You can find out if your renewable equipment is safe by carrying out suitable checks, such as inspection and / or testing. The level of inspection or testing should depend upon the risks and loads that is applicable at all time. A simple visual inspection is likely to be sufficient for equipment used in a clean, dry environment. In addition, equipment that is more likely to become damaged, or is operated in a harsh environment, is likely to require more demanding electrical tests.
Checks/ routine maintenance should be carried out often enough to ensure there is little chance the equipment will become unsafe between checks. It is good practice to make a decision on how often each piece of equipment should be checked, write this down, make sure checks are carried out accordingly and write down the results. You should change how often you carry out checks, according to the number and severity of faults found.
The best way to find out if specialized equipment is safe is to have it inspected and tested by a person with specific competence on that type of equipment. This may be the original manufacturer or their authorized service and repair agent. A reputable servicing company that deals with that type of equipment should also be competent to check its safety.