This one gets very tricky.

Look at the dates, when you read stuff. You linked to something dated April 2021. Some of it no longer applies. Look at the wording, too. "Residential Energy Efficient Property Credit" is changed to "Residential Clean Energy Credit." The new name is under the Inflation Reduction Act of 2022. Try these:

https://www.irs.gov/credits-deductions/residential-clean-energy-credit

https://www.irs.gov/credits-deductions/home-energy-tax-credits