I wouldn't want to install them on an old roof as you would have to remove the solar panels to replace the roof, then put them back, which would be very expensive. At 17 years, you may be close to needing to replace the roof anyway.

I don't understand free panels...are they being leased to you? What are the other costs involved...inverters, installation, meters and shut offs, etc.

I don't like to discourage people from solar energy, but in your case, it sounds like you need a lot more info before you can make a sound decision.

Also, does your roof face south? At what pitch? Are there trees shading it?

I have to agree with Annie and I also have to wonder..."if it's too good to be true...it probably is?" Now, if this is part of a research program, it might be worth it and it might be valid. I would call your power company and make sure they are actually offering that and then tell them about your concerns about the age of the roof. If they are NOT offering a program such as this, you have to ask yourself WHAT did you actually sign and with whom? There are too many scam artists out there. Did you supply your SSN and other private information when you signed to get the permits? I think I'd be very concerned and cautious going forward. If this is legitimate, they will understand your concerns and work with you...if NOT, you may be averting a disaster by posting here. Good luck to you!