All important topics Balcony power plant / Mini PV

Introduction

For a half year now, I have been planning Balcony power plant and looked around me a little.

Due to the long delivery times and a promotion I receive for this, this project has drawn a little.

But now the subject is almost finished with me and for this reason I would like to write a small blog post as many times, so that you can get the information collected in one place and not like me, to search the most diverse sources.

Disclaimer

At the moment, a lot is discussed in politics (including an increase in the possible AC power (currently 600W). I try to keep the data in this post as good as it is, but I cannot guarantee that I can provide up-to-date information. As always, I do not accept any liability for the information written here :).

What is Balcony power plant?

At first, as always, I want to make sure that everyone knows the principles in every case. Most of them already know balcony power plants from the media, but here I also want to briefly give a small "definition" of a balcony power plant / Mini PV /etc.

A Balcony power plant, also designated as a mini-PV system, Guerilla PV or also Plug & Play PV. This is a small photovoltaic system that is conventionally mounted on a balcony or a terrace and serves to generate electrical energy from sunlight. This type of system usually has a power of 300 watts (1 module) to 600 Watt (2 modules) and can cover the electricity requirement of a household partially or possibly completely. As a rule, the energy produced is consumed directly in the household and is primarily intended for own consumption. Balcony power plants are simplified in approval and often do not require any approval (although no more).

What types of balcony power plant are there?

Balcony power plants are generally more homogeneous. Mostly, a balcony power plant consists of one or two modules and are then attached to an aluminum frame.

The biggest difference is probably the inverter and its maximum output power (AC side). There are mainly 2 species. The smaller version can feed a maximum of 300 watts into the home network and is usually intended for use with a solar module. Furthermore, there is the "big" version which is intended for the use of 2 solar modules. However, it should be noted that these values are based on Output power of the inverter. So the value that in the end flows into your socket as a "power". The DC side (the input side at which the solar modules are connected can usually record at least 800W or more. In this way, for example, even in the case of poor weather or not very optimal weather conditions, up to 600 W can be achieved and conversion losses are thus slightly damped so that the maximum power of the inverter can be achieved at all. Normally, the inverter should have an efficiency of 95% up.

From Balcony power plant?

A balcony power plant is composed of two functional components.

1. The solar modules => The solar modules "generate" the current and pass it on to the inverter.

Two. The inverter => The solar modules generate no alternating current but DC (equivalent voltage) unlike in our home network. Furthermore, the modules do not generate the correct voltage (normally the output voltage of a solar module is approximately 30VDC-50VDC). This form cannot use the home network. The inverter is (and some other things) because the voltage of the solar modules for the home network is adjusted (to 230VAC). More precisely, the inverter converts the DC voltage of the PV modules into AC voltage.

3. The frame (optional) => Finally, a balcony power plant can be installed on the roof either with a roof structure, on a balcony or on the lawn. With such a frame, the solar panels are kept in position and, if necessary, also prevent the modules from being destroyed or removed by wind or other. EIn frame is optional. In principle, at least these modules could be placed on the lawn/terrace. However, this has several disadvantages. I will describe them a little later.

What to consider in the PV modules? (Only important for DIY)

In order to be able to generate electricity at all, PV modules must also be present. There are many manufacturers and even more performance figures.

The PV modules should meet your needs in principle (the modules should be able to perform at least 400W (more) to produce something even in bad weather).

With the PV modules, I could easily write another blog post, which is why I look very briefly at this topic.

Every solar system is a money system. You're going to the minus first and you're investing your money in this facility. For this reason, make sure that the system lasts as long as possible and additionally includes a good manufacturer warranty (min. 20 years, better 25 years at 80% of the rated power).

Furthermore, the PV modules must be compatible with the inverter. For this purpose, for example, the so-called idling voltage of the solar module must be smaller (or equal) than the maximum DC voltage of the inverter. If your solar cell can supply more voltage than the inverter can absorb, it destroys the inverter and this is no longer usable.

In addition, the maximum current must not be greater than the permissible current of the inverter, since otherwise this can happen and should lastly be taken into account for the maximum power per channel. Not every inverter comes up with 450W modules, for example.

For this reason, in most cases, a plurality of solar modules cannot be packed on a channel, since voltage or current may become too high and the inverter is thereby destroyed.

Another topic is the "type" of the solar module (e.g. poly- or monochristallin). In this case, in the case of micro-plants, mono-christallin can actually be put on a flat-rate basis, since these at least still have the best services.

There are also topics such as shading tolerance, temperature coefficients, certifications, sizes, module efficiency, etc. However, this is a very important contribution. This is primarily about the classic balcony power plant, which you can buy as a complete set. There are usually so-called. "Half-Cut" panels used. The module is divided into 2 areas. Thus, a certain shading tolerance is introduced. Furthermore, there are also "Hotspot Free", but these are a little more expensive. These only make sense when, for example, several trees are in the immimable environment that the modules could shadow. As soon as a module is only partially shaded, which is not Hotspot Free, it can either fail completely or no longer bring full performance.

What needs to be done Inverters to be observed? (Only important for DIY)

The Inverters is selected very quickly at the balcony power plant, as there is relatively little (good) choice here. In principle, the desired output power (300W or 600W) must be observed here.

In addition, MUSS the inverters be certified according to VDE-AR-N 4100 in addition to the "Standard Certifications". This certification certifies (the inverter) that it only provides voltage/current when a proper sinusoidal voltage 230V is present at the connection point (plus tolerance). If this is not the case, the inverter must switch to less than 100ms voltage-free.
The reason is that if there should be a power failure, no external voltages may be present at distribution boxes and other network nodes, since otherwise, for example, maintenance personnel could be at risk, since the current does not stop at the transfer point to their own house, but can also flow into the public network. For this reason, the inverter must reliably switch voltage-free in case of power failure. The second reason is that the inverter may be plugged into the socket on the terrace or on the balcony with a type F plug (This is the "normal" power plug for the socket). On this side, the inverter 230V has to deliver up to 600W (2,6A) into the home network. If there were no such protection, 230V would be in contact with the blank contacts of the plug, which would also be dangerous to life for the buyer. For this reason, the inverter switches off as soon as it does not detect a sine voltage on the AC side. There are also other examples (for example in the case of a ground closure (FI), but I think the basic idea should be clear:).

Finally, the inverter should have its own MPPT tracker per channel. The MPPT tracker uses the respective solar module as best as possible. If there are only 1 trackers for 2 modules, both solar modules have to work the same, even if they do not run the same way (for example, if a module is shown in another direction of the sky).

In principle, the maximum voltage at the input points would also have to be considered, but in large quantities a defacto standard has prevailed here, so that the usable areas, in fact, fit almost all commercially available modules.

There are also some additional features that are nice to have, but do not necessarily have to be there.

The Deye Sun 600 as an example has integrated a WiFi module including Web server, whereby the power data can be accessed directly. Soon I will also post a blog post that shows how these devices can be integrated into Homeassistant, for example.

Alternatively, you can also Intermediate connector, as the general Shellys are building, this is basically just as good. However, the inverters with Wi-Fi are currently insignificantly more or are sometimes only available on the market.

Are there any more to consider when building?

In short, yes.

When building up, for example, inverters and solar modules should be grounded in any case, with a copper cable at least 6mm2 strong. In addition to protection against damage, the efficiency can also be increased if necessary, since static electricity can be derived.

In addition, the mount should be both storm and snowproof, as snow can weigh a lot.

In alignment, an inclination from 35 degrees to the south is optimal. This should be maintained if possible, since otherwise the current yield drops very quickly. In the following you will see a picture of how the yield deviates when you deviate from this "optimal" setting. Before buying this should be checked in any case.

Funding

There are promotions in many municipalities by building a solar system. This usually applies to large analgesics (multiple KWh performance), but also to balcony power plants (300W and 600W).

In Kreis Oldenburg, as an example for a balcony power plant with 600W, you will currently receive up to 400€.

That's why you should ask both the city and the county once or see how much funding is available.

What devices do you get the power?

I have now heard from many in my circle (and even from a network technician working for a large company that manages lower power grids), that the devices all have to be on the same phase as the balcony power plant, otherwise everything is fed into the public network for free.

But here I can actually give a flat-rate warning. In the normal case, the counters in Germany are >salding <. This means that the power of all three phases is added. So, if you consume 400 watts on Phase 1 (L1) but your solar system is plugged into Phase 2 (L2) and produces 300 watts there, then only 100 watts are released into the public network, as the counter calculates all three phases against each other.
If you want to check this, you can call your network operator. It is sometimes not the same as your power provider. However, you can ask the power provider who the network operator is or look on the internet.

Bureaucracy:)

We would not be in Germany if not even for "simplified" things bureaucracy would fall. In this case, you must report the system to your network operator as well as to the market master files register.

The network operator needs this information because it can be traced where decentralized energy is generated everywhere and it is also important to check whether your meter is correct.

In the case of a balcony power plant, a digital current meter is required either with a reverse shut-off, but normally a two-way counter is required.

Thus, your excess energy can be delivered to the public power grid if you cannot consume it completely. Here it is also worth noting that you are not rewarded for this energy! - If you have an old Ferrari counter, this would possibly turn backwards. That's Illegal, it's gonna be fine.

Topic Powerstation - Brings what?

Currently, many manufacturers, youtuber and other advertising for your power stations (mobile batteries) and sometimes go to the point Mini PV. Some batteries even have connections for solar modules.

But it can usually be said that from an economic point of view it is not worth creating such a plant.

This has two reasons in this case:

1. If you build the battery yourself and install it on the DC side for example, you have a few hundred euros more on expenses plus. battery maintenance and casing. Current prices have already fallen (currently 30 ct/kWh). A balcony power plant can generate 600W at the moment, there is not too much left in the normal case, even if one also directs a little the daily routine according to the solar system (for example, switch on a washing machine or dishwasher when the sun shines). Then the batteries are loaded only minimally and a large battery does not make any sense. Here you have to look at whether this acquisition is economically viable, for that it is best to have the solar system run once a year and see how much electricity you feed on average per day. This size could then be built as a battery if it is worth the price. For buying a power station for 1000€ will hardly be able to amortize.

Two. Some manufacturers also advertise that in the case of a blackout you can use the system, but that's not true. The solar system is allowed to run!NOT! in island operation, as described above, the system only switches on when grid voltage (Sinus 50Hz) is applied (the system must run grid synchronizer). So you would have two options. The first is to manually load the power station (for example, clamp the modules every time, otherwise you have quite a lot of losses) and then replug it. In case of a power failure, you need to plug all devices individually to the power station. You should not use a cable with double-time plug for the above reasons, here is a danger of life. Only a grid-free circuit including a fixed installation would be possible, but then the economic side is again in the way.

That's why I'd get rid of such a station for the start, except you know that it's going to be economically worthwhile.

My balcony power plant as emergency power supply

Also the subject, I have read in some forums and pages. The solar system can supply electricity in a blackout (which is unlikely with us in Germany) over the day to operate the refrigerator, for example.

This actually seems to be a quite fixed thought, but as mentioned above, the system automatically switches off when no mains voltage is applied to protect you and others.

The balcony power plants are not island-capable, which is why no power will be delivered in case of a power failure.

Where can I buy a balcony power plant?

Finally, I would like to mention the subject of purchase.

Balcony power plants are present at almost every supermarket, but also at Amazon at very reasonable prices.
In the end, it doesn't matter where you buy the DInger. I bought mine on Amazon, because I am sure that they can help me in 20 years if there are problems and Amazon has appeared as very cunning in the past. If I were to buy my balcony power plant at net or anywhere else, I wouldn't go so confidently. In the end, it doesn't matter where you buy it. Most plants are similar in price.

Final

I hope I could give you a little insight into the topic of balcony power plant.

In this paper, I think I raised the most important issues. If I forgot something, please write me a E-mail. I will then like to add the missing parts. If you have any questions, you can also write to me :).