Is a balcony solar system worth it?

Short answer: yes, usually. At a reasonably sunny site, a balcony solar system (a plug-in PV setup, known in Germany as a Balkonkraftwerk) typically pays for itself in 3 to 6 years — and with modules lasting 20 years or more, that leaves many years of real profit. The honest caveat: this holds for an unshaded balcony. Whether balcony solar is worth it on your balcony is almost always decided by shading — and shading can be measured.

How does the math work in practice?

The basic calculation is simple:

• Purchase: A complete balcony solar kit with an 800 W inverter and two panels costs around €300–600 today (excluding mounting hardware).
• Theoretical yield: At a good, unshaded south-facing site in Central Europe, 800–1000 Wp delivers roughly 600–900 kWh per year.
• Self-consumption: Only the electricity you use yourself saves money — surplus usually flows into the grid uncompensated. Depending on your consumption profile, 60–80% self-consumption is realistic.
• Savings: At an electricity price around €0.35/kWh, that works out to roughly €130–250 per year.

That is where the typical 3–6 year payback comes from. So much for theory — and this is where most online calculators stop.

Why do online calculators only tell half the truth?

Standard web calculators (such as the HTW Berlin plug-in solar simulator, or PVGIS used directly) assume laboratory conditions: a free horizon, no obstacles. That is useful as a first orientation — phase 1 of planning.

Real balconies are rarely laboratories, though: trees, neighboring buildings, roof overhangs, railings, and building edges cast shade, often precisely during the most productive hours. Depending on the site, 20–60% of the theoretical yield is lost this way. A system that pays for itself in 4 years on paper may take 10 years in reality — or the other way round: a supposedly unfavorable east-facing balcony can outperform expectations because it is completely unobstructed in the morning.

So the decisive question is not “What does balcony solar deliver in my region?” but “What does balcony solar deliver on this exact balcony?”

How do you measure the real yield of your own balcony?

That is phase 2 of planning — and where HoriSol comes in. HoriSol is an iOS app that does not estimate shading, it measures it:

1. You photograph the horizon from your balcony — camera and compass measure the horizon line including every obstacle.
2. HoriSol simulates the sun’s position for every hour of the year and checks when the sun disappears behind an obstacle.
3. The result is your real annual yield in kWh, the savings in euros, the payback time, and the CO₂ savings — with actual shading losses included.

The measurement takes about 2 minutes and runs entirely offline on your iPhone. So you know before buying whether balcony solar pays off at your site — and which orientation and tilt deliver the most.

What data is the calculation based on?

HoriSol does not work with rules of thumb but with datasets from recognized institutions: NOAA solar math for the hourly sun position, and irradiance data from JRC PVGIS (European Commission), NASA POWER, and NREL PVWatts. The full methodology with all model assumptions is disclosed in the methodology documentation.

Frequently asked questions about the economics

How quickly does a balcony solar system pay for itself?

At a good site, typically in 3 to 6 years. With heavy shading, payback can stretch to 10 years or more — which is why it pays to measure shading before buying, for example with HoriSol.

Is balcony solar worth it with partial shading?

Often yes — but there is no blanket answer. Depending on when and for how long trees, neighboring buildings, or roof overhangs cast shade, 20 to 60 percent of the theoretical yield is lost. HoriSol measures the actual shading with camera and compass and factors it into the yield forecast hour by hour.

Is balcony solar worth it on a north-facing balcony?

A purely north-facing balcony delivers roughly a third to half the yield of a south-facing setup and usually only pays off with a very cheap purchase and an unobstructed horizon. East- and west-facing balconies, however, are often better than their reputation: they produce in the morning and evening — exactly when many households actually use electricity.

How do I find out what my balcony will really deliver?

With a shading measurement taken right at the site. HoriSol photographs the horizon using camera and compass, simulates the sun’s position for every hour of the year, and computes the annual yield, savings, and payback time — in about 2 minutes.

Ready for the honest number? Get HoriSol on the App Store and measure the real yield of your balcony — free, offline, no account required.