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, today I want to tell you about how many solar panels you need for a house or cottage, a private house, etc. This article will not contain formulas or complex calculations, I will try to convey everything in simple words that are understandable to any person. The article promises to be quite large, but I think you will not waste your time, leave comments under the article.
The most important thing to determine the number of solar panels is to understand what they are capable of, how much energy one solar panel can provide, in order to determine the required quantity. You also need to understand that in addition to the panels themselves, you will need batteries, a charge controller, and a voltage converter (inverter).
Calculation of solar panels for a private house or cottage
Regions: Moscow, Novosibirsk, Krasnodar.
Installing solar panels to power a home requires careful preliminary calculations. The capabilities of such equipment are limited and largely depend on external conditions:
- geographical location of the region
- climatic and weather conditions
- daylight hours
The performance of the complex always depends on external conditions. The same set of equipment under different conditions demonstrates different results, so in each case a specialized calculation will be required. It can be ordered from specialized organizations or done independently. Let's look at how to calculate solar panels for a home in order to get an efficient electricity production installation.
Electricity needs
Calculation of solar panels for a summer house or private home must begin with determining the electricity needs. This value can be found from the electricity meter readings or calculated based on the energy consumption of each consumer and the time of its use. The second option is much more complicated and is fraught with errors, so it is more correct to be guided by the meter readings.
Number of sunny days
The second step will be to determine the number of sunny days in the region and the duration of daylight hours by season. The SNiP annexes contain a map of insolation of Russian regions, which gives the amount of solar energy in different parts of the country. It determines the average annual amount of available energy for a given city or region. This is an important indicator that demonstrates the upper limit of equipment capabilities in a given location.
Having determined these values, you can begin to calculate the power of solar panels for your home.
Calculation of solar panel power
When starting to calculate a solar battery, you should take into account that daylight hours are primarily a geographical indicator. When calculating solar panels for a home, one must proceed from the actual energy production, which drops significantly in the morning and evening hours due to a decrease in the intensity of the sun's glow.
Typically, in the summer, the maximum performance of the panels is observed in the period from 9 to 16 hours , and during the rest of the daylight hours they produce 20-30% of their power. In addition, significant adjustments are made by weather conditions, which can reduce energy production by half or more. Therefore, the actual performance of the solar battery should be taken as a maximum of half that indicated in the passport and the amount of energy should be calculated for 70% of the daylight hours.
Experts recommend not taking morning and evening hours into account in calculations at all, attributing them to the required safety margin of the system. In addition, it is necessary to take into account the most unfavorable conditions and add to them a certain percentage of the impact of negative factors.
This will not be superfluous, since some details are always left unaccounted for, significantly changing the operating conditions and the required power of solar panels per square meter.
Formula
The formula for calculating solar panels is as follows:
Psp=Ep*k* Pins / Eins,
- where Psp is the power of the solar panel
- Ep is the daily amount of energy required to power all consumers at home
- K - loss coefficient, usually equal to 1.2-1.4
- Rins - insolation power on the earth's surface
- Eins - table value of average monthly insolation in a given region
Using this formula, find the required power of a solar battery per 1 sq. meter. The power determines how many solar panels are needed for a private home; the number of panels is calculated by dividing the total value by the parameters of one element.
Calculation of battery capacity for solar panels
The capacity of the batteries must match the performance of the solar panels and ensure home consumption in both daylight and darkness. It is necessary to limit the battery capacity so as not to waste extra money. However, it is necessary to have a certain reserve of capacity, since the batteries cannot be completely discharged.
The amount of permissible discharge is different for each type of battery; for example, the charge of car batteries can only be used up to 50%. The best option is to have a daily supply of energy. It is not advisable to have more, as it will greatly increase the cost of the system. A smaller supply could leave home residents without power if unfavorable external conditions occur.
In addition, it is necessary to take into account the efficiency of batteries, inverter and the possibility of poor functioning of solar panels due to bad weather, snow covering the surface of photocells, etc. These losses are usually estimated at 40%, but the efficiency of the controller must also be added to them.
This is important , since some models have virtually no effect on the energy transfer process, but cheaper models can reduce transmission by 20%.
Calculation and selection of inverter
The calculation of a solar power plant ends with the choice of inverter power. This is a device that converts direct current from batteries into alternating voltage with standard parameters 220 V 50 Hz.
The simplest option for calculating the power of an inverter is to determine the daily electricity demand of a home (according to meter readings), which the inverter must correspond to. To take into account possible force majeure situations, the peak load is calculated by multiplying the daily consumption by a factor of 1.3.
There is another option for calculating the inverter - based on the performance of solar panels and battery capacity. It relates the result to the existing equipment, but it was also initially calculated based on daily energy consumption, so both options are almost equivalent. At this point, the calculation of a solar power plant for a home can be considered complete and we can proceed to the actual creation of the kit.
The choice of a finished inverter, as in the case of batteries, is made by selecting a device based on the data received. It is recommended to choose an inverter with slightly increased performance by 10-15% to compensate for the drop in performance over time.
How to calculate battery parameters
Batteries make up a significant portion of the cost of the entire solar system. First of all, this is due to their regular replacements during operation. These devices have different capacities and service life, so the price is significantly different. There is a certain procedure that determines the calculation of a solar battery for a home, on the basis of which everyone decides to purchase one or another battery model.
The main parameters of any battery are the capacity and the number of charge and discharge cycles. Demonstrative calculations can be performed using the example of a conventional acid battery, the voltage of which is 12 V and the capacity is 100 Ah. It is required to calculate the possible amount of energy accumulated at one time and the amount of the same energy released over 1000 cycles, which constitute the battery life. All calculations are carried out taking into account compliance with rules and operational standards. For example, increasing the temperature shortens the life of the device, and decreasing it leads to a decrease in capacity.
So, how much energy can a battery produce when fully charged and then completely discharged? To obtain the result, a capacity of 100 A*h is multiplied by the average voltage value of 12 V. The final figure will be 1200 Wh or 1.2 kW*h. However, in practice, the full depletion of a battery is considered to be 40 percent remaining of the initial capacity. In this case, the average capacity indicator for the entire period of operation will not be 100 A*h, but only 70. Therefore, the real supply of electricity is: 70 A*h x 12 V = 840 Wh or 0.84 kW*h.
The instructions for the battery indicate that it is not advisable to discharge it by more than 20% of the total capacity. That is, in the dark, only 0.164 kWh can be taken from the battery without consequences. Normal battery discharge should occur within 20 hours. If this process occurs under the influence of high current, then the capacity will decrease even more. Thus, the most optimal discharge current will be 5 A, and the battery output power will be 60 W. If you need to solve the problem of how to calculate power with an increased value, in this case the number of batteries increases or the operating mode of existing devices changes.
Great importance in ensuring the operating mode is attached to the correct settings of the charging and discharging controller. When a certain charge voltage is reached, it is switched off, otherwise the electrolyte will begin to boil and begin to evaporate intensively. Consumers are switched off in the same way when the battery is discharged to 80%. Compliance with the operating mode and manufacturer's recommendations significantly increases the service life of the batteries.
Cost of solar panels and batteries
The prices of panels and batteries have a wide range, due to the many options for design, power and other parameters. However, costs should be calculated only based on the design composition of the solar power plant, which includes very specific types of equipment.
Attention! Purchasing equipment separately is impractical, since the result can be heterogeneous equipment that is not capable of working together. It is more correct to purchase ready-made complexes made up of fully compatible equipment.
The initial cost of the station is 5 thousand rubles. and increases in proportion to power, battery capacity and other capabilities of the complex. There is practically no upper limit, since the number of solar panels can be infinite.
Determining the cost of the system
It is impossible to say exactly how much solar panels will cost you along with the necessary technical equipment and installation. Since today there are a huge number of companies on the market that offer various panels both in terms of quality and power, warranty periods, and additional characteristics. There are even similar options in their parameters, but the price will be different. Therefore, evaluate all factors together and choose trusted suppliers. On average, the cost of a 1 kW battery is somewhere around 70,000 rubles. But if you need to buy not one panel, but several, then you can safely count on a discount or free shipping.
In addition to the costs associated with the purchase of solar panels, you will definitely need to purchase other elements of the system, namely: a specialized battery, an inverter and a high-quality controller. For example, a powerful 12V and 200Ah battery will cost about 20,000 rubles. There are also more expensive ones, which have a long service life of more than 10 years. As an alternative, you can buy a car battery, its price will be much lower, but it cannot be used in residential buildings, and they do not last long, usually no more than 5 years.
And, of course, you can’t do without an inverter. With the help of an inverter, direct current from the solar battery is converted into alternating current with a voltage of 220V, which we use for our domestic needs. Inverters also differ in design, technical characteristics, manufacturers and warranty period. Sinusoidal ones are considered the best. Their price ranges from 13,000 to 20,000 rubles. Therefore, you can calculate the total cost of installing a solar system only based on your needs, financial capabilities and quality of equipment.
conclusions
It is not easy to perform an independent calculation of a solar station. The participation of an experienced specialist or an order to carry out design work in a specialized organization is required. However, there is a completely simple and free option - calculating a solar power plant for a home online. A solar power plant calculator is used, of which there are many on the Internet. To get the result, you just need to insert your data into the appropriate windows of the program and get the result almost instantly. It is recommended to duplicate the calculation a couple of times on other sites in order to use the average value.
How to make solar panels work at full capacity
First, it is important to adjust the angle of the batteries throughout the year. To do this, during installation, provide the ability to adjust the frame.
You will also have to regularly clean the surface of the solar panels from all kinds of contaminants: dirt, leaves and branches, bird droppings.
The most sophisticated ones can pump up the solar power plant to get maximum energy during the day. Ideally, you can use trackers that will move the panels following the sun so that they are exposed to direct rays for as long as possible. Another useful solution is a cooling system for photocells, which allows them to maintain an optimal surface temperature.
The power of solar panels indicated by manufacturers is an indicator under ideal conditions. Calculating the actual power is not difficult; the main thing is to correctly substitute all the values into the formula. These indicators can be improved simply by timely maintenance of the panels or with the help of additional technical solutions.
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Counting the number of panels
When two parameters are known - energy consumption and insolation level, you can proceed to calculating the number of panels that will cover the needs of a specific user.
The electricity rate for this is divided sequentially by monthly insolation. Next, the resulting figure is divided again by the power of the installation (available in the data sheet), and the desired value is obtained.
Example: If the buyer lives in Moscow, where in July the insolation is 5.3 kW/h, and your energy consumption per day is no more than 20 kW/h, then with a battery power of 240 W (0.24 kW), 16 panels will be required (20:5.3:0.24=15.7).
If a panel is selected for a summer residence and the choice is made on a device whose power is 185 W (0.185 kW), 5 panels will be sufficient (5: 5.3: 0.185 = 5).
For a more accurate result and the right choice, it is necessary to calculate these indicators for all months.
Basic criteria for choosing equipment
The provision of power supply from solar collectors is affected by:
- Length of day and night (at night solar systems stop supplying energy);
- Weather conditions (on cloudy days the level of energy supply decreases);
- Seasonality (when days become shorter than nights).
In this regard, it is recommended to choose a 12 volt battery capacity:
- Only for the summer period - at least 400 A/h per 1 kW/h of daily consumption in minimum mode;
- For year-round energy consumption - at least 800 A/h per 1 kW/h in the minimum consumption mode.
When choosing a panel, three main factors are taken into account:
- Geometry;
- Type of photocells;
- Rated output voltage.
When the question is: “should you buy one large panel or several small ones,” our advice is that one is better. It is good to install small panels where it is not possible to install a large panel (its size does not exceed 1.5 - 2 meters). In this case, the connection area will be smaller and the level of reliability will increase.
When choosing a solar battery voltage, it is recommended to stop at 24 volt panels, since they have half the operating currents of 12 volt panels of the same power.
The most commonly offered types of photocells are:
- On monocrystalline silicon;
- On polycrystalline silicon.
The monocrystalline type is more expensive, but its advantages are much higher than the polycrystalline type.
If the total power of the panels exceeds the power of the inverter, this will be justified many times over, even taking into account the constant powerful load and a powerful battery pack.
When choosing the placement of panels, the orientation of the house to the cardinal directions and its “landing” on the terrain are taken into account. The traditional orientation is to place the panels to the south.
Nowadays it is not a problem to purchase a solar tracking system. Whether the cost of such additional equipment for a solar collector will be justified or not is a purely individual decision.
When choosing panels, it is important to take into account the characteristics of the controllers, which are distinguished by types of charge and power controllers. In some cases, it is more effective to install multivoltage controllers (designed for several voltages).
When making calculations, it is important to take into account the service life of the system, which can last 20–25 years without a significant decrease in efficiency.
The cost of the system may vary depending on the components: batteries, photomodules and inverters. Approximately the price of 1 kW of power varies between 2.5 – 3 €.
It is not so difficult to calculate which system to buy for your home, how much money to spend on its purchase and whether these costs will be recouped.
Publication date:
May 26, 2014
Determining Electricity Loss in a Home System
The magnitude of these losses is taken into account by Kpot. These losses may be in:
- Seeing off. The value is 1%.
- . They range from 3 to 7%.
- Shunt diodes (0.5%).
- The battery itself at very low solar radiation (1-3%).
Also, power losses can occur due to strong heating of the module
(4-8%) and due to the presence of dirt on the solar panels or their darkening (1-3%).
An autonomous electrical system for a home is considered optimal if the total losses do not exceed 15%. Then the payback period is reduced, and the batteries accumulate more current. Kpot
is 0.85.
However, poor quality equipment or poor selection of components can lead to 30 percent losses. Kpot
will already be 0.7.
Calculation example for Moscow
Table for providing different modes of operation of solar panels
Let's assume that you need to calculate a tilt of 70°, but there is no such data for Moscow, but there is data on the panel tilt angles of 40° and 90°. In this case, the average value between these data is taken and rounded down to 1 kW/h. When calculating power, the total efficiency of the controller and inverter is taken into account - 91%. The value “deficit mode” indicates that there is not enough power even for the constant operation of the system itself.
Latitude and longitude depth of the problem
Imagine that you are a scientist. You come across an interesting article, but the results/experiments cannot be reproduced in the laboratory. It is logical to write about this to the authors of the original article, ask for advice and ask clarifying questions. According to the survey, less than 20% have done this at any time in their scientific career!
The authors of the study note that perhaps such contacts and conversations are too difficult for the scientists themselves, because they reveal their incompetence and failure in certain issues or reveal too many details of the current project.
Moreover, a vast minority of scientists have attempted to publish refutations of irreproducible results, but have faced opposition from editors and reviewers to downplay comparisons with the original study. Is it any wonder that the chance of reporting the irreproducibility of scientific results is about 50%.
First question: Have you tried to reproduce the results of the experiment?
Second question: Have you tried to publish your attempt to reproduce the results?
Maybe then it’s worth at least checking reproducibility inside the laboratory? The saddest thing is that a third of respondents have NEVER even thought about creating methods for checking data for reproducibility. Only 40% indicated that they regularly use such techniques.
Question: Have you ever developed special techniques/technical processes to improve the reproducibility of results?
In another example, a biochemist in the United Kingdom who did not want to be named says that trying to replicate work for her lab project simply doubles the time and cost without adding anything new to the work. Additional checks are carried out only for innovative projects and unusual results.
And of course, the eternal Russian questions that began to torture our foreign colleagues: who is to blame and what to do?
