The gap in most hybrid solar quotes is a behaviour line, not a price. What is missing is the sentence that says what your house will actually do when the grid goes down, and there are four of them: the inverter's backup output as a stated figure, the storage expressed as usable kilowatt-hours rather than a nameplate size, the scope of the changeover and distribution board work, and the compliance documents. A quote that leaves those out is not cheaper than the others. It is unfinished, and the unfinished part gets priced later, after the deposit has cleared and the boards are already open.
I do this at the kitchen table, usually on a wet afternoon when the schedule has already bitten once. I move the fruit bowl aside, put the municipal bill on the left, and fan the quotes out across the wood. The rain on the tin roof is loud enough that I read with a finger on the page. Somewhere behind me the fridge motor kicks in, then the chest freezer, and I catch myself doing what I always do — listening to the house and counting what is running, because the house is the one thing no quote ever describes.
You will do the same within a minute of sitting down next to me. You will read a line that says something like, hybrid system installed, eight panels, five kilowatt inverter, five kilowatt-hour battery, and realise you cannot tell from that sentence whether the fridge, the freezer, the lights, the TV and the Wi-Fi survive a four-hour outage, or whether only the lights and the Wi-Fi do. That is not an equipment problem. It is a paperwork problem, and it starts on the page in front of you.
So I write the same sentence at the top of every quote I study:
During a four-hour outage, this system will run at kW, for hours, and here is the paper that proves it.
If I cannot fill those blanks from the quote alone, I do not phone the installer to ask what he meant. I write the blanks down as questions instead, because the answers become the comparison. Everything below is how I sort it.
Backup output is a figure, not a list of appliances
Weak quotes all describe backup the same way: with a count of appliances. Runs your TV, decoder, Wi-Fi, fridge and lights. That sentence sounds generous and tells you almost nothing, because the list changes the moment somebody boils a kettle or the freezer's compressor starts against a warm afternoon.
The figure I want on the page is the inverter's backup output rating, in kW or kVA, with the power factor it is quoted at, and the duration for which it can hold a surge above that. Those are three separate things and a quote can quietly blur them into one number. I also check whether the figure is the inverter's rated output or its backup output, because they are not always the same — plenty of units have a lower continuous output when they are running from the battery than when they are passing grid power straight through.
The other half of the same number is time. A rating without a duration is a peak, not a capability.
Then I sit with that figure against my own house at that exact moment — freezer recovering, fridge cycling, kettle off — and only then can I tell whether backup means breakfast for the whole house or three rooms and the router. That judgement belongs to me. No quote makes it on my behalf.
The number that quietly changes meaning
Watch for a quote that lists a big inverter and a small battery bank without ever connecting the two. The battery's discharge capability can cap the very output the inverter is boasting about. I have seen this described as a good, strong inverter on a page where nothing states what the pack can actually deliver at once. If the quote does not tell you, you are comparing two advertisements, not two systems.
Nameplate and usable capacity are not the same figure
When a hybrid quote says five kilowatt-hours of battery, it has told you what the box is called, not what your house can draw from it. What the house draws is the usable figure, and it is smaller. The gap between the two is the depth-of-discharge assumption — how far the installer intends to run the pack down on a normal cycle — plus the fact that the rated number is usually quoted at the beginning of life, at a middling discharge rate, in a comfortable temperature.
I know the shape of this disappointment without needing anybody's name attached to it. The fourth hour of load shedding arrives, the lights go out early, and nothing is faulty. The pack was simply never described to the household as usable capacity, so the household was measuring against the wrong number the whole time.
What I ask to see is the usable figure the installer is willing to stand behind, the depth-of-discharge assumption behind it, and whether the number is beginning-of-life or end-of-warranty. If only one capacity appears on the quote, the assumption is hidden, and a hidden assumption is the thing that makes two quotes look identical when they are not.
Surge, and the appliances that decide it
An induction hob, a kettle and a microwave cycling together pull hard and briefly. A quote that gives you a storage figure but no sense of instantaneous delivery is describing an evening of gentle loads. I mark that gap and ask about it, because the answer changes the shape of the system far more than panel count does.
Changeover and the board split are scope, not accessories
This is where quotes get vague in a way that reads as reassuring. Installation included. Full backup. The phrase tells you nothing about which circuits move to the backup side of the distribution board and which stay on the grid side, whether the existing board is reused or a dedicated essential-loads board is added, whether changeover is manual or automatic, and how the earth leakage and surge protection arrangement is being handled — priced, or assumed.
The reason this matters to me is simple. The split of the board is the thing that determines which rooms go dark. I have read quotes where the entire backup scope was one line, and I have read quotes where it ran to eight lines naming each circuit. The second quote is not automatically better. It is simply comparable, which the first one is not.
If you want a single question to carry to every installer, make it this one: put in writing which circuits will be on backup and which will not. That answer plus the kW figure on the page tells you more about the system than any description of the equipment does.
The board work that arrives as a surprise
Older boards sometimes cannot simply be extended. Whether the quote anticipated that, or whether it will surface as an extra once the cover is off, is worth knowing before you commit rather than after. I look for a scope line that acknowledges the existing board at all. If the quote does not mention it, it did not price it.
The compliance paper trail is more than one document
Three things live here, and they are often missing from the quote entirely.
The first is the Certificate of Compliance, issued under SANS 10142-1 by someone competent to issue it. The second is the SSEG application to your municipality, with whatever drawings, forms and sign-off that submission requires. The third is the inverter's compliance with NRS 097-2-1 — which matters because a unit that is not on the approved list can leave you with a system nobody will register, however well it performs.
Then there is the meter. Whether your prepaid or AMI meter needs to change, who arranges that, and who carries the cost, is a line item. I have seen households discover the metering question only after the panels were on the roof, which is the worst possible time to discover anything.
I treat all of this as part of the price of the system, not as admin that happens afterwards. A quote that omits the compliance scope has not quoted a compliant system. It has quoted equipment and labour, and left the paperwork for you to discover.
The lines that are absent because nobody priced them
Labour, scaffolding, cable runs, containment, roof penetration sealing, any structural work, a hoist or crane for a double-storey roof, waste removal, painting. When these are not on the page, the usual explanation is not that they are free. It is that they were not considered.
I do not assume malice here. Most of the time it is habit — the same template the installer has used for years. But the effect on your comparison is the same either way: a quote without them is not the price of the job, it is the price of part of the job.
VAT, deposit and the payment schedule
These change the ranking between quotes as much as the equipment totals do. Is the figure VAT inclusive or exclusive? What percentage is the deposit, and how much is due on which milestone? Is there a retention amount held back until commissioning? What happens to the schedule if municipal approval takes longer than anyone expects?
I write the payment terms underneath each quote in my own hand, in the same format, so the comparison is like for like. A quote that arrives with a small deposit and a large balance on delivery is a different financial object from one with staged payments and a hold-back, even when the equipment lines match exactly.
The page I build before I decide anything
By now the routine is fixed. For every quote I write the same questions down the left-hand side of a sheet and leave a column for each installer:
- Continuous backup output in kW or kVA, with the power factor stated.
- Surge duration, and whether the figure is the inverter's rated output or its backup output.
- Usable storage in kilowatt-hours, with the depth-of-discharge assumption and whether it is beginning-of-life or end-of-warranty.
- Instantaneous delivery from the pack, so the output figure is not capped by the battery.
- A written list of which circuits are on backup and which are not.
- Changeover type, and whether the board split is in scope.
- Certificate of Compliance, SSEG submission, NRS 097-2-1 listing, and the metering arrangement, each as its own line.
- Labour, access equipment, cable runs, containment and any structural work as separate items.
- VAT treatment, deposit, milestones and retention.
The blanks fill in or they do not. When two quotes both state the output, both state usable capacity, both name the compliance scope and both price the access and cabling, they finally sit side by side without any interpretation from me. That is the whole point of the exercise.
What I have learned to ignore
Descriptions that lean on premium or quality without a figure attached. Savings projections with no assumptions written next to them. Appliance lists standing in for ratings. None of these are lies. They are just not comparable, and a comparison built on them is a comparison of sales styles.
Where this gets honest
A fully itemised quote is not automatically the better one. Some installers bundle the small items because they carry that risk themselves and would rather not nickel-and-dime you, and that is a legitimate way to work. A missing line is a question, not an accusation.
The real limitation is this: two systems cannot be compared if one states its backup output and the other lists appliances. You cannot average them, adjust them or rank them. One of them has told you what it will do; the other has told you what it hopes you will imagine. The only fix is to go back and ask for the figure, and to be willing to wait for the answer.
So the test stays the sentence I write at the top of the page. During a four-hour outage, this system will run at kW, for hours, and here is the paper that proves it. If the quote cannot fill those blanks, what is missing is not a price and not a mistake. It is the part of the job that has not been thought through yet, and someone will pay for that thinking later. Better it is them, on paper, before the deposit goes anywhere.
