Hey. I’m Annie, GetSolar’s summer intern. As one would hope for an intern here, I like solar panels and playing with numbers. As a result, I think our beta calculator might be the coolest thing since sliced bread. Let me show you how it works.
If you start at the top left hand corner and submit your Customer Type (ie Residential or Commercial) and Zip Code, our calculator will fill in your City and State, as well as your Utility. Next, plug in your Electric Rate Name, Monthly Electric Bill, and Annual Bill Escalation.
Now, I grew up in the always classy Garden State, which, I’m proud to say, is a solar hot spot. Even with our lowered rebate levels, Solar Renewable Energy Certificates (SRECs) make New Jersey a particularly strong solar market. So, for calculator purposes, I’m going to be masquerading as a New Jersey homeowner:
For my fantasy solar home, I have a Residential Service Time of Use Electric Rate, meaning the price I pay for my electricity depends on the time of day when I switch on the lights. You can find this on your monthly electric bill, along with the actual dollar amount you pay per month. Annual Bill Escalation is a trickier estimate, and for New Jersey I chose a rough estimate of 5 percent per year.
Next I sized my PV System.
My roof will have room for a 5 kW system Size at an initial Cost of $7,000 per kilowatt (kW) installed. Now it’s likely that you would be able to install panels at a lower per kW cost, but for our purposes a conservative estimate is best. My roof also has a 30 degree Tilt and one side faces south (Orientation). In real life, you would have to go outside and estimate tilt based on your actual roof, and the directions that sides of your roof face are easily visible on Google Maps. The renewable energy credit (REC) estimates, which are called SRECs in New Jersey, may not apply in every state, but for the Garden State current SREC information shows us that generating renewable energy will earn homeowners an REC Value of about $0.56 per kWh we generate in the 2009-2010 reporting year. Also, this value will decrease at an Annual Rate of 2.5%. Other states without RECs may be eligible for Federal or State Tax Credits and State/Utility rebates. Our calculator will add these for you automatically.
Then comes the cool part. The calculator creates clear graphs of your kWh production, solar savings, and cash flows. I included my system’s cumulative net cash flow here:
Beautiful isn’t it? My system saved me $674 per year and will pay for itself by 2018. From then on, my system will continue to generate SRECs and utility savings for, oh, another 17 years or so.
As with any financial model, standard caveats apply — and changing the assumptions (where you are, your utility bill, taxable income, roof tilt, etc.) can yield drastically different results. So for those of you using this for an actual home instead of the fantasy version I tried, make sure your basic information is as accurate as possible.
That being said, I would love to hear how the calculator works for you in general. We’re still looking to improve it, so your stories matter a lot. Send me questions, challenge my assumptions, or point out grammar errors at