Why do quotations for the 'same' system differ so much?

Almost always because of items 3–7. One price is equipment-only at a port; the other is delivered, installed and commissioned. Normalise both to delivered-and-commissioned cost at your site before comparing anything else.

Should installation be in the supplier's scope?

It depends on your market and who you trust on site. What matters is that the split is written down — the most expensive disputes come from both parties assuming the other handles the interface.

What documentation should come with the delivery?

At minimum: factory test record, equipment datasheets, as-built configuration table, and the single-line diagram the system was actually built to. If these arrive late or not at all, commissioning and future warranty claims both get harder.

What is included in a complete commercial solar quotation?

Prepared by Mars Solar Technical Team · Reviewed by Mars Solar Engineering Review · Last updated 2 November 2026

In short

A complete commercial solar quotation lists twelve things line by line: equipment itemised by subsystem, balance of system, packaging and inland transport, freight, insurance, duties and taxes, installation, commissioning, training, documentation, warranty terms per component, and the scope split — what the supplier does and what stays with you. If any line is missing or merged into 'miscellaneous', the price is not comparable and the gap will surface at delivery.

The short answer

This page is written from the buyer's side of the table. Whether you are comparing our quotation or a competitor's, the test is the same: can you trace every line from the equipment list to the delivered, working system? The twelve items below are what makes that possible.

The twelve items, and what each one tells you

#	Item	What it should state
1	Equipment, itemised	Each subsystem — modules, converter, battery, distribution — with brand, model and quantity
2	Balance of system	Mounting, cabling, protection, monitoring — the parts that decide whether the design is buildable
3	Packaging and inland transport	Up to which port, stated separately from sea freight
4	Freight	To your named destination, with the Incoterm spelled out
5	Insurance	Covered or excluded, and up to which point
6	Duties and taxes	Included or excluded — a line that is blank is a line you will pay later
7	Installation	Included, excluded, or quoted as a separate option with a defined scope
8	Commissioning	Distinct from installation — who runs the first energisation and accepts the test results
9	Training	For whom, on what, and with what deliverable
10	Documentation	Test record, datasheets, as-built configuration table, single-line diagram
11	Warranty terms	Per component — modules, converter and battery are separate warranties with separate claim paths
12	Scope split	A written table of what the supplier does, what your team does, and what is jointly accepted

How to read this table: items 3–6 determine whether two quotations can be compared at all, and item 12 determines whether the project finishes the way the quotation reads. Everything else is detail you can negotiate.

Three vague patterns that hide real cost

Pattern	What it looks like	What to ask
Mixed Incoterms	An FOB price and a delivered price appear in the same document without labels, or 'CIF' is used for a destination that is not a port	"Up to which named point is each figure valid?"
Installation without commissioning	'Installation included' appears, but nobody is named to energise, test and accept the system	"Who signs the commissioning record, and is their time in this number?"
Tax without clearance	'Taxes included' — but import clearance, duties at destination, or local levies sit outside the number	"List the duties and taxes that are excluded, by name."

A quotation that resists these three questions is not necessarily dishonest — but it is not comparable yet, and signing it means pricing the gaps yourself.

How to compare two quotations

Normalise both to delivered-and-commissioned cost at your site: add to each quotation whatever its excluded lines will actually cost you, using your freight forwarder's rates and your country's duty schedule — not the supplier's guesses. Then compare item 1 and item 11 line by line: equipment of different brands is not the same product at a different price, and a warranty is only as good as the party that must answer the claim. For cross-border purchases specifically, the China procurement checklist covers the verification steps that come before the quotation stage.

Project evidence

A sample quotation in the twelve-item format, filled with anonymised figures, is part of our sample documentation pack — ask for it with your enquiry and you can review the format before requesting a live one.

When a quotation should be rejected outright

It quotes a single lump sum with no itemisation at all: nothing can be checked, so nothing can be compared.
It quotes a runtime figure derived by dividing nameplate battery kWh by converter kW — that number is wrong before the project starts. Ask instead what usable SOC window and efficiency were assumed, as explained on our 100 kW / 215 kWh configuration page.
It promises performance results that depend on site conditions the supplier has never measured: fuel savings, payback periods, generation yields. These are estimates at best and must be labelled as such.

Next step

Send your electricity bill or load list and we will return a quotation in the twelve-item format above — every line marked included or excluded, so you can compare it against anything.