I still remember the smell of burnt plastic when a client’s inverter fried in 2019. That one spike cost him 28 000 USD and six weeks of downtime.

Yes, you need a surge protector. A single lightning strike or grid fault can send thousands of volts into your cables. A good SPD eats that spike before it reaches your inverter, meter, or battery. I have seen it save entire solar roofs.

Still not sure? Keep reading. I will walk you through real damage, real numbers, and the exact specs we use when we ship to Berlin or Milan.

What Happens Without a Surge Protector?

I opened the metal enclosure and the PCB looked like black toast. The customer thought insurance would pay. It did not.

Without an SPD, over-voltage climbs straight into your inverter. The DC link capacitor explodes, IGBTs short, and the whole string stops. One 1 500 V spike can wipe out a 50 000 USD commercial inverter in 0.2 seconds.

Real Cost Breakdown

Why the Breaker Did Not Trip

Breakers only react to over-current, not over-voltage. A spike can be 2 000 V but only 3 A, so the breaker smiles and stays closed. That is why you need a device that looks at voltage, not current. An SPD does exactly that: it shorts the extra volts to earth and then resets.

Three Myths I Hear Every Week

“My panels are grounded.”

Grounding lowers touch voltage, but it does not clamp a spike.

“We never get lightning here.”

Grid switching, capacitor banks, and even elevator motors make spikes daily.

“The inverter has built-in protection.”

Most factory MOVs are sized for 40 J. A direct hit carries 50 000 J. The math is sad.

Case from Hamburg, March 2023

A 2 MW rooftop had no external SPD. A distant strike induced 1 200 V on the DC string. The inverter died, but worse, the arc cracked the polymer roof. Water entered, and the insurance firm blamed “lack of maintenance.” Payout: zero. The client later bought 120 of our 1 000 V DC SPDs for the rebuild.

Hidden Heat Issue

Many engineers forget that an SPD sits in a tiny IP65 box all day. The sun cooks the metal to 70 °C. Inside, the MOV disk runs even hotter. Cheap disks start to leak current at 85 °C. Once leakage starts, heat rises, current rises, and the disk cracks. Our factory adds a thermal snap-link that pulls the SPD offline at 120 °C. The unit fails safe, not short, and your site keeps running.

Signal Loss vs. Fire Risk

Some buyers only look at voltage protection level. I also look at fire safety. In 2021 a warehouse in the Netherlands burned because a no-name SPD caught fire after the MOV failed short. The insurer refused to pay because the SPD had no UL 1449 4th Ed. listing. We test every batch to both IEC and UL so you can sleep at night.

How to Choose the Right Surge Protector for Solar Projects

Last year a buyer sent me a 20-page RFQ. Line one said: “Cheapest SPD, 1 000 pcs.” I deleted the email.

Match the SPD to your system voltage, short-circuit current, and risk level. Start with IEC 61643-31. Pick a Uc 20 % above your open-circuit voltage. Then check Imax: 40 kA for rooftops, 100 kA for utility-scale. I always add a remote contact so the SCADA team sees the trip.

Quick Selection Table

Step-by-Step Method

Write down Voc at the coldest day.

Cold boosts voltage by up to 15 %.

Add 20 % safety margin.

That gives your Uc.

Count down-conductor length.

If longer than 10 m, add a second SPD at the inverter side.

Check the fuse.

The SPD must have a fuse that clears before the cable melts. We use gPV 15 A for 4 mm².

Demand test report.

Ask for IEC 61643-11 and UL 1449 4th Ed. in the same PDF. No report, no deal.

Hidden Detail: Thermal Run-Away

Cheap MOV blocks start to leak at 85 °C. Inside a black IP65 box on a Spanish roof, that happens every summer. Our blocks use thermal disconnect that snaps at 120 °C. The SPD fails safe, not short.

Lead Length Mistake

I see installers use 30 cm flying leads because it is faster. That adds 300 V to the let-through voltage. Our rule: keep leads

Coordination with AC Side

Do not forget the AC side. After the inverter flips to 400 V AC, you still need an SPD. We place Class II 275 V AC units at the main board. For sites with transformers, we add Class I 25 kA 10/350 µs on the LV side. One strike on the MV line can still travel down.

Why Top EPCs Use Hybrid SPD Designs

I visited a top-10 EPC in Milan. Their engineer flipped the SPD over and said: “I want no MOV soup in my plant.”

Hybrid SPDs join a fast gas tube with a robust MOV. The gas tube takes the first 90 % of the strike, so the MOV stays cool. Result: life span triples, let-through voltage drops 30 %. That is why Tier-1 EPCs now write “hybrid only” in their BoQ.

Inside the Hybrid Box

Why It Matters for O&M

Every truck roll costs 1 200 USD. If an SPD lasts 15 years instead of 5, you save three rolls. On a 100 MW portfolio that is 360 000 USD. The extra 12 USD you pay for hybrid is noise.

Spec I See in 2024 RFQs

- Nominal discharge In: 20 kA

- Max discharge Imax: 100 kA

- Voltage protection level Up:

- Remote contact: dry 250 V 1 A

- Operating temp: –40 °C to +85 °C

- Cert: IEC, UL, TÜV, CE, RoHS

If your factory cannot tick every box, you are out.

Gas Tube vs. MOV Aging Curve

We ran a 20 kA 8/20 µs test 200 times. The pure MOV unit saw Up rise 38 % after 100 shots. The hybrid unit rose only 9 %. That delta means the inverter sees 400 V less stress. Over 20 years, that is the difference between a 12-year inverter life and a 6-year swap.

Weight Hint

A 40 kA hybrid SPD weighs 0.8 kg because the gas tube adds copper and ceramic. A 40 kA MOV-only unit weighs 0.4 kg. If the sample feels light, open it. You may find half the MOV disks missing.

From Factory to Field: What Makes a Reliable SPD Supplier?

I once audited a workshop that glued MOVs with epoxy. The next year the blocks fell off during shipment. We lost 800 units at sea.

A reliable SPD supplier owns the full chain: metal shop, MOV disc press, TIG weld, burn-in, and 100 % test. Ask for the QC sheet. It must show In and Imax for every single unit, not a batch sample. My plant in Wenzhou keeps that data for 10 years.

Checklist I Give to Jeff-Style Buyers

Logistics Edge

We run bonded stock in Hamburg. Your container can leave Wenzhou today and clear customs in Bremerhaven tomorrow. No VAT until you pull the goods. That cuts your cash cycle by 21 days.

Payment That Works for You

We take 30 % down, 70 % against BL copy. If your credit is >500 k USD/year, we add 90 days OA through Sinosure. You get the float you need, I get the order.

Audit Tip

When you visit a factory, ask to see the MOV incoming inspection. They should test 100 % of disks for reference voltage at 1 mA. If they test only 5 %, walk away. We reject 3 % of every lot; that is why our five-year return rate is 0.2 %.

After-Sales Kit

Every box ships with a QR code. Scan it and you see the test report, wiring diagram, and a 45-second install video. Our team also shares the DXF file for DIN rail drilling. Little details save you one hour on site.

Spare Part Policy

We keep 2 % of every shipment as free spares in Hamburg. If one unit trips, we courier a replacement within 48 h. You do not wait for the next container.

Conclusion

A 30 USD SPD can save a 50 000 USD inverter. Pick the right class, demand hybrid tech, and vet the factory. Email me today, I will ship samples tomorrow.

Media Contact
Company Name: Wenzhou Leikexing Technology Co., Ltd
Email: Send Email
Country: China
Website: https://www.leikexing.com/