Two quotations for the same house arrive on the same day, and one of them totals lower. That total is the first thing anyone reads and the last thing that should be compared. The published cost comparison for this range divides a home battery cost into hardware, installation and lifetime service, and the reason two quotes can sit twenty percent apart is that most of them collapse those layers into a single figure before the scope behind each one has been aligned.
The gap that is not a difference
The first reading is a total. The useful reading is the line list.
Two published project records in this range show how differently the same capacity gets assembled. One is a 30 kWh build made from three wall-mounted 10 kWh units on a Sunsynk hybrid inverter, and the other is a 75 kWh build made from five wall-mounted 15 kWh units on a Deye inverter. In both records the inverter is a named separate item rather than part of the battery.
So two quotations can name the same capacity and describe two different hardware populations. Capacity is the part that matches, which is why it gets compared.
Delete the prices first
The discipline that makes the rest work is to take the totals off the page before comparing anything. A total anchors a reader, and once visible every later judgement bends toward it: a missing line becomes an argument to win rather than a cost to add.
What replaces the total is a deviation table, built line by line, with each line recorded as in scope, not in scope, or needing clarification. The list has to cover the lines usually left implicit.
The line items follow the three cost layers published for this range, in which hardware is counted per usable kWh, installation per handling unit and connection, and lifetime service per kWh delivered, verified as of 2026-09. The packing list row reflects the published position that no product page in this range lists carton contents, mounting hardware or accessories in its published specification.
Re-price the difference instead of arguing about it
Ask the supplier to confirm every blank line in writing, because a blank is ambiguous between excluded and forgotten. The normalisation step is arithmetic, and it is where most comparisons stop early. Wherever one quotation includes a line and the other does not, the missing item gets a price, and the price is added to the quote that lacks it. Deleting the line instead makes two scopes look identical and hides the cost.
Worked example. Consider two hypothetical quotes for the same three-unit build. Quote A includes the three battery units and the hybrid inverter, and does not include the cable set, the metering or the commissioning visit. Quote B includes the three battery units, the cable set and a current transformer, and does not include the inverter. The aligned comparison adds the cable set, the metering and the commissioning visit to A at the prices A quotes for them, and adds the inverter to B at the price B quotes. Neither original total survives, and the two totals that remain are finally describing the same delivery.
The assumptions are the quoted prices for the missing lines, which is why every one of them belongs in the table rather than in a conversation.
If a seller will not price a missing line, that line stays as an open item rather than becoming a zero. When both quotes include the same line at different specifications, the difference between the two specifications is what gets priced, not an average of the two.
What is left when the scope matches
Once the line lists agree, the remaining differences are the ones that do not appear as hardware. Warranty scope is the largest: two quotes can cover the same equipment for the same period and still differ on what is excluded, and on whether cover is at module level or at system level. Spare availability is the second, because a service commitment is only as good as the parts that can be delivered against it. Ask for the warranty exclusion list and the spare-part lead time beside the price. Change notification is the third, since the configuration that was quoted is the configuration that has to be certified. Payment schedule is the fourth, and it moves the date of the money rather than only its amount.
Two quotations can carry identical line lists and still place the risk in different places. That is the comparison worth making, and it is not a price comparison.
Who wins, and under what conditions
The verdict is conditional, and the conditions are about what the buyer already has rather than about the product.
If the buyer already holds the inverter, the cable set specification and its own installers, the quote that prices capability rather than labour is the cheaper route, and the difference is not recoverable later by renegotiation. When the buyer is selling a single warranty to a household and holding the service relationship itself, the quote that consolidates responsibility into one party wins even at a higher total, because the cost of the first unresolved fault exceeds the saving.
The published pages for the Ruibit range name the electrical attributes of each model and leave the packing list unwritten, which is why the cable set and the mounting hardware arrive as questions rather than as line items in most first drafts.
Two items cannot be changed once the order is placed. The delivery point fixes who carries the risk of the shipment, and the payment milestones fix when the money moves relative to the goods. Both are on the deviation table, and both are expensive to reopen.
At handover, keep the agreed deviation table with the order rather than with the technical file. It answers a later claim about what was bought, and it is the only version of the comparison in which both sellers described the same delivery.
FAQs
1. Why should prices be removed before comparing two quotations?
Because a total anchors the comparison. Once the figure is visible, a line that is missing becomes an argument to win rather than a cost to add. Building the line-by-line deviation table first, with each item marked in scope, not in scope or needing clarification, keeps the comparison about the delivery rather than about the number.
2. What should the deviation table cover?
Storage units and unit count, whether the inverter is in scope, mounting and handling, the DC and communication cable set, metering and monitoring, commissioning and the handover record, warranty scope and exclusions, freight terms, and the payment schedule. The list has to cover the lines usually left implicit.
3. How is a genuine scope difference handled?
By pricing it rather than deleting it. Where one quotation includes a line and the other does not, the missing item gets a price and that price is added to the quote that lacked it. If a seller will not price a missing line, the line stays open rather than becoming a zero.
4. What differences remain once both quotes cover the same scope?
Warranty scope, spare-part availability, change notification and the payment schedule. Two quotations can carry identical line lists and still place the risk in different places, which is the comparison worth making.
5. Which quotation wins?
It depends on what the buyer already holds. If the buyer has the inverter, the cable specification and its own installers, the quote that prices capability rather than labour is cheaper. When the buyer carries a single warranty for a household, the quote that consolidates responsibility into one party wins even at a higher total.
