I am looking at getting some solar panels and considering Georgia Power’s Community Solar program, but in order to do that, I need to know how much my electricity really costs, specifically if I save a kilowatt-hour, how much do I save in money? My bill in May was $45.95 for 176 kwh, a very low amount because I wasn’t heating or cooling the house very much. You could take the bill amount and divide by the 176 kwh to get a price per kwh of 26 cents per kwh and conclude that a 165 kwh reduction would save me $42.90. That would be completely wrong. Instead most of the bill, $35.42, is a line item called “Current Service,” but even that is not directly proportional to usage. I found a site at the Georgia Public Service Commission that can calculate a Georgia Power bill and break it down more clearly. First, there are different rates for Winter and Summer, with Summer (June to September) being higher, so May is considered Winter. Current Service actually consists of several different items, the first of which is the Base Charge and it is based only on the number of days in the billing period, so for me that was $13.35 for 29 days. The second is Tier 1 Component, the amount charged for the electricity up to 650 kwh. For me this amount was $28.51. There are other tiers above 650 kwh per month, but I almost never go above that. In Summer, Tier 2 is significantly more expensive, but in Winter Tiers 2 and 3 are the same rate as Tier 1. These two combined are called the Base Bill. The key take away is that for this month a third of that amount is not based on power consumption at all, just the price of being a customer. Next is a Fuel Cost Recovery Rider, which is based on the amount of kwh used, basically just a way of increasing the cost of electricity by 4.3 cents per kwh. For me this was $8.07. The last piece of Current Service is called Demand Side Management Residential Rider, a long name for a small fee of 35 cents, based on the Base Bill amount. Those 4 together are Current Service.
The monthly bill has other line items besides Current Service. First is the Simple Solar program, where they charge me 1.25 cents per kwh that I used, for a total of $2.22. Next is the Environmental Compliance Cost, which again is based on the Base Bill amount that is a hidden part of Current Service, and came out to $3.64. Then there is a Municipal Franchise Fee of $1.27 which is based on the total of Current Service, Environmental Compliance, and Simple Solar. My fee is a little higher because I live within city limits. The last item on the bill is Sales Tax of $3.42. If I take 8% of all of the fees combined, I am a penny or two lower than their amount, so maybe there is some weird rounding thing going on. I was able to track down all of the fees on Georgia Power’s website for seasonal residential rates, and of course do a spreadsheet to make sure I am getting everything right, which I am except for sales tax for some reason. The PSC web page worksheet doesn’t include the Simple Solar program or its impact on other fees and sales taxes, but Simple Solar is totally based on consumption, but otherwise breaks everything down really well including all of the Georgia Power rates to 4 decimal places.
I still wanted to figure out the cost per kilowatt-hour of electricity. An easy way to do this would be to go to the PSC website and calculate a bill with 100 kwh of usage and then run another bill with 500 kwh of usage. Then I could subtract those two and divide by 400. That gets me pretty close and is easy, but it doesn’t include the optional Simple Solar program. Another thing I could do is take two bills from the same time of year (winter or summer) and then, knowing the days and kwh of usage, I would have two equations and two unknowns, and solve for the two unknowns which are the final rates for kwh and days since those are the only two variables involved. That still has a little error due to penny round offs. The hard way, which I put off for a while, was to come up with an equation combining all the rates and percentages I describe above to get an answer, which is eventually what I did, but I was glad to have the other methods as a check because that formula was long and involved. Then there is another easy way, which is once the spreadsheet is working, calculate a bill for 1 kwh and 0 days without any rounding and showing more decimal points. The nice thing is once I have those equations, I can use that for winter rates or summer rates, and if they change the rates, which they did right after I started figuring all of this out. In the end, the price per kwh in Winter was 16.4334 cents and per day of usage it was 58.6511 cents. In Summer the daily rate is the same, but the price per kwh rises a little to 17.4725 cents. That’s if I stay out of Tier 2 Summer prices for consumption over 650 kwh which have a nominal rate of 14.3 cents, which would almost double with all the taxes and fees.
