Any new technology only becomes truly mass when it has a so-called killer application, literally from English - “killer application”. That is, an application that everyone needs and that while it would be difficult or simply impossible to implement in the framework of previously existing technologies. In Russia, rich in minerals, microgeneration has become a “killer application” for renewable energy sources (RES). Own power station is a new quality of life when you do not depend on external electricity suppliers.
According to the definition of the World Distributed Energy Union (WADE), microgeneration refers to the use of a facility of decentralized generation of very low power, sufficient only for one private house. In the amendments to the law "On Energy", which as of the beginning of January 2019 were submitted to the State Duma of the Russian Federation, but were not yet adopted, generating facilities with a capacity of up to 15 kW are referred to microgeneration facilities. As we can see, the Russian norm fully complies with international rules, since in our country there is a practice of allocating 15 kW of power to a house for new objects of individual housing construction.
Limiting the power of a generator to the needs of a private house, in turn, arises from the principle of decentralized energy itself, which provides for the maximum approximation of generation to the consumer. If necessary, microgeneration should provide at least the needs of backup power supply.
Neither in the international definition of microgeneration, nor in the Russian draft law on this subject is there anywhere a direct mention that microgeneration must necessarily be built on the basis of renewable energy sources. Therefore, diesel generators, used as backup, and in some places the main sources of electricity for private houses, also belong to the microgeneration facilities. This technology did not appear today or even yesterday. And no laws for its use were required. More than half a century ago, the technology of supplying electricity to a network from a consumer, produced when braking an electric motor (the so-called recuperation), appeared.
Why is microgeneration and its legal regulation started talking only now?

RES as an engine of microgeneration development
A diesel generator is a device whose energy production is completely controlled by man. There is a need for electricity - we fill in the fuel and start the generator. No need - stop the generator. The constant operation of the diesel generator in idle mode is impractical because it is wasting fuel. In addition, the diesel generator requires a constant supply of fuel, which is very expensive. That is why a diesel generator can be used to service a specific building, but there is no surplus of electricity that could be supplied to the network. Moreover, the diesel generator is turned on only when there is no voltage in the network, perhaps there is an accident, and it is undesirable to give energy to the network, since it will not reach consumers anyway. Another option for the use of a diesel generator is when there is no electric network at all and the laying of power lines is certainly more expensive than using fuel. In parallel with a normally functioning power grid, diesel generators are practically not used to reduce electricity costs.
Microgeneration, when the owner of a power plant is the only consumer of the electricity generated by it, and the connection to the grid is used only to extract energy from it, is possible within the framework of existing legislation. Changes to the law on "energy" are needed in order to be able to sell excess energy to a sales company.
The situation with solar and wind generation is completely different. To begin with, the generation of electricity depends on the time of day and weather conditions. Once thick, once empty. Accumulators are installed that smooth oscillations of generation. Finally, at night, solar batteries do not generate electricity, but just then you can buy electricity at a reduced rate. That is why alternative generation systems are often purchased with a power grid to reduce energy costs. Accordingly, there is where to supply surplus electricity.
Solar panels and wind turbines do not require fuel supply. They generate electricity, even if you are not at home. Gone to work - electricity is generated. We left somewhere for a long time from home - the electricity is still generated, it is rational to sell it.
Windmills are the best option for microgeneration farms

Technical aspects of joining
The amendments to the State Duma Act on the Energy Sector simplify the connection of microgeneration facilities to the power grid in order to sell surplus electricity. For them, coordination with Rostechnadzor is canceled, but this does not mean that you do not have to coordinate the sale of energy with your sales organization. Specific technical details of the connection are not spelled out in the bill, they will have to create a lot of bylaws.
Technically, there is nothing complicated about the transfer of electricity from the client to the network. In imported models of solar power plants, as a rule, there is such a function, and for the time being, Russian users have to turn it off. An inverter is used, the frequency of which is adjusted to the frequency of the mains voltage to ensure complete synchronism. It is important that the inverter gives a pure sine wave, and not its approximation. In order to avoid phase distortion, a three-phase network connection is recommended. It is possible that the presence of a three-phase connection in the house (and for modern individual buildings this is quite a common thing) will be indicated by sales companies as an obligatory condition for allowing the client to sell surplus electricity.
You will also have to change electricity meters. Most of the existing models of electric meters equally take into account both the energy received from the network and the energy supplied to it. By the way, this leads to funny cases when the owner of a solar power station connects it to the network to provide backup power, having forgotten to turn off the transmission of surplus electricity to the network. As a result, the counter starts spinning at double speed.
At first, due to the small number of microgeneration facilities and the low power they give to the network, no changes should be made to the power management systems. In the longer term (second half of the 2020s), the rapid development of microgeneration will be accompanied by total digitalization of electrical networks, which completely solves the problem of distributed generation control.

Sun or wind?
In the 2000s, wind generators were very popular with microgeneration enthusiasts, since in those years they were much cheaper than solar batteries of the same power. But for mass use, solar panels turned out to be more convenient.
Solar panels can be placed on the roof without spoiling the landscape.
The most compact design of a windmill, capable of fully providing electricity to a house where a family of three resides, is a vertical turbine with a diameter of 5 m and blades 4 m long. This turbine is installed on a 12-meter mast. most importantly, will be well visible from afar. If, for example, a family of 5 people lives permanently, an even larger turbine will be needed, installed at a much higher height. In general, be prepared for negotiations with neighbors who may not like such a structure. For the price of equipment per unit of electricity generated, wind turbines and solar power plants are about the same today, but a wind turbine can be more expensive to install. That's why windmills are a “niche” product for farms, the territory of which is calculated in hectares. In a clean field, on a hill, where there are no barriers to air flow, the wind generator is still much more profitable than solar batteries. There is also no alternative to wind turbines in northern latitudes.

Other microgeneration options
RES is a fashionable, modern trend, but in reality, RES is one of the oldest ways of generating electricity, namely, hydrogeneration. Micro hydro power plants have been known for over 100 years. Modern technology has given new impetus to the development of this area. Abroad in several countries, for example, Canada, micro-hydro are very popular. Even in our neighboring Kazakhstan, micro-hydro are actively used. On the websites of Alibaba and Maide-in-China you can find hundreds of different models of micro-hydro.
Micro-HPPs are popular abroad, but in Russia their use is constrained by the complexity of the installation approval process.
Unfortunately, the current Russian legislation does not make discounts on the size of hydroelectric power plants when it is agreed on its installation. Complicated approval procedure still hinders the development of microgeneration based on hydroelectric power plants in Russia. Although for our country, based on its natural conditions, this method is very promising.
Another “ancient” technology is the steam boiler. Burning wood chips, waste products (for example, hell from sunflower seeds) or peat, heat the water and use a steam engine to generate electricity. The problem lies in the need to supply fuel (unless the power station does not supply energy to the power-saw mill or a plant for the production of vegetable oil). In addition, the power plant based on the steam boiler begins to be efficient, starting with a power of 200 kW, which already goes beyond the limits of microgeneration.
More promising for microgeneration is the production of biogas, which is fed to a gas engine, which rotates an electric generator. The fuel used is manure produced in personal subsidiary farming. You can also use wood chips, husks from seeds, and even food waste, decomposed in the bioreactor by special bacteria. With regard to microgeneration, this will be more efficient than incineration of organic waste. At the output, in addition to heat and electricity (as well as gas for the stove), we also get excellent fertilizer. A biogas power plant must continuously generate electricity so that gas does not escape into the atmosphere. This opens up broad prospects for the sale of surplus electricity.
The disadvantage of biogas power plants is that they are built according to individual projects. “Boxed” solutions, which have long been available for solar power plants, windmills and micro-hydro, do not yet exist here.

Is it possible to make money on microgeneration?
In order to understand what amounts can be gained by selling the electric power generated in a private household, consider this example. Imagine a country house in the Moscow region, where a family of three lives. The house has modern high-performance equipment, electricity for heating is not used, but it cooks food. Such a house will consume about 200 kWh per month, which corresponds to an energy consumption of 2400 kWh per year.
The house is powered by a solar power station. It is designed in such a way that in the most problematic for solar generation, the month of December, the house is fully provided with electricity at the expense of solar panels. The house is connected to the mains, but only for the sale of surplus electricity.
In the Moscow region 1 square. m of modern solar panels with their proper installation can give for December 4 kWh of electricity, taking into account all sorts of losses. So, you must have 50 square meters. m of solar panels. They can easily fit on the roof of the house, without occupying the expensive land near Moscow.
The highest generation is reached in July, when for the month one square. m. solar cells can give 57 kWh. Accordingly, the entire installation will give for the month 2850 kWh, of which a surplus of 2650 kWh can be sold.
For the whole year 1 square. m of solar panels produces 200 kWh, for 50 square meters. m this figure will be 10 000 kWh. That is, in a year we get a surplus of energy of 7600 kWh. This surplus was formed due to the fact that the generation of electricity depends on the time of year, but the power plant must produce enough for the needs of the owner, even in winter.
The scale of power generation during microgeneration is not so significant as to talk about some serious earnings. The main purpose of selling surplus electricity is to ensure the payback of the power plant within a reasonable time.
According to Leonid Neganov, Minister of Energy of the Moscow Region, energy retail companies will purchase electric power from microgeneration facilities at a price approximately equal to half of the tariff for retail consumers. Suppose that retail consumers receive electricity at a price of 6 rubles. per kWh Then the surplus will be bought from microgeneration facilities at a price of 3 rubles. (The given data are estimated and are not a forecast). In a year it will be possible to receive from the sale of surplus 3 rubles / kWh * 7600 kWh = 22 800 rubles. In Russia, the income from the sale of surplus electricity in the amount of up to 30,000 rubles. not taxed.
The cost of the solar power plant in view of delivery and installation is about 500,000 rubles. For ease of calculation, we assume that the tariff is 6 rubles. per kWh does not change over the years. For a year, a solar power station saves electricity in the amount of 6 rubles / kWh * 2400 kWh = 14,400 rubles. If there is no possibility of selling surplus electricity, the payback period will be 500,000 rubles. / 14 400 rub. per year = 34.7 years. The declared service life of solar power plants for household applications, as a rule, is 25 years, but some elements of the power plant, such as batteries, have to be replaced even earlier. That is, the power plant will not pay for itself, unless a sharp jump in electricity prices occurs, which is impossible to predict in the conditions of our country.
When selling surplus electricity, the savings in electricity and the revenue from sales are added up. In total, the annual operation of a personal power station gives an annual gain in the amount of 22,800 + 14,400 = 37,200 rubles. The payback period of the power plant is reduced to 500,000 rubles. / 37 200 rubles. per year = 13.4 years. The power plant will pay for itself in full and in the second half of the declared service life will begin to bring a small profit.

Matter of national importance
In Great Britain, the development of microgeneration is considered as an element of the country's energy independence. Therefore, until 2018, the owners of microgeneration facilities were supposed to give half of the generated electricity to the grid for free. Now, sales companies buy electricity from them, yet the obligation to sell part of the electricity produced remains.
As applied to Russia, microgeneration is hardly of the same importance, since we have plenty of hydrocarbons. Moreover, in our country there are many critics of microgeneration based on renewable energy sources, who believe that it upsets the balance in the power system. It would seem, why to generate additional electricity during the day in the summer? However, just in fine days in the summer energy consumption peaks are now observed due to the intensive work of air conditioners. Then, there are a lot of places - holiday villages, resorts, places of mass recreation for people, where the peak of energy consumption falls on the summer period. Microgeneration will smooth the local power shortage.
But this is not the main reason why microgeneration is currently receiving attention at the highest level. The developers of the draft law do not conceal that their main task is to support the high-tech industry in Russia. Microgeneration is just the industry where domestic products can compete with imported ones. At the same time, microgeneration will also become a deterrent to the growth of electricity prices in the context of the actual monopolism of sales companies. The rise in electricity prices is a good reason to think about buying your own power station. That is, to vote with a ruble for the development of the domestic high-tech industry, and therefore for the reduction of the notorious raw material dependence of the country.

Source:  Alexey Vasilyev, Electrotechnical Market Magazine

 By link - https://www.elec.ru/articles/mikrogeneraciya-i-vie-dve-storony-odnoj-medali/