Unlike the powerful and expensive heating system that is equipped in normal homes, an energy-efficient house does not burn fuel or convert electricity from the grid into heat (except in cases of critical temperature drop). Such a house tenaciously retains inside, thanks to careful 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 entering through the windows;
- the heat generated by 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 we will talk about later.
Solar panels fit harmoniously into a passive house, since they fully comply with the fundamental principle of its construction: using 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 that hits the silicon wafers into electricity;
- Solar panels make it possible to use solar energy to operate appliances, ventilation systems and (partially) heating;
- If the capacity of the solar panels is greater than household needs, then the excess energy can be used in systems to store and convert electricity.
- If the electricity demand exceeds the capacity of the panels, the missing part can be obtained from the grid (on-grid solar station option) or from a liquid fuel generator (stand-alone solar station).
Types of solar modules
The 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 powerful and the most expensive), the efficiency is 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 from cadmium telluride, indium copper selenide, and polymers. They have a lower price, but also a lower performance (efficiency 5-14%), so to adapt the battery to the "appetites" of the home it will be necessary to increase the surface area that receives the radiation.
The consumer properties of solar energy panels are described by the following characteristics:
- Force.The larger the area of the solar panel, the higher its power; To generate energy of 1 kWh/day in summer, around 1. 5 m2 of solar panels will be needed. The most efficient power is manifested when the rays fall perpendicularly on the surface of the battery, which cannot be guaranteed constantly, so changing the performance of the panel during daylight hours is a natural process. To ensure that the necessary amount of energy is obtained in spring and autumn, approximately 30% must be added to this surface;
- 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 and 25 years). with a power reduction guarantee of no more than 10%). Crystalline modules are the most durable, their estimated useful life is 30 years. The world's first solar battery has been in operation for more than 60 years. The decrease in the production of solar modules occurs mainly due to the gradual destruction of the sealing film and clouding of the layer between the glass and the solar cells, due to humidity, ultraviolet radiation and temperature changes;
- Battery included, which guarantees the operation of the panel at night, is a good complement to the capabilities of the solar generator. The battery usually lasts less than the solar module itself, an average of 4 to 10 years;
- Availability of additional nodes– such as a voltage stabilizer, a battery charge controller, an inverter (220 V DC to AC converter for home use) make it more convenient to operate the device and its integration into the "Smart Home" system;
- Battery cost– depends directly on its surface: the more powerful the device, the more expensive it is. In addition, panels made abroad are still cheaper than domestic ones, since solar panels are more popular there than in our country. But when comparing the prices of our devices and imported ones, it is necessary, first of all, to compare the operational 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, we base ourselves, first of all, on the load they will have to support. 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 by solar energy (room lighting, household electrical consumers, security and automation devices, etc. ). It should be borne in mind that charging and discharging batteries also consumes energy (about 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 their geometry;
- The ability to clean the working surfaces of batteries from dirt, snow and other factors that affect the operation of photoconverters.
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 short circuits and/or corrosion);
- In adverse weather 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 one unit of energy generated by the panels (about 60 rubles per 1 W), it is necessary to take into account the cost of additional equipment: from accessories and wiring to batteries, protection devices and inverters (which represents at least 5% of the total cost, but prices can vary significantly, depending on manufacturers and power).
According to expert recommendations, the optimal costs for a year-round solar system are obtained using the "summer option plus a backup electric generator" scheme. True, the generator will need to be turned on in spring and autumn, and even less so in winter (solar batteries are never designed to be fully charged in the winter season).
When calculating the payback period of a solar energy installation, its production is compared with the parameter that is taken as a base. At a grid solar station these are electricity rates, in the case of a stand-alone solar power system this is the cost of energy produced by a liquid fuel electric generator. 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 of a solar grid station will be: 80, 000 rubles / 5 rubles * 1000 kWh = 16 years.
With a 30-year guarantee for a grid-based solar installation, payback (at a rate 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 will produce per year will be less than the designated 1, 000 kWh, which it shares with the electric generator. But for approximate calculations, it is not necessary to reduce this number, to approximately take into account the increase in specific fuel consumption that occurs when the generator is partially loaded (that is, periodically, not constantly). So, 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 their payback period, which is 6 years.
Tariffs are not reduced.
But the examples of solar energy installations given suggest that tariffs can now be "frozen" individually and savings can begin by taking advantage of the capabilities of photovoltaic panels. You only need to buy them from proven brand manufacturers on the market so that their parameters are predictable both in design and operation.
And it is better to address such issues as: even at the design stage of an energy-efficient house:
- ensure that the south façade is not in shadow;
- selection of the angle of inclination of the roof and working surfaces of the panels;
- correct orientation of the house to the cardinal points;
- avoiding shading of the solar panel work areas, their obstruction with tree leaves, etc.
In this case, all parameters will be optimally linked to each other and the most efficient operation of solar panels for a particular structure will be ensured.