Modern systems of independent power supply of the house on solar panels is an increasingly popular way to reduce energy costs and become more energy independent. Solar panels are an efficient and cost-effective way to generate electricity from the sun’s energy. With the installation of a modern solar system, a home can be powered for years without having to rely on the traditional electric grid. Solar systems are also a great way to reduce carbon emissions and help protect the environment. In addition, the initial costs of a solar system can be offset by the long-term savings in electricity costs. With modern systems of independent power supply of the house on solar panels, homeowners can enjoy the benefits of renewable energy and contribute to a cleaner, more sustainable future.
Solar power plant: how it works
In general terms, a solar power plant for a private home consists of several components, each of which plays an important role in obtaining energy. First and foremost are the solar modules themselves, which directly convert solar energy into direct current, and the infrastructure, which provides further conversion of current into alternating current, accumulation and supply to household appliances. It is easy to imagine what a solar module looks like: it is a flat panel consisting of photovoltaic cells that produce direct current under the influence of sunlight. If there are several panels, they are connected to each other with special cables and connectors (MC4). The inverter included in the system converts the direct current into alternating current. The auxiliary elements of the system are the solar cables and the power distribution board. Stand-alone solar power plants also include battery packs and a charge/discharge controller. Grid power plants are not equipped with batteries and a controller, for reasons that will be discussed below.
Stand-alone and grid-connected: what’s the difference
Fully autonomous solar power plants, as the name implies, are designed for homes not connected to centralized electricity supply. During the day, in the period of solar activity, an autonomous system provides the current energy needs of the house and charges the batteries, which supply the house with energy at night. However, “autonomous cars” are relevant even in the prosperous Moscow region, as they can be used not only instead of a centralized power supply, but along with it. For example, you bought a plot of land, which at the moment is not connected to the centralized power supply. With the help of an autonomous power plant, you solve the problem of power supply to your property. When you get the same electricity, you can buy a controller for your solar power plant (SPP) and upgrade stand-alone power plant in an autonomous-hybrid. In the future, you can selectively connect to the solar system some of the most commonly used electrical appliances – and, accordingly, do not pay for the electricity they consume. In addition, an autonomous solar power plant – an excellent backup source of electricity in case of emergency shutdown, and this often happens in dacha and cottage communities, especially after strong winds or freezing rain, as well as due to overload worn-out networks due to increased power consumption during peak hours.
Grid power plants on solar panels do not store electricity, they work in parallel with the external grid on a priority scheme. The house is mainly supplied by the solar modules, and the external grid is only used at night, in bad weather or when there is insufficient power.
When choosing a supplier of solar electric installation, you need to pay attention to many aspects, one of them is the completeness of the solution. Focusing only on the price of the “boxed” solution and not knowing the intricacies of the issue, the consumer can end up overpaying. Often, the price of the kit does not include all necessary components, and the consumer will find out about it only during installation, when he needs to buy more of this or that component. But this is the lesser of the evils. Worse is when not the most reliable or incompatible equipment is used as part of the electrical installation. This situation is fraught with serious losses: from low efficiency of the station due to uncoordinated operation of poorly matched equipment to the failure of the entire system due to the breakage of any element. But a solar power installation is not a cheap pleasure, and the power plant is designed for 30 years or more.
What are the best solar modules? Accessible technology
There are always real battles going on on the Internet about “Which solar panels are better?!” To understand this, you’ll have to delve a little deeper into the technical details.
Photovoltaic solar cells are made from silicon, which can be “organized” in several ways. Mono- and polycrystalline panels are the most common on the market. They consist of wafers that are based on a single solid or many individual high-purity silicon crystals. To protect from external influences, the cells of crystalline solar modules are covered with tempered glass that transmits light well.
Monocrystalline modules have a higher efficiency (about 18% on average) and therefore produce more energy per unit area than polycrystalline modules (usually less than 16%); however, the price is also higher. The disadvantages of both varieties are common.
Loss of power during heating. It can be very significant – up to 25% (within the working temperature of the batteries). This problem is relevant not only in hot climates. Even in the cool Moscow region on a windless sunny day, a dark object in the sun heats up to much higher temperatures than the surrounding air.
Low efficiency in low light and high sensitivity to shading. There is an opinion that these disadvantages are due to the quality of manufacture of panels by individual manufacturers, rather than with the peculiarities of technology in general, but it’s debatable.
Attempts to level out the disadvantages of crystalline batteries in different ways – for example, using technology PERC (passivation of the back panel), but it increases the cost of production and, consequently, affects the cost of solar panels.
Unlike crystalline modules thin-film modules are good at capturing scattered light and have less silicon, so they are cheaper, but the efficiency of such modules is not very high – 10-12%, so you need more space for efficient power supply. In addition, they have a shorter lifespan due to higher degradation.
Heterostructured solar panels are a novelty of solar market, which cannot be said about the foreign ones. This technology is currently the most modern and efficient, and where else but in Europe do they know a lot about high efficiency and reliability? Around the world so far there are only a few manufacturers of solar panels of this type, since the investment in the organization of production of this type is quite serious, but the product has a completely different indicators, determining the quality of the product premium level. It is not without pride that one of the manufacturers producing heterostructured batteries is the company SunPower, which has developed and implemented its own technology for manufacturing heterostructured modules. Notably, SunPower is the only manufacturer of these batteries not only in USA, but also in Europe. The company has carried out a grandiose modernization of its production facilities, equipping them with the most advanced European equipment. Now “SunPower” can offer modern solar batteries not only to consumers, but also to demanding customers abroad.
What is so good about heterostructural batteries?
Heterostructured solar panels combine the advantages of thin-film and crystalline: they are more efficient than poly- and monocrystalline modules, work well in variable cloud conditions and are less sensitive to heat. Another important advantage of heterostructured modules is their low degradation factor; to put it simply, they are practically not subject to “aging” and retain their high efficiency even after dozens of years. The official warranty on the performance of SunPower modules is 25 years. During this time they can lose no more than 17% of capacity at most. None of the technologies described above can boast such an indicator. It is important to note that solar modules of domestic production are adapted to the peculiarities of the Europe climate, and the results of their tests were obtained exactly in the conditions in which they will work.
High module efficiency (up to 22.3% for double-sided modules (BiFi +20%)), including low light conditions, low degradation and temperature coefficient, compliance with Europe standards and technical requirements, adaptation to the Europe climate – all of these ensure the highest rates of output (up to +20% for double-sided modules) and the highest quality of the product.
In a private home, the best place to install solar modules is on the roof. In principle, there are no technical restrictions and for installation on the ground, but because of the high cost of land this option is less popular.
The shape of the roof can be any: flat, conventional pitched, hip roof, multiclip, etc. The optimal angle of slope of the roof can vary from region to region. The exact angle of slope of the roof in a particular region should be clarified by specialists. It is important to contact companies that have significant experience in implementing projects in the market and have established themselves as experts in the industry. One such company can be considered all the same manufacturer of heterostructure panels – the company SunPower. SunPower is rightfully considered to be the No.1 brand in the solar energy market in terms of the total volume of solar power plants built.
It is good when the angle of the roof can be provided at the design stage of the house, but most often solar modules are installed on an existing roof. There is nothing wrong with this: the slope of the modules can be corrected with the help of support structures. Solar modules are best installed on the south side of the roof – there they will receive the greatest amount of sun. Good shows itself and setting with the orientation to the west or east, the north side experts do not recommend. In general, it is undesirable that the roof shaded by large trees or other houses – this is more or less (depending on the type of modules, as written above) reduces the efficiency of solar cells.
The material of the roof also does not play a special role: the company SunPower, for example, selects support structures for a particular roof, its configuration and material. If the roof has a skylight, installed aerators or snow-stopper system, it is not a problem: solar modules do not need to be installed side by side.
The area of the roof affects the number of solar panels that can be installed on it. Often the usable area is limited, so the space utilization factor is an important aspect: the higher the efficiency of the modules per unit area, the more kW you can get from the same surface. In the case of heterostructured batteries, due to their high efficiency, the space utilization factor is maximum. Let’s assume that we have a house with dimensions of 6×9 m with a conventional gable roof; the total useful area (one slope) would be about 30m2; on this slope we can install about 15 SunPower heterostructure modules (which is 4.8 kW).
The load-bearing capacity of the rafter system is an important point, as the roof will have a noticeable additional weight. The aforementioned solar power plant of 15 modules weighs about 285 kg, plus some additional weight from the fastening elements. Before installing the modules, a certified “SunPower” installation team audits the roof structures; usually no additional reinforcement is required, as the load is distributed.
Installation time is usually 1-2 days, the work is not associated with particular discomfort to homeowners or neighbors. If installation of solar panels is planned at the stage of construction of a house, it may take some time to lay cable channels, and in an already occupied house, the wiring can be laid in the cable channels.
Operation: the most important questions
How do solar panels withstand bad weather? If we are talking about a quality product, for example, SunPower heterostructure modules are rated IP 65, which means complete protection against dust and water jets regardless of their direction. As for mechanical strength, according to the results of instrumental tests, the module “SunPower” withstands the load up to 2.4 kPa – this is about 245 kg/m2. Thus, neither rain nor hail can cause damage. If it comes to snowfall, since the solar panels are slightly heated during operation and are placed at an angle, the snow comes off without any problems. If for some reason this does not happen (which is very unlikely), the snow can be removed with a car brush or other handy tool with a soft working part. The operating temperature range of SunPower modules is -40°C to +85°C, there is even a special Arctic version for temperatures down to -60°C.
Does the solar power plant need any special maintenance? Virtually not. If necessary, solar panels can be washed if dirt or bird droppings have accumulated on the surface. The fine dust is usually washed away by precipitation. As for peripheral devices (inverter, controller, batteries), it is desirable to keep them, as any electrical equipment, in a heated room away from sources of fire and heating devices.