Unlike the powerful and costly heating system that is equipped in ordinary housing, an energy-efficient house does not burn fuel or convert network electricity into heat (except in cases of critical temperature drop). Such a house tenaciously retains inside itself - thanks to thoughtful thermal insulation, ventilation with recovery and the optimal location of the building - the so-called passive heat. And anything can be used as a source of this passive energy:
- direct sunlight penetrating through the windows;
- heat generated by household appliances, and even by residents and pets;
- and, of course, devices whose main function is to supply solar energy to the house - solar panels (batteries), which will be discussed.
Solar panels fit harmoniously into a passive house, since they fully comply with the main principle of its 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 thermal radiation affecting silicon wafers into electricity;
- Solar panels allow you to use solar energy to operate household appliances, ventilation systems and (partially) heating;
- If the capabilities of solar panels are higher than household demands, then the energy surplus can be used in systems for storing and converting electricity.
- If the demand for electricity exceeds the capacity of the panels, the missing part can be obtained from the network (option of a network solar station) or from a liquid fuel generator (autonomous solar station).
Types of solar modules
Classification of photovoltaic systems is carried out according to the criteria of the materials and designs used. Solar batteries are:
- In the form of silicon panels (the most common, the most high-performance and the most expensive), efficiency - up to 22%; They are manufactured in three subtypes: monocrystalline (the 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 polymers. They have a lower price, but also lower performance (efficiency 5-14%), so to match the battery to the "appetites" of the home, an increase in the area that receives radiation will be required.
The consumer properties of solar energy panels are described by the following characteristics:
- Power.The larger the area of the solar panel, the greater its power; To generate energy of 1 kWh/day in summer, about 1. 5 m2 of solar panels will be required. The most efficient power is manifested when the rays fall perpendicularly onto the surface of the battery, which cannot be ensured constantly, so changing the performance of the panel during daylight hours is a natural process. To ensure that the required amount of energy is obtained in spring and autumn, approximately 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 reduction in power during this period of no more than 20% of the original (for some manufacturers, the service life varies between 10-25 years with a guarantee of a reduction in power of no more than10%). Crystalline modules are the most durable, their estimated service life is 30 years. The world's first solar battery has been in operation for over 60 years. The decrease in the production of solar modules itself occurs mainly due to the gradual destruction of the sealing film and clouding of the layer between the glass and solar cells - from moisture, ultraviolet radiation and temperature changes;
- Battery included, which ensures the operation of the panel at night, is a good addition to the capabilities of the solar generator. The battery usually lasts less than the solar module itself, on average 4-10 years;
- Availability of additional nodes– such as a voltage stabilizer, a battery charge controller, an inverter (DC to AC 220 V converter for household use) makes it more convenient to operate the device and its integration into the "Smart Home" system;
- Battery cost– is directly dependent on its area: the more powerful the device, the more expensive it is. Moreover, foreign-made panels are still cheaper than domestic ones, since solar panels are more popular there than in our country. But when comparing the prices of our and imported devices, it is necessary, first of all, to compare the operating efficiency of solar panels with each other - here domestic manufacturers achieve good efficiency indicators - up to 20%.
Selection and use of photovoltaic batteries
When selecting solar panels for a private home, they are based, first of all, on the load they will have to bear. In addition, it is necessary to relate to 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 that are planned to be powered from solar energy (room lighting, household electrical consumers, security and automation devices, etc. ). It should be taken into account that charging and discharging batteries also consumes energy (approximately 20%), and additional equipment will also have its losses (for example, in an inverter on average - 15-20%);
- The relationship between the required dimensions of the working panels and the corresponding roof areas and its geometry;
- The ability to clean the working surfaces of batteries from dirt, snow and other factors affecting the operation of photo converters.
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 lead to shorted contacts and/or corrosion);
- In harsh climatic conditions, it is recommended to equip solar stations with wind-blocking structures;
- Regular inspections, cleaning and maintenance are mandatory.
Cost and payback of solar panels
For the middle 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 costs of an autonomous solar station, in addition to the cost of a unit of power generated by the panels (about 60 rubles per 1 W), you need to take into account the cost of additional equipment: from fastenings and wiring to batteries, protective devices and inverters (which is at least 5% of the total cost, but prices can vary significantly, depending on manufacturers and power).
According to the recommendations of experts, the optimal costs for a year-round solar system are obtained by using the "summer option plus a backup electric generator" scheme. True, the generator will have to be turned on in spring and autumn, not to mention in winter (solar batteries are never designed to be fully loaded in the winter season).
When calculating the payback period of a solar power installation, its output is compared with the parameter that is taken as the base one. In a network solar station, these are electricity tariffs; in the case of an autonomous solar power system, this is the cost of energy produced by a liquid fuel electric generator. The payback is estimated based on the fact that a 1 kW solar battery will produce approximately 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 a network solar station will be: 80, 000 rubles / 5 rubles * 1000 kWh = 16 years.
With a 30-year guarantee for a network solar installation, payback (at a tariff of 5 rubles/kWh) will occur within 16 years, and in the next 14 years, electricity will be supplied free of charge.
As for an autonomous solar energy system, strictly speaking, the amount of energy it produces per year will be less than the designated 1000 kWh, which it shares with the electric generator. But for rough calculations, this number need not be reduced - in order to approximately take into account the increase in specific fuel consumption that occurs when the generator is partially (that is, periodically, not constantly) loaded. Then the payback period of the autonomous system (based on the cost of the 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 their payback period, which is 6 years.
Tariffs are not reduced
But the examples of solar energy installations given suggest that now tariffs can be individually "frozen" and you can start saving by taking advantage of the capabilities of photovoltaic panels. You just need to buy them from branded, market-tested manufacturers so that their parameters are predictable both in design and in operation.
And it’s best to deal with issues such as: even at the design stage of an energy-efficient house:
- ensuring that the southern façade is not shaded;
- selection of roof inclination angle and working surfaces of panels;
- correct orientation of the house to the cardinal points;
- preventing shading of the working areas of solar panels, their clogging with tree leaves, etc.
In this case, all parameters will be optimally linked with each other and the most efficient operation of solar panels for a particular structure will be ensured.