“How much would I save on my electric bill if I installed solar panels?” That’s the question I asked myself the day I called Real Goods Solar to install my photovoltaic system here in Denver, Colorado. The answer? Good news and bad news.

I still have an electric bill. I don’t get a check from Excel Energy each month. And we’re still careful (more than ever actually) about turning off lights when we leave the room. But what HAS changed is that my electric bill is a quarter of the price, I’m more conscious of the energy I use and even though my solar panels won’t pay for themselves for another five years if I keep living in this house, thanks to Colorado and Federal rebates they’ve already increased the value of my home by more than the amount that I paid for them. So, in a sense, I got them for free.

One thing I didn’t calculate that day though is the “environmental savings” my solar panels would provide me. If you’ve ever wondered whether the choice of a single, solitary household to install solar panels really makes a difference to the world, here’s a simple tool to help you estimate just how important your decision to go solar could be for the environment. All you have to do is enter the number of years you want to estimate on. FYI: Most solar panels have a warranty of 30 years and pay for themselves in about 5 years.