It is what passes for winter in Austin right now with today’s high reaching 73F (about 23C), and we are still enjoying a riot of sunshine in the city. It’s been a month since Austin Energy updated their utility billing model, and I started to think about the impact on solar photo voltaic production in the area.

The new rate for solar produced grid-tied electricity in Austin is the Value of Solar Factor, which at present is $0.128 per kWh. This value can be updated each year by the utility.

What does this mean for someone with a small rooftop solar PV system?

Now with the Value of Solar Factor, there’s a degree of simplicity. Calculating the value of your production is now a simple monitoring and multiplication task. Previously, there would be complexities based on the usage in your home due to the different costs of different tiers of usage. So in the old system, if your solar production meant that your net use moved to a lower tier, you would be savingĀ  a different amount from someone who used less electricity and their solar production kept them in the same tier. Confusing? Not any more.

Under the new billing system, all you need to figure out the value of solar production for a given year is the amount of power produced. For fun, let’s take a look at an example. It’s for a nominal 3kW system – one of the smaller in the Mueller neighborhood. It lives on my roof.


The last few years of solar production at my house. I pulled this from

The annual average production of this system for the two full years is 4,728 kWh. The system is degrading slowly over time, but for now I’ll ignore that – two years data is a good start. In the past system, under which most of the generation occurred, I would have to go to Austin Energy and pull a whole bunch of data to figure out a dollar value for this. Now, all I do is multiply by $0.128 per kWh and get $605.

Now before you all start undoing all the benefits of multiplication to get the payback period for your 3kW solar PV systems, don’t forget that there is an additional consideration – the resale value of your PV equipped home, as I talked about in a previous post. Unlike upgrading your master bathroom, adding solar gives you both an increase in resale value and an annual income from your investment. This adds some extra dimensions to selling your Mueller home, which I’ll write about soon. Call me at +1 (512) 829-1351if you want to talk.