Check my math, please. LED power savings.

[mcphock]

I am considering switching from 500 watts of Metal Halides to ~200 watts of LEDs.

I know there are other concerns (fixture cost -vs- bulb replacement and additional A/C in the summer), but I wanted to see if switching to LEDs would really make a dent in my powerbill.

From my power bill from the past month, I calculated my my cost per Kwh to be 8.9 cents. If I understand correctly, that means that running 1000w for one hour costs me 8.9 cents.

My current MH usage is 4000W per day (8 * 5000). Using LED would result in 1600W per day. (8 * 200). That's a reduction of 2400W/day.

Over a 30 day month, that reduction of 2400W equals 72,000W. (2400 * 30). Here is where I am unclear... Is it correct to divide that 72,000W by 1000wh, equaling 72Kwh/monthly? If so, at 8.9cents/hour, switching to LED would save me $6.4 monthly.

 

[kemmer]

McPhock;612082 wrote: Here is where I am unclear... Is it correct to divide that 72,000W by 1000wh, equaling 72Kwh/monthly? If so, at 8.9cents/hour, switching to LED would save me $6.4 monthly.

Yes that's correct

Energy Usage of MH per month
8hrs/day*500W = 4kWh/day
4kWh/day*30days/month = 120kWh/month

Energy Usage of LED per month
8hrs/day*200W = 1.6kWh/day
1.6kWh/day*30days/month = 48kWh/month

Energy Savings per month
120kWh/month-48kWh/month = 72kWh/month

Cost Savings per month (@$0.089/kWh)
$0.089/kWh*72kWh/month = $6.4/month

 

[mcphock]

Kemmer;612105 wrote: Yes that's correct

Somehow I feel that your proof and occupation go hand in hand :up:

 

[lifestudent]

Your math appears to be correct.

However, I should point out that my EMC adds a Wholesale surcharge that brings my actual KW cost to 10.4 cents a KW during the winter (Labor Day thru Memorial Day).

Also, you should review one of your electics bill from this past summer since many utility companies charge a different and higher rate during the summer. For example, my EMC charges almost 12 cents a KW during the summer.

 

[mcphock]

It seems like the main reason to run LEDs at this point, at least for me, is because I want to. There is no compelling cost savings, especially after factoring in the high price of the fixtures.

 

[pamelahaley]

is it worth it to possible lose out on the growth in your tank? Losing 300watts of grow power?

 

[mcphock]

LEDs supposedly pack significant PAR/PUR in a much lower wattage. Much cooler too! And the bulbs last 50,000 hours, although I'm not sure how much research has been done to verify when the LEDs will lose their spectral integrity.

 

[darcurr]

don't forget to add the savings from not replacing bulbs. That will be a larger portion than the energy savings.:thumbs:

 

[morganatlanta]

You've got to compare something like PAR, not watts compare different light types.

Electricity here is pretty cheap, so the savings from electricity doesn't really add up to much.

The ongoing cost of MH bulbs is more a driver, and if you can save yourself buying a chiller by going to LED, that will help the overall cost equation as well.

The off the shelf fixtures are still pretty expensive right now, so I don't think you can really justify them on cost (yet). DIY is pretty cost competitive with a MH set up on a 5 year cost basis and is not that hard to do with some of the kits out there.

 

[pamelahaley]

I'm considering purchasing LEDs meant for christmas lights or as automotive parts and going DIY.

http://www.ledlight.com/par38-ultra-bright-led-light.aspx">http://www.ledlight.com/par38-ultra-bright-led-light.aspx</a>

LED Light above is the same as light below only "meant" for a car and half the price!

[IMG]http://www.nanotuners.com/product_info.php?cPath=74&products_id=699">http://www.nanotuners.com/product_info.php?cPath=74&products_id=699</a>