Most sourcing failures are visible before the deposit is paid. They appear as a certificate issued to another company, a datasheet that does not match the quoted model, or a supplier who cannot explain who owns the factory.
This checklist is the sequence we recommend to first-time buyers of on-grid systems. It applies whether you are ordering a 100 kW rooftop kit or a 1 MW ground-mounted plant.
1. Confirm the legal entity and the factory address
Ask for the business licence and the unified social credit code. Compare the registered address with the address on the quotation and the address shown in the factory video.
A supplier with a trading company licence is not automatically a problem. The problem is a trading company presenting itself as a manufacturer. Ask directly: do you own the production lines, or do you subcontract? Both answers can be acceptable; an unclear answer is not.
2. Check what the supplier actually makes
On-grid systems contain modules, inverters, mounting structures, cables, combiner boxes and monitoring. Very few companies manufacture all of them.
Ask which components are produced in-house and which are sourced. A supplier that claims to manufacture every item is either unusual or inaccurate. A clear split - for example, in-house mounting and assembly, partnered module lines - is a sign of an honest operation.
3. Verify certificates at the issuing body, not the PDF
For modules, the two core standards are IEC 61215 (design qualification and type approval) and IEC 61730 (safety). For grid-connected inverters, IEC 62109-1 and IEC 62109-2 apply.
Check four things on every certificate: the certificate holder's legal name, the manufacturing site, the exact model list and the expiry date. A certificate in the name of a different company, or one that lists a model you are not buying, does not cover your shipment.
4. Distinguish a certificate from a test report
A certificate confirms that a design family passed type testing at a recognised laboratory. A test report records the measurements for a specific sample. Buyers often receive one and assume the other.
Request both, and request the flash test data for the actual batch you are buying. A type certificate from 2021 says nothing about the modules in container number three.
5. Compare the datasheet with the quoted model
Check power tolerance, temperature coefficient of Pmax, first-year and annual degradation, maximum system voltage, fire rating and connector type. These parameters decide compatibility with the inverter and the mounting system.
A common sourcing error is a quotation that names a 580 W module while the attached datasheet covers a 540–560 W family. Ask for the datasheet of the exact model, revision dated.
6. Ask for the bill of materials
For modules: cell supplier and type, glass thickness, backsheet or glass-glass construction, junction box, connector brand. For inverters: topology, MPPT count, protection rating, communication interface.
A supplier who cannot provide a BOM is asking you to buy a black box. A supplier who provides one is giving you the ability to compare like with like.
7. Confirm grid-code compliance for the destination
IEC 62109 is a safety standard. It does not certify that an inverter can connect to the grid in your country. Grid connection is governed by national codes such as VDE-AR-N 4105 in Germany, CEI 0-21 in Italy, EN 50549-1 in much of Europe, G99 in the UK and AS/NZS 4777.2 in Australia.
State the destination country and the grid operator at the quotation stage. Retrofitting a firmware profile after arrival is possible for some models and impossible for others.
8. Read the warranty as a document, not a headline
Separate the product warranty from the power output warranty. Confirm who honours the claim: the manufacturer, the supplier, or a third party. Confirm who pays freight for a replacement module and what evidence is required.
A 25-year power warranty with no named entity behind it is a marketing sentence. Ask for the warranty document with the company chop and the claim procedure.
9. Ask for QC records from a comparable order
Request anonymised records from a recent shipment of similar size: incoming material inspection, EL images, flash test summary, pre-shipment inspection report and packing list.
Redact customer names if necessary. A supplier who has these documents can send them within a day. A supplier who does not will send a brochure instead.
10. Review packaging and container loading
Modules travel badly when corner protection is inadequate or when pallets are not secured. Ask how many modules fit in a 40HQ container, how the load is braced, and whether the loading plan accounts for mixed items such as mounting rails.
For projects with multiple delivery phases, confirm how partial shipments are labelled. Missing rails at the site are more expensive than a slightly higher freight rate.
11. Agree on Incoterms, payment and inspection
FOB, CIF and DDP shift risk in different ways. DDP looks convenient but can hide import VAT and customs exposure. CIF leaves inland transport and insurance gaps that buyers discover at the port.
A common structure is 30% deposit, balance against a pre-shipment inspection report or a copy of the bill of lading. Third-party inspection by SGS, BV or TÜV is inexpensive relative to the order value.
12. Speak to a reference customer
Ask for two references in your region or your application type. Ask them three questions: did the system arrive complete, did the output match the simulation in the first year, and how did the supplier respond to the first problem?
Every supplier has happy customers. The useful signal is how they behave when something goes wrong.
How to audit a supplier remotely in five working days
Most buyers cannot visit China before the first order. A remote audit can still surface the facts that matter, if it is structured.
Day one: request the business licence, factory address, certificate list and a model-level BOM. Day two: verify each certificate in the issuing laboratory's database. Day three: hold a live video call and ask to walk from the material store to the packing area without cuts.
Day four: request QC records from a recent comparable shipment and check that the dates, models and quantities are consistent. Day five: speak to one reference customer and ask about the first problem they had, not the overall experience.
A supplier who can complete this sequence in a week is operationally organised. A supplier who cannot is telling you something about how the order will be handled after the deposit.
Contract clauses worth negotiating
Four clauses prevent most disputes. The first is a technical specification annex that locks the BOM, not just the system size. The second is an inspection clause allowing a third party to inspect before shipment and a balance payment tied to that report.
The third is a delay clause with a defined remedy, including the delivery date basis - production completion or arrival at port. The fourth is a warranty procedure that states who pays freight, what evidence is required and the response time for a claim.
None of these clauses is unusual. Suppliers who resist all four are signalling where the risk will land.
Red flags worth walking away from
|
Red flag |
Why it matters |
|
Price 25–35% below other quotes for the same BOM |
Something is missing: certification, insurance, cell grade or after-sales |
|
Certificate holder is a different company |
The certificate does not cover your goods |
|
Refuses a live video tour of production |
The factory may not exist or may not be theirs |
|
Warranty stated as a number without terms |
No enforceable claim process |
|
Cannot name the cell or inverter supplier |
BOM opacity usually hides grade substitution |
|
Pushes DDP without explaining duties |
Hidden cost or customs risk lands on you |
How we handle these checks
DS New Energy is a Hangzhou-based supplier of on-grid, off-grid and hybrid solar systems, with 13 product lines under one roof, 18 projects delivered in 10 countries and an engineering team with 15+ years in PV. We provide IEC certificates, batch flash test data and pre-shipment inspection records with every order, and we welcome factory visits in person or by video.
Frequently asked questions
Is it safe to buy solar systems directly from a Chinese supplier?
Yes, with verification. Confirm the legal entity, check certificates at the issuing laboratory, require a BOM, and use a pre-shipment inspection. Most disputes come from skipped verification, not from the country of origin.
How do I verify an IEC certificate?
Ask for the certificate number and the issuing laboratory, then check the laboratory's online certificate database. Confirm the holder name, factory address, model list and validity period match the quotation.
What payment terms are normal?
30% deposit with the balance against a pre-shipment inspection or shipping document is common. Every company has different payment methods, so it depends on the actual situation.. Letters of credit are workable for larger orders.
Should I use FOB or DDP?
FOB gives you control over freight and insurance and is the simplest to compare. DDP is convenient only when the supplier is transparent about duties and import VAT. For a first order, FOB plus your own forwarder is usually safer.
How long does production take?
Standard on-grid systems typically take 15–25 days after drawing approval and deposit. Custom mounting structures and non-standard voltages add time. Always add buffer before a fixed commissioning date.
Request our certificate pack and BOM
Send us the system size and destination country. We will reply with the certificate list, a model-level BOM, reference configurations and current lead times.
