Solar self-consumption: advice and design

• Advice. Whether it makes sense, at what size, with or without a battery, what to expect and what not to expect.
• Sizing. From real consumption, we calculate the power to install and the share of production the home can actually use.
• Design. The system diagram, the connection to the switchboard, protection on the DC and AC sides, the cables and their routes.
• Installation oversight. The work is done by an installer of your choice. We check that what is fitted matches what was designed and contracted.

BASHATEC neither sells nor installs solar panels. For the buyer, that has a practical consequence: the sizing does not depend on the equipment available or on the size of the sale. The installer supplies and fits, and answers for that work. Our job is to tell you beforehand what system you need and to confirm afterwards that this is what was installed.

We start from twelve months of consumption, if available, and from the daily profile. A house that is empty during the day makes little use of a large system; a house with a heat pump, a pool or an electric car charged in daytime makes more. We add the orientation and pitch of the roof, the shading and the space available.

The result is a recommended power, the estimated production and the share of that production that will be used on site. That last figure matters most: energy used on site is energy not bought from the grid.

On batteries, we tell you what your consumption shows: how much energy is left over by day and how much is needed at night. We do not publish payback periods. They depend on the price of energy, the consumption profile and the cost of the system, and are worked out case by case, with the assumptions on the table.

Production for self-consumption is subject to prior control by DGEG, Portugal's Directorate-General for Energy and Geology, which varies with installed power. According to DGEG (information checked in October 2026), a unit of up to 700 W that does not export to the grid is exempt; above 700 W and up to 30 kW, prior notification (comunicação prévia) applies; above 30 kW and up to 1 MW, prior registration and an operating certificate. We tell you which case your system falls into, so that you know what to ask of whoever installs it.

If you already have quotations, we help you read them: whether the powers are comparable, whether the inverter suits the panels, what protection is included, how the connection to the switchboard is made, what is and is not in the proposal. It is a technical opinion, not a brand recommendation.

• Electricity bills for the last twelve months, or consumption data from the meter if you have it.
• Photographs of the roof, and its orientation.
• Photographs of the switchboard.
• The contracted power (potência contratada) and the type of supply, single-phase or three-phase.
• Any quotations you have received.

As a rule, the work starts with an analysis of consumption and of the site, followed by the sizing. You receive a written document with the sizing, the assumptions used, the system diagram and the recommendations. If the installation is overseen, you also receive a record of what was checked.

Where there is not enough consumption data, measuring consumption provides the missing basis.