I used a HIES registered installer, the company got a bit cute as regard the solar battery including the were were advertising and registered MSC for the battery installation and refused any paperwork or guarntee in any shape or form they were only MSC for solar panels. To add insult they informed all contact will be made in writing.
I complained to the HIES after their solicitor investigated within a day they completed all the work supplied all the paperwork including the 10 year warranty, 11 months later the inverter went down, the installer came out within 48 hours.
Unfortunately I have suffered a brain injury and occasionally I get confused and often say the wrong thing.