How to Verify a Solar Water Heater Supplier Before Paying

Most supplier checks happen after the money moves. That is the wrong order, and everyone in the trade knows it.

Before the deposit you have leverage: a supplier will answer slow emails, take a video call and let your inspector walk the floor. After it, you are waiting on a production line you cannot see, in a city you have not visited.

So the useful question is not “is this a good factory”. It is “which claims can I check now, and which ones am I about to take on trust”. What follows is the checklist we would hand a friend who asked us to audit us. It takes about a week of emails, plus one inspection visit if the order justifies it.

The master checklist: four gates before you pay

Work these in order. Do not start at price.

Gate 1 — Claims you can check from your desk

• Company registration name, the invoice name and the bank account name are the same legal entity
• Factory address given, with a live video call during working hours
• A technical drawing with dimensions and material call-outs, not only a catalogue page
• Lead time, MOQ and warranty written into the quotation itself, with the lead-time starting point defined

Gate 2 — Sample and first-article approval

• A sample built on the production line, from the same materials as your order
• A dated approval sheet signed by both sides, one copy kept by each
• A written list of what may change between sample and bulk, and what may not

Gate 3 — Loading-floor evidence

• Packing list split into tank cartons and collector cartons as separate lines
• Photos of the loaded rows, the carton marks and the container number before the doors close
• Spare parts packed in labelled bags, separate from the main fittings
• Container loading plan agreed before production starts, not on loading day

Gate 4 — Spares and after-sales on paper

• A spare-part list naming the items that actually travel in your container
• Warranty terms in writing, including what sits outside the warranty
• A named contact and a reply window you can hold them to

Now the parts that need more than a tick.

Gate 1 — Claims you can check from your desk

This is the table we send when a buyer asks how to check us without flying to Tai’an.

What a supplier claims	What to ask for	How you check it
“We are a real factory”	Workshop address and a live video call in their working hours	Ask to see the tank welding line and the tube racks, then ask about a machine you did not raise yourself
“This is our own model”	Technical drawing with dimensions and materials	Compare the drawing against the catalogue photo. A photo with no drawing usually means the unit is assembled to your order
“We ship a lot to this region”	Two or three markets, and the model numbers shipped there	Ask what had to change in those orders. A supplier who has never shipped there answers in general terms
“Our lead time is fixed”	The lead time written into the quotation, with the clock defined	Confirm whether it starts at deposit or at drawing approval. That one sentence can move a delivery by weeks
“We handle all the documents”	The export documents named in the offer, and who pays which fee	Ask which party files each document, and which charges are yours

The bank-account check is the one buyers skip, and it is the one that protects the money. Registration name, invoice name and account name should point to one legal entity. If three different names appear, settle that before the deposit.

One more desk test costs nothing: ask for a photo of the material racks taken that day, with the phone time visible. It tells you whether the person answering you stands in the workshop or in an office.

The desk checks above are the same documents we hand over in how our ordering process runs, from first inquiry to loading.

Gate 2 — A sample is worth what the approval sheet says

A sample with no signed approval sheet is a gift, not a reference. This is how our production process runs first-article approval, and how you can ask any supplier to run it.

Build the sample on the production line, with the same steel, the same glass tubes and the same insulation as your order. A unit pulled from the showroom has been polished for two years and tells you nothing about the line you are buying from.

Then put two lists in one email. May change: bracket frame thickness, carton printing, small hardware. May not change: tube grade, tank shell thickness, coil material. Ask for a written answer to both.

Keep one approved sample at the factory and one with you, each labelled with the date and the order number. When a dispute appears eight months later, this is the paper that ends it. If you cannot travel, ask for a single-take video of the sample being built, from the raw tube rack to the finished unit — not an edited clip that shows only the parts the supplier chose.

Gate 3 — The loading floor is where your claim record is made

No catalogue covers this section, and it decides whether a damage claim is payable.

Three things should be agreed before the container is booked, on the floor and in the paperwork.

Carton marks and counting. Ask for the packing list split into tank cartons and collector cartons as separate lines. On a mixed order that split lets your agent count the container at the port in an hour instead of a day. Our loading team marks every carton with the order number, model and position in the sequence, so a missing piece shows up at once.

A photo record before the doors close. We photograph the stacked rows, the carton marks and the closed container number. Ask any supplier for those photos as a condition of the order — it takes the loading team ten minutes and it settles a claim later. See our standard packaging notes for what that record includes.

Fragile items never sit at the bottom. Vacuum tubes travel in their own cartons and are never stacked under a tank. The glass is the most fragile item in the order and the hardest to replace in your market. Ask where the tube cartons sit in the stack, and ask for the photo that shows it.

Settle the container loading plan at the same time. If the tank and collector sections are fixed before production, the factory can adjust the frame packing to fit. If the plan is drawn on loading day, the last pallets get forced in, and forced pallets are where dents come from.

While you are on this subject, ask who issues the bill of lading, who handles the origin paperwork and who pays the destination charges. Our export team covers clearance and paperwork as part of our DDP shipping and delivery arrangement.

Gate 4 — Settle the spares and the warranty boundary in writing

Two lines in a quotation do more for your second order than any discount: the spare-part list and the warranty boundary.

Item	What to settle before the order	Why it matters
Vacuum tubes	How many spares travel in your container, and the price on a reorder	One broken tube should not stop a whole system
Seals and gaskets	Whether a spare set is packed per unit	A low-cost part to add and an annoying one to source locally
Pressure relief valve	On pressurized tanks, whether spares are supplied	It is a wear part, and a local substitute becomes the part your brand is judged on
Heating element	Where backup heating is fitted, the voltage and plug type for your market	The wrong voltage makes the unit useless on arrival
Vent and feed-tank fittings	Which small parts installers lose first	Cheap at the factory, hard to buy in your market

On the warranty, ask for the boundary in writing. Most exclusions sit in four places: frost where no drain-down was done, water quality and scaling, installation against the manual, and late-reported transport damage. Our warranty runs three years, and we put the covered and uncovered list in writing on request, alongside our documented quality control steps. Agree the reply window too — we answer spare-parts questions within 12 hours, so ask any supplier to name a number instead of promising “fast support”.

Running this list with a third-party inspector

If the order is large enough, hire an inspector and tell the factory before production. Full-process inspection runs on every order we ship, we work to AQL 2.5, and a third-party inspector is welcome at our workshop in Tai’an. The same welcome applies to OEM/ODM projects built to your drawing.

Two things make an inspection worth its cost.

Book it after the tubes are packed and before the container is loaded. A failed lot can still be replaced at that point. Once the doors are sealed, your options shrink to a claim.

Ask for batch numbers in the report, so the inspected units can be traced to the ones in your container. A report that describes “some units” is a report you cannot use later.

We have been making these systems since 2013 and have shipped to more than 30 countries. MOQ is one set and lead time runs 18–25 working days, so a small first order is a normal way to test a supplier before you commit a full container. A trial batch also tells you more about a factory than any document set.

The audit window closes when the deposit clears. Whatever is still unchecked after that, you are no longer verifying — you are hoping.