Before you sign a solar quote, almost nobody asks the uncomfortable questions. They look at the price, the roof photo and the “save 70 %” promise. Years later they discover the helpdesk is a voicemail, a blown fuse has cost months of production, or the company on the contract no longer exists. This article is a checklist of 12 questions for any installer. No fake ranking: objective criteria to filter out 80 % of problems before you pay.
Updated August 2026. A Todo Sol Instalaciones Fotovoltaicas SL (VAT B72775315) works across Spain. Our main focus is Alicante, Murcia and the Valencian Community, but we install anywhere in the country. PV, solar pergolas, batteries and EV chargers. If you are comparing quotes, use this list with everyone equally — including us.
There is no single “best solar company” for everyone. There are installers who still answer in 2031 and others who vanish when the boom ends. After Social Energy’s insolvency in March 2026 and three years of sector contraction, choosing well matters more than saving €800 today. More context: track record vs. cheap price.
The 12 questions (summary table)
| # | Question | Answer you want | Red flag |
|---|---|---|---|
| 1 | Who provides after-sales support? | The installer, with its own technicians | “Call the manufacturer” or “only with a maintenance plan” |
| 2 | Do you monitor strings or only the inverter app? | String/fuse monitoring with alerts | “The app already shows total production” |
| 3 | Is the price fixed? | Binding quote; extras only if you change scope | “Estimate” that rises on site without a signed change order |
| 4 | Sales and support hours? | Past 15:00; weekends and holidays (e.g. Mon–Sun 7:00–22:00) | “Mornings only” or voicemail after 15:00 (almost everyone) |
| 5 | Installation (work) warranty? | Concrete years in writing (labour, cabling, fixings) | “The panel warranty covers everything” |
| 6 | Which paperwork does the company handle and where must I appear? | Clear list: installer-managed vs owner/representative required | “We do everything” with no breakdown |
| 7 | Does backup cover the whole home on full critical load? | Whole house on critical load; no utility needed to enable backup | One circuit only or backup needing distributor approval |
| 8 | Do you include a battery or will I rely on export tariffs? | Sized storage; real self-consumption, not just selling to the grid | “Exports pay for it” with no battery or consumption study |
| 9 | Alerts if the grid is down +24 h? | Yes, proactive monitoring | “No power is the utility’s problem” |
| 10 | 100 % financing with no down payment? | Named lender; instalment and APR on paper | “No deposit” with no clear credit contract |
| 11 | How long active and how many installs? | Years trading, volume, in-house technical staff | They dodge or only cite “Google reviews” |
| 12 | What if the company closes? | Clear plan: docs, manufacturer warranties, adoption | “That won’t happen” or silence |
1. Who provides technical support after installation?
A solar system lasts 25 years. The inverter may need new WiFi, an RCD may trip, or something rattles on the roof. Ask: who picks up the phone?
- Good answer: the installer with its own technicians, including after-sales. Our real cases: 12 minutes, 32 minutes, 4:57 a.m.
- Bad answer: “Open a ticket with Huawei/Sungrow” or “optional €400/year maintenance”.
2. Do you monitor strings or only the inverter app?
The manufacturer app shows total production. It does not warn if a string fuse has blown: the system “works” but produces half. Ask about string monitoring (each string, every night). On pergolas it is critical: you see shade every day but not a fuse. More: how we monitor and why we monitor rather than sell cleaning.
3. Is the quoted price fixed?
“Estimate” hides more inflated quotes than any other word. Ask for a fixed price unless you change scope (more panels, extra battery). If the roof “turns out worse on site”, there should be a signed change order, not a sales call.
4. What are sales and technical support hours?
Ask this before you sign: not only “do you work weekends?” but when does the phone switch off on weekdays?
In the Spanish solar sector the usual pattern is harsh: almost every company stops answering after 15:00. Morning office hours, then voicemail. Saturdays and Sundays: silence. In August, many do not even open. If your quote question arrives at 16:30 or a fault on Friday afternoon, you are alone until Monday — or until September.
- Red flag: “We answer 9 to 15”, “call in the morning” or support that vanishes at lunchtime.
- Good answer: sales and technical support after 15:00, also Saturday, Sunday and during holidays.
At A Todo Sol, sales and technical support are active Monday to Sunday, 7:00 to 22:00 — when the customer is home, not when the office opens on Monday. We install in one day and answer when others have already closed. More: if your installer closes at 15:00, you do not have real support and real support cases.
5. What installation (labour) warranty do you offer?
Separate product warranty (panel 25–30 years, inverter 10) from work warranty (cabling, fixings, weatherproofing). Ask for labour years in writing. Hail and extras: hail warranty. Same for 10 % VAT “tricks”: the risk is yours — 10 % vs 21 % VAT.
6. Which procedures does the company handle and where must I appear?
In practice the installer usually handles self-consumption registration, legalisation and many grants. But not everything can go with the company as representative: some filings require the owner or an authorised representative. Ask explicitly:
- What does the installer process end to end?
- Where must I sign or appear as the interested party?
- How will they alert me if the administration requests a fix?
Beware “we do everything” with no list. No “two grants” promises without a study: IBI rebates and 40 % vs 60 % income tax.
7. Does backup cover the whole home on full critical load?
Many “backup” systems feed only one socket circuit or depend on the distributor authorising or enabling something. Ask whether the design covers the whole home on full critical load — fridge, lights, pump, essential kitchen — without relying on Iberdrola, i-DE or another distributor to make backup work when the grid fails.
At A Todo Sol we always design for whole-house critical load: backup is not held up by a grid permission or a call to the distributor. More: single-phase vs three-phase and whole-house Deye backup.
8. Do you include a battery or will I depend on export tariffs?
Selling cheap exports to the grid is plan B for installers who do not size storage. Ask whether the quote includes a battery (or hybrid storage) for real self-consumption, not just bill compensation.
At A Todo Sol we include storage on almost every installation so you do not depend on export tariffs or your supplier’s mood. The energy you produce stays at home. More: home batteries and why 2026 is the year of storage.
9. Do you include alerts if the grid is down +24 hours?
Without grid, many inverters do not produce even in sunshine. Proactive alerts (not “check the app when you remember”) catch long outages. Part of serious monitoring, not a luxury.
10. How does 100 % financing with no down payment work?
Ask for the lender, APR, monthly payment and cancellation terms. “No deposit” without a clear credit contract is usually marketing. 100 % financing is fine when documented.
11. How many years trading and how many installations?
Google stars are not enough. Ask years active, approximate volume, whether they have in-house technical staff. On Trustpilot look at recent trend and % of 1-star reviews, not only the historical average (see Social Energy).
12. What happens if the company closes?
Nobody wants to think about it, but in 2026 it is realistic. Ask: full documentation in your hands? Manufacturer warranties claimable without the installer? Can another company adopt the system? If they have no answer, assume there is no plan.
Close: use the list with everyone equally
These 12 questions do not automatically pick A Todo Sol. They filter installers who will not be there when a fuse blows in year 12. When you compare, keep answers in writing (email or WhatsApp). A pretty quote without clear support is a 25-year lease with a landlord who has vanished.
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Editorial guide from A Todo Sol Instalaciones Fotovoltaicas SL. General information as of August 2026. Does not replace individual legal or tax advice. Context: Social Energy insolvency (March 2026, OCU/FACUA), self-consumption contraction 2023–2026.