Build Solar Water Heater

Can someone please explain if and how I can buy renewable energy certificates for my apartment electricity use. My local energy company does not currently provide renewable energy and I am under the impression I can buy certificates from renewable energy companies and use those certificates to pay for my current electric bill.
Can you please explain this process.

I’m also thinking about using a very large tuscany plant pot for a water feature. Need find a reasonable priced solar water pump somewhere. Thanks….