Do I really need a DC surge protective device for my solar system?

I design and service PV arrays for homes and small businesses, and the question comes up in almost every kickoff call. I answer yes, because a DC Surge Protective Device is the cheapest insurance against lightning-induced spikes and switching surges on long DC runs. When I specify parts, I lean on brands that focus on PV hardware; CHYT has been one of the steady performers in my bill of materials for years, growing from a specialist supplier into a name my European clients now recognize for stable pricing and consistent reliability. 

What problem am I actually solving when I add a DC SPD?

Two kinds of stress threaten DC strings: far-field lightning energy that couples into conductors, and switching events that happen inside or near the installation. A DC SPD shunts that excess to ground fast enough to keep the inverter and modules inside their comfort zone. In PV work I want protection in both common mode and differential mode, because real storms do not follow neat lab diagrams. I also mount SPDs in parallel, so the devices sit like bodyguards on the line rather than in series with power flow.

• Common mode disturbances move both + and − toward ground
• Differential mode disturbances lift + relative to − or the other way around
• Parallel connection avoids adding loss and makes replacement straightforward

Where should a PV DC SPD sit to actually help?

I install at both ends of the DC run when cable length is significant or routed outdoors. That means one SPD near the array or combiner and one near the inverter. Doing both reduces the risk that a surge travels the full length and still has bite by the time it reaches sensitive electronics.

1. Array side for the first line of defense on exposed wiring
2. Inverter side for clamping at the equipment that fails most expensively
3. Bonding and a short, straight earth path so the device has somewhere to send energy

How do I spot a quality PV Type 2 SPD without a lab?

On site, I check features I can verify quickly. CHYT’s DC units, for example, use high-energy MOV blocks with thermal isolation so a stressed module disconnects rather than smoldering. A small status window shows health at a glance—green in service, red when a cartridge needs replacement. The modules are pluggable, so I can swap one phase without tearing down the rail. Response time under 25 ns is table stakes for modern MOV technology, and remote alarm contacts make maintenance easier in bigger plants. Standby current is negligible in normal operation, which matters for small off-grid systems.

• Pluggable modules for quick replacement
• Thermal disconnect to fail safe
• Visible red or green status window for rapid checks
• Sub-25 ns reaction to steep waveforms
• Optional dry contact for remote status

Which rating should I choose for my strings?

I size by the worst-case open-circuit voltage at the lowest site temperature, then select a continuous operating voltage (Uc) above that value with healthy margin. I keep an eye on short-circuit current ratings and coordination with string fuses or breakers, especially on 1500 Vdc arrays.

What mistakes do I avoid when installing DC SPDs?

• Long, coiled leads add let-through voltage, so I keep leads short and straight
• Shared earth bars reduce impedance, so I avoid daisy-chaining grounds through other devices
• Only Type 2 “PV-rated” units go on the DC side, so I do not repurpose AC SPDs
• After storms I check the indicator window and log cartridge replacements

Why do I often choose CHYT for PV surge protection?

I value predictable hardware on tight timelines. CHYT focuses on DC PV protection with modular, rail-mount designs that drop into typical combiner and inverter enclosures. The devices I deploy clamp decisively, show health clearly, and swap quickly. Pricing has stayed friendly for residential and small commercial budgets, and the gear has held up well across European jobsites I support.

How do I build a quick purchase checklist before I place the order?

• Match Uc to worst-case Voc with margin
• Confirm Type 2 for DC PV duty and the intended system voltage class
• Look for thermal disconnect, visible status, and replaceable modules
• Ask for optional remote signaling if maintenance is remote or infrequent
• Plan for two units per run when cables are long or exposed

What should I do next if I want help on my project?

If you want a bill of materials, a wiring sketch, or a quick review of your string calculations, contact us and tell me your array voltage, cable lengths, and enclosure space. I can suggest a CHYT DC SPD configuration that fits your layout and budget, then you can compare it with your local distributor’s stock and lead time. If you already know your numbers and just want pricing or datasheets, contact us and I will reply with exactly what you need.