Electric homebrewing update... (cost, parts, etc)

I brewed a simple single hop 3% pale ale about a week ago using electricity and propane.  The entire electric brewing system isn't complete yet, but, it was definitely cool to heat up water with a flick of a switch.  Right now I have a hot liquor tank with 5500 watt 220 volt electric element in it.  I don't remember exactly how long it took to boil 12 gallons of water, but, I'm pretty sure it was less than an hour.  I'll provide some exact numbers next time around.  All numbers below are based on en electric brewing spreadsheet I found via http://www.homebrewtalk.com.  I used my current electricity rate and current tap water temperature.

I used this formula to calculate the cost to get 14 gallons of water to boil. (don't really need 14 gallons, but I didn't have my pickup tube installed so that's what I needed to boil to get 12 gallon or so)

kilowatts used per hour * hours it takes to get to boil * cost per kilowat hour = cost
5500 watt electric element = 5.5 kilowatts per hour
61 minutes to boil = 61/60 = 1.02 hours
$0.097 cents per kilowatt
5.5 * 1.02 * .097 = $0.54 to get 14 gallons of water to boil from starting temp of 56F.

Now I just need to add to that the cost of a 60 minute boil.  In this last brew I used propane for this.  Next time I hope to have a smaller element installed in my kettle to maintain a good boil.  I think 5500 watts would probably be too much.  I'm thinking 4000w or 4500w to maintain a boil.  That would cost even less.  Here's the projected cost for a 60 minute boil with a 4500w element.

kilowatts used per hour * hours * cost per kilowat hour = cost
4500 watt electric element = 5.5 kilowatts per hour
1 hour boil
$0.097 cents per kilowatt
4.5 * 1 * .097 = $0.44 to boil for 1 hour

So it would cost a little less than a dollar to brew a 10 gallon batch of homebrew using extract :-)  Shouldn't be much different for all grain.  I would imagine that propane costs between 3 and 6 dollars per brew session.  Assuming a savings of $5 a brew session it would take 4 brews to pay for the element, 10 brews to pay for the wire, etc.  IF I brew often (if...heheh), it would take one to two years to pay for the investments in electric equipment (wire, plugs, spa box with GFCI, elements, o-ring, nut, switch, switch box, items for waterproof cover for element wire connection).

Why go electric?  Mostly because I can safely brew in my garage with the door closed all year around.  Not to mention eliminating the need for propane refills.  Eventually it will be cheaper to brew this way too.  I will need to keep propane and a burner around in case the power goes out in the middle of a brew session ;-)

NOTE:  Need to revisit with actual numbers from next brew session.