Lightning is one of the most common causes of solar equipment failure in Kenya. The Lake Victoria basin, including much of western Kenya, has some of the most frequent thunderstorms in the world, and storms are common across the highlands in the rainy seasons. A strike does not have to hit the building: a nearby strike can send a surge through long cables into the inverter, charge controller or battery management system.
What protects a solar system
1. Proper earthing
Every metal part of the system, including panel frames, mounting rails and the inverter enclosure, should be bonded together and connected to a good earth electrode. A poor or missing earth is the most common weakness on site.
- Ask the installer for the earth resistance measurement and keep it on record.
- Dry, rocky or sandy ground may need extra rods or treatment to reach a good value.
2. Surge protection devices (SPDs)
Surge protection devices divert surges to earth before they reach the electronics. A well-protected system has them in more than one place:
- On the DC side, between the panels and the inverter, rated for the array's DC voltage.
- On the AC side, at the inverter output and at the main distribution board.
- On communication cables, such as the inverter's data or monitoring lines, which are easily overlooked.
SPDs wear out as they absorb surges. Many have a status window; check them after storms and replace any that show a fault.
3. A lightning protection system where it is needed
Tall or exposed buildings, hilltop sites, schools, hospitals and telecom sites in high-lightning areas may need a full lightning protection system with air terminals and down conductors. The solar array must be designed to sit within its zone of protection, with safe separation distances.
4. Good wiring practice
- Keep cable runs short and run the positive and negative DC cables close together to reduce the loop that surges can induce into.
- Avoid running DC cables alongside lightning conductors.
- Use proper enclosures and glands so water cannot enter and corrode connections.
What it costs compared with what it saves
Surge protection devices and good earthing are a small part of the total price of a solar system, while an inverter is one of its most expensive parts and may take weeks to replace. A quote that leaves out surge protection to look cheaper is a false saving; see how to compare solar quotes.
During and after a storm
- Modern systems do not need to be switched off for every storm, but if your installer advises isolation for severe storms, know where the DC and AC isolators are.
- After a nearby strike, check the inverter for error codes, check SPD indicators, and ask for an inspection if anything looks wrong.
- Check that your insurance covers lightning damage to the solar equipment, and keep the installation and earthing records the insurer may ask for.
Related reading
- On-grid, off-grid or hybrid inverters explains the equipment you are protecting.
- Solar by county shows the rainy months for your area, when storms are most frequent.