Perhaps it helps to understand the differences:

You installed a Pellet Stove to replace a wood stove, in your House.

Or;

You installed a Pellet Stove to generate Heat, using it to turn a turbine to generate electricity, which you sell to the electrical grid.

One is personal residence improvement. One is generating. Also, there can be conservation projects, alternative fuels, etc.

Have you used the IRS resources?

https://www.irs.gov/pub/irs-pdf/i3468.pdf

https://www.irs.gov/instructions/i5695

All of these instructions include, in the first part, Why or Who uses this form.