Unlike the powerful and expensive heating system that is equipped in ordinary dwellings, an energy-efficient house does not burn fuel or convert grid electricity into heat (except in cases of critical temperature drop). Such a house persistently stores within itself - thanks to thoughtful thermal insulation, recovery ventilation 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 windows;
- heat generated by household appliances, 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, 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 that affects the 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 the solar panels are higher than the household requirements, then the excess energy can be used in systems for the storage and conversion of electrical energy.
- If the demand for electricity exceeds the capacity of the panels, the missing part can be taken from the grid (on-grid solar station option) or from a liquid fuel generator (autonomous solar station).
Types of solar modules
The classification of photovoltaic systems is carried out according to the criteria of materials and designs used. Solar batteries are:
- In the form of silicon panels (the most common, highest and most expensive), efficiency - up to 22%; They are produced in three subtypes: monocrystalline (more 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 a lower performance (efficiency 5-14%), so to adapt the battery to the "appetites" of the house, an increase in the area that receives radiation will be required.
The consumer characteristics 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 perpendicular to 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 necessary amount of energy is obtained in spring and autumn, approximately 30% should be added to this area;
- efficacy(efficiency) of modern solar panels - on average about 15-17%;
- Battery life and power loss over time. Manufacturers, as a rule, offer a guarantee for the operation of solar panels for 25 years, promising a decrease in power during this period of no more than 20% of the original (for some manufacturers, the service life varies between 10-25 years witha guarantee of a power reduction of no more than 10%). Crystal modules are more durable, their estimated service life is 30 years. The world's first solar battery has been in operation for more than 60 years. The decline in the production of solar modules itself occurs mainly due to the gradual destruction of the sealing film and the fogging 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– such as a voltage stabilizer, a battery charge controller, an inverter (DC to AC 220 V converter for home use) makes the operation of the device and its integration into the "Smart Home" system more convenient;
- Battery cost– directly depends on its area: the more powerful the device, the more expensive it is. Moreover, the panels produced abroad are still cheaper than the domestic ones, since solar panels are more popular there than in our country. But when comparing the prices of our equipment and imported ones, it is necessary, first of all, 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 house, they are based, first of all, on the load they will have to carry. 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 equipment that is planned to be powered by solar energy (room lighting, household electrical consumers, security and automation equipment, etc. ). It should be taken into account that charging and discharging batteries also consumes energy (approximately 20%), and additional devices will also have their losses (for example, in an inverter on average - 15-20%);
- The relationship between the required dimensions of the working panels and the corresponding areas of the roof and its geometry;
- The ability to clean the working surfaces of batteries from dirt, snow and other factors that affect 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 short 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.
Cost and payback of solar panels
For the middle area of our country, each kilowatt of solar panel energy 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 energy generated by the panels (about 60 rubles per 1 W), you need to take into account the cost of additional equipment: from fixtures and wiring to batteries, protection devices and inverters (which is at least 5% of the total cost, but prices can vary significantly, depending on the manufacturer and power).
According to the recommendations of experts, the optimal costs for a solar system throughout the year are obtained using the "summer option plus a backup electric generator" scheme. True, the generator will have 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 energy installation, its output is compared to the parameter that is taken as a base. In a grid solar station, these are the electricity charges; in the case of an autonomous solar energy system, this is the cost of the energy produced by a liquid-fueled 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 for a grid solar station will be: 80, 000 rubles / 5 rubles * 1000 kWh = 16 years.
With a 30-year guarantee for a solar installation on the grid, 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 produces per year will be less than the specified 1000 kWh, which it shares with the electric generator. But for rough calculations, this number does not need to be reduced - in order to take into account approximately the increase in specific fuel consumption that occurs when the generator is partially loaded (that is, periodically, not continuously). Then 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.
Fees are not reduced
But the given examples of solar energy installations suggest that now the tariffs can be "raised" individually and you can start saving by taking advantage of the capabilities of photovoltaic panels. You just need to buy them from branded manufacturers, tested by the market, so that their parameters are predictable both in design and in operation.
And it is better to deal with issues such as: even at the design stage of an energy efficient house:
- ensuring that the southern facade does not have shadows;
- choosing the angle of the roof slope and the working surfaces of the panels;
- the correct orientation of the house to the cardinal points;
- preventing the 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 given structure will be ensured.