Unlike the powerful and expensive heating system that ordinary homes are equipped with, an energy efficient home does not burn fuel or convert grid power into heat (except during critical temperature drops). A house like this persistently retains the so-called passive heat - thanks to well-thought-out thermal insulation, ventilation with recovery and the optimal location of the building. And everything can be used as a source of this passive energy:
- direct sunlight entering through windows;
- Heat generated by household appliances and even residents and pets;
- and of course devices whose main function is to provide the house with solar energy - solar panels (batteries), which will be discussed.
Solar panels fit harmoniously into a passive house, as they fully correspond to 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 modules is based on converting the thermal radiation acting on silicon wafers into electricity;
- Solar panels allow you to use solar energy to operate household appliances, ventilation systems and (partially) heating systems;
- When the performance of solar panels is higher than household needs, the excess energy can be used in systems to store and convert electricity.
- If the power demand exceeds the capacity of the modules, the missing part can be obtained from the grid (network solar station option) or from a liquid fuel generator (autonomous solar station).
Types of solar panels
Photovoltaic systems are classified according to the criteria of the materials and designs used. Solar batteries are:
- In the form of silicon plates (the most common, powerful and expensive), efficiency – up to 22%; They are produced in three subtypes: monocrystalline (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, in order to adapt the battery to the "appetites" of the house, an increase in the radiation area is required.
The consumer characteristics of solar energy modules are described by the following characteristics:
- Perfomance.The larger the area of the solar panel, the greater its output; To generate an amount of energy of 1 kWh/day in summer, around 1. 5 m2 of solar panels are required. The most efficient performance occurs when the rays fall perpendicularly on the surface of the battery, which cannot be guaranteed constantly, so a change in the performance of the panel in daylight is a natural process. To ensure that the required amount of energy is provided in spring and autumn, approximately 30% must be added to this area;
- Efficiency(Efficiency) of modern solar modules – on average around 15-17%;
- Battery life and performance loss over time. Manufacturers usually give a guarantee for the operation of solar modules for 25 years and promise a power reduction of a maximum of 20% of the original during this period (for some manufacturers the service life varies between 10 and 25 years). with a guarantee of a reduction in performance of no more than 10%. Crystalline modules are the most durable, their estimated lifespan is 30 years. The world's first solar battery has been in operation for over 60 years. The decline in the production of solar modules themselves is mainly due to the gradual destruction of the sealing film and the clouding of the layer between the glass and solar cells - due to moisture, ultraviolet radiation and temperature fluctuations;
- Battery included, which ensures the operation of the panel at night, is a good complement to the capabilities of the solar generator. The battery usually lasts less than the solar panel 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 domestic use) facilitate the operation of the device and its integration into the "smart home" system;
- Battery costs– depends directly on the area: the more powerful the device, the more expensive it is. In addition, modules made abroad are still cheaper than domestic ones, since solar panels are more popular there than here. However, when comparing the prices of our and imported devices, it is first necessary to compare the operating efficiency of solar modules - here domestic manufacturers achieve good efficiency indicators - up to 20%.
Selection and use of photovoltaic batteries
When choosing solar panels for a private house, the first thing that matters is the load that they have to 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 intended to be powered by solar energy (room lighting, household 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 devices also cause losses (for example, for an inverter on average - 15–20%);
- The relationship between the required dimensions of the countertops and the corresponding roof surfaces and their 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 when operating solar modules
- Avoid physical damage to the panel (scratches and damage to the protective film can lead to short circuits and/or corrosion);
- In harsh climatic conditions, it is advisable to equip solar stations with wind protection structures;
- Regular inspections, cleaning and maintenance are mandatory.
Costs and amortization of solar modules
For the middle zone of our country, each kilowatt of solar panel power 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 cost of a unit of electricity generated by the modules (about 60 rubles per 1 W), you need to take into account the cost of additional equipment: from fasteners and wiring to batteries, protective devices and inverters (This is at least 5% of the total cost, but prices can vary significantly depending on the manufacturer and performance).
According to experts, the optimal costs for a year-round solar system arise with the "summer variant plus emergency generator" regulation. The generator must be switched on in spring and autumn, not to mention in winter (solar batteries are never designed to be fully charged in winterto be).
When calculating the payback period of a solar power system, its performance is compared with the underlying parameter. A networked solar system involves electricity tariffs; for an autonomous solar power system, it is the cost of the energy produced by a liquid fuel generator. The payback is estimated based on the fact that a 1 kW solar battery will produce approximately 1000 kWh of energy per year.
If we take the average price of 1 kWh of electricity to be 5 rubles, the payback period of a network solar station will be: 80, 000 rubles / 5 rubles * 1000 kWh = 16 years.
With a 30-year warranty for a network solar system, payback (at a tariff of 5 rubles/kWh) occurs within 16 years, and in the next 14 years electricity is supplied free of charge.
As for an autonomous solar energy system, the amount of energy produced per year will, strictly speaking, be less than the intended 1000 kWh that it shares with the electricity generator. However, for rough calculations, this number does not need to be reduced to approximately account for the increase in specific fuel consumption that occurs with partial (i. e. periodic, not constant) load on the generator. 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) will be as follows: 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 of 6 years.
Tariffs will not be reduced
However, the listed examples of solar energy systems indicate that the tariffs can now be "frozen" individually and you can start saving by using the possibilities of photovoltaic modules. You just need to buy them from well-known, market-tested manufacturers so that their parametersare predictable in both design and operation.
And it's best to deal with topics such as: in the planning phase of an energy-saving house:
- Ensure that the south facade is not shaded;
- Selection of the roof slope angle and working surfaces of the panels;
- correct orientation of the house to the cardinal points;
- Prevents the working areas of solar modules from being shaded, blocked by tree leaves, etc.
In this case, all parameters are optimally linked and the most efficient operation of the solar modules for a specific structure is guaranteed.