Unlike the powerful and expensive heating system that is equipped in normal homes, an energy-efficient home does not burn fuel or convert grid electricity into heat (except in cases of critical temperature drops). Such a house tenaciously retains within itself - thanks to careful thermal insulation, recovery ventilation and the ideal 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 and even by residents and pets;
- and, of course, devices whose main function is to provide 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 fundamental principle of its construction - using renewable energy from the environment.
The working principle 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 capacities of solar panels are greater than household needs, then the surplus energy can be used in electricity storage and conversion systems.
- If the demand for electrical energy 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 (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, the highest performance and the most 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 with 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 area that receives radiation.
The consumer 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, around 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 guaranteed constantly, so changing the panel's performance during the day is a natural process. To ensure that the required amount of energy is obtained in spring and autumn, it is necessary to add approximately 30% 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, offer a guarantee for the operation of solar panels for 25 years, promising a reduction in power during this period of no more than 20% of the original (for some manufacturers, the useful life varies between 10-25 years with a guaranteed reduction power not exceeding 10%). Crystalline modules are the most durable, their estimated useful life is 30 years. The world's first solar battery has been in operation for more than 60 years. The decrease in the production of solar modules itself occurs mainly due to the gradual destruction of the sealing film and clouding of the layer between the glass and the solar cells - due to 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 generally lasts less than the solar module itself, on average 4 to 10 years;
- Availability of additional nodes– as a voltage stabilizer, a battery charge controller, an inverter (DC to AC 220 V converter for home use) make it more convenient to operate the device and integrate it into the "Smart Home" system;
- Battery cost– depends directly on your area: the more powerful the device, the more expensive it is. Furthermore, foreign panels are still cheaper than domestic ones, since solar panels are more popular there than in our country. But when comparing the prices of our devices and imported ones, it is necessary, first of all, to compare the operational 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 first of all based on what load they will have to withstand. 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 devices planned to be powered by solar energy (environmental lighting, domestic 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 work panels and the corresponding roof areas and their 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 a short circuit and/or corrosion);
- In adverse weather 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 zone of our country, each kilowatt of energy from the 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 energy generated by the panels (about 60 rubles per 1 W), it is necessary to take into account the cost of additional equipment: from fastenings and wiring to batteries, devices protection and inverters (which represent 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 year-round solar system are obtained using the "summer option plus backup electric generator" scheme. True, the generator will have to be turned on in spring and autumn, not to mention winter (solar batteries are never designed to be fully charged in winter).
When calculating the payback period of a solar energy installation, its production is compared with the parameter that is taken as a basis. In a grid solar station, these are the electricity rates; In the case of a stand-alone solar power system, this is the cost of the energy produced by a liquid fuel electrical generator. The return 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, payback (at a tariff of 5 rubles/kWh) will occur within 16 years, and for the next 14 years electricity will be provided 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 designated 1000 kWh, which it shares with the electric generator. But for approximate calculations, this figure does not need to be reduced - to approximately take into account the increase in specific fuel consumption that occurs when the generator is partially (that is, periodically, not constantly) loaded. So, 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 that are part of an autonomous solar power plant is confirmed by their payback period, which is 6 years.
Rates are not reduced
But the examples of solar energy installations given suggest that tariffs can now be "frozen" individually and you can start to save by taking advantage of the capabilities of photovoltaic panels. You just need to buy them from branded manufacturers tested on 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:
- ensure that the south facade is not shadowed;
- selection of the angle of inclination of the roof and working surfaces of the panels;
- correct orientation of the house to the cardinal points;
- avoiding shading of the solar panel working areas, their clogging with tree leaves, etc.
In this case, all parameters will be perfectly interconnected and the most efficient operation of solar panels for a given structure will be guaranteed.