Balcony solar panels — one-year results

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Using renewable energy is a popular trend in the 21st century. But how it really works? The best way to get an answer is to build such a system and to test it on their own. I bought two 160 Watt panels and installed them on my balcony. Results and details you will see in this article.

Before we begin, an important note: I live in Europe, in the Netherlands. In other countries and continents, energy export laws (and also a city grid voltage) can vary. This article is presented for information purposes only. I would appreciate it if somebody will repeat similar experiments on their own, but please check your local laws and contact professionals, if needed, before doing any electrical work. The author shall have neither liability nor responsibility to any person with respect to any loss or damage caused, or alleged to be caused, directly or indirectly by the information contained in this article.

General Information

As we know, there are two main principles of using solar power.

1. Store the energy in batteries.
2. Feed the energy directly to the power grid.

The first method is perfect when we need an autonomous energy source that can work without external electricity, i.e. when there is either no electricity at all, or it is irregularly supplied. In this case, solar energy is charging a large array of batteries. A special inverter is converting the DC battery voltage (usually 24 or 48V) to a “normal” 230/120V AC. The advantage of having batteries is that the system can work completely off the grid. Alas, there are much more disadvantages. Batteries are expensive, and their life span is limited, especially for lead-acid batteries. The second issue is efficiency — if the battery is already charged, then solar energy is wasted in vain. The newest devices, like Tesla Powerwall, are having better and more efficient lithium batteries, but with a price of about $6500, the payback of such a thing is still in question.

The second method, and it is also the most effective, is to transfer electricity directly from solar panels to the electricity grid. In this case, the panels are connected to a special grid-tie inverter, which not only converts the DC energy from the panels to the 230/120V grid AC voltage but also synchronizes the phase with the mains. The electricity is first consumed inside the house, the excess goes into the city grid, so we not only produce electricity for…