Small photovoltaic systems for balconies, roofs or terraces – the so-called balcony power plants (guide) – are now not only found on the Internet or hardware stores, the small solar systems are even available from discounters. But is it worth buying and what should you pay attention to?
Anyone who finds little or no potential for savings in their own consumption can also reduce their electricity bill with electricity they produce themselves. The cheapest and easiest option for this are balcony power plants. Their advantages are the low price, the simple commissioning and the very little bureaucratic effort compared to a large photovoltaic system.
The legislature still allows a maximum feed-in of up to 600 watts, but this limit is to be increased to 800 watts in the near future. We show why it is still worthwhile to use a balcony power plant with 600 watts. The article Balcony power plants from 500 euros offers more background knowledge: Buy, plug in and save immediately.
Differences balcony power plants
The range of balcony power plants is large and the sets differ not only in price. So where are the differences and what do you have to consider when buying? As a rule, the manufacturers offer a performance guarantee of up to 25 years on the solar modules. The guarantee for the inverter or rotary converter is significantly lower at two to a maximum of five years. An integrated WLAN function for checking the performance and yield data is common, but not always available. If in doubt, a WLAN socket with an integrated current meter is sufficient. The biggest difference in the systems available is their performance. There are several factors that are important here.
How much power in watts your own photovoltaic system can feed into the power grid depends on the inverter used. Most currently available models for balcony power plants allow the currently permissible maximum feed-in of 600 watts. But inverters with less power and devices with 800 watts are also available. According to the current status of the regulations, however, these may not yet be used.
However, individual suppliers such as Ecoflow or Priwatt offer inverters with update options. As soon as the legal requirements change, a firmware update is sufficient and the inverter will output up to 800 watts instead of the previous 600 watts. This applies, for example, to the Priwall Duo balcony power plant with two panels for currently only 638 euros (with discount code: PRIFLAT100). The manufacturer Yuma goes the opposite way. An 800 watt inverter is available here from 829 euros with the option of downgrading to 600 watts.
However, how high the actual feed-in is then depends on the solar panels used and the weather conditions. In reality, the nominal output of the connected solar modules will almost never be reached, or at best only for a few hours a day. In order to be able to feed in as much electricity as possible even when it is cloudy, it is worth calculating the panels more generously.
The already tested 600-watt balcony power station from Netto (test report) contains two 420-watt panels. With a good orientation and ideal weather conditions, even more electricity is generated here at lunchtime than can actually be used. In cloudy weather or in partial shade, the amount then drops to double-digit performance values and we wished for even more panels.
The small solar power plant from Yuma (test report) for 369 euros only comes with a 300 watt inverter and a 400 watt panel. The bundle with 800 watt panels is 729 euros. The variant with an 800-watt inverter costs about 100 euros more. The Klimaworld BS-SET-300K bundle for 430 euros only includes a panel with an output of 300 watts. The maximum permissible feed-in can then no longer be achieved mathematically.
Required power
When it comes to the question of whether the inverter should have an output of 600 or 800 watts, opinions differ. Sure, more power always sounds better, but are the extra costs worth it?
If you want to buy a solar system for your balcony or terrace, you should first consider your own electricity consumption. The background is the fact that in the case of balcony power plants, the unused electricity is fed into the electricity grid free of charge. In case of doubt, others will benefit from a high feed-in. Two exciting exceptions are the Powerstream balcony power plants from Ecoflow (test report) and the newly installed set from Zendure (test coming soon). A battery is also connected here, which stores the “excess” electricity produced and can feed it in at night or in bad weather. Normally, the electricity produced is lost for the user; to be more precise, it is fed into the general power grid free of charge.
The small solar systems for terraces and balconies are primarily suitable for carrying the base load (or at least part of it) during the day. The base load refers to all consumers that consume electricity inconspicuously in the background. These include refrigerators, freezers, routers, smart home components and other stand-by consumers. Depending on the size and equipment of the household, the power required varies greatly. In a modern single-family home, almost 300 watts of feed-in are enough to stop the electricity meter. Small apartments usually have a much lower base load and so do small sets with less power. In old houses with electrical appliances that are decades old, 600 watts and more quickly flow through the lines in the background. The small solar systems are too weak to operate energy-hungry consumers such as stoves, washing machines or garden tools via photovoltaics. By taking over the base load, the monthly electricity costs can still be noticeably reduced.
Cost
Even if you don’t have a problem with losing too much electricity, you should think twice about whether a 600-watt system isn’t enough. The reason for this is the currently still noticeably higher costs. Aside from the fact that inverters with 800 watts or an update option are more expensive, more powerful (and larger) panels are also required for efficient operation. But what does that mean in concrete terms? We have selected a few examples in which the output of the solar modules provided is at least sufficient to enable the inverter to feed in fully.
The cheapest set in the Offgridtec Solar-Direct price comparison with a 600 watt inverter and two 360 watt panels (720 Wp) is available from 449 euros. The sets from Netto (test report) and the Vale MiniPV 600 system with two 420 watt panels (840 Wp) and 600 watt inverter cost 499 euros. The cheapest set with an 800-watt inverter is only 20 euros more expensive, but the Naka balcony power plant for 520 euros also contains “only” two 420-watt panels. Although 800 watts are possible in the best weather, the performance drops quickly in less than ideal conditions. Experience has shown that not even 600 watts are then reached. In order to use the more powerful inverters efficiently, the solar power should ideally also be designed more generously. From our point of view, at least 1000 to 1200 watts of solar power (Wp) would make sense. Such noticeably stronger sets, such as the Solarway Plug&Play Deye Sun800 with two 500 watt panels, then cost at least 645 euros.
Although such systems then perform better, the difference is not huge. If we look at the current yield of our set with a 600 watt inverter and two 420 watt panels (840 Wp), then we would generate around 700 to 850 watt hours (Wh) more with such a larger set. With a working price of around 40 cents per kWh, that means around 26 to 34 cents in additional electricity costs per day – but only on sunny days and when all the electricity fed into the grid is actually consumed.
Usually, however, only a few consumers are active during the day, when the balcony power plant is producing electricity, and the base load is therefore low. The electricity requirement is usually highest in the evening, but then the balcony power plant no longer delivers any output. It doesn’t matter whether the device can theoretically feed in 600 or 800 watts. The only exception are balcony power plants with additional power storage, such as the Ecoflow Powerstream (test report). These store excess energy during the day and then release it in the evening.
There is also the problem that not all inverters can be conveniently plugged into a normal Schuko socket. Instead, the Deye inverter from the Netto balcony power plant has the frequently recommended Wieland connector on board. From a technical point of view, this is safer, but a corresponding socket must be installed by qualified personnel, which involves costs from around 200 euros. A suitable adapter is already included in the scope of delivery of the Netto set, so you can use the classic socket here at no cost. With the newly arrived balcony power plant from Parkside (Lidl), things are even more complicated. No standard Wieland connection is used here, but a proprietary solution. If you don’t want to spend hours looking for the right adapter, you have to have the special socket installed, which incurs additional costs.
Prices
Balcony power plants with an inverter for 600 watts are available as a complete set from 450 euros. Versions with inverters up to 800 watts cost around 100 euros more. Individual inverters for 800 watts are around 60 euros more expensive (30 percent) than for 600 watts.
Conclusion
Whether it makes sense or not, most buyers currently seem to be interested in 800-watt inverters, so the prices for the 600-watt models are falling noticeably. If you want to buy cheap and only want to supply a moderate base load, you should definitely keep an eye on the prices of the inverters and balcony power station complete sets with 600 watts. These are currently more worthwhile because they are cheaper and still offer sufficient cost savings in terms of electricity consumption. In the case of systems with more power, the advantage for the user is lost if the excess electricity is fed into the grid free of charge.
If higher acquisition costs and possibly unused electricity are not a problem, sets with 800 watts are of course also possible. If you already use a balcony power station and also have an Ecoflow power station, you can replace the existing inverter with the Ecoflow Powerstream (test report), which can be upgraded to 800 watts, and store the electricity produced during the day and also feed it in at night. Basically, you should pay close attention to everything that is included in the scope of delivery with complete sets in order to avoid unplanned costs.