Unlike the powerful and expensive heating system that is equipped in ordinary homes, an energy-efficient house does not burn fuel and does not convert grid electricity into heat (except in cases of critical temperature drop). Such a house persistently retains inside itself - thanks to the well-thought-out 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.
The solar panels fit harmoniously into the passive house, as they fully comply with the basic 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 the silicon wafers into electricity;
- Solar panels allow you to use solar energy to operate household appliances, ventilation systems and (partial) heating;
- If the capabilities of the solar panels are higher than the needs of households, then the excess energy can be used in electricity storage and conversion systems.
- If the demand for electricity exceeds the capacity of the panels, the missing part can be supplied from the grid (grid solar plant option) or from a liquid fuel generator (standalone solar plant).
Types of solar modules
The classification of photovoltaic systems is carried out according to the criteria of the materials and constructions used. Solar batteries are:
- In the form of silicon panels (the most common, the most productive and the most expensive), efficiency - up to 22%; They are produced 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 of cadmium telluride, copper indium 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 area that receives radiation.
The user 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 needed. The most efficient power is manifested when the rays fall perpendicularly on the surface of the battery, which cannot be ensured constantly, so the change in 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 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 guaranteeno more than 10%). Crystal modules are the most durable, their expected service life is 30 years. The world's first solar battery has been working for more than 60 years. The decrease in the production of solar modules itself is mainly due to the gradual destruction of the sealing film and clouding of the layer between the glass and the 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– as a voltage stabilizer, battery charge controller, inverter (DC to AC 220 V converter for household needs) facilitates working with the device and integrating it into the Smart Home system;
- Battery cost– is directly dependent on its area: the more powerful the device, the more expensive it is. Also, panels made abroad are still cheaper than domestic ones because solar panels are more popular there than here. But when comparing the prices of our and imported devices, it is first 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, they are based primarily on the load they will have to bear. In addition, it is necessary to pay attention 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 expected 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 (approximately 20%), and additional equipment will also have its losses (for example, in an inverter on average - 15-20%);
- The ratio between the required dimensions of the work panels and the corresponding roof areas and its geometry;
- Ability to clean the working surfaces of the batteries from dirt, snow and other factors affecting the operation of the photoconverters.
Important moments in the operation of solar panels
- Avoid physical damage to the panel (scratching and damage to the integrity of the protective film may lead to short-circuiting of the contacts and/or corrosion);
- In harsh climatic conditions, it is recommended to equip solar stations with wind protection structures;
- Regular inspections, cleaning and maintenance are mandatory.
Cost and Payback of Solar Panels
For the average area of our country, each kilowatt of power from a solar panel 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 a unit of power generated by the panels (about 60 rubles for 1 W), you need to take into account the cost of additional equipment: from fastening and wiring to batteries, protective devices and inverters (whichis at least 5% of the total price, but prices can vary widely depending on manufacturers and power).
According to the recommendations of experts, the optimal costs for a year-round solar system are obtained when using the "summer option plus backup generator" scheme. It is true that the generator will have to be turned on in the spring and autumn, not to mention the winter (solar batteries are neverdesigned to be fully charged during the winter season).
When calculating the payback period of a solar installation, its power is compared with the parameter that is taken as the main one. In a grid solar plant, these are electricity rates; in the case of an autonomous solar energy system, this is the cost of the energy produced by a liquid fuel electric generator. The return is calculated 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 grid solar station will be: 80, 000 rubles / 5 rubles * 1000 kWh = 16 years.
With a 30-year guarantee for a grid solar installation, payback (at a tariff of 5 rubles/kWh) will occur within 16 years, and for the next 14 years the electricity will be supplied free of charge.
As for the autonomous solar energy system, strictly speaking, the amount of energy it produces annually will be less than the specified 1000 kWh that it shares with the electric generator. But for rough calculations, this number should not be reduced - to take into account approximately the increase in specific fuel consumption that occurs when the generator is partially (ie periodically, not constantly) loaded. Then the payback period of the autonomous system (based on the cost of energy produced by the liquid fuel generator - 25 rubles for 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 plant is confirmed by their payback period, which is 6 years.
Tariffs are not reduced
But the given examples of solar energy installations suggest that tariffs can now be individually "frozen" and you can start saving by taking advantage of the possibilities of photovoltaic panels. You just need to buy them from branded, market-tested manufacturers, sothat their parameters are predictable in both design and operation.
And it is best to deal with issues such as: even at the design stage of an energy efficient house:
- ensuring that the southern facade is not overshadowed;
- selection of the angle of inclination of the roof and working surfaces of the panels;
- correct orientation of the house to the cardinal points;
- preventing shading of the working areas of the solar panels, blocking them with tree leaves, etc.
In this case, all parameters will be optimally interconnected and the most efficient operation of the solar panels for a certain structure will be ensured.