"Hinder" means to make difficult, which appears to be what the government is doing. "Block" means to prevent entirely, which they are not doing. So, "hinder" would be the appropriate word in this case.

Since it's a tax that is reducing the desire to install the panels, I'd use the verb "discourage". The government is discouraging the installation. Hinder might be ok, but it would apply more if there were a complicated approval process that was limiting the installation. Block is too strong. It means prohibit, which they are not doing. Even though they are campaigning for it.