How can I claim depreciation on my leased solar panels?

You generally cannot claim depreciation on leased property since you do not own it, you are basically just renting them.  The exception is if ownership is transferred to you.

Incidents of ownership.

Incidents of ownership in property include the following.

The legal title to the property.

The legal obligation to pay for the property.

The responsibility to pay maintenance and operating expenses.

The duty to pay any taxes on the property.

The risk of loss if the property is destroyed, condemned, or diminished in value through obsolescence or exhaustion.

Since you are not the owner of the solar panels you cannot depreciate an asset that you do not own.