Ted's Blog

I thought maybe I could make a dent in my home electricity usage by buying a couple of solar panels and a solar generator. A solar generator is a battery that can be charged up and has USB, AC electrical, and DC ports that you can use like a gas-powered generator. My electrical usage isn’t that high, maybe 300 kilowatt-hours per month on average, including the intensive summer months when usage goes to twice that for the central air system. So that only comes out to 10 kwh per day. There are a number of solar generator out there that can store 2 kwh, so if I could fill one of those every day and use that power, I could save 20% of my electricity, however, that only comes out to about 34 cents per day. Still, that’s $10 a month or $120 a year, so eventually a system could pay for itself.

Continue reading “Small Solar Power System”

While researching Georgia Power’s rates and shopping for a solar generator, I found out Georgia Power has a program called Overnight Advantage that you can sign up for which charges different amounts depending on what time of day you use power, with really low rates overnight (2.2 cents per kwh nominally as opposed to the standard rate of 8.1 cents). Then you pay higher than normal rates of 10.2 cents during waking hours 7 AM to 11 PM and then really high rates of 29.8 cents at peak 2-7 PM Monday thru Friday. This program might be good if you charge your electric car overnight. Electric cars have batteries of 50 kwh or more so you want the best discount on that that you can get. 2.2 cents makes it sound like you can fill up your car for a little over a dollar, but with fees and taxes, it would actually cost you about $4 to fill up your car. Still, really cheap, and even on a regular plan it would be only $8. However it could also work if you have a large home battery that you lets you run your house with stored power. I doubt that would work out for a 2 kwh battery, especially not in summer when AC use drives my power consumption up to 20 kwh per day. Home batteries are really expensive, like $6,000 to cover my 10 kwh daily usage and would need another one in Summer for air conditioning. I only use $800 of power a year.

However, it does kind of bring up the idea of bi-directional charging for electric cars, where you use your car as a home battery, charging it at night and then letting it power your entire house during the day. And taking it further, if you filled up your car overnight with 50 kwh at 2 cents per kwh, you could use 20 kwh from the car to run your house very cheaply all day and then sell another 20 kwh back to the utilty at the peak at a much higher price than you paid (Georgia Power does not do this, but they should). If Georgia Power is going to charge you 29.8 cents for peak power, wouldn’t they be willing to buy peak power from you for 15 cents? You could still make a good profit on what you sell back to them. If this could work on a large scale, the world would be a better place because we would burn less fuel and need fewer power plants. Using batteries, not even solar power, though obviously it works even better with solar. However, in places like California where about a third of the electricity is solar already, the disparity in peak and off peak prices isn’t as much because during the daytime they are generating a lot of solar, though it is still a demand peak so rates are maybe twice the off peak rates.

Getting free power from the sun has always been an appealing idea for me, but costs have always been high. Costs have come down a lot over the years, but it would probably still cost me $10,000 to install meaningful solar at my house and since I only use about $800 of electricity per year, that would take too long to pay off. Going off the grid is even more expensive because then you have to have a way to store the power in a battery to use at night or when demand is higher than what you are getting from the sun. Instead, for years I have paid Georgia Power a little extra to receive solar power (or, really, Renewable Energy Credits). At one time I thought I could get a small solar panel and hook it up to a car battery and then use the car battery to charge my phone or my laptop or whatever, and have a small and simple system, but a phone uses only a few cents of power per day and car batteries don’t last forever, so it seemed like that might not work either.

Continue reading “Solar Power at Home”

I am now in my tenth year on Georgia Power’s Simple Solar plan which charges me about 10% more than regular customers and all of my electricity is solar. Sort of. Really I am buying Renewable Energy Credits (RECs), which are an accounting gimmick so that you can buy and sell solar energy credits. The RECs are purchased from someone producing solar energy and then they use or sell the electricity back to the grid. It is like buying a carbon offset. But if a big company wants to run its factory on solar and builds a 1 megawatt solar plant to run it, it would probably say it is running the factory on solar, but I bet it would still sell the RECs. So it is kind of second hand solar. RECs are fairly cheap to buy which is why I am not paying that much. Still maybe it means something. Georgia Power’s mix of electricity sources is now up to 7% solar, which is better than in the past, but not great.

Georgia Power also has a program called Community Solar where you pay $24 per month to buy the output of a 1000 watt block of actual solar cells that Georgia Power operates somewhere in Georgia. Georgia Power then lets you reduce your power bill by the actual number of kilowatt-hours those cells produce, which they say on average is 165 kwh per month, but can vary from 115 to 215 kwh. At first glance it looks like this would generally save me money, but it isn’t easy calculating the costs.

Continue reading “Community Solar”

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.