Solar Inverter Passive Components in Spain: 36 of 2,014 Parts Above 1 kV Publish a Temperature Grade

We counted every Walsin MLCC row rated 1 kV or above: 2,014 rows, 1,874 distinct part numbers. Only 36 of them sit in an AEC-Q200-compliant series, and not one sits in the HT high-temperature series — because HT stops at 100 Vdc. Choosing solar inverter passive components in Spain means choosing voltage or temperature grade. The catalogue barely lets you have both.

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Venatech Limited, an authorised Walsin distributor in Hong Kong, holds all 203 Walsin Technology (Walsin) parametric export files and 28 Walsin datasheets. This post is a bill-of-materials cut, not a series tour — for the series tour see middle and high voltage MLCC, 200 V to 4 kV. It is measured from 00_ALL_MLCC_parts_combined.xlsx, Walsin_MOV_ALL.xlsx and the four non-empty Thick_Film_High_Voltage_Chip_Resistor_*.xlsx files. Every part number is real; every count is of part numbers, not pieces.

How many Walsin parts clear 1 kV and publish a temperature grade?

Thirty-six, out of 2,014. A string inverter in Spain is a sealed box on a mounting structure in direct sun, so ambient is the constraint that decides the capacitor, not the DC-link voltage. We checked all 24,026 MLCC rows: 2,014 are rated 1,000 Vdc or above. Of those, 36 are in a series Walsin labels as qualified to AEC-Q200 — 20 in MT and 16 in ST — and zero are in the HT high-temperature series. That is 1.8 % of the high-voltage shelf carrying any temperature signal at all.

Series	Rows at 1 kV or above	Temperature signal published
Middle to High Voltage (200 V – 4 kV)	1,261	None
Big sizes 1825 / 2220 / 2225	258	None
Soft Termination SH (Ag-poly)	256	None
Safety Certificated X1/Y2 (S2)	173	None
Automotive MT, qualified to AEC-Q200	20	AEC-Q200 compliant
Automotive soft-term ST, qualified to AEC-Q200	16	AEC-Q200 compliant
Microwave RF series	15	None
Soft Termination SG (Cu-poly)	12	None
Automotive MG, not AEC-Q200	3	None
High Temperature (HT)	0	n/a — the series caps at 100 Vdc
Total	2,014 (1,874 distinct)	36 with a grade

We have not seen this intersection counted anywhere. It is the single most useful number on this page for an inverter programme, because it turns “which 1 kV capacitor?” into a choice between 36 parts with a published grade and 1,978 without one.

Why does the high-temperature MLCC series stop at 100 V?

We do not know why, but we can show that it does. We read all 128 rows of the HT series: 67 are rated 100 Vdc and 61 are rated 50 Vdc. There is no third voltage. The dielectrics are X8G on 102 rows and X8R on 26, the case sizes run 0402 to 1210, and the whole series is a low-voltage shelf wearing a high-temperature name.

So the HT series belongs on the control board of a string inverter, near the gate driver and the microcontroller, and nowhere near the DC link. HT15G470J500 — 0402, X8G, 47 pF, ±5 %, 50 Vdc — is a timing and matching part, not a snubber. The practical consequence is that the hottest capacitors in the box, the ones across the DC link, are the ones with no temperature grade published. See high temperature MLCC to 150 °C: the HT series.

Can the MOV export size a part for the DC string side?

No. We read the Max Working Volt. column on all 379 MOV rows and every single value is stated in Vac. Not one row states a DC working voltage, and the AC ceiling is 750 Vac, on one part number. A PV string sits at 1,000 or 1,500 Vdc, so the field you need to size a DC-side surge device does not exist in this export.

The Varistor Voltage column is in Vdc on all 379 rows, but that is the nominal breakdown measurement, not a continuous rating, and using it as one is how a varistor ends up conducting in service. Three more columns in the file — Packing, SPQ and MOQ — are empty on all 379 rows, so the export cannot answer an ordering question either.

Part number	Series	Body	Max working volt. (as exported)	Varistor voltage	Peak current	Match / mismatch vs a 1,000 Vdc string
SR122K53D	Industrial	53 mm	750 Vac	1,181 Vdc	70,000 A	Mismatch — highest in the file and still an AC rating
SR112K53D	Industrial	53 mm	680 Vac	1,068.5 Vdc	70,000 A	Mismatch — no DC continuous rating published
SR102K34RD	Industrial	34 mm Square	625 Vac	1,000 Vdc	80,000 A	Mismatch — highest surge in the file, AC rating only
SR102K20D	Standard (D)	20 mm	625 Vac	1,000 Vdc	6,500 A	Mismatch — small body, 12× less surge than the 34 mm
SR102K34RD vs SR102K20D	Industrial vs D	34 mm sq vs 20 mm	Same 625 Vac	Same 1,000 Vdc	80,000 A vs 6,500 A	Same two headline fields, 12× apart on surge

That last row is the point. Two parts agree on both voltage columns and differ by more than an order of magnitude on the field that decides whether the device survives. For the AC output side, where this export can be used, see how to choose an MOV varistor.

What does the high-voltage resistor export leave out of a divider?

A voltage column, and a UL option below 100 kΩ. We parsed the four non-empty high-voltage chip resistor files: 20,244 distinct part numbers across five case sizes and four series, and no column anywhere states a working voltage, an overload voltage or a dielectric withstanding voltage. That you cannot filter high-voltage resistors on voltage is ours and already published in high voltage chip resistors and the limit nobody checks.

What we measured today is the UL subset, and it is unusually tidy. Exactly 1,502 part numbers carry the UL Safety Certification series name, and exactly 1,502 more are their automotive twins, formed by appending a single J — all 1,502 pair with no exceptions. The subset’s resistance range begins at precisely 100,000 Ω and ends at 100,000,000 Ω.

Part number	Series as exported	Size	Resistance	Tolerance	TCR	Match / mismatch vs a DC-link divider
WF06N1003FTL	High Voltage, UL Safety Certification	0603	100 kΩ	±1 %	≦±100	Match — lowest UL-certified value in the export
WF06N1003FTLJ	…UL Safety Certification (Automotive)	0603	100 kΩ	±1 %	≦±100	Match — identical fields, AEC-Q200 grade added
WK25V47R0DTL	High Voltage (no UL)	2512	47 Ω	±0.5 %	-200～+500	Mismatch — low-side leg, no UL option, one-sided TCR

Read the implication for the divider. The top leg of a 1,000 Vdc sensing divider sits in the hundreds of kilohms to megohms and has 1,502 UL-named candidates. The bottom leg is a low-value part, and at 47 Ω there is no UL-certified option in this export at all. Note also that the 2512 part states its TCR as -200～+500, a one-sided band that 168 rows use and that will not sort numerically against the ≦±100 and ≦±200 entries on the other 20,076.

What would actually go on a string inverter bill of materials?

Five positions, and only two of them come with a grade. Of the 36 AEC-Q200 rows above 1 kV, capacitance runs from 22 pF to 100 nF; 29 are at 1,000 Vdc, 5 at 3,000 Vdc and 2 at 1,250 Vdc; case sizes are 1210 on 17, 1206 on 12, 2220 on 4, 1825 on 2 and 1812 on 1.

Position	Part number	Key fields	Match / mismatch vs the inverter requirement
DC-link bulk, 1 kV	ST46B104K102	1825, X7R, 100 nF, ±10 %, 1,000 Vdc, soft termination, AEC-Q200	Match — largest capacitance above 1 kV with a grade; mismatch — 1825 flex risk is why it is soft-terminated
DC-link snubber, 3 kV	ST55B103K302	2220, X7R, 10 nF, ±10 %, 3,000 Vdc, AEC-Q200	Match on voltage headroom; mismatch — 10× less capacitance
IGBT snubber, 1 kV	MT32B103K102	1210, X7R, 10 nF, ±10 %, 1,000 Vdc, AEC-Q200	Match — smallest graded body at 10 nF
Bulk, no grade	1206B472K102	1206, X7R, 4,700 pF, ±10 %, 1,000 Vdc	Match on electricals; mismatch — no temperature grade published
2 kV filter	1206B151J202	1206, X7R, 150 pF, ±5 %, 2,000 Vdc, 0.80 mm thick	Match on voltage; mismatch — 0.80 mm body against 1.25 mm on the 1 kV parts

Four of the five match on every electrical field a schematic states and differ on the field a Spanish rooftop actually tests. Remember too that an X7R part delivers its nameplate capacitance at zero volts, not at the DC link — see MLCC DC bias and voltage derating. We will not tell you a part is equivalent. We will show you where it differs.

What documentation does Venatech hold on these three lines?

MLCC fully, the other two not at all. We hold 28 Walsin datasheets, 451 pages: 26 MLCC, covering all 16 series present in the export, and 2 chip resistor. We hold zero MOV datasheets and zero datasheets for the thick film high voltage resistor families. So the MLCC figures above are checkable against a document we can send you; the MOV and resistor figures are the export’s own values.

Check us on what is checkable. UL file E182369 is searchable in UL’s own public database. Two named TUV certificates and two named CQC certificates cover the S2 safety series — which is itself 173 of the 2,014 rows above 1 kV — and all five numbers are listed in five safety capacitor certificate numbers you can check without asking us. Lot and date-code traceability, a certificate of conformity per shipment on request and original sealed Walsin packaging are what a supplier-approval questionnaire asks for. REACH, SVHC, PFAS, ISO 9001, IATF 16949, PPAP and IMDS appear nowhere in our 451 pages, and we say so because nobody else does.

What should a Spanish inverter programme do next?

Put the temperature requirement in the specification before the voltage, then cross the list in one pass. 36 parts above 1 kV carry a grade; 1,978 do not; the MOV export cannot answer a DC question; the resistor export cannot answer a voltage question. The trade press reported MLCC lead times in the 26 to 32 week range through 2026 as AI server and EV build-outs drew on the same capacity, which is why a visible second source matters more than it did.

1. Decide whether your DC-link position needs an AEC-Q200 grade. If it does, you are choosing among 36 part numbers, and the choice is largely made for you. If it does not, say so in the requirement so nobody re-opens it at qualification.
2. Cross the whole inverter bill of materials at once. Paste up to 500 part numbers or drop your Excel or CSV into the free cross-reference tool. It is matched against Walsin’s published catalogue and returns candidates field by field, with every difference stated rather than hidden. Filter by commercial or automotive grade, or for soft termination, high temperature, safety certified, high Q / low ESR or low profile.
3. Check Hong Kong before you commit. Ready stock is a dated snapshot as at 23 September 2026, not a live feed; on that date 864 of the 1,125 catalogue codes were MLCC and 254 were chip resistors.

For the inductive side of the same box see Walsin inductors for Spanish solar inverter manufacturing, and the varistor range is on the Walsin MOV product page.

The short version

For a Spanish string inverter the binding constraint is temperature, and the data barely addresses it. 2,014 Walsin MLCC rows reach 1,000 Vdc, 1,874 of them distinct; 36 sit in an AEC-Q200-compliant series; zero sit in the HT series, which caps at 100 Vdc on all 128 rows. All 379 MOV rows state a working voltage in Vac and none in Vdc, with a 750 Vac ceiling on one part. The 20,244-row high-voltage resistor export states no voltage at all, its UL subset is exactly 1,502 parts mirrored by 1,502 automotive twins, and it begins at 100 kΩ, so a divider’s low-side leg has no UL option. We hold 26 MLCC datasheets and none for MOV or high-voltage resistors. Qualification stays with you.

Send us the inverter bill of materials with the ambient you actually design to, and we will come back with Walsin candidates field by field, differences included, and tell you plainly which positions we can only answer from an export. Here is the question worth arguing about: if 1,978 of the 2,014 parts above 1 kV publish no temperature grade, is an AEC-Q200 part the only defensible choice for a DC link — or is the grade doing less work than the derating curve?

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Frequently asked questions

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