Unlike a powerful and expensive heating system that is equipped in an ordinary housing, an energy-efficient house does not burn fuel or convert grid electricity into heat (except in cases of critical temperature drop). Such a house firmly retains in itself - thanks to thoughtful thermal insulation, ventilation with recuperation 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 produced by household appliances and even residents and pets;
- and, of course, devices whose basic function is to supply the house with solar energy - solar panels (batteries), which will be discussed.
Solar panels fit harmoniously into a passive house, since they are fully in line with the main principle of its construction - the use of 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 affects silicon tiles into electrical energy;
- Solar panels allow you to use solar energy to operate household appliances, ventilation systems and (partially) heating;
- If the capabilities of solar panels are greater than the needs of households, then the excess energy 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 grid (grid solar station option) or from a liquid fuel generator (autonomous solar station).
Types of solar modules
Photovoltaic systems are classified according to the criteria of materials used and design. Solar batteries are:
- In the form of silicon plates (the most common, most effective and 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 polymer. They have a lower price, but also lower performance (efficiency 5-14%), so to match the battery with the "appetites" of the home, it will be necessary to increase the surface that receives radiation.
The consumer properties of solar panels are described by the following characteristics:
- Power.The larger the surface of the solar panel, the greater its power; To produce 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 vertically on the surface of the battery, which cannot be ensured constantly, so the change in panel performance during the day 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, give a guarantee for the operation of solar panels for 25 years, promising a power reduction during that period of no more than 20% from the original (for some manufacturers, the life span varies between 10-25 years with a guarantee of a power reduction of no more than 10%). Crystal modules are the most durable, their estimated 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 is mainly due to the gradual destruction of the sealing film and the 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 panels 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 voltage stabilizer, battery charge controller, inverter (DC to AC 220 V converter for household use) facilitates the operation of the device and its integration into the "Smart Home" system;
- Battery cost– directly depends on its surface: the more powerful the device, the more expensive it is. Moreover, foreign-made panels 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 necessary, first of all, to compare the working efficiency of solar panels - here domestic manufacturers achieve good efficiency indicators - up to 20%.
Selection and use of photovoltaic batteries
When choosing solar panels for a private house, they are based, first of all, on the load they will have to bear. In addition, it is necessary to refer 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 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 surfaces and its geometry;
- The ability to clean the working surfaces of batteries 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 board (scratches and damage to the integrity of the protective film can lead to a short circuit of the contacts and/or corrosion);
- In difficult climatic conditions, it is recommended to equip solar stations with wind blocking structures;
- Regular inspections, cleaning and maintenance are mandatory.
Price and profitability of solar panels
For the middle zone of our country, each kilowatt of solar panel energy produces 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 price of a unit of power produced by the panels (about 60 rubles per 1 W), you must also take into account the cost of additional equipment: from fastening and wiring to batteries, protective devices and inverters (which is at least 5% of the totalprices, but prices can vary significantly, depending on the manufacturer and power).
According to the recommendations of experts, the optimal costs for a year-round solar system are achieved by using the "summer option plus backup electric generator" scheme. True, the generator will need to be turned on in the spring and fall, not to mention in the winter (solar batteries are never designed to be fully charged in the winter season).
When calculating the payback period of a solar installation, its performance is compared to a parameter that is taken as a baseline. In a grid solar station, these are electricity tariffs; in the case of an autonomous solar system, it is the price of the energy produced by the liquid fuel electric generator. Payback is estimated based on the fact that a 1 kW solar cell 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 the grid solar station will be: 80, 000 rubles / 5 rubles * 1000 kWh = 16 years.
With a 30-year guarantee for grid solar installation, payback (at a tariff of 5 rubles/kWh) will occur within 16 years, and for the next 14 years 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 predicted 1000 kWh, which it shares with the electric generator. But for rough calculations, this number should not be reduced - to roughly 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 price 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 above examples of solar energy installations suggest that now tariffs can be individually "frozen" and you can start saving by taking advantage of photovoltaic panels. You just need to buy them from branded, market-tested manufacturers so that their parameters are predictable in both design and operation.
And it is best to solve problems such as: even at the stage of designing an energy-efficient house:
- ensure that the southern facade is not overshadowed;
- the choice of the angle of inclination of the roof and the working surfaces of the panels;
- correct orientation of the house according 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 connected to each other and the most efficient operation of solar panels for a specific construction will be ensured.