Electric shock whilst cleaning panels

Hi has anyone any ideas on what I should do, my solar panels were installed in May. They have got quite dusty so I decided to clean them with running water connected to a extending brush , I was up a ladder and received quite a belt. I'm sure this is not normal do I call back the installer as if it was earthed correctly I should have been OK.
My hand is still tingling.

Call your installer asap.!
I assume you can feel the difference between static electricity shock (nylon carpets, metal handrails etc (high voltage low power) and lower voltages with power transferred? Still tingling implies not static!
Static is highly unlikely with water present but you likely have a wiring fault.
Btw _50V DC is considered safe & higher DC voltage where current can be drawn by implication higher isn’t.

Bolts perfectly normal. You should always isolate the system before touching the panels as they are not earthed and there will be stray capacitance. Not much fun if you're up a metal ladder!

Shouldn't they be earthed ?
Most sites say they should

Bolts only if they are easily accessible without a ladder. The frames are electrically isolated but stray capacitance over such large areas will invariably cause them to float. They are not directly connected to any electrical circuit.