Most people getting solar quotes are comparing documents that are not really comparable. One is two pages and a price. Another runs to twelve pages and buries the important detail on page nine. A third quotes a bigger system for less money and does not explain why.
You do not need to become an electrical engineer to judge them. You need to know which handful of things actually determine whether the system performs — and which omissions should make you ask harder questions.
Start with the design, not the price
The single most useful question about any quote is: what consumption was this system sized against?
A quote that was designed properly will show some evidence that somebody looked at how you actually use electricity — your bills, your day/night split, when your load occurs. A quote that was not will simply propose whatever fills the roof, or whatever hits a familiar price point.
This matters because the value of a solar system comes overwhelmingly from electricity you use, not electricity you generate. Exported units are worth considerably less than units you avoid buying. A system sized to your roof rather than your consumption can generate impressively and still underperform financially.
If a quote arrived without anyone asking to see a bill, that is a genuine warning sign.
Check that the equipment is actually named
Every quote should tell you, specifically:
- Panel — manufacturer, model, wattage per panel, and how many
- Inverter — manufacturer, model and rated output
- Mounting system — manufacturer, and whether it is specified for your roof type
- Battery, if included — manufacturer, model, usable capacity (not just nominal capacity)
“Tier 1 panels” is not a specification. Neither is “premium inverter”. Those phrases appear when the installer wants the freedom to substitute, and substitution is exactly what you are trying to pin down before you sign.
On batteries, watch the difference between nominal and usable capacity. They are not the same number, and the usable figure is the one that affects you.
Look for what is missing
Quotes are more often misleading by omission than by error. The common gaps:
Scaffolding. On a two-storey house this is not a trivial line. If it is not mentioned, ask whether it is included.
Electrical works. Does the price include any consumer unit upgrade, earthing or bonding work that the installation requires? These are sometimes discovered mid-job and charged as extras.
Grid application and registration. Connecting a system involves paperwork with the network operator. Someone has to do it. The quote should say who.
Grant handling. If the installer is applying on your behalf, that should be explicit. If you are expected to do it yourself, you should know that before you sign, not after.
Making good. Who repairs and reinstates anything disturbed during installation?
Scaffold-free roof access assumptions. Some quotes assume access that your site does not actually allow.
Understand the three different warranties
People hear “25-year warranty” and assume it covers the system. It almost never does. There are normally three separate things:
- Panel product warranty — covers the panel itself failing
- Panel performance warranty — guarantees the panel still produces a stated percentage of its original output after a given number of years
- Inverter warranty — usually much shorter than the panel warranties
There is also a fourth, and it is the one that matters most in practice: the installer’s own workmanship warranty, covering the quality of the installation itself. Panels rarely fail. Roof penetrations, cable management and mounting are what cause problems, and those are the installer’s work, not the manufacturer’s.
Ask how long the workmanship warranty runs, and what happens to it if the company ceases trading.
Also worth knowing: inverters have a shorter service life than panels and should be expected to need replacement at least once over the life of a system. A quote that presents 25 years of operation with no inverter replacement is not being straight with you.
Treat savings projections with care
Almost every quote includes a savings or payback figure. These are the least reliable numbers in the document, because they depend on assumptions that are rarely stated:
- What unit rate was assumed, and does it escalate?
- What export rate was assumed?
- What proportion of generation was assumed to be self-consumed?
- What annual degradation was applied?
- Was the inverter replacement cost included?
A projection is only as good as those inputs. If they are not written down, the figure is decoration. It is entirely reasonable to ask an installer to show you the assumptions behind their number — and telling, if they cannot.
Check the installer, not just the quote
For a domestic grant you need an SEAI-registered installer, and electrical work in Ireland must be carried out by a registered electrical contractor. Both are verifiable, and both are worth verifying rather than taking on trust from a logo on a PDF.
Beyond registration, the practical questions:
- Who actually carries out the work — employed crews or subcontractors?
- Who do you call in three years if something stops working?
- How long has the company been trading under its current name?
Aftercare is where the difference between installers shows up, and it is invisible at the point of sale.
A reasonable set of questions to ask
If you take nothing else from this, take these:
- What did you size this system against?
- What proportion of the generation do you expect to be self-consumed?
- Is scaffolding included?
- What electrical works are included, and what would be charged as an extra?
- How long is your workmanship warranty?
- Who handles the grant application and the grid paperwork?
- What happens if the survey finds something the quote did not anticipate?
Any competent installer will be comfortable answering all seven. If a quote gets vague under those questions, that tells you something useful before you have committed to anything.
If you would like a quote laid out this way — with the design rationale and the assumptions written down rather than implied — get in touch. We would also happily read through a quote you have received from someone else and tell you what we would ask about it.