Deal Type / Custom Fields Based on Deal "Type"

In our company, as well as I'm sure most others, different services / products are sold. 

Based on product / service type, or "DEAL TYPE", we would like to have the option to display a different set of custom fields. 

 So basically, if we sell SOLAR, we want to see fields X Y Z. 

If we are selling HVAC, we want to see a different set of fields that are relevant to HVAC.