Floor Illumination

I can't answer all of your questions, but I can give you some partial answers to some of them, and you can go from there.

One question for you, to start: Why such a low level of lighting? A half of a foot candle is a pretty low level of illumination.

1. How many Lumens per Watt does a CFL deliver? It varies on the type and shape of the lamp and the color temperature. Straight tube FLs often run in the range of 30 to 60 lumens per watt -- but remember there is a lot of power dissipated in the ballast, too.

2. How many CF Lamps would be necessary in this case? That depends A LOT on the lamp chosen, the geometry of the room and the reflectivity of the walls and floor. For example, a difference of 5% in reflectivity (say, comparing a white paint of 90% diffuse reflectance vs a white paint of 85% diffuse reflectance) can make a 30% difference in the illuminance that reaches the floor.

3. Is it necessary to use reflectors like GLS Lamps? A very matte white surround (ceiling, walls, floor - yes the floor, too) would provide the most uniform lighting, all other things being equal.

4. What should be the distance between Lamps & Floor? As great as possible. There are a lot of optical diffusers that will help distribute the light uniformly, but all of them work best when you can use as much distance as possible.

5. What would be their distribution pattern for uniform lighting? My first guess would just be uniform spacing, not knowing anything else about your situation.

You did not clarify if you wished to do this once, or every day. Once is not so bad, you can take as long as you need to charge battery before and recharge day after! Car batteries would do.

1. If you want to do repeatedly, "float" batteries are not suitable - they are good for continuous charge (constant voltage - self regulating) with rare discharge - you need "deep cycle" batteries.
2. Wikipedia indicates VRLA batteries should not be discharged more than 50% before re-charge. In general, for batteries, deep cycling shortens life drastically.
3. For 100 Ah battery then, you are looking at 3 amps for 15 hours = 45 A-h maximum discharge. This will be no more than 3 lamps/10W each.
4. Cycling batteries are no more than 80% efficient, you must put in 45/0.8 = 56 A-h.
5. Over 10 hours with 6 amps charge rate you might restore the charge!
6. But I think you will get much less than 1 amp output per panel over a whole day, the sun keeps moving, at low sun angles available intensity falls.Clouds!!
7. Batteries must be kept as cool as possible, over 30 Celsius halves life.
8. Suitable 100 A-h battery can be charged at 30 Amp with strict voltage control, tropical ambient temperature may limit this. Latest Battery packs have temperature sensor built in (connected to suitable compatible charger) - this is the only reliable way to avoid overcharging and damage by high rate charge once charge gets to 80% rate must be reduced to normal of about 10% x amp-hour capacity.
9. Experiment with say 30 A-h battery and one 10W lamp seems good idea, to establish possibility and effective light intensity.
10. The open circuit voltage of a L.A. battery is an indication of charge. OC voltage = 0.84 + specific gravity of acid (e.g. 1.25 S.G. gives 2.09 V/cell. But OC voltage takes 24 h open circuit after charge or a brief discharge at normal rate to remove excess voltage on charge.
11. Other post gives about 30 lumen/watt - 300 lumens for 10W CFL. 0.5 foot - candle is 0.5 lumens per square foot. Hence 2000 sq foot needs 1000 lumens minimum. With 100 foot long room, 3 lamps will not give any uniformity, guess 5 or 20 x 20 feet each lamp may be workable.
12. A digital camera may a useful tool for light intensity estimation. If you keep focus fixed and distance from surface constant each exposure (F) stop is 2:1 light ratio.
    

10 x 20 watt phillips tornado bulbs, set either open drop or upside down with rear reflection to white roof. (equals 1 foot + candlepower half that for your lower light)

batteries VRLA 100amp hour x 4 (3 for actual 4th for really bad full week of light)

panels use 140 watt in preferenece to circa 180watt panels the performance is far greater to the rating.

so basic math 5 bulbs equals 100 watts plus 5 percent losses in transmission, 105 watts x 15 hours 1575 watts required from 8 hours of 50 percent light (accounting for melbourne winter shite weather for months) so you need 3150 watts over 8 hours or 394 watts per hour panel input, 3 x 140 panels should be perfect, the batteries will provide for a week of near black days and still running optimum.

This is a max system, in short the only type we design, "failsafe" cannot ever fail in power supplied by power required not ever.

Sure you could use less batteries and panels, but at some point it would fail, solar runs houses perfectly if they are designed failsafe, people are only dissapointed with solar because 99 percent of suppliers know nothing about the realities of what they are selling, thus the systems they sell are too small. why so many? because its a hard sell to tell someone a failsafe standard 3 bedroom house on solar will cost them 45,000, so they try to make a crap cheaper smaller system sound good.

PS only use the phillips tornado daylight bulbs, generics and the others are yellowish, easy try with a power board and 5 extension leads to test you will see what i mean instantly.