Unlike a powerful and expensive heating system equipped in a conventional apartment, an energy-efficient house does not burn fuel or convert grid electricity into heat (except in cases of critical temperature drops). Such a house stubbornly keeps inside itself - thanks to thoughtful thermal insulation, ventilation with recovery and the optimal location of the building - the so-called passive heating. And everything can be used as this passive energy source:
- penetration of direct sunlight through windows;
- heat generated by household appliances, even residents and pets;
- and, of course, we will talk about devices whose main function is to supply solar energy to the house - solar panels (batteries).
Solar panels fit harmoniously into a passive house, as they fully comply 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 affecting silicon wafers into electrical energy;
- Solar panels enable the use of solar energy for household appliances, ventilation systems and (partly) heating;
- If the capacity of the solar panels is higher than the household demand, 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 obtained from the grid (grid solar plant option) or from a liquid fuel generator (autonomous solar plant).
Types of solar modules
Photovoltaic systems are classified according to the criteria of materials and designs used. Solar cells are:
- In the form of silicon panels (the most common, the highest performance 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 applied to the substrate;
- The film is made using cadmium telluride, copper-indium selenide and polymers. They have a lower price, but at the same time they have a lower performance (efficiency 5-14%), so to adapt the battery to the "appetite" of the house, it will be necessary to increase the area receiving radiation.
The consumption characteristics of solar energy panels are described by the following characteristics:
- Power.The larger the area of the solar panel, the greater the power; About 1. 5 m2 of solar panels will be required to produce 1 kWh of energy per day in the summer. The most efficient power is manifested when the rays fall perpendicular to the surface of the battery, which cannot be ensured all the time, so it is a natural process to change the operation of the panel during daylight hours. About 30% should be added to this area to ensure the necessary amount of energy is received in spring and autumn;
- Efficiency(efficiency) of modern solar panels - about 15-17% on average;
- Battery life and power loss over time. Manufacturers, as a rule, guarantee the operation of solar panels for 25 years, during which time they promise that the power will not decrease by more than 20% from the original (for some manufacturers, the service life varies from 10 to 25 years) a decrease in power by not more than 10%with a guarantee. Crystal modules are the most durable, their estimated service life is 30 years. The world's first solar cell 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 clouding of the layer between the glass and solar cells - moisture, ultraviolet radiation and temperature changes;
- Battery includedIt is a good addition to the capabilities of the solar generator, which ensures that the panel works at night. The battery usually lasts less than the solar module itself, on average 4-10 years;
- Availability of additional nodes– voltage stabilizer, battery charge regulator, converter (converter from DC to AC 220 V for household use) makes it more convenient to control the device and integrate it into the "Smart home" system;
- Battery price– directly depends on its field: the more powerful the device, the more expensive it is. Moreover, foreign-made panels are still cheaper than domestic panels, because solar panels are more popular there than in our country. But when comparing the prices of our and imported devices, first of all, it is necessary 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 home, they are primarily based on the load they will carry. In addition, it is necessary to refer to the geometry of the house and the planning of preventive maintenance measures, which together require careful consideration of the following aspects:
- Daily energy consumption of devices planned to be equipped with solar energy (room lighting, household electrical consumers, protection and automation devices, etc. ). It should be taken into account that charging and discharging batteries also consumes energy (about 20%), and additional equipment will also have losses (for example, an average converter - 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 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 cause short-term contacts and/or corrosion);
- In harsh climates, it is recommended to equip solar plants with windproof constructions;
- 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 energy produces the following amount of energy:
- in summer - 5 kW/h (May-August);
- in spring and autumn - 3-4 kWh (March-April, September-October);
- in winter - 1 kW/h.
When calculating the costs of an autonomous solar plant, in addition to the cost of a unit of power generated by the panels (about 60 rubles per 1 W), it is necessary to take into account the cost of additional equipment: from fasteners and wires to batteries, protective devices and converters (this 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 and backup electric generator" scheme. Granted, the generator will need to be run in the spring and fall, not to mention the winter (solar panels are never designed to be fully charged in the winter).
When calculating the payback period of a solar power plant, its output is compared to a reference parameter. In a grid solar plant, these are electricity tariffs; in the case of an autonomous solar power system, this is the cost of the energy produced by the liquid fuel electric generator. The payback is calculated 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, the payback period for the grid solar plant will be: 80, 000 rubles / 5 rubles * 1000 kWh = 16 years.
With a 30-year guarantee of a grid solar installation, the payback (at a rate of 5 rubles/kW) will take place in 16 years, and the electricity will be provided free of charge for the next 14 years.
As for the autonomous solar power system, strictly speaking, the amount of energy it produces per year will be less than the 1000 kWh it shares with the electricity generator. But it is not necessary to reduce this figure for rough calculations - 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 kW) 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 6-year payback period.
Tariffs are not lowered
But the given examples of solar energy installations suggest that now tariffs can be individually "frozen" and you can start saving by using the possibilities 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 better to deal with such issues: even at the design stage of an energy-efficient house:
- ensuring that the southern facade is not shaded;
- choosing the angle of inclination of the roof and the working surfaces of the panels;
- correct orientation of the house to the cardinal points;
- preventing solar panels from shading work areas, blocking them with tree leaves, etc.
In this case, all parameters will be optimally coordinated with each other and the most efficient operation of solar panels for a given structure will be ensured.