Unlike the powerful and expensive heating system that ordinary houses are equipped with, an energy-efficient house does not burn fuel or convert electricity from the grid into heat (unless there is a critical drop in temperature). Such a house tenaciously retains inside itself - thanks to thoughtful thermal insulation, ventilation with recovery and the optimal location of the building - the so-called passive heat. And everything can be used as a source of this passive energy:
- direct sunlight streaming in through windows;
- heat generated by household appliances, or even by residents and pets;
- and, of course, devices whose main function is to provide solar energy to the house - solar panels (batteries), which we will talk about.
Solar panels fit harmoniously into a passive house, because they fully respect the main 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 affecting the silicon wafers into electricity;
- Solar panels make it possible to use solar energy to operate household appliances, ventilation systems and (partially) heating;
- If the capacities of solar panels are greater than household needs, the surplus energy can then be used in electricity storage and conversion systems.
- 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 (standalone 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, high-performance and expensive), efficiency - 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, copper-indium selenide and polymers. They have a lower price, but also lower performance (efficiency 5-14%), so to adapt the battery to the "appetites" of the house, it will be necessary to increase the surface that receives the radiation.
The consumer properties of solar panels are described by the following characteristics:
- Power.The larger the surface area of the solar panel, the greater its power; To produce energy of 1 kWh/day in summer, approximately 1. 5 m2 of solar panels will be required. The most effective power is manifested when the rays fall perpendicularly on the surface of the battery, which cannot be ensured continuously. Changing the panel's performance during the day is therefore 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. As a rule, manufacturers provide a guarantee of operation of solar panels for 25 years, promising a power reduction during this period of no more than 20% compared to the original (for some manufacturers, the service life varies between 10 and25 years with a guarantee of a power reduction not exceeding 10%). Crystalline modules are the most durable, their estimated lifespan is 30 years. The world's first solar battery has been in operation for more than 60 years. The decrease in solar module production itself is mainly due to the gradual destruction of the sealing film and the clouding of the layer between the glass and the solar cells - due to humidity, ultraviolet radiation andtemperature changes;
- Battery included, which ensures the operation of the panel at night, is a good complement to the capabilities of the solar generator. The battery generally lasts less than the solar module itself, on average 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 domestic use) facilitate the operation of the device and its integration into the "Smart Home" system;
- Battery cost– depends directly on its surface area: the more powerful the device, the more expensive it is. In addition, panels manufactured abroad are always cheaper than domestic ones, because solar panels are more popular there than in our country. But when comparing the prices of our devices and imported ones, first of all it is necessary to compare the operating 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 house, they are primarily based on the load that they will have to withstand. In addition, it is necessary to take into account the geometry of the house and the planning of preventive maintenance activities, which together require special attention to the following aspects:
- Daily energy consumption of devices intended to be powered by solar energy (room lighting, domestic 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 a UPS on average - 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 affecting 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 circuiting of contacts and/or corrosion);
- In difficult climatic conditions, it is recommended to equip solar stations with windproof structures;
- Regular inspections, cleaning and maintenance are mandatory.
Cost and return on investment of solar panels
For the middle 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 costs of an autonomous solar station, in addition to the cost of a unit of power generated by the panels (about 60 rubles per 1 W), you should take into account the cost of additional equipment: fasteners andwiring 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 permanent solar system are obtained by using the "summer option plus emergency electric generator" scheme. Certainly, the generator will need to be turned on in spring and fall, not to mention winter (solar batteries are never designed to be fully charged in winter).
When calculating the payback period of a solar installation, its power is compared to the parameter taken as the base parameter. In a grid solar station, these are electricity rates; in the case of a stand-alone solar system, this is the cost of the energy produced by a liquid fuel electric generator. The return on investment is estimated based on the fact that a 1 kW solar battery will produce approximately 1, 000 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 * 1, 000 kWh = 16 years.
With a 30-year warranty for an on-grid solar installation, the return on investment (at a rate of 5 rubles/kWh) will occur within 16 years, and in the next 14 years electricity will be provided free of charge.
As for a standalone solar power system, strictly speaking, the amount of energy it produces each year will be less than the designated 1, 000 kWh it shares with the electric generator. But for approximate calculations, this number does not need to be reduced - in order to approximately take into account the increase in specific fuel consumption that occurs when the generator is partially (i. e. periodically, not constantly) charged. 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 * 1, 000 kWh = 6 years.
In addition to technical indicators, the efficiency of solar panels as part of an autonomous solar power plant is confirmed by their payback period, which is 6 years.
Prices are not reduced
But the given examples of solar energy installations suggest that now tariffs can be "frozen" individually and you can start saving by taking advantage of the capabilities of photovoltaic panels. You just need to buy them from branded and market-tested manufacturers so that their parameters are predictable in both design and operation.
And it is best to address issues such as: from the design phase of an energy-efficient home:
- ensure that the south facade is not shaded;
- selection of the angle of inclination of the roof and working surfaces of the panels;
- correct orientation of the house in relation to the cardinal points;
- prevent solar panel work areas from being shaded, blocked by tree leaves, etc.
In this case, all parameters will be optimally related to each other and the most efficient operation of solar panels for a particular structure will be ensured.