Over 20 years ago I put in my first 400 watts of solar electric power. It was expensive but I’d recently sold a house and had some investment money. They are rigid monocrystalline panels. That type are more efficient than polycrystalline but also more expensive. Rigid panels are also longer lasting but heavier. However, as the old saying goes: quality only hurts once.
I’ve added more panels to the array, but the original ones are still putting out excellent power. There’s been so little efficiency drop that it’s not noticeable.
In addition to my house system I’ve four small solar electric systems. There’s a 105 watt rigid monocrystalline on a removable roof rack used for off-grid camping. I have a flexible 50 watt panel also for camping. That is a light weight panel so it can easily be moved around to follow the sun. There’s a 50 watt rigid panel that provides power to a remote shed.
The last panel in regular use is a 10 year old extremely cheap 30 watt Chinese rigid moncrystalline mounted on the sailboat to charge electronics. That’s had a lot of abuse in harsh conditions and I’ve no idea how it keeps working.
As you can see I’ve gone heavily into monocrystalline panels instead of polycrystalline. Mono panels are more efficient so take up less space and generally last longer. Polycrystalline do have an advantage in lower light conditions, along with the cost savings.
The biggest issue with solar is the up front costs. After that the sun is free. Had I invested the money instead I’d have either lost it or spent it by now -judging how things have gone over the years. As it is, those old panels are quietly doing their job.