Nine times out of ten if a pv solar system fails it will fail very early after the installation and is the faulty of the inverter.
The solar industry has grown very quickly over the last couple of years and yes there are many new companies. As a result, government regulations have addressed of the most technical issues through rigorous standards.
My best advice is get three quotes, make sure the companies are REAL assured and MCS accredited. Check any facts given and were possible use a company that has a few years experience under its belt.