Solar panels for heating and electrification of the house

Latitude and longitude depth of the problem

Imagine that you are a scientist. You come across an interesting paper, but the results/experiments cannot be replicated in the lab. 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 ever done so 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 inconsistency in certain issues or reveal too many details of the current project.

Moreover, an absolute minority of scientists attempted to publish rebuttals of irreproducible results, while facing opposition from editors and reviewers who demanded that the comparison with the original study be downplayed. Is it any wonder that the chance to report non-reproducible 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 it's worth then inside the laboratory at least to carry out a test for reproducibility? The saddest thing is that a third of the 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 methods/technological processes to improve the reproducibility of results?

In another example, a biochemist from the United Kingdom, who did not wish to be identified, says that trying to replicate work for her lab project simply doubles the time and money, without adding or adding anything new to the work. Additional checks are carried out only for innovative projects and unusual results.

And of course, the age-old Russian questions that began to torture foreign colleagues: who is to blame and what to do?

What are first generation solar cells made of?

Structurally, such modules consist of the following elements:

• base metal sheet - base contact;
• the lower additive layer of a silicon semiconductor with a predominance of n-type electrons - due to the addition of phosphorus;
• the upper crystalline layer saturated with p-type electrons - usually by doping with boron;
• anti-reflective coating - to maximize radiation absorption;
• thin metallized grid-type contact with a wire for closing the network;
• thick protective glass - usually heavy-duty tempered;
• framing frame.

The thickness of monocrystalline Mono-Si or polycrystalline Poli-Si silicon wafers in cells is about 200-300 µm. The service life is estimated at 20-25 years, with a drop in productivity of an average of 0.5% annually. The efficiency under ideal lighting conditions reaches 22-24% and decreases sharply at high temperatures or a partial drop in illumination.

The principle of using solar energy

Often, faced with the need to install solar panels, a person wonders about the feasibility of the enterprise. Because in most cases the percentage of sunny days significantly loses to the same value of cloudy ones.

A similar ratio is typical for the regions of the middle zone, and the climate of the northern regions is characterized by an even greater number of cloudy days.

The insufficient number of sunny days is directly related to the efficiency of the devices that process the energy of the earthly body. This reduces the amount of sunlight reaching the surface of the battery. This process is called insolation.

Its essence lies in the fact that any plane, regardless of its purpose, takes on a certain amount of solar energy. In the southern regions, this number is naturally higher, which makes the installation of solar panels more relevant.

However, as practice shows, the market for technological equipment in the field of solar energy synthesis is constantly improving its products, so modern photovoltaic cells in solar panels function perfectly even in areas with a low level of insolation.

Types of silicon solar cells

Polycrystalline

The main element of such panels are semiconductor elements of polycrystalline structure. They are much cheaper than single-crystal ones, since they are essentially made from scraps left over from single-crystal elements. During the manufacturing process, the silicon alloy is simply cooled without further processing.

The efficiency of polycrystalline solar cells is on average 12 - 18%, while the efficiency of monocrystalline solar cells reaches 22%. However, given the lower price, you can buy a little more panels and get the same "exhaust" for the same money as monocrystals. This is only possible if there is a lot of space on the roof. Also, polycrystals differ from single crystals in the heterogeneity of the color gamut.

How much do polycrystalline solar panels cost? Average 3500 rubles per 100 W (much depends on the manufacturer). One of the most inexpensive polycrystalline batteries is Vostok Pro FSM 150 P with a power of 150 watts.

Monocrystalline

For monocrystalline solar panels, a single crystal is specially grown using the Czochralski method. Then a whole panel of a certain power is assembled from several silicon cells. Most often, the panel consists of 36 or 72 modules. The efficiency of monocrystalline panels is much higher than that of polycrystalline panels, and is about 18 - 22%.

Due to this feature, with the same size, single-crystal converts more solar energy than polycrystalline. Which solar panels are better: polycrystalline or monocrystalline? Everything depends on the budget. If it is possible to spend a little more, then it is worth buying monocrystals, which have a faster payback. Also, monocrystalline batteries will be preferable if the roof area is relatively small. The average lifespan is 25 years.

If you want to save money and you only need a solar battery to power a refrigerator or a pumping station in the country, then you can take a polycrystalline model.

amorphous

Amorphous batteries are made up of silicon hydrogen (SiH4), which is produced by applying an electrical current to silicon. As a result, silicon evaporates, and then a thin layer is deposited on the substrate.

The efficiency of amorphous panels is about the same as that of polycrystalline ones. However, amorphous models have some advantages. For example, they can generate electricity even in cloudy weather, rain, when there is a high concentration of dust in the air, or during sunset / dawn.

Efficiency

To use solar energy to heat a private house, it will be much easier to assemble a circuit from collectors - but this is not always possible, so you have to consider other options. For example, it may well be that the site already has a working solar panel system that is only used to provide the house with electricity and hot water.

Acquiring new equipment under such conditions will be too unprofitable due to its high cost.To ensure the heating of the house with solar panels, the best solution would be to increase the power of the module system. The easiest option is to purchase a few additional silicon panels and connect them to an electrically powered heating boiler system.

Proper distribution of electrical energy will provide both a hot water supply system and a heating circuit. It will take a lot of solar panels to have enough power for everything - stand-alone buildings that use only solar energy are usually completely covered with photovoltaic panels. The power of solar panels must be calculated in advance. Often it is necessary to complete the additional structure on which the panels will be installed.

It is impossible to determine the efficiency of a solar system before it is used, so all calculations are only approximate. The complexity of preliminary calculations is due to the fact that there are a lot of factors, the influence of which on the efficiency of energy collection cannot be calculated. Of course, if you have some experience, you can make a more or less accurate calculation, but only professionals specializing in the design and installation of solar systems have such experience.

The following factors have the greatest influence on the efficiency of the system:

• Weather instability - it is impossible to determine in advance the number of sunny days even in sunny regions, not to mention the northern regions;
• Unstable energy consumption, which also depends on the geographical location of the building that receives heat and electricity from sunlight;
• The possibility of system failure - the complexity of the design indicates that it will often break down, and in some cases it is difficult to determine the malfunction.

Who is a home solar power plant suitable for?

1. For those who do not have electricity in the area. Solar batteries will be able to autonomously provide the facility with electricity. Alternatively, you can also consider a windmill (for which there must be an appropriate wind rose) or a diesel generator (which is not very convenient to operate and uneconomical).
2. Also, a solar station can be considered as an investment in order to pay less for electricity in the future against the background of ever-increasing tariffs. In addition, the battery life is very long, and the sun always shines.
3. And the last option is for everyone who wants to earn money. In Ukraine, there is a law on the feed-in tariff, according to which the state buys the generated electricity using alternative energy sources at a special price.

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How to calculate the power of a solar power plant

You need to start from how much electricity you need for the normal functioning of the building. The easiest way is to write out all email. appliances that you plan to use, their operating time and power consumption.

Example:

• Refrigerator: 100W - 24h - 2400W
• Lighting: 100W - 5h - 500W
• Kettle: 15min - 1.5kW - 0.03kW
• Washing machine:
• Notebook:
• …
• Total: 3kW

3 kW is the power that a solar power plant must produce for the building to function normally. Those. you will need 12 panels with a power of 260W each. In practice, their productivity will be higher (with a solar activity coefficient of 4.5, the daily output of the station will be 14 kW), but we start from the most pessimistic scenario, in which every day is cloudy. Also keep in mind: if you are not connected to the feed-in tariff or do not store energy for the battery, then the excess will burn out.

If you are installing a solar power plant to make money on a feed-in tariff, then you can start with any capacity and gradually increase it.

Solar battery or generator with internal combustion engine

Objectively, the generator has two main advantages - its size and the ability to fully operate not only in clear weather. But far from always, these characteristics are decisive, and in all other aspects, solar panels clearly win:

The most important point, which is usually paid attention in the first place, is the initial cost of equipment, which is really about 2 times higher for solar panels. But even here, if you figure it out, then the generator needs to be set a minus - just look at the cost of generating one kW / h

We take the initial cost of the equipment + the cost of maintenance + the cost of fuel and divide everything by the amount of electricity generated during the declared service life. As a result, for a generator and solar panels of approximately equal power, the ratio of the cost of generating one kilowatt will be approximately 1 / 2.5 in favor of the latter. Of course, these are very approximate calculations, but the point is that solar panels are investments now, but tangible savings in the future.

An example of a connection diagram for a kit with a gas generator

Service life of solar panels

To evaluate the benefits, you need to figure out how long the panels last and whether they will have to be changed after the warranty period ends. There are several features to consider here:

1. Monocrystalline and polycrystalline options are the most durable.For 25 years of use, they lose no more than 10% of their capacity. But even further, the drop in power is insignificant, over the next 10-15 years, about the same amount is lost. That is, we can say with confidence that the service life of such options is 35-40 years, and maybe more.
2. Thin-film options have a much lower service life - 10-20 years. Moreover, for the first 2 years, the capacity loss can be 10-30%, most manufacturers provide a power reserve to compensate for this problem. In the future, the losses are not so significant.
3. To increase the service life, damage to parts of the system must be avoided. Trim the branches of closely spaced trees, wash the surface at least several times per season. Check the reliability of fastening and contacts so that they do not overheat.
4. Take into account the cost of replacing other elements of the system. So, rechargeable batteries usually last from 6 to 10 years (the most reliable ones - 15 years), power electronics have a resource of about 10-12 years. The cost of replacing these nodes is also rather big and this must be taken into account when calculating the payback.

Solar panels need to be washed periodically to prevent them from being damaged by tree branches.

When choosing solar panels for your home, it is better to give preference to reliable and proven monocrystalline and polycrystalline options. High-quality modules will last about 40 years, while the power loss during this time will be about 20%.

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The principle of operation of the solar battery

The device is designed to directly convert the sun's rays into electricity.This action is called the photoelectric effect. Semiconductors (silicon wafers), which are used to make elements, have positive and negative charged electrons and consist of two layers, the n-layer (-) and the p-layer (+). Excess electrons under the influence of sunlight are knocked out of the layers and occupy empty places in another layer. This causes free electrons to constantly move, moving from one plate to another, generating electricity that is stored in the battery.

How a solar battery works depends largely on its design. Solar cells were originally made from silicon. They are still very popular, but since the process of cleaning silicon is quite laborious and costly, models are being developed with alternative photocells from compounds of cadmium, copper, gallium and indium, but they are less productive.

The efficiency of solar panels has increased with the development of technology. Today, this figure has increased from one percent, which was recorded at the beginning of the century, to more than twenty percent. This allows us to use panels today not only for domestic needs, but also for production.

Specifications

The device of the solar battery is quite simple, and consists of several components:

Directly solar cells / solar panel;

An inverter that converts direct current to alternating current;

Battery level controller.

Buy batteries for solar panels should be based on the required functions. They store and distribute electricity. Storage and consumption occurs throughout the day, and at night the accumulated charge is only consumed.Thus, there is a constant and continuous supply of energy.

Excessive charging and discharging of the battery will shorten its useful life. The solar battery charge controller automatically suspends the accumulation of energy in the battery when it has reached its maximum parameters, and turns off the load of the device when it is heavily discharged.

(Tesla Powerwall - a 7 kW solar panel battery - and home charging for electric vehicles)

The grid inverter for solar panels is the most important design element. It converts the energy received from the sun's rays into alternating current of various capacities. Being a synchronous converter, it combines the output voltage of electric current in frequency and phase with a stationary network.

Photocells can be connected both in series and in parallel. The latter option increases the power, voltage and current parameters and allows the device to work even if one element loses functionality. Combined models are made using both schemes. The service life of the plates is about 25 years.

General characteristics and availability of purchase

The equipment does not harm the environment and provides stable power without power surges. And, most importantly, it supplies free energy: for which utility bills do not come.

The appearance of solar panels has changed little after their invention, which cannot be said about the internal "stuffing"

The solar module converts light into electrical energy by generating direct current. The area of ​​panels can reach several meters. When it is necessary to increase the power of the system, increase the number of modules.Their effectiveness depends on the intensity of sunlight and the angle of incidence of the rays: on location, season, climatic conditions and time of day. To correctly take into account all these nuances, installation should be carried out by professionals.

Types of modules:

Monocrystalline.

Consist of silicone cells that convert solar energy. Differ in the compact sizes. In terms of performance, this is until recently the most efficient (efficiency up to 22%) solar battery for the home. A set (its price is one of the most expensive) will cost from 100 thousand rubles.

Polycrystalline.

They use polycrystalline silicon. They are not as efficient (up to 18% efficiency) as monocrystalline solar cells. But their cost is much lower, so they are available to the general population.

Amorphous.

They have thin-film silicon-based solar cells. They are inferior to mono and polycrystals in terms of energy generation, but they are also cheaper. Their advantage is the ability to function in diffuse and even low light.

Heterostructural.

Modern and most efficient solar modules today, with an efficiency of 22-25% (throughout the entire service life!). They work effectively both in cloudy weather and at high temperatures).

In Russia, the only manufacturer of modules for this technology is the Hevel company, which is one of the five world manufacturers producing heterostructure solar modules.

In 2016, the R&D center of the company patented its own technology for creating heterostructural modules and is now actively developing it.

Hevel solar panels

The system also includes the following components:

• An inverter that converts direct current to alternating current.
• Accumulator battery. It not only accumulates energy, but also levels out voltage drops when the light level changes.
• Controller for battery charging voltage, charging mode, temperature and other parameters.

In stores, you can purchase both individual components and entire systems. In this case, the power of the devices is determined based on specific needs.

What capacity to take a solar battery?

It also depends on the needs of the user. For autonomous power supply of the whole house, it makes no sense to take less than 1000 watts. And if you need to power the heating system in the country, theoretically you need a kit with a capacity of up to 10 kW. However, it is worth remembering that such a solar panel will cost a lot of money. Only one solar modules (even the most inexpensive ones without a controller, inverter and other components) with a capacity of 10 kW will cost at least 300,000 rubles. Therefore, such batteries can be considered as an additional source of energy, but not the main one.

If you need a solar panel to power your refrigerator and TV, then a 500W panel will suffice. For example, you can take two One-Sun 250P polycrystalline solar modules, which will cost you only 16,500 rubles.

If you have never used solar panels, then we recommend buying a small folding panel of low power for your phone or tablet.