In Lisbon, rising energy bills are putting more pressure on households. Heating domestic hot water can account for around 4% of a typical Lisbon family’s electricity use. Facing high power costs, our customersAna and João Ferreira, a family of four, decided to try a smarter solution: replace their old electric water heater with a wall-mounted solar water heaterdesigned for balconies and exterior walls.
That is where the Flowatt horizontal wall-mounted hybrid solar water heater (FLW-H-60) fits in. Unlike traditional solar water heaters that need a rooftop, this compactsolar storage water heater can be installed on an apartment balcony or outdoor wall — a practical option for urban homes with limited space.
It combines DC solar (photovoltaic) heating with AC backup power, and uses smart MPPT technology to make better use of sunlight even on cloudy days. The result is less reliance on grid electric heating, helping Lisbon families like the Ferreiras cut electricity use and save on everyday hot water costs.
Lisbon’s Why It Fits a Solar Water Heater
In terms of solar resource, Lisbon’s annual horizontal irradiation is around 2,000 kWh/m²(see EU Solar Calculator – Lisbon). According to estimates based on the EU Joint Research Centre’s PVGIS, each 1 kWp of PV installed in the Lisbon area can generate about 1,773 kWh per year — nearly double typical output in northern Europe (cited via Durgesta).
That is why a wall-mounted photovoltaic storage water heater works especially well in Lisbon apartments: in spring and summer, strong sunlight supports high DC solar heating; in winter, when irradiance drops, AC backup heating still keeps hot water available. For a family of four like Ana and João, Lisbon’s high solar resource pairs well with the Flowatt FLW-H horizontal wall-mounted solar water heater, helping them use local sunshine to cut electricity costs while maintaining reliable daily hot water.
Solar Panel Solutions When Rooftop Installation Is Restricted
Because so much of central Lisbon sits in protected historic districts — including areas such as Baixa Pombalina — rooftop alterations are often tightly controlled. Installing solar panels on the roof may not be allowed, or may require lengthy heritage approvals that many apartment households find impractical.
That is why Ana and João chose a different layout: they mounted the Flowatt 60L horizontal wall-mounted solar water heater tank (FLW-H-60) on an exterior wall, and placed the photovoltaic panels in their private courtyard instead. To use solar energy to power their water heater, Ana and João installed two photovoltaic panels in the courtyard — a compact array of about 500W in total, closely matched to the Flowatt FLW-H-60’s DC rating of 42V / 445W.
What Changed After Solar Water Pump Installation
After installing the Flowatt 60L horizontal wall-mounted solar water heater tank (SKU: FLW-H-60) , the biggest change for the Ferreira family was simple: daytime domestic hot water no longer depended mainly on grid electric heating. Their two courtyard photovoltaic panels — about 500W in total — feed the tank’s DC solar heating circuit (DC42V / 445W).
On sunny Lisbon days, this compact solar storage water heater can warm the water to a usable temperature by late morning. The thick insulation then helps hold the heat, so evening showers and dishwashing do not always trigger a full electric reheat the way their old water heater did.
For a family of four, a 60L wall-mounted solar water heater works best with staggered use — mornings and evenings split apart, rather than four long showers at once. Through spring and summer, solar energy covers a large share of daytime reheating. On cloudy days or during peak demand, the AC/DC hybrid system automatically switches to AC backup heating (AC220V / 2000W), so hot water stays available.
They did not reach “zero-electricity” hot water, but their reliance on the grid for water heating dropped clearly — roughly an estimated 40% to 60% less electricity for everyday hot water — easing bill pressure and matching their goal of a smarter solar water heater solution for life in Lisbon.
