Energy saving efficiency of solar panels

Unlike the powerful and expensive heating systems found in ordinary homes, energy-efficient homes do not burn fuel or convert network electricity into heat (unless there is a critical temperature drop). Such a house tenaciously retains in its interior – thanks to thoughtful insulation, restorable ventilation and the building’s optimal position – so-called passive heat. Anything can be used as a source of this passive energy:

• direct sunlight through the windows;
• heat generated by household appliances and even residents and pets;
• Of course, there are also devices whose main function is to provide solar energy to the house - solar panels (batteries), which we will discuss.

Solar panels integrate harmoniously into a Passive House, as they are fully consistent with the main principle of its construction - the use of renewable energy from the environment.

How solar panels work and how they interact with other home systems

• The operation of solar panels is based on converting thermal radiation affecting silicon wafers into electrical energy;
• Solar panels allow you to use solar energy to operate household appliances, ventilation systems and (part of) heating;
• If the solar panel capacity is higher than the household needs, then the remaining energy can be used in a system that stores and converts electricity.
• If power demand exceeds the capacity of the panels, the missing portion can be sourced from the network (option for networked solar stations) or liquid fuel generators (autonomous solar stations).

Types of solar modules

Photovoltaic systems are classified according to criteria of materials used and design. Solar cells include:

• In the form of silicon plates (the most common, highest performing and most expensive), efficiency - up to 22%; they are divided into three subtypes: monocrystalline (the most reliable), polycrystalline and amorphous; pure silicon is used in the first two positions, The third position uses silicon hydrogen, which is applied to the substrate;
• Thin Films - Made using cadmium telluride, copper indium selenide and polymers. They are less expensive, but also have lower performance (efficiency 5-14%), so in order to make the battery suitable for the "appetite" of the household, the area that receives the radiation needs to be increased.

The consumption attributes of solar panels are described by the following characteristics:

• strength.The larger the solar panel area, the greater its power; to generate 1 kWh of electricity per day in summer, approximately 1. 5 square meters of solar panels are needed. The most efficient power occurs when light falls vertically on the cell surface, but this cannot always be ensured, so changing the panel's performance during the day is a natural process. To ensure that the required energy is obtained in spring and autumn, about 30% must be replenished in this area;
• efficiencyThe (efficiency) of modern solar panels – averages around 15-17%;
• Battery life and charge loss over time. Manufacturers typically offer a 25-year guarantee on the operation of solar panels, promising that the power will be reduced by no more than 20% of the original value during this period (for some manufacturers, the service life is between 10-25 years) and that the power will be reduced by no more than10%). Crystal components are the most durable, with an estimated service life of 30 years. The world's first solar cells have been operating for more than 60 years. The decrease in the yield of the solar module itself is mainly due to the gradual breakdown of the sealing film and the clouding of the layer between the glass and the solar cell - moisture, UV radiation and temperature changes;
• Battery included, ensuring the operation of the panel at night, which is a good supplement to the function of the solar generator. The service life of the battery is usually shorter than the solar module itself, averaging 4-10 years;
• Availability of additional nodes– Such as voltage regulators, battery charge controllers, inverters (domestic DC to AC 220 V converter) making the operation and integration of the device into a "smart home" system easier;
• battery cost– Directly depends on its area: the more powerful the device, the more expensive it will be. Additionally, foreign-made 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 and imported equipment, it is first necessary to compare the operating efficiency of solar panels - here domestic manufacturers achieve good efficiency indicators - up to 20%.

Photovoltaic cell selection and use

When choosing solar panels for a private home, first consider the load they must withstand. Additionally, there is the need to consider the geometry of the house and the planning of preventive maintenance activities, which requires careful consideration of the following aspects:

• Plan the daily energy consumption of equipment powered by solar energy (indoor lighting, home appliances, security and automation equipment, etc. ). It should be taken into account that charging and discharging the battery also consumes energy (about 20%), as well as losses in additional equipment (for example, inverters have an average loss of 15-20%);
• The relationship between the required dimensions of the working panels and the corresponding roof area and its geometry;
• Able to remove dirt, snow and other factors that affect the operation of the photoelectric converter on the battery working surface.

Key points in the operation of solar panels

• Avoid physical damage to the panel (scratches and damage to the integrity of the protective film may lead to contact shorting and/or corrosion);
• In harsh climate conditions, it is recommended that solar power stations be equipped with wind-shielding structures;
• Regular inspection, cleaning and maintenance are mandatory.

Solar Panel Cost and Return on Investment

For the central region of my country, the power generation per kilowatt of solar panels is as follows:

• Summer - 5 kWh/day (May to August);
• Spring and Autumn - 3-4 kWh/day (March-April, September-October);
• Winter - 1 kWh/day.

When calculating the cost of an autonomous solar power station, in addition to the cost of the unit of electricity generated by the panels (about 60 rubles per 1 W), it is also necessary to take into account the cost of additional equipment: from fasteners and wiring to batteries, protection devices and invertersconverter (at least 5% of total cost, but price can vary widely depending on manufacturer and power).According to expert advice, the best cost for a year-round solar system is obtained by using the "summer option plus backup generator" scenario. Granted, generators must be turned on in the spring and fall, let alone in the winter (solar cells were never designed to be fully loaded in the winter).When calculating the payback period of a solar power installation, its output is compared with parameters that are basic parameters. In the case of network solar stations, these are the electricity prices; in the case of autonomous solar power systems, this is the cost of the energy produced by the liquid fuel generator. The payback period is estimated based on the fact that a 1 kW solar cell produces approximately 1000 kWh of energy per year.If we consider the average price of 1 kWh of electricity as 5 rubles, then the payback period of a grid-connected solar power plant will be: 80, 000 rubles / 5 rubles * 1000 kWh = 16 years.The grid-connected solar installation has a 30-year warranty, the payback period (electricity price is 5 rubles/kWh) will be within 16 years, and the electricity will be provided free of charge for the next 14 years.For an autonomous solar system, strictly speaking, it will produce less than the specified 1, 000 kWh per year, which it shares with a generator. But for a rough calculation, there is no need to reduce this figure - in order to roughly take into account the increase in specific fuel consumption that occurs when the generator is partially (i. e. periodically rather than continuously) loaded. Then the payback period of an autonomous system (based on the cost of energy generated by a liquid fuel generator - 25 rubles per 1 kWh) is as follows: 150, 000 rubles / 25 rubles * 1000 kWh = 6 years.In addition to technical indicators, the efficiency of solar panels of an autonomous solar power plant also depends on its payback period, which is 6 years.

Tariffs have not been reduced

But the example of a solar installation given shows that now that tariffs can be "frozen" individually, you can start saving by taking advantage of the capabilities of photovoltaic panels. You simply buy them from market-tested brand manufacturers so that their parameters are predictable in design and operation.It is best to address the following issues, even during the design phase of an energy-efficient home:

• Ensure that the south facade is not obscured;
• Roof pitch angle and panel working surface selection;
• The correct direction of the house towards the cardinal point;
• Prevent solar panel working area from being blocked, leaves clogging, etc.

In this case, all parameters will be optimally related to each other and ensure the most efficient operation of the solar panels of a specific structure.