We talk a lot on this blog about how solar panels can cut monthly electricity costs and, in some states (like New Jersey, California, Arizona, Hawaii, Colorado and Pennsylvania) offer homeowners a stunningly attractive return on investment. Sometimes it’s worth remembering, however, that solar panels produce clean, emissions-free electricity. In other words, solar power can be good for your checkbook and for the environment.

It would make sense, then, if one of the world’s most well established solar panel manufacturers were to join a growing movement in the corporate world to measure and report its greenhouse gas emissions. That’s exactly what happened yesterday when SunPower Corporation announced it submitted its first response to the Carbon Disclosure Project (CDP), an organization that “works with shareholders and businesses to disclose the greenhouse gas emissions of major corporations.” The group exists in part to help companies prep for future climate- and carbon-related regulation.

Now, in the case of SunPower, there’s a bit of a snafu. As noted above, solar panels generate electricity without producing greenhouse gases. But that doesn’t mean that the energy used to make the panels themselves comes from an emissions-free source. It’s not unthinkable, in other words, that a solar panel maker would purchase electricity generated using coal or natural gas.

(Important side note: on balance, the amount of energy that goes into making a solar panel is significantly less than the amount of energy produced over that panel’s lifetime. See here for more.)

All these observations point to an obvious question: Does SunPower add up all the greenhouse gas emissions released during the manufacturing process and then subtract the carbon-dioxide emissions that are offset by the solar panels? Or does the company count only the emissions released during normal operations, ignoring the effect of its end product?

As much as SunPower executives seem to want — and potentially deserve — credit for producing a carbon net-negative product, it appears SunPower will be reporting its so-called “internal” carbon footprint. Here’s SunPower Tom Werner:

Beyond our internal carbon footprint reductions, our solar rooftop systems and power plants operate without generating greenhouse gas emissions, and therefore our customers’ use of SunPower systems avoids many times the amount of greenhouse gases generated in their own manufacturing and delivery operations.

As far as we’re aware, the California-based solar panel maker is the first solar power company to submit information to the CDP. If you know of any other solar companies that are involved in similar initiatives, please bring them to our attention.