And never again do you need to pay for fuels at the petrol station, because your car now runs for free on the power you generate yourself. In the process, you positively contribute to the protection of the environment. All of this thanks to a few photovoltaic panels placed on your roof or in your garden.

But as the saying goes “if something seems too good to be true, it usually is”. Where is the line between myth and reality in this matter?

Before we start: Photovoltaic solar panels generate electricity. They should not be confused with the similar looking water-boiler panels that directly heat up water. These are also interesting, but worth another story.

Off-grid or grid-connected

The average of 300 days a year with sunshine in the Algarve is a reality. And so is the tendency for energy prices to grow. This combination makes many people wonder if it is possible for them to go “off-grid”, charmed with the idea to become fully self-supporting.

Although the latter ambition certainly follows logic and is also technically possible, theory and practice differ when it comes down to the pondering of pros and cons among a wider range of options.

The first question has to be about motivation; Is the wish to become independent based on the fear of grid blackouts, on the desire to help protecting the environment, or on the idea to save money?

Even if all three are true, saving money is often the decisive factor and in being so, a logical starting point.

Identifying such a starting point is crucial because it directly influences one basic ingredient: The number of panels required.

From an economic standpoint, the best calculation starts with the energy consumption in its average demand, not in its peaks. Illustrating this: Modern panels are able to produce around 410 watts each. A hairdryer may require 2000 watts. So, feeding just a hairdryer in operation requires five panels. But then again, one uses a hairdryer just a few minutes per day. In short, from a purely financial point of view, the most interesting is to have enough panels to cover the average consumption, and to use the grid as a “back-up” for the short peak demands above that.

Disconnected from the grid, however, that back-up option obviously does not exist. So off-grid systems should be large enough to always cope with full demand, and must therefore have a considerable number of panels.

Off-grid also means that no energy is available at night or during dark days, so a reserve of energy in batteries is needed. And that, in turn, requires a double job from the panels: Providing enough energy for all requirements during the day, and at the same time supply enough energy for the charging of batteries for all night-time requirements. This is another reason why an extra-large number of panels is needed for off-grid situations. By the way, not having the grid as a back-up makes it wise to also invest in a power-generator, in case the batteries go flat. And they easily may when a few dark days follow in a row.

All in all, going fully off-grid is a necessary option for those who cannot get a grid connection in the first place, or perhaps a comforting idea for people who like to feel independent. But it requires investments not yet fully justifiable from a pure economic point of view.

Of course, there is also the hybrid option to have both batteries and a grid connection, acting as a kind of double back-up. Read part two about solar panels in next week’s edition to find out more.

Hans is a Dutch citizen who helps a local supplier of PV-systems to answer the high and growing number of daily quote-requests from Algarve residents. The above text reflects the most common doubts and curiosities he encounters while providing advice and suggesting solutions.

For the Dutch speaking community, he will be guest speaker at a webinar organized by the NCA Association, to be held May the 9th starting at 7pm. Information can be obtained via