Is there a tax rebate for solar windows? Is the entire system cost eligible for the ITC credit?

Yes, there are various local tax rebates and incentives across different jurisdictions. There is also the Federal Solar Incentive Tax Credit (ITC) that applies which is currently at 26% and sunsets to 10% for commercial use and 0% for residential use after 2023. The entire installed cost of the transparent solar window would be eligible for the ITC credit as the entire system is a solar system.