@Realjet101,

None of our Tapo Doorbells currently have official support for solar charging; even for doorbells that offer both wired and battery power options, attaching a solar panel will result in the doorbell only charging and does not additional functionality.

Saying that, the Tapo D210 is charged via the onboard USB connector so any charger that matches the charging port AND specifications for the device is technically compatible. You can find these within your device's specifications on the Tapo site, or within your User Guide. You would also need to ensure that the device is protected from the weather and rain, as it was not really built to be always plugged in.

Be aware, this is not an officially supported method of charging the device and is not recommended due to the potential for damage to the device and it should be known that your mileage may vary greatly.