

This is the type column I have in mind. One on each side of my driveway, where it meets the street.
These columns are about 20 - 24 inches wide, and about 36 - 48 inches tall.

The leds would be placed inside, behind the glass blocks. I assume the leds would
be contained in a fixture, sort of like a flood light fixture.

I don't know how to convert the light from a 75W incandescent bulb into lumens or watts
for an LED light. I'm guessing 1000 lumens?

Also, I would like the leds to be on full all night, or possible fade a bit towards morning,
then turn off when it becomes light outside.

If the leds run off a 12v battery, how much of a battery would I need,
and how much of a solar charger would I need?

Would I need some kind of a charge controller?

Sorry for the newbie questions!

[BigBand]

This is the type column I have in mind. One on each side of my driveway, where it meets the street.
These columns are about 20 - 24 inches wide, and about 36 - 48 inches tall.

The leds would be placed inside, behind the glass blocks. I assume the leds would
be contained in a fixture, sort of like a flood light fixture.

I don't know how to convert the light from a 75W incandescent bulb into lumens or watts
for an LED light. I'm guessing 1000 lumens?

Also, I would like the leds to be on full all night, or possible fade a bit towards morning,
then turn off when it becomes light outside.

If the leds run off a 12v battery, how much of a battery would I need,
and how much of a solar charger would I need?

Would I need some kind of a charge controller?

Sorry for the newbie questions!

Posts somehow got out of order, but I'm still looking for some advice on these lights and charger.

[azdave]

I know enough to tell you it will not be worth the hassle if you want the brightness of a 75W incandescent to glow nearly all night under all conditions like summer/winter sun angles, weeks of cloudy weather and such. Let alone the battery maintenance and replacement costs every few years.

I would 1st pay to run grid power, 2nd, go with a packaged light solution such as posted by littleharbor or 3rd, do nothing at all.

[BigBand]

I know enough to tell you it will not be worth the hassle if you want the brightness of a 75W incandescent to glow nearly all night under all conditions like summer/winter sun angles, weeks of cloudy weather and such. Let alone the battery maintenance and replacement costs every few years.

I would 1st pay to run grid power, 2nd, go with a packaged light solution such as posted by littleharbor or 3rd, do nothing at all.

Well, heck. I figured I was probably going to need a car battery. Fortunately I have a good source for those.

[jflorey2]

Well, heck. I figured I was probably going to need a car battery. Fortunately I have a good source for those.

You do NOT want a car battery.

Let's run some simple numbers. First do a worst case. I'll assume you are in Chicago, because why not. That will give you an average of about 1 hour/day of direct sunlight in the winter, assuming a horizontal collector (i.e. solar panel on top of the post.) You said you have 24 inch wide posts. The Solarland 30 watt panel is 21 by 20, so let's use that as a starting point.

That means you have about 24 watt-hours to work with a day, average. So let's go with that. On all night? That's about 14 hours of darkness. So first off you can reasonably expect to power a 1.8 watt light. That's equivalent to about a 10 watt incandescent.

Next you need a battery. Ideally you want 3 days of autonomy (i.e. no sun for 3 days and it still works) so that's 72 watt-hours, or 6 amp hours. Never want to go below 50%, so that's 12 amp hours.

The usual formula for minimum battery charge rate is C/12. So for 12 amp hours you'd need a charge rate of at least an amp. That 30 watt panel (really 24 watts in the real world) will give you 1.7 amps so you are good there. That margin means you can also go to a slightly larger battery if desired.

Chicago freezes, so that means you're going to need an AGM battery. If you bury the battery it will tend to last longer (fewer temp extremes.)

So let's do a quick pricing.

2W LED light - $5
Solartech panel - $87
Cheapo lighting/charge controller - $15
12AH 12V AGM battery - $30

So that's $137 per post for the electrical stuff. Probably add $10 per post for fuses, wiring, wiring devices etc. Look at replacing the batteries every 2 years.

You can save money by:

-Tilting the panel to a more ideal winter angle (more energy collected in winter)
-Wiring them all in a string (one bigger system will be cheaper than several smaller systems)
-Going to a smaller light