Unlike powerful and expensive heating systems equipped in ordinary housing, an energy-efficient house does not burn fuel or convert network electricity into heat (except in the case of a critical temperature drop). Such a house persistently maintains in itself - thanks to clever thermal insulation, ventilation with restoration and optimal location of the building - the so-called passive heat. And anything can be used as a source of this passive energy:
- direct sunlight penetrates through the window;
- heat produced by household appliances, as well as by residents and pets;
- and, of course, a device whose main function is to supply solar energy to the house - solar panels (batteries), which will be discussed.
Solar panels fit harmoniously into passive houses, because they fully comply with the main principle of their construction - to use renewable energy from the environment.
The principle of operation of solar panels and their interaction with other home systems
- The operation of solar panels is based on the conversion of heat radiation affecting the silicon wafer into electricity;
- Solar panels allow you to use solar energy to operate household appliances, ventilation systems and (partially) heating;
- If the capacity of the solar panels is higher than the household demand, then the excess energy can be used in the system to store and convert electricity.
- If the demand for electricity exceeds the capacity of the panels, the missing part can be obtained from the grid (optional grid solar station) or from a liquid fuel generator (autonomous solar station).
Types of solar modules
The classification of photovoltaic systems is carried out according to the material and design criteria used. Solar batteries are:
- In the form of silicon panels (the most common, the most high-performing and the most expensive), efficiency - up to 22%; It is produced in three subtypes: monocrystalline (most reliable), polycrystalline and amorphous; in the first two positions pure silicon is used, in the third - silicon hydrogen, which is applied to the substrate;
- Film - made using cadmium telluride, copper-indium selenide and polymer. They have a lower price, but also a lower performance (5-14% efficiency), so to match the battery with the "taste" of the house, an increase in the area that receives radiation will be required.
The user properties of solar energy panels are described by the following characteristics:
- Power.The larger the area of the solar panel, the greater the power; To generate 1 kWh/day of energy in summer, approximately 1. 5 m2 of solar panels will be required. The most efficient power is shown when the rays fall perpendicular to the surface of the battery, which cannot be ensured continuously, so changing the performance of the panel during the day is a natural process. To ensure that the required amount of energy is obtained in spring and autumn, about 30% must be added to this area;
- Efficiency(efficiency) of modern solar panels - on average about 15-17%;
- Battery life and power loss over time. Manufacturers, as a rule, provide a guarantee for the operation of solar panels for 25 years, promising a power reduction during this period of no more than 20% of the original (for some manufacturers, the service life varies between 10-25 years with a power reduction guarantee of no more than 10%). The crystal module is the most durable, its estimated service life is 30 years. The world's first solar battery has been in operation for over 60 years. The reduction in the production of the solar module itself is mainly due to the gradual destruction of the sealing film and clouding of the layer between the glass and the solar cell - from moisture, ultraviolet radiation and temperature changes;
- Battery included, which ensures the operation of the panels at night, is a good addition to the capabilities of the solar generator. Batteries usually last less than the solar module itself, on average 4-10 years;
- Additional node availability– such as voltage stabilizers, battery charge controllers, inverters (DC to AC 220 V converter for household use) making it easier to operate the device and its integration into the "Smart Home" system;
- Battery cost– depends directly on its area: the more powerful the device, the more expensive it is. In addition, foreign-made panels are still cheaper than domestic ones, because solar panels are more popular there than in our country. But when comparing the prices of our devices and imported ones, first of all, it is necessary to compare the efficiency of operation of solar panels with each other - here domestic manufacturers achieve good efficiency indicators - up to 20%.
Selection and use of photovoltaic batteries
When choosing solar panels for a private home, it is based, first of all, on the load they have to bear. In addition, it is necessary to relate the geometry of the house and the planning of preventive maintenance activities, which together require careful consideration of the following aspects:
- Daily energy consumption of devices designed to be powered from solar energy (room lights, household electrical consumers, security and automation devices, etc. ). It should be taken into account that charging and discharging the battery also consumes energy (about 20%), and additional equipment will also experience losses (for example, in the inverter on average - 15-20%);
- The relationship between the required dimensions of the work panel and the corresponding roof area and its geometry;
- The ability to clean the working surface of the battery from dirt, snow and other factors that affect the operation of the photoconverter.
Important points in the operation of solar panels
- Avoid physical damage to the panel (scratches and damage to the integrity of the protective film can cause shorted contacts and/or corrosion);
- In severe climatic conditions, it is recommended to equip the solar station with a windproof structure;
- Periodic inspection, cleaning and maintenance are mandatory.
Cost and payback of solar panels
For the central zone of our country, each kilowatt of solar panel power generates the following amount of energy:
- in summer - 5 kWh/day (May-August);
- in spring and autumn - 3-4 kWh/day (March-April, September-October);
- in winter - 1 kWh/day.
When calculating the cost of an autonomous solar station, in addition to the cost of the power unit produced by the panel (about 60 rubles per 1 W), you need to take into account the cost of additional equipment: from fasteners and wiring to batteries, protective devices and inverters (i. e. at least-at least 5% of the total cost, but the price can vary significantly, depending on the manufacturer and power).
According to expert recommendations, the optimal cost for a year-round solar system is obtained by using the "summer option plus back-up electricity generator" scheme. True, the generator needs to be turned on in the spring and fall, let alone in the winter (solar batteries are never designed to be fully loaded in the winter).
When calculating the payback period of a solar energy installation, the output is compared to the parameters taken as a basis. In grid solar stations, this is the electricity tariff; in the case of an autonomous solar power system, this is the cost of the energy produced by the liquid fuel electricity generator. The payback is estimated based on the fact that a 1 kW solar battery will produce about 1000 kWh of energy per year.
If we take the average price of 1 kWh of electricity as 5 rubles, then the payback period for the network solar station is: 80, 000 rubles / 5 rubles * 1000 kWh = 16 years.
With a 30-year guarantee for grid solar installations, payback (at a tariff of 5 rubles/kWh) will occur in 16 years, and in the next 14 years, electricity will be supplied for free.
For autonomous solar energy systems, strictly speaking, the amount of energy produced each year will be less than the set 1000 kWh, which is shared with the electricity generator. But for rough calculations, this number does not need to be reduced - to roughly take into account the increase in certain fuel consumption that occurs when the generator is partially (that is, periodically, not always) loaded. Then the payback period of the autonomous system (based on the cost of energy produced by the liquid fuel generator - 25 rubles per 1 kWh) looks like this: 150, 000 rubles / 25 rubles * 1000 kWh = 6 years.
In addition to technical indicators, the efficiency of solar panels that are part of an autonomous solar power plant is confirmed by its payback period, which is 6 years.
The tariff is not reduced
But the examples of solar energy installations given show that now tariffs can be "frozen" individually and you can start saving by taking advantage of the capabilities of photovoltaic panels. You only need to buy it from a branded manufacturer that is market-tested so that its parameters are predictable in design and in operation.
And it is best to address issues such as: even at the design stage of an energy-efficient home:
- ensure that the south front is not shaded;
- the selection of the angle of inclination of the roof and the working surface of the panel;
- the correct orientation of the house to the cardinal points;
- preventing the shading of the solar panel work area, blocking it with tree leaves, etc.
In this case, all parameters will be optimally connected to each other and the most efficient operation of the solar panel for a given structure will be ensured.