No two quotes are alike: here is what to look at

First: compare comparable things

Before looking at the final price, level the base. A serious quote states the peak power in panels and the inverter's nominal power, with exact brand and model for each component, not a vague category. As a market reference, the annual report of APPA, the Spanish renewables association, puts the average Spanish home installation around 5.5 kilowatts and an average 2025 price of about 1,215 euros per kilowatt, with typical paybacks of six to seven years before deductions. That is not your case, it is the national average: it serves to spot offers out of range, high or low.

What must be in writing

If anything on this list is not on paper, it is not included, whatever the conversation said:

• Brand and model of panels, inverter and mounting, with their product warranties in years.
• An annual production estimate for your specific roof, naming the tool used. If it does not mention your orientation and your shading, it is a template.
• The complete paperwork: town hall, industry legalisation, self-consumption register and the energy certificates for the tax deduction. Turnkey offers that do not itemise these tend to leave out the laborious ones.
• Who signs the project or technical report, and whether the installers are in-house staff or a subcontractor you will never see again.

The warning signs

None of these is illegal; all of them are reasons to ask more:

• Artificial urgency: the offer that expires on Friday is a sales technique, not a real market condition.
• Miraculous production: if the annual estimate comfortably beats the area's ranges, someone is stretching PVGIS.
• Savings calculated on one hundred percent of the bill: regulated fees and charges do not vanish because you have panels, and whoever erases them is showing you a number you will never see.
• Silence about the after: no monitoring, no maintenance, no phone number with a name attached for three years from now.

The three questions that uncover everything

First: who legalises the installation and which papers will you hand me at the end, one by one. Second: what annual production do you estimate for my roof and with which tool did you calculate it. Third: who answers me in five years if a string stops producing, and how will you find out before I do.

A good installer answers all three without flinching, because they are the job. We answer them in writing in every study, and the third one is exactly why our promise ends with we stay.

The number missing from almost every quote: expected production

Quotes compete on kWp and brands, but what you will see on your bill is kWh. Two installations with the same power can produce very different amounts depending on orientation, tilt and shading. For the Xàtiva area, the public PVGIS reference puts production between 1,350 and 1,500 kWh per kWp per year for a well-oriented installation. That is the number everything else gets compared against.

The most common case where this matters: pitched roofs facing east and west, very common in the towns of the comarca. Splitting the panels across both slopes works, but it produces between 0.82 and 0.85 of what the same power would deliver facing south. A serious quote says so; a weak one gives you the south-facing figure and leaves it at that.

Ask each installer for a production simulation based on your actual roof: orientation, tilt and the specific shading, which in Xàtiva and the villages of la Costera usually comes from chimneys, aerials and the building next door, not from mountains. If two quotes with similar power show very different production figures, that is the conversation to have before signing anything.

The extras that turn up after you have signed

The most repeated complaint is not about panels, it is about surprises: the quote was one figure and the job ended up being another. Almost always because of items that were never written down and someone took for granted. In village houses with old Arabic roof tiles it is common for broken tiles to appear the moment someone steps on the roof; in older homes, for the electrical panel to need adapting for the new protections; and in the narrow streets of the old town, for lifting equipment nobody mentioned to become necessary.

Before signing, ask for the quote to state in writing what happens with these items:

The point is not that everything must be included, it is that nothing should appear by surprise. A serious installer has no problem writing that, if broken tiles turn up, replacement is billed separately and at a stated price per unit. What should make you hesitate is the vague answer: we will sort that out later.

• Adapting the electrical panel and protections, including surge protection
• Replacing tiles or waterproofing if the roof suffers during installation
• Lifting equipment or scaffolding where the street or the height requires it
• The cabling from the inverter to the panel when the run is long
• Full legalisation of the installation and whose name each procedure is handled under

Frequently asked questions