Deductions & credits

Thanks.  If there is a guidance document or example to estimate the home value due to solar etc; please provide.  Thanks again for all the help!  I actually paid a professional solar estimator to calculate the value of the home about the time we were looking into the rental etc.  I assume that I can use that value to add to the home value?  

Considering that the home value fluctuated the last year quite a bit (zestimate went up 10% then down 15% in my area), what is the process to calculate the estimated home value I should use to which I can add the solar value?