solar flood light?

[CowboyUp]

I think you're wise to be looking at fluorescent for use with a solar panel, IMHO. Even so, you're looking at a few more items besides the pv panel if you're going to run the light independent from another power source. You'll have to have a charge controller to go with a battery bank. Are you using solar as a 'just to do it' purpose or do you need the lighting to be independent? Have you considered a small gas generator simply for running a few lights? There are some inexpensive small portables that aren't too noisy. Of course, you can run a dc light array, too, and use a battery bank for it. I ran a dc well pump off batteries and charged the batteries with a trickle charger before I set my solar panels. I'm not sure what you're hunting for, but if you're looking to experiment with solar power, I wish you all the best. The initial cost is expensive, but it's rewarding to know you're generating your own power. I would think for a fluorescent light, you wouldn't need too large of a pv panel. Be careful with the panels that are sold on ebay. You might try visiting a solar site and calling a help line. Most of the places I've dealt with offer excellent advice and counsel by techs over the telephone.
Good luck.

[alteng]

Ken, I have decades in electronics and alternate energy , and I agree with what Pat says. Forget incandescent bulbs, and go flourescent. There are many small 12V flourescent units available, and they basicly all have a small built-in inverter which makes ~120VAC from 12DC, in order to run the bulb.
Problem is, that most of these I've seen have poor quality inverters inside them, so they're prone to failure. Do the best you can to try to find one that's built well (inside) - hard to do when you can't even see the inards until they fail!
Paying a high price is no guarantee either, and there's no easy way to weed out the good from the bad (and ugly ;O).
The worst designed I've seen have been the round 12V automotive "trouble light" variety. All I've bought have soon failed. On inspection, I found a pitifully built inverter - not up to the task. Bad design - poor quality, IMHO.
Another alternative is to buy a small 12VDC-120VAC inverter, under 75 watts($10-$35), and use it to power a standard mini flourescent fixture. I 've been looking at mini flourescents at Lowes lately, for under $12 (~15-20 watts - equal to 60-100 watt incandescent). That will be my choice for the system I've been planning.
There are a number of inexpensive charge regulators available for small systems such as the one you describe. Some come in kit form, so maybe you could get an electronics friend to help you build one, or tackle it yourself . It's not that big a task, especially in kit form. Pat may have included a schematic diagram for one - I don't remember - but if not, a Goggle search will turn up some.
With such kits available from ~$10-20, it's hardly worth the trouble of NOT buying the kit - and getting components one by one. Same goes for both the inverter and regulator, if you're feeling brave. On a small, simple system like you're proposing it's not so daunting as with a high power system.

[Pat]

!2 VDC fluorescents don't really have inverters to make 120VAC 60Hz in them. They operate at much higher frequencies and regulate the current through the tubes rather than the voltage applied as fluorescent tubes are controlled that way. The higher freq reduces the size/cost of some components such as inductors,transformers, and capacitors. They are actually inverter ballasts. Good ones aren't as cheap as some but can be found at marine outlets and better RV supply houses. They are available in one and two linear tube styles as well as circuline tubes. I have used many over the years on boats and in campers and motorhomes. A high price doesn't guarantee a good unit but a low price pretty well assures you of a poor one.

I haven't "run" the numbers to compare a 120VAC inverter and CFL lamps vs a 12 VDC inverter ballast type but lean toward the inverter ballast. It is a small distinction but I prefer a shunt charge controller (shorts out the solar cell to limit battery charging when battery is full) vs the series regulator which goes open (high resistance) when the battery is charged. Shorting a solar panel does no harm. Very little power is produced when shorted since P (Power) = I (current in amps) times E (in volts) When shorted E is essentially 0 so power is nearly 0.

Going the inverter and CFL route locks you into 60 Hz which raises the cost of the inverter. This might be worth it to you if you will ever need to plug in any other "normal" 120VAC load (within the inverter's capability.)

Even Harbor Freight has solar panels and charge controllers.

http://www.harborfreignt.com

Try to beat $8-9/watt on the solar panel by shopping around.

[img]/forums/images/icons/smile.gif[/img] Pat

[John_D]

I needed light in my garage at the farm - more than 400' away from the house, and didn't want to run wires - the voltage drop would have been a problem. So, I installed a single 18x36" Solar panel (50Watts) a few years back - bolted to the south side of the garage wall. Running that to a deep cycle battery, via a Charge Controller. Out of the battery case, I ran 12v wiring through the garage to run 3 standard 4 foot T-8 (small diameter) single fluorescent tubes. I bought 12volt ballasts from Solar Power. They provide enough light to see inside the main 22x28' structure and the 11x28' shed addition. I also put in a 1200 watt inverter, and run a couple of 110v fluorescent lamps over the workbench when I really need to see. I can use small electric hand tools as well. I am careful not to over tax the system, but it sure makes a difference when working outdoors until the last of the natural light is gone, and being able to see inside to put tools away, or work on a tractor in the evening. I wired the garage for 110v too. Total cost was around $600, including the custom made heavy duty battery cables for the inverter, and a GROUNDING BAR & CABLE for the solar panel. Safety!

I toyed with the idea of LED lighting, but the price (lower now) and the fact that they don't "throw" much light were issues. At a short distance, they are fantastic and use much less power than any other light source. But if you are mounting an LED "flood" light outside on the side of a building, don't expect it to light up too much area.

[Pat]

John_D, Yeah each individual LED won't light up much area so you need a massive array to do area lighting. At some point it just isn't too practical as area increases.

Some day... Meanwhile fluorescent is tough to beat and good quality inverter ballasts fed from a deep cycle battery are good way to go. I have a 100 amp-hour deep cycle and a couple RV type inverter ballast fluorescents installed in my mom's safe room. Oodles of light for hours and hours and hours.

[img]/forums/images/icons/smile.gif[/img] Pat [img]/forums/images/icons/smile.gif[/img]