I'm thinking about installing solar panels on my apartment in Lisbon, but I'm not sure if it makes financial sense. I have a south-facing balcony and I'd like to know if it's possible to install them without doing major work on the facade.
The short answer is: it really depends on the exact orientation, the shade you get, and how much you're paying for electricity now. A south-facing balcony in Lisbon is theoretically perfect, but the problem is that apartments usually have serious limitations - neighbors blocking light, buildings across the way, trees. Before you spend money, you really need to know how many hours of direct sunlight that spot actually gets, because if your balcony only gets sun between 11am and 4pm, it's not the miracle it seems.
As for the work involved, the good news is there are portable or semi-portable panel systems that don't require drilling into the facade - basically you install them on top of a support structure on the ground or wall, without damaging anything. The problem is these systems tend to be more expensive per watt, because smaller and less integrated panels don't pay off as much. There are also mini panels you can put on a shelf, but then we're talking pretty modest power - maybe 1 or 2 kilowatts maximum, which won't make much difference on a typical electricity bill.
If you actually want to know whether it's worth it, do the math: how much you're paying per month now, how much you're consuming on average, and what a system like this would cost for your balcony (with installation). Then you see how many years it would take to break even. In Lisbon you get some sun, but it's not the Algarve - if the payback is more than 10 or 12 years, honestly it might be smarter to invest that money elsewhere. Still, it's worth talking to people who sell panels locally, because they might have solutions I haven't thought of and they'll know better what the limitations are for buildings in your neighborhood.
First, check with your condo board if it's allowed - a lot of apartments have restrictions and you could end up in unnecessary trouble. Panels on a balcony are totally doable without major construction work, you can set up lightweight structures that don't mess with the building's facade. The financial payback in Lisbon is reasonable, maybe around 6-8 years depending on your electricity consumption and whether you can use the power you generate on the same day (because a battery gets pretty expensive). If your electricity bill is low, it might not be worth it as much, but if you use a lot of electricity during the day, a south-facing balcony is basically perfect for the investment.
Panels on a balcony work well if they don't get shaded by neighboring buildings during the day (that's the tricky part in Lisbon, often the building next door ruins everything), but yes, you can install them without messing with the facade.
What nobody mentioned is the actual return: in Lisbon, with a small balcony, you're looking at something like 10-15 years to break even on your investment, depending on how much you're paying for electricity now. If your bill is high (over 100-150 euros a month) and the balcony gets direct sunlight all day, then yeah it makes sense; if not, better to wait a few years for panels to get cheaper.
You can do a pretty practical test before spending money: put a phone with a solar light measurement app on your balcony for a few days, at different times of day, and see if it gets those 4-5 hours of direct daily sunlight that panels need to actually work. If it passes that test and your condo allows it, a balcony system really does work - people are right that you don't need major construction, but that detail about measuring the actual shade is what most people ignore and end up disappointed about.
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