Electricity costs

xmpraedicta(3b Saskatoon)October 2, 2007

Hi - new to this forum. I'm usually over with the orchid growers.

I was just calculating the electricity costs of installing 2 400watt HPS grow lights (fantasizing about future winter setups). I feel like two of these suckers would allow me to maintain my current modest collection pretty comfortably. Anyway, I was always under the impression that powering these things for 8 hours a day would result in atrocious electricity bills...but I was reading up on current rates of electricity in Ontario (around 7 cents/kilowatt) and I realized that if I run two of these for 8 hours a day, 31 days a month:

(2*(400watts)*8hrs a day * 31 days a month)/1000 = around 200kilowatts.

200kw * 7 cents = around 14 dollars

Which actually isn't that outrageous...especially if this is only for 5 winter months (around 70 dollars a season). Am I calculating this correctly? I mean, of course you have the initial investment of the lights and ballasts which can cost $200+. But then again, hopefully in a few years I'll be out of my current 'poor student' rut.

The other thing I was wondering is how damaging this kind of behavior is for the environment. We all talk about saving energy and turning off lights when we leave the room. This counter-productive activity of maintaining grow lights fills me with guilt. Has anyone experimented in using ecological energy sources (solar, human powered) to generate electricity?

Thank you for reporting this comment. Undo
shrubs_n_bulbs(z8/9 UK)

7c!!!!!! Canadian? One more reason I should move to Canada :)

Not every month has 31 days but otherwise you're spot on.

Only 8 hours a day? Are orchids photoperiodic?

Running your lights will be approximately equally damaging to the environment as any other use of electricity that costs $14 ;)

    Bookmark   October 2, 2007 at 5:09PM
Thank you for reporting this comment. Undo
xmpraedicta(3b Saskatoon)

I have supplemental natural sunlight for four hours in the morning, so along with 8 hours of artificial light, I'm hoping things will be adequate. I can't maintain adequate humidity and temperatures to mimic summer conditions anyway, but I'm thinking the increased light will help the plants get through the winter (not really looking at setting up a completely indoors grow system yet).

Thanks for the reply! I'm glad my hobby won't end up emptying my pockets!

    Bookmark   October 2, 2007 at 10:29PM
Thank you for reporting this comment. Undo
sandy0225(z5 Indiana)

My 1,000 w MH light with a light rail costs about $25 a month to run. It's in a basement so I run it about 14 hours a day for seed starting. And overwintering tropical plants that I can't afford to heat the greenhouse adequately enough for, like diffenbachias.

    Bookmark   October 5, 2007 at 7:22AM
Thank you for reporting this comment. Undo

I also live in Ontario and my electricity cost is about 12 cents per kWh. Do not forget all the additional charges and taxes

    Bookmark   October 13, 2007 at 7:54PM
Thank you for reporting this comment. Undo

Each kilowatt-hour (note correct units) of electricity releases about one kilogram of CO2 to the atmosphere during its generation.

    Bookmark   October 14, 2007 at 3:25AM
Thank you for reporting this comment. Undo

cool! more c02 for the worlds pants!

    Bookmark   October 22, 2007 at 1:33PM
Thank you for reporting this comment. Undo

Adrianjz is right my bill is actually 13 cents/Kwh when every fee is included.

I wish those CO2 guys would stop proselytizing their enviro-religion and their prophet Al "Ron" Gore. It's just another wealth redistribution scheme.

    Bookmark   November 3, 2007 at 7:06PM
Thank you for reporting this comment. Undo

Well this is depressing me....
We do run a indoor greenhouse with 2 1000 watt ballasts going in different areas, and the living room set up and the bath room set up and it costs us a bunch of $$ a month.
I do get to feeling guilty for the electricity we use (well there is no we involved, it is me), however as most people are I do rationalize my hogging up of electricity like everyone else.
At one point and time we had a solar powered electric fence set up to teach my young gelding (horse) to not go through fences. I do not think I would want to chance my beloved plants with this kind of set up.
Anyhoo we are also heating our house with the heat the lights give off......a good 80 degrees.

    Bookmark   November 13, 2007 at 11:54PM
Thank you for reporting this comment. Undo
pushindirt(z8 OR)

Each kilowatt-hour (note correct units) of electricity releases about one kilogram of CO2 to the atmosphere during its generation

Doesn't that depend on how it's generated?

    Bookmark   December 18, 2007 at 9:07PM
Thank you for reporting this comment. Undo

A lot of electricity in Ontario comes from nuclear.

Remember, many people heat with electricity, so before we worry about being guilty about the environmental cost of electricity to run some gro lamps, we should abolish electric heating for homes, or make everyone wear sweaters and coats indoors.

Remember, the added electric bill has a beneficial side effect, if you are running the lamps primarily during the cold season, the help to heat your house, and your heating bill will be correspondingly reduced.

    Bookmark   December 19, 2007 at 12:48AM
Thank you for reporting this comment. Undo

Hello, I was actually looking through Posts trying to figure out how much my seedstarter setup would cost to operate.

If you are concerned about the use of electricity, why not contact your electric company and see if you can have your "source" switched from coal/oil to renewable sources. I have switched mine to 100% renewable. It costs a little more but but for me, it means PSEG is buying alt energy.

    Bookmark   December 31, 2007 at 8:35AM
Thank you for reporting this comment. Undo
engineeredgarden(7, nw Alabama)

I'm going to be using a couple of 2 bulb,4ft, t8 fixtures to grow my transplants, and was wondering if my calculations were correct. The ballast has it's own current rating, and then there are the 2 bulbs - which are rated at 32 watts. Should there be an overall wattage entered (ballast wattage + 32 + 32 ) into the original poster's formula given, for my application, for each light fixture? Thanks


    Bookmark   November 13, 2008 at 11:19PM
Thank you for reporting this comment. Undo


The ballastÂs job is to regulate the current supplied to the bulbs. If it is a rapid-start ballast, then it also supplies a small amount of current to heat the filaments in the ends of the tube to aid in starting the lamp. For 2-lamp Electronic Ballasts, a Rapid-Start ballast consumes approximately 3.5 watts, and an Instant-Start ballast uses about 2.5 watts. The older Magnetic Rapid-Start ballast uses about 6 watts.

Your average ballasts do not actually supply 100% of the design current that the lamp is rated for. This is a design parameter called "ballast factor" (not to be confused with power factor). A 32 watt bulb actually consumes from 29 to 31 watts because of the BF. The Ballast Factor is rarely ever printed on the ballast label, but the Power Factor is usually stated. The Power Factor (a measure of circuit efficiency) can always be ignored because your home electric meter does NOT register this inefficiency (called "apparent power").

So, a 2-lamp shoplight should normally consume about:
30+30+3.5 = 63.5 watts (Rapid Start Electronic Ballast)
30+30+2.5 = 62.5 watts (Instant Start Electronic Ballast)
30+30+6.0 = 66 watts (Rapid Start Magnetic Ballast)

These numbers have been verified by measurement and would be plus or minus a few watts.


    Bookmark   November 14, 2008 at 2:56PM
Thank you for reporting this comment. Undo
engineeredgarden(7, nw Alabama)

zink - Thanks alot, Dude! I understood every bit of that....I've been an industrial electrician for 21 years, and of course get into vfd's, PLC'S, pf (because of inductance on the supply system) and such all the time, but really know very little when it comes to the technical aspects of lights, and their performance criteria. I've read several of your threads concerning OD'ing various ballasts, and that's very good reading material! Thanks for answering my question, it was greatly appreciated...


    Bookmark   November 14, 2008 at 5:04PM
Thank you for reporting this comment. Undo


You are welcome. I didn't know what your expertise was, but if you deal with variable-frequency drives then you would have to know power factor. I took a class in rotating electrical machinery and found the subject of motors had way more depth than I personally was ready to absorb.

I have seen folks in this group questioning power factor, but I think having a voltage-current/lead-lag discussion would lose most everybody else here. Growers in this forum correctly suspect that a low power factor represents an inefficient use of electricity, but they don't realize they are not the ones who pay for it, due to the fact that standard house meters don't register it. Unfortunately, your electric company still has to generate the wasted power that you don't use. That might be of concern for the environmentally conscious grower.

Speaking of efficiency discussions, extra lighting may be considered one-to-one trade-off on your heating bill (BTUs) ONLY if you use electric heat. If you apply that same electricity to the operation of a heat pump motor, you get 3-4 times the BTUs.


    Bookmark   November 15, 2008 at 7:46PM
Thank you for reporting this comment. Undo
engineeredgarden(7, nw Alabama)

Zink - Oh yes, I know quite a bit about power factor. My company pays about $12k/year in fines, because of the poor power factor that we have. Since the payback on installing the necessary capacitors on the system is 5+ years, they are content with paying the annual fine. Of course, you already know that this is caused by inductance, and must be corrected with either capacitors or synchronous motors on the overall electrical distribution system. Also, 100% power factor always exists in a purely resistive circuit. I agree, this thread would be pretty boring for everyone else if we started talking about all kinds of other electrical stuff. :) But, if you ever need help with any kind of motor theory, please let me know. I know all of them - both A.C. and D.C., and all of their connections for the various voltages. And yes, I also know all VFD's and 4 different PLC programming languages. Like I said, my weakness is lights. :) I'll give you a link to my garden blog, and hope that you will stop by sometime. I build all kinds of crazy stuff! Thanks again....


Here is a link that might be useful: EG's garden/composting/building blog

    Bookmark   November 15, 2008 at 8:29PM
Sign Up to comment
More Discussions
Seeking advice about current indoor seed starting setup
Hello, I am new to gardening and would like to start...
6" Inch Titan Inline Fan 440 CFM Industrial Grade
The 6" Inch Titan Inline Fan 440 CFM Industrial...
Dane Theisen
Pepper Leaf Problem
I am new to the forum, but have a question about a...
what do you use under heat mats
I have some large heat mats that I use under lights....
Energy efficient grow lighting
We are probably going to buying a nice heavy duty heated...
People viewed this after searching for:
© 2015 Houzz Inc. Houzz® The new way to design your home™