PHOTOVOLTAICS - THE KNOWLEDGE BASE
Financing your photovoltaic installation
Here you will find the most important information about photovoltaics, useful for anyone who starts their adventure with photovoltaic installations. Photovoltaics - knowledge base. Basic definitions can be found in the glossary of terms. Many of your doubts will be dispelled by the answers to the most frequently asked questions, which you can view in the form of a drop-down list. In the investor's guide, which we update regularly, you will learn about new products and interesting facts that will be useful for you.
Panels (modules)
The rectangular panel, consisting of photovoltaic cells, covered with glass. Under the influence of daylight (sunlight), it produces electricity. In a photovoltaic installation, several to several dozen panels are connected to obtain the expected production capacity.
Inverter
Otherwise known as an inverter or converter. Its task is to change the value of voltage and current to suit the reception by electrical devices. Converts direct current into alternating current, ensuring that energy can be used in the facility's electrical system.
Constant current
Direct Current - DC. The electricity produced by photovoltaic panels is characterized by a constant return and direction of the flow of electric charge. To use direct current, we need to adjust it to the parameters of our electrical installation (inverter).
AC
Alternating Current - AC. The current in our electrical sockets (low voltage networks) is characterized by a variable instantaneous intensity value. The voltage in Poland is 230V / 50Hz and this is the output value transmitted by the inverter to the electrical installation.
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Questions and Answers
PHOTOVOLTAICS
What is a photovoltaic installation for?
The photovoltaic installation allows for the independent production of electricity, using for this purpose renewable energy sources (RES), i.e. solar energy. Such installations primarily serve the environment - they are pro-ecological and emission-free. But what is it for its user? In the simplest terms, it will save you on daily electricity bills.
How does a photovoltaic installation work?
The purpose of the installation is to generate electricity from sunlight. The cells in photovoltaic panels are responsible for converting solar energy into electricity. Then, with the help of dedicated devices and security, we can transform energy into alternating current - exactly as it is in our electrical sockets.
What does a photovoltaic installation consist of?
The basic elements of a photovoltaic installation are panels and an inverter. Panels exposed to sunlight are designed to produce direct current. An inverter, also known as an inverter, converts direct current into alternating current. Besides, for the proper operation of the installation, wiring, protection and grounding are necessary - all these elements ensure the safe use of our electrical installation.
Solar panels or solar thermal collectors?
Photovoltaic arrays are not the same as solar thermal collectors. Collectors are used to obtain heat - for the needs of domestic hot water or central heating systems. They work mechanically - the conductor, heated by the sun's rays, gives off the heat of the cooler liquid stored in the tank. The panels, using the photovoltaic phenomenon, produce electricity - the same that we take from the electricity grid every day - which is then fed into our electrical installation.
What is the difference between an off-grid system and an on-grid system?
Although these two systems seem to be separate installations, the only difference is in the way electricity is stored. The off-grid system is based on the use of storage elements - e.g. batteries, and the on-grid system - connection to the power grid. The first of them allows for energy independence from the grid, using self-stored energy. The on-grid system allows you to use electricity without restrictions - excess energy will be fed to the grid and then used as part of our needs.
What's the difference between 1-phase and 3-phase installation?
First of all, an inverter. Single-phase inverters are used in installations with lower power - they allow you to connect the obtained current to one phase of the electric current, satisfying the demand of the devices operating in it. Then the phase that is most loaded with 24-hour power consumption is selected - e.g. kitchen appliances or cooling devices. The three-phase inverter allows you to connect the production to the entire electrical installation and dispose of energy wherever we currently use energy.
Do I need a south roof for my installation to be profitable?
The direction of the world does not determine the profitability of an installation. With a well-designed installation, we can get the same high production from the southern and eastern-western exhibition. In addition to the exposure and the angle of inclination of the panels themselves, there are also important elements that can shade them - such as chimneys, roof swallows or nearby trees.
How to choose the perfect size of the installation?
When selecting the power of a photovoltaic installation, it mustn't be too low or too high. The easiest way to choose the ideal size is based on annual energy consumption (electricity bills). However, it is not always the case that the ideal power installation will fit on the roof - that is why the professional selection of the arrangement and power of individual devices is so important.
What does it mean that the installation has a power of 5kWp?
It is assumed that in our latitude from 1kW it is possible to produce approx. 1000kWh per year. The number of kWh consumed can be checked on the electricity bill. This will approximately allow us to estimate how much electricity we use and how much we need. The installation will not always be able to operate at its peak power - hence it is recommended to adopt an installation slightly larger than our needs.
EQUIPMENT AND ASSEMBLY
Where can a photovoltaic installation be installed?
While pitched roof installations are most often seen, this is not the only possible installation location. The panels can be installed on buildings, e.g. on the roof, flat roof (flat roof), facade and on the ground. Installations on the ground and a flat roof can be both anchored in the ground and laid in a ballast (load) system.
On what type of roofing can photovoltaic panels be attached?
System solutions dedicated to all the most popular types of roofing are available on the market - for a sloped roof, flat roof and free-standing systems. Professional assembly systems ensure failure-free, tightness, stability and safety of mounting the substructure, and thus durability of the entire installation.
How long does the assembly take? Will it damage my roof?
The duration of the installation depends on the size of the installation, but most installations for single-family residential buildings last one day. The panels are installed with the use of dedicated assembly systems, they do not damage the roofing or affect the tightness of the roof.
What are the types of panels and how do they differ?
The most popular panels are monocrystalline and polycrystalline panels. Polycrystalline ones are those in many shades of blue with a visible, irregular grid. Monocrystalline ones are single-colour, dark blue or black, with a texture equal to a grid of squares. They differ in the structure of silicon used in the modules, but in most cases, with the same surface area, monocrystalline panels will have more power.
How much do solar panels weigh? What is the size? Does the price matter?
Most of the panels are rectangular, measuring approximately 1 x 1.7 m and weighing approximately 20 kg. Is it worth paying more for the product? All panels available on the European market are characterized by high aesthetics, efficiency and failure-free operation. However, a higher price usually means better technical parameters - a panel of the same size has more power, a longer warranty or a nicer finish.
Are photovoltaic panels resistant to external factors?
The installed panels are resistant to wind, rain, frost, temperature changes, snow and hail. The tempered glass in an aluminium frame provides resistance to external factors and weather conditions, guaranteed by the manufacturer. In our climate, panels do not require washing, cleaning or snow removal.
Do panels, devices and accessories have a warranty?
Photovoltaic panels have a 10-year product warranty and 25-year guaranteed production capacity (guarantee of yield, efficiency). Inverters (inverters) have a 5-year manufacturer's warranty. Additionally, on our projects, we provide a 5-year warranty for the assembly of installation parts.
What does the performance guarantee of photovoltaic panels mean?
Panel manufacturers, in addition to the standard product warranty of 10 years, also offer a performance guarantee (yield, production). This is a multi-level guarantee: the manufacturer guarantees that after 10 years the power of the installation will not be lower than 90% of the nominal factory power, and after 25 years - 80%. These values may be higher, they vary depending on the manufacturer.
How much space does the installation take up inside the building?
In addition to the photovoltaic panels, the installation consists of an inverter, security and wiring. Indoor and weatherproof inverters are available. Usually, the inverter is mounted on the wall, with two security boxes next to it. The inverter, depending on the size of the installation, has dimensions similar to a small suitcase on wheels and requires approx. 30 cm of assembly clearance on all sides. The whole thing does not take up much space and will fit on the wall of the garage or boiler room.
What is the cable routing to the installation?
In existing buildings, the cable connection between the roof and the inverter is carried out in the attic layers, ventilation risers or facade insulation. Then the cables between the boxes, inverter and switchgear are led in cable trays or wall grooves.
I'm building a house, can I prepare somehow?
Installation does not require any special preparation before assembly. Completed roofing material is required to fix the panels to the roof. To make the wiring invisible after execution, you can prepare grooves in the walls or spread the wires before plastering.
FORMALITIES
When will my PV plant pay for itself?
A properly selected installation for the needs of a residential building should meet almost the entire annual electricity demand. Currently, the return on investment is very short, around 4.5 - 6 years. The installed installation will work without failure for years - the performance guarantee of 80% of the power is up to 25 years.
Is installation on a single-family house cheaper than installation on another building?
For installations that are performed for natural persons for the needs of a single-family residential building with an area not exceeding 300 m2, located on the roof of this building, VAT in the amount of 8% may be applied. In the case of installation on the ground or other building (e.g. utility, production, office, multi-family), as well as installation for companies, the VAT rate is 23%. Comparing these solutions, for the needs of a single-family house, the installation cost will be the lowest on the roof of this house.
Does the installation require ongoing maintenance?
The photovoltaic installation is maintenance-free. Most inverters have a screen on which production data are displayed and several LEDs signalling the correct operation of the device. Most manufacturers also provide a dedicated application that allows for a detailed analysis of the power produced. The installation, apart from enjoying the visible profit - does not require any maintenance.
Do I need approvals to install the installation?
Installation of photovoltaic devices with an electric power of up to 40kW does not require a building permit or notification. This applies to both roof-mounted installations and free-standing installations on the ground. There is also no need to report the installation anywhere before installation - only after the installation is completed, connection to the Power Plant [Zakład Energetyczny (ZE)] is reported.
How to make a notification to ZE?
After completing the installation of the installation, the Application for connection of the micro-installation to the power grid should be submitted to the Power Plant appropriate for the region. Within 30 days of applying, ZE is obliged to replace the meter with a bidirectional one, which will have a measuring system that allows determining the amount of energy consumed and fed into the grid. The meter replacement is free of charge. The final step is to sign a contract regulating the sale of electricity to the grid.
What happens to unused energy?
The installation produces energy during the day and the electricity supplied to the building will meet the current consumption as a priority. What happens when the power produced is greater than the current consumption? The energy is counted by the meter and then fed into the electricity grid. In a situation where the installation is not working (e.g. during the night), consumption will be satisfied first with the energy that we have introduced, and only after it is depleted from the RES resources.
Can I install a larger installation and sell energy?
A common question is whether it is possible to oversize the installation so that it produces much more than the building needs. Of course, you can - but it's not a small-scale profitable business. The sale of energy will take place on the terms of the ZE - for the energy price announced by the Energy Regulatory Office [Urząd Regulacji Energetyki (URE)] for the previous quarter.
Do I pay for putting electricity into the grid?
The settlement is based on the amount of energy introduced and taken from the network. The energy fed into the grid is received with priority. It means that, for example, with high energy production in the summer (we introduce surpluses to the grid), we can then use it in the period when production is lower and consumption is greater, e.g. in winter. A settlement with ZE takes place in the proportion of 1: 0.8, i.e. we recover 80% of the energy fed into the grid.
Are there any limitations when selecting the power of the installation on the part of ZE?
Yes, it should be remembered that we cannot produce a capacity greater than the currently signed connection capacity for the facility. If the installation is to exceed this value, you must first submit an application for increasing the connection capacity, and only after signing the contract with ZE, install the photovoltaic installation.
Can I install batteries instead of connecting to the network?
Yes, it is possible, we are talking about an off-grid system that can ensure the building's energy independence. However, one should bear in mind the cost of the batteries, their performance and their lifetime, which is currently quite short and amounts to several years. This means that after a few years it may be necessary to replace the energy storage with a new one.