Ten solar panel myths still doing the rounds in La Costera

Where these myths come from and why they last so long

Self-consumption myths do not appear out of thin air. Almost all of them come from three places: regulations that no longer exist, poorly executed installations from the sector's early years, and the classic tale of a friend of a friend who had a bad experience. Since stories travel faster than official gazettes in small towns, a rule repealed in 2018 can still be deciding in 2026 whether a family in Ontinyent fits panels or not.

In this article we go through the ten myths heard most often around La Costera, the Canal de Navarrés and the Vall d'Albaida. For each one we explain where it comes from, what truth it once held, and what engineering and the law say today. The aim is not to talk anyone into anything: it is for the decision, whatever it turns out to be, to rest on real information rather than inherited phrases.

Panels never pay for themselves

This myth dates from the sector's early days, when equipment cost far more and some systems were sized to fill the roof rather than to match the household's consumption. With those numbers, payback dragged on and the reputation stuck.

The picture today is different. According to APPA's 2025 sector data, the average Spanish installation is around 5.5 kW, costs roughly 1,215 euros per kW and has a typical payback of 6 to 7 years before any tax deductions. And that is the Spanish average: the Xàtiva area, according to PVGIS, produces between 1,350 and 1,500 kWh per kWp a year, with a well-oriented south-facing roof close to 1,500, one of the better solar resources in Europe. A system that pays for itself within that window keeps producing for decades after it has been paid off.

On top of that come the deductions available to those who meet the requirements: the state income tax deduction of 40% on a base of up to 7,500 euros (RDL 2/2026, in force until 31-12-2026, which requires before and after energy performance certificates registered within the deadline) and the Valencian regional deduction of 40% on a base of 8,800 euros, at 20% for second homes, carried forward for up to 4 tax years, and conditional on self-consumption registration and the IVACE certificate.

• Shortens payback: using the panels' output during the day, rather than exporting nearly all of it to the grid.
• Shortens payback: sizing the system to the household's real consumption, not to the available roof.
• Shortens payback: applying the deductions with certificates and registrations in order.
• Lengthens it: unstudied shading, forced orientations or a poorly arranged surplus compensation contract.

The sun tax still exists

The famous sun tax did exist. Royal Decree 900/2015 introduced charges on self-consumed energy in certain cases and, above all, an administrative maze that put a great many people off. That rule did real damage to the sector and left a mark that still lingers in village conversations.

But it was repealed by Royal Decree-Law 15/2018, and the regulation that followed went in the opposite direction: Royal Decree 244/2019 created simplified surplus compensation, under which your electricity supplier credits your bill for the energy you export to the grid. In other words, self-consumption is not penalised today: your surplus is given value. Anyone telling you in 2026 that the sun tax is still alive is quoting a rule that left the statute book years ago.

They produce nothing in winter

The origin is intuitive: shorter days, a lower sun, the odd bank of fog along the riu dels Sants. And it is true that winter output is lower. But there is a world of difference between lower and nothing. The annual PVGIS figures for the area, between 1,350 and 1,500 kWh per kWp, already include every winter: the sector's 6 to 7 year payback is calculated counting December and January, not just July.

Cold weather is no enemy of photovoltaics either: modules work well at low temperatures, and this comarca has plenty of clear winter days. On east-west roofs, common in village houses, production sits between 82% and 85% of an optimal south-facing roof, and in exchange it spreads more evenly between morning and evening, which is when many homes actually consume. A well-designed system counts winter in from day one.

They ruin the roof and need cleaning every month

The fear for the roof comes from old installations that were badly anchored or badly sealed, and those did exist. A serious installation starts by surveying the roof and its structure, uses fixings and sealing designed for that specific tile or sandwich panel, and documents the roof's prior condition. If the roof is in poor shape, that comes to light at the design stage, which is exactly when you want to know. Properly mounted, panels do not damage the roof, and the area they cover is in fact shielded from the sun and from direct impacts.

Monthly cleaning does not hold up either. Rain does most of the work, and in this area the dirt that matters tends to be dust or pollen at specific times of year. The reasonable maintenance of a domestic system takes very little time.

• A glance at the monitoring now and then: a drop in output shows up there before it shows from the street.
• A visual check after a strong wind or hail storm.
• A rinse with water if dust or pollen builds up, with no harsh products.
• A periodic once-over of connections, mounting structure and protections.

A battery is essential, or better still, I will go off-grid

These are two cousin myths and they deserve separating. A battery is not essential: surplus compensation already gives value to the energy you export, and for many households with daytime consumption the system stacks up without storage. A battery earns its place when consumption is concentrated at night or when backup against outages matters, and it is a decision to be studied with the consumption profile in front of you, not a compulsory box to tick.

Disconnecting entirely is another story. Living off-grid with the mains at your front wall means oversizing batteries and planning backup for spells of bad weather, and it makes the system needlessly expensive. The grid is the cheapest backup there is: the sensible formula in Xàtiva, Enguera or any town with a supply is to produce your own, export the surplus and keep the grid for whatever is missing.

Chinese panels are poor quality

This myth mixes the memory of cheap first-wave modules with a general reflex against anything made in Asia. The industrial reality is that the vast majority of the world's photovoltaic production, including that of top-tier brands installed all over Europe, comes out of Asian factories. A panel's origin, on its own, says almost nothing about its quality.

What does say something is who answers for it and with what paperwork. Serious manufacturers offer long-term product and performance warranties in writing, and on top of that the law gives the buyer a 3-year statutory conformity guarantee against the company that sells and installs. In practice, problems are almost never in the panel brand: they are in weak designs, careless workmanship or companies that vanish. That is why where the panel was made matters less than who fits it and whether they will still be around when needed.

This is for villas, and if I sell the house I lose it all

The village houses of Xàtiva, Canals or l'Alcúdia de Crespins have perfectly usable roofs. Many face east-west, and as we have seen, that 82% to 85% factor does not sink the project, it merely shapes it. On urban land, the Valencian framework (Decree-Law 14/2020, today consolidated in the TRLOTUP) allows rooftop self-consumption photovoltaics to be processed with a responsible declaration, filed with the town hall and then followed up. The exception is listed buildings and BIC protection zones, such as parts of Xàtiva's old town, where a licence or heritage authorisation may be required, and there it pays to study the situation before making a move.

As for selling: nothing is lost. The installation stays with the house, improves its energy performance certificate and passes to the buyer with its paperwork, its warranties and its history. The seller does not lose an installation: they sell a house that costs less to run, and that shows in any negotiation.

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