Ok, so how much does it cost to purchase and operate artificial lighting?
Lighting expenses continue to be a concern for my indoor growing endeavor because I want to keep this cost neutral or preferably net positive if at all possible. After all, this is "Frugal Hydroponics" right?
The lights I use are simple 2-bulb, 32W, T8, 48" shop lights with on/off pull chains. "T8" fluorescent bulbs are much more efficient than the standard T12 40W bulbs. "T5" systems are more expensive for the initial purchase, but are more efficient than the T8s. I may switch to T5 in the future, but for now I am happy with the results and efficiency of the T8 system.
I bought 3 of these shop lights for less than $9 each and fashioned them together to operate as one 48", 6 bulb fixture of which all are plugged into the same light timer. In effect, I have 6 32W bulbs covering a 48" x 24" growing area. This easily accommodates several standard starter trays or least 3 of the hydro systems. I recommend watching your local big box stores for sales and manufacturers rebates. The lights I bought normally retailed at over $20 each, so wait for the sale.
Since vegetative growth is achieved in the "blue" spectrum, I use 6500k bulbs. A 2-pack of Sylvania T8 6500k bulbs is around $3.50. Since I am growing lettuce, herbs, and my spring starters, the blue spectrum is all I need. If I were to grow plants requiring a flowering stage (peppers, cucumber, tomatoes, decorative flowers etc.), I would need red spectrum bulbs and additional shop light fixtures. At this point, I believe that is cost prohibitive for me as I will grow those type plants outdoors.
Calculating Energy Consumption: 32W bulb x 6 bulbs = 192 watts. 14 hours of use per day x 30 days = 420 running hours. 420 running hours x 192 watts = 80640 monthly watts used. 80640 / 1000 = 80.64 Kilowatts used. My energy company charges $.0783 per kilowatt, so my total monthly expense to run these lights is $6.31.
Expense re-cap: Total cost of shop lights: $27. Total cost of bulbs (replace yearly): $10.50 or $.875 per month. Total energy usage per month: $6-$7.
I feel this is economically feasible for the production I am wanting to achieve. I recommend researching "High Intensity Discharge" systems for anyone wishing to produce flowering plants or increasing production by several magnitude. These systems do require many additional considerations, so research diligently.