Using Technova nozzles (yellow) and Rainbird pop-up sprinkler-4" nozzle- 18 VAN (black), I have made solar rooftop auto cleaning (DIY) system. This is 3.9kw (325 watts x 12 nos Waree panels) Solar PV roofop system. All 12 nos of PV panels are placed in one slope.3 panels are kept side by side and in 4 raws. So that with minimum use of water,minimum use of nozzles,minimum size of water pump(1/2 hp monoblock), without using any additional pressure pump booster switch, all panels can be cleaned. It is cleaned in just 2 mins only. No wastage of water(used water directly goes in garden). It's Water pump control switch is kept at ground floor. It will be operated with Android application base timer switch lateron. Thus it will be completely automatic operation. With Android application, it can be switched OFF/ON and it's time setting can be done with remotely accessed from any place and any where through mobile application. The water pump is kept just near the over head tank.All solar rooftop PV panels, 0.5 HP monoblock water pump and overhead water tank are just located side by side at bungalow terrace. The solar rooftop PV panel structure is designed in such a way that solar rooftop looks like a weather shed. No much drilling are required for fixing solar rooftop structure on terrace flooring. This is to minimize any water penetration through anchor bolts which are drilled to hold two pillars/legs of rooftop structure.Thus Entire terrace floor is free for use.
Materials used:

Half HP monoblock water pump(Harsh make)

3/4"dia. UPVC pipe from pump discharge side upto nozzles, then pipe is reduced to 1/2"dia. to get sufficient pressure in nozzles
3 - Nos Technova make (yellow)specially designed nozzles for cleaning solar panels.(available online on Indiamart)whattsup no.9082858645 and see link https://youtu.be/PduE2UjCE40

1 - Nos Rainbird(black) Pop-up sprinkler 4"nozzle 18VAN, to clean panels thoroughly beyond 12' length from top end.(Available on Amazon)

Notes: In case ,if needed to clean occasionally entire rooftop manually with pressure water , a separate valve is placed in pump water dischage line.

Specially porpose meant for sealing solar panel gap , a special tape is used, SIKA multiseal -T tape, to seal a gap between panels. So that water flows down totally without any leaking from panel gaps. It is designed for UV protection.As per universal reviews, it's life is as long as Solar PV panel's life.

By regular cleaning efficiency in solar power generation is increasing to @26%...See this video

https://youtu.be/9gvOGiBp3lU