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How to compare solar quotes in Portugal: the technical handover test
A homeowner-friendly method for comparing Portugal solar quotes by production assumptions, scope, DGEG and E-REDES responsibilities, controls, warranties and handover evidence.
A quote is a model of your home, not a promise of savings
Two proposals can use the same panel wattage and still describe very different projects. One may include a battery, export control, scaffolding, monitoring and commissioning; another may leave those items as options. One may model a permanent resident, while the other assumes a holiday villa with a pool and no daytime demand. Compare the assumptions before comparing the total. If the installer will not show how the number was produced, the number is not yet a decision tool.
For an Algarve property, the brief should include roof orientation and shading, air conditioning, water heating, pool equipment, guest or occupancy patterns and any planned EV charging. Ask for one page showing PV production, direct household use, battery charge, export and grid import. This energy-flow picture makes hidden differences visible and gives you a way to challenge an optimistic forecast without needing to be an engineer.
Normalise the proposals field by field
| Field | Question to ask | Evidence to keep |
|---|---|---|
| Consumption baseline | Which bills, readings and occupancy assumptions were used? | Bills, interval data, calendar and written assumptions |
| PV production | What orientation, tilt, shading and loss factors were modelled? | Roof plan, production report and method such as PVGIS |
| System power | What are the panel DC power and inverter AC power? | Equipment schedule and single-line diagram |
| Self-consumption | How much is used directly, stored, exported or curtailed? | Monthly table with the energy flow, not only annual yield |
| Battery | Are figures nominal or usable, and what is the power and reserve? | Data sheet, warranty and operating modes |
| Installation scope | What roof, electrical, access, protection and finishing work is included? | Itemised scope, exclusions and site photographs |
| Network and paperwork | Who handles DGEG, E-REDES, meter and production steps? | Named responsible person, deliverables and status updates |
| Handover | What will I receive and how will I operate the system? | Commissioning record, credentials, diagrams and training |
Keep the three columns together. A verbal answer is not equivalent to an item in the signed scope.
Test the production estimate instead of admiring it
PVGIS, the European Commission JRC’s photovoltaic tool, provides location-based solar radiation and PV performance information and can show how production changes through the year. It is not a guarantee of what your roof will deliver, but it gives you a transparent reference for checking a proposal. Ask why the installer’s production differs from a PVGIS run and which shading, temperature, inverter, dirt or availability losses have been applied.
A useful estimate includes monthly values and a clear separation between production and savings. Production is what the system generates. Direct self-consumption is what the property uses at the same time. Battery throughput is subject to power and efficiency. Export has its own meter and commercial assumptions. Grid import may remain high in winter or at night. If a quote collapses all of these into ‘annual savings’, ask for the missing steps.
Read the installation price as a scope document
The lowest headline price is not necessarily the lowest project cost. Look for the items that appear only after a site visit: roof access, cable routes, protection, board changes, scaffold or lifting, waterproofing, equipment supports, commissioning, monitoring, certification, meter work and future service. Ask which taxes and optional items are included, but do not rely on a generic ‘turnkey’ label. The signed scope should say what happens when the roof or electrical board differs from the first photograph.
| Area | Make the quote explicit about |
|---|---|
| Roof and access | Fixings, tiles, waterproofing, access equipment and making good |
| Electrical works | Cable length, protection, earth, board changes, isolators and labelling |
| Controls | Export limitation, energy management, battery control, pool or EV interface |
| Administrative steps | Technical file, DGEG route, E-REDES contact, meter and production data |
| Handover and service | Commissioning test, app account, diagrams, training, response and warranty route |
The purpose is not to force every installer into the same package; it is to make exclusions comparable.
Understand the current Portugal route before signing
E-REDES currently says a consumer needs DGEG Portal registration when intending to inject or sell surplus, or when installed power is above 700 W. It describes a journey involving a qualified technician, E-REDES analysis and a meter check. DGEG provides the self-consumption and renewable-energy-community procedures and legal information. Ask the installer to identify exactly which configuration your quote assumes and which steps are included, instead of assuming that ‘registration handled’ covers every network and commercial action.
The electricity bill is another useful check. ERSE explains that bills contain contracted power, actual or estimated consumption, energy prices, network access tariffs, taxes and other required information. Use a recent bill and the ERSE guidance to confirm the delivery point, consumption history and contract context used in the proposal. If the property changed owner or supplier, verify the CPE and contract details before anyone submits a project.
A practical decision table for three common quotes
| Proposal pattern | Potential strength | What must be clarified |
|---|---|---|
| Lower price, fewer controls | Simple hardware and fewer failure points | What happens to surplus, monitoring, pool/EV loads and future expansion? |
| Higher price with battery | More control over timing and possible resilience | Usable capacity, backup circuits, cycle assumptions, warranty and remote service |
| Similar hardware, very different yield | One model may include better site data | Shading, orientation, losses, monthly production and self-consumption calculation |
| ‘Turnkey’ with one total | Fewer separate invoices | Itemised inclusions, exclusions, administrative deliverables and variation rules |
There is no universal winner. The credible proposal is the one whose assumptions and responsibilities remain clear after the sales conversation.
Red flags before you pay a deposit
- The proposal lists panels but not a roof layout, inverter, protection, cable route or commissioning scope.
- Annual production or savings is shown without monthly values, shading assumptions or the difference between generation and self-consumption.
- A battery is described only by nominal kWh, with no usable capacity, power, reserve, warranty or backup boundary.
- ‘Sell the surplus’ appears as a benefit without identifying metering, supplier arrangement or who completes each step.
- A holiday-home quote ignores the pool, air conditioning, vacancy period, remote monitoring or local service response.
- The installer wants a deposit before a site survey, a written scope and a named technical responsibility.
The pre-deposit checklist
- Attach the latest bill and mark the CPE, contract holder and typical occupancy pattern.
- Ask for a roof plan, equipment list, single-line diagram and monthly production/energy-flow table.
- Get exclusions in writing, including access, electrical-board changes, protection, meter and network tasks.
- Confirm the responsible technician, DGEG/E-REDES deliverables and how you receive status updates.
- Check monitoring access, warranty contact, service response, safe shutdown and handover training.
- Compare the same system boundary across quotes before comparing price or score.
Frequently asked questions
Should I choose the quote with the most panels?
Not without checking roof fit, shading, inverter limits, export assumptions, direct use and future loads. More panels can be useful, but only if the complete design and connection route support them.
Is a production estimate from PVGIS a guarantee?
No. PVGIS is a transparent reference tool for solar resource and PV performance. Your roof, shade, equipment, losses, availability and maintenance still affect actual results.
What does turnkey need to include?
The words are not enough. Ask for an itemised scope covering design, access, electrical work, protection, controls, registration or network responsibilities, commissioning, monitoring, documents and after-sales support.
Do all solar quotes include DGEG and E-REDES work?
Do not assume so. E-REDES and DGEG describe current processes and thresholds, but the quote should name the exact configuration, responsible people and deliverables for your property.
How many quotes should I get?
There is no magic number. The important part is giving each installer the same bill, property information and scope, then comparing auditable assumptions rather than collecting incompatible headline totals.
Bottom line
A good solar quote is easy for a homeowner to interrogate. It shows the roof, the loads, the monthly production, the energy flow, the equipment boundary, the Portugal network route and the handover evidence. Put those items side by side, ask for missing assumptions and choose the proposal whose responsibilities remain clear after installation—not simply the one with the most impressive number.
Use the free estimate or send a question to get more practical guidance.
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