The first step in the solar electric array design process is the calculating the number of Kilowatt (kWh) hours you’re purchasing from your electric company. You can also see it as how many kWh you’re using – which is how the electricity company wants you to see it. For myself, it’s a more realistic attitude to look at my electric bill as how many kWh I’m buying.
Buying electricity from your utility company is actually a pretty low-tech process. They determine the price per kWh – just like you’re buying potatoes….you pay by the pound.
Solar Electric-The Nitty-Gritty
If you’re a PG&E customer (some would sneer at the epithet ‘customer’) you can access your consumption history (also known as ‘usage’) from your pge.com account. On the homepage of your pge.com, click on ‘ENERGY USAGE DETAILS’.
Click and a sub-menu appears with a default selection to export all bill totals. The download comes in as a zip file, which you then open to reveal an excel-like usage file.
Even if you don’t pursue solar electric for your home or business, your usage (i.e. your purchases) and costs are there to see. There’s also a way to download interval data, which gives consumption and cost in 15-minute intervals. But for the purposes of system design, monthly data is sufficient.
Design, Engineer, Install
The next step is to review the usage and costs for the past 365 days or 12-month period. A simple division of the number of kWh by the monthly dollars gives the average monthly cost of your electricity. When the designer knows how many kWh to offset, the amount of solar electric equipment becomes clear, as does material, install and labor costs. Now we know what we need to charge our customer and you know how much money is at stake, and whether or not your ROI is sufficient.
I’ll post more on how to determine ROI in a separate post.
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