The point of the annual check is not to find something. It is to be able to compare this year with last year.
Outside first
Panel glass, frames and fixings. Cable supported rather than hanging, with nothing chafing at a roof edge or a penetration. Connectors seated and undamaged. Sealant and gland integrity, which is where water eventually gets in.
Then the joints, under load
Run the system hard and check for heat along the main cable and at every terminal, busbar, fuse holder and isolator. This is the single most productive part of the list.
Then the numbers
Daily energy in and out over a typical week, compared with the same period last year. A monitor that has been running makes this a matter of reading rather than measuring, and the comparison is what turns an impression into evidence.
Then the battery, if the numbers suggest it
A counted discharge from full to the system cut-off at a known load. It is the only measurement that establishes state of health, and it is worth doing when the trend has moved rather than every year.
Then write it down
What was checked, what was measured, what was changed. The file is worth more each year, and it is what makes the fifth annual check a diagnosis rather than a first impression.
What people ask before they order
What is worth recording rather than just checking?
Anything that becomes meaningful as a trend: daily energy in and out for a typical week, a counted discharge if one is done, and the torque or condition of the main terminals. A single reading tells you little; five years of them tell you a great deal.
Does anything need re-torquing?
Where a component maker publishes a torque figure for its terminals or busbars, it is worth checking against that figure. Where none is published, the check is for looseness and heat rather than to a number.
Last reviewed 16 September 2026