How to compare solar quotes in the Algarve without choosing on price alone

Algarve homeowners often receive quotes that look similar at first glance: a number of panels, an inverter, an optional battery and a single price. The hard part is that the same-looking package can be designed for very different roofs and households. A flat roof in Faro, a tiled villa in Lagos and a holiday home in Tavira have different shade, access, occupancy and wiring questions. The comparison should therefore start with the assumptions, not the headline hardware.

You do not need to be an electrical engineer to compare proposals well. You need a repeatable checklist and enough detail to identify missing scope. Ask each company to use the same recent bills, the same occupancy information and the same future loads. If one quote assumes a pool heat pump and another does not, their annual production or payback numbers are not directly comparable.

Ask for a one-page summary before comparing totals

Request a plain-language summary that lists the address or municipality, roof faces, estimated shade, panel count and power, inverter model, battery model if included, annual and monthly production, expected direct self-consumption, expected export, monitoring method and the total scope. It should also say whether the estimate is based on actual bills or a generic profile. This page lets you spot a cheap quote that is simply missing important work.

Compare the production forecast, not just panel wattage

The European Commission’s JRC provides PVGIS as a public tool for estimating photovoltaic production by location and system assumptions. Use it to sanity-check the order of magnitude and ask why an installer’s result differs. The difference may be reasonable: roof orientation, tilt, horizon, shade, temperature, inverter losses and layout spacing can all change the result. A quote should state these assumptions rather than presenting a single annual kWh figure with no explanation.

Ask for a month-by-month forecast. Annual totals can hide the reason a system is useful or disappointing. A pool villa may value summer daytime production, while a permanent home may need a different balance in winter. A holiday home may have high production during vacancy. The monthly table should connect production to demand and explain what happens to energy that is not used immediately.

Read the equipment section like a scope of work

Panel brand is only one line. Check the exact model or at least the electrical characteristics, physical dimensions, mounting method and warranty description. For the inverter, check power, monitoring, location, future compatibility and how it behaves during an outage. If a battery appears, separate nominal and usable capacity, continuous power, reserve, warranty terms and backup circuits. A quote that says ‘premium equipment’ without model information is marketing, not a technical comparison.

Make the Portuguese process part of the comparison

DGEG’s autoconsumption portal links to registration, legal information, certified equipment and FAQs. E-REDES explains the steps for becoming an individual autoconsumer, including the meter check and the information used for injection or sale of surplus. Ask the installer which route applies to your project and which steps are included in the price. The answer should be specific to the installation, not a generic statement that ‘all permits are covered’.

Ask what you will receive at handover: equipment records, diagrams, commissioning results, monitoring access, warranty documents and evidence of the relevant process. Keep copies yourself. If the property will be sold, rented or managed by someone else, these documents matter. A quote that is slightly more expensive but clear about ownership of the records can be easier to support later.

After-sales support is part of the system

Solar equipment is installed once but monitored for years. Ask who owns the monitoring account, who receives fault alerts, how support is requested and what happens if the original installer stops trading. Check whether labour, travel, replacement equipment and software support are covered separately from the manufacturer warranty. For holiday homes, ask how a remote diagnosis works and who can attend the property with permission from the manager.

Also ask what the handover includes for ordinary use. Can you understand the app? Do you know which switch isolates what? Is there a clear instruction for a shutdown or a grid outage? Can the installer show that the pool pump, battery and essential circuits do what the quote promised? A commissioning conversation prevents small misunderstandings from becoming expensive service calls.

Red flags in a solar proposal

• The quote gives a panel count and price but no roof layout, shade assumptions or monthly production.
• The savings claim is based on an unnamed electricity price or guaranteed export income.
• A battery is labelled by nominal capacity with no usable energy, power, reserve or warranty detail.
• ‘Backup’ is advertised without naming the circuits that remain powered.
• Permits, registration, meter work, board upgrades or cable routes are described as ‘included’ but not itemised.
• The company wants a deposit before a site survey or cannot identify the technical responsible person for the project.
• The proposal pressures you to decide immediately or dismisses questions about monitoring and support.
• Two quotes use different bills, occupancy, pool or future-load assumptions but are compared as if equivalent.

Questions to ask before selecting a company

• Can you mark every panel, cable route, inverter and protection component on a drawing?
• What exact production assumptions did you use, and can I see monthly results?
• How did you model my pool, air conditioning, hot water, guests and vacant periods?
• Which work is included at the roof, meter, distribution board and pool plant room?
• Which DGEG and E-REDES steps apply, who completes them and what do I receive?
• If the system exports surplus, what assumptions did you make and where is the uncertainty?
• What happens during a grid outage, and which circuits are backed up?
• Who provides monitoring, warranty support and service if I am not at the property?

Frequently asked questions