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Frequently Asked Questions

  • Technical/structural requirements
    • Can I install a solar PV system myself?
      The ready-made configurations of solar PV systems that we offer include connection diagrams that make their installation easy to perform by the customer. Off-grid systems, depending on their size, require basic knowledge of electrical engineering and their self-assembly is completely acceptable. It is important to follow the attached diagrams and instructions for installation and use of the separate components. In on-grid systems, the requirements for compliance with security conditions are slightly different. Relevant protocols and declarations of conformity by technical persons must be submitted for connection to the network.
    • What is the technical warranty of the solar PV modules ?
      The technical warranty of the solar PV modules, which we integrate into our solar PV systems is guaranteed by Munich Reinsurance Company:
      Гаранционен период на панелите
      A chart of the length of the warranty period of the CSUN solar PV modules
      The modules come with a 12-year technical warranty. Additionaly, there is a 12 year guarantee for maintaining 90% of the power capacity of the modules and a 20 year guarantee for 83% of their power capacity. The solar PV modules, which we integrate into our ready-made solar PV systems and the off-grid systems which we design come with a 10 year tehnical warranty and 25 years for maintaining 80% of their power capacity. Detailed information about the technical characteristics of the solar PV panels which we offer, can be found in our online store at www.solarhouse.bg.
    • I have a house and I would like to power it with solar energy entirely. How many solar PV modules do I need?
      With off-grid solar PV systems households rely entirely on the electricity they produce. These systems are most often used when there is no access to the grid or it is very expensive to connect to it. Or you aim to avoid the lengthy procedure that comes with getting connected to the grid. This type of solar PV system can have all kinds of power capacity. An off-grid system can power from a simple lamp to an entire production base. The sizing of off-grid systems is a complex process and depends on many factors. It depends on whether the system will be used all year round or seasonally. It depends on the power of the appliances, how many hours a day they will be used, the location of the system and many more. In order to calculate exactly what kind of off-grid system you need, you must first gather information about the appliances you will use and their unit capacities. Estimate how many hours a day they will work and then send us an inquiry so that we can offer you the best solution. Contact us for a free consultation.
    • Can I use a three-phase inverter with a single-phase grid?
      No, unfortunately it is not possible to connect a three-phase inverter to a single-phase network. Only the opposite option is possible - the connection of a single-phase inverter with a three-phase network.  The three-phase inverter will not start without seeing three phases and zero. You could contact us for a free consultation.
    • How much will the efficincy of the solar panel decrease if it faces south-west, with a 40 degree slope?
      A specialized software is required to calculate the fall in efficiency at different orientations and at different inclines. It is also possible to calculate what the losses are and, accordingly, what the production will be if you change the slope or orientation of the solar PV panels. For this purpose, however, it is good to consult with experts in the field. You could contact us for a free consultation.
    • Can a hybrid system be transformed into a battery-free off-grid system?
      The term "battery-free off-grid system" is a bit confusing, because a battery-free solar PV system can hardly be off-grid. That is, in the absence of batteries, it can only work when the amount of energy produced by solar panels is large enough to power the energy appliances. If there is no additional power supply from the mains or from a generator, the solar system becomes very unreliable. In our opinion, the answer to this question is rather NO, because we say again, the system would lose its autonomy.
    • How can I curtail the "excess" electricity from the inverter to the grid?
      The curtailment of "excess" energy to the main grid in most inverters is done by means of the so-called "smart" electricity meter or also known as a Smart Meter. Its function is to constantly monitor the consumption on site, whether it is a house, warehouse or a large production facility.The device transmits this information to the inverter 24/7. In this way, the inverter knows at any given point in time whether the amount of energy produced is greater than the amount consumed. It is when production exceeds consumption that this "excess" energy begins to return to the grid. If the inverter detects a situation in which the production is greater than the consumption, it immediately reduces its production so that it is equal to or less than the consumption of the site. In this way, the return of energy back to the EDC network is avoided.
    • What is the annual yield of a 5kW,10kW, 30kW solar PV plant?
      The annual yield of a solar PV system depends on a number of factors, including its location, whether it will be built on a rooftop or land, the slope and orientation of the property / building with regards to the sun. The figure below shows the estimated production of a ground-mounted solar PV plant with a capacity of 30kW, located in the region of Pazardzhik, with an ideal slope and orientation with regards to the sun. This system will produce 39,265.12 kWh per year. A system with a power capacity of 5kW will produce 6,544.19kWh under the same conditions, and a system of 10kW - 13,088.37kWh per year. In general, in Bulgaria, a power plant operates between 1200 and 1400 hours per year, depending on the region in which it is installed. That is, if it is 10kWp, at 1200 hours per year, it will produce about 12,000kW of energy per calendar year. месечно производство на слънчев енергия от 30kW система
    • What is the area required for the installation of a solar PV plant?
      The area required to install a solar PV system depends on a number of factors, including its location, whether it will be built on a rooftop or land, the slope and orientation of the property / building to the sun. The size of the solar PV panels that the system will be equipped with are also a factor, given that technology is evolving and over time has managed to gather more and more power capacity on a smaller area. You can use the following values ​​as a reference point:
      • ground-mounted installation - the required area is about 10 sq.m. for 1kW installed power.
      • ground-mounted installation (with "canopy" type construction) - the required area is about 5 sq.m. for 1kW installed power.
      • roof (flat or with imperfect exposure / slope) - the required area is 8-10 sq.m. for 1kW installed power.
      • roof (with good exposure and slope - south, 15 degrees or more) - the required area is 5 sq.m. for 1kW installed power.
      The data is, of course, indicative and depends on the specificity of the site, as well as on the type of solar PV system.
  • Energy production and return
    • If I sign a PPA, the contract will be valid for 15 years, but feed in tariffs will be changed annually or will the tariff which was set at the time of contract signing be valid for the duration of the contract?
      The feed-in tariffs for solar PV energy are determined annually by a decision of the Energy and Water Regulatory Commission (EWRC) on July 1. The new tariff applies to all new investments in solar PV systems which are connected to the grid after this date. Its value is fixed for the term of the Power Purchase Agreement (until 2035). That is, at whatever price you sign a contract, it will remain the same until the end of 2035.
    • Is it possible for feed-in tariffs to be cancelled for solar PV systems up to 30kWp?
      The preferential prices for purchasing energy from the FEC are determined by a decision of The Commission for Energy and Water Regulation (KEVR) every year on July 1 and is fixed for the term of the Purchase Agreement, but not longer than 31.12.2035. After this date, all PV plants start selling the produced electricity on the free electricity market, as all plants above 30kWp trade the produced energy at the moment.  Until 1-07-23. the preferential price for purchasing energy from photovoltaic plants with a capacity of 5 to 30 kW inclusive is BGN 168.24 per mWh.  There are constant rumors about what will happen to preferential prices. Our advice is not to believe everything you hear, because the people who actually know what will happen are very few and they work in the State Environmental Protection Agency and are not in the habit of sharing such information.
    • What is the total value of the investment in a 30kW solar PV system and what are the associated monthly costs and revenues from the system?
      The value of the investment in a networked photovoltaic power plant (PEP) with a capacity of 30kW depends on a number of factors. It depends on the type of equipment, the location of the property, as well as the type of structure on which the panels will be installed. Equipment prices also often change based on supply and demand at any given time. At the moment, we offer design, supply of equipment, construction and commissioning of a 30kWp power plant for a total value between BGN 42,000 and BGN 44,000 including VAT. Income from the investment depends mostly on the preferential price for which the respective purchase contract was concluded. The purchase price is determined by a decision of KEVR every year on July 1. It is fixed for the term of the Purchase Agreement, but not longer than 12/31/2035. After this date, all photovoltaic plants start selling the produced electricity on the free electricity market. From 1-07-2023. the preferential price for buying energy from a FPP with a capacity of 5 to 30 kilowatts inclusive is BGN 172.88 per MWh excluding VAT. By law, the PSUs are required to purchase the entire amount of energy produced by these PEPs until reaching 1,406 hours of annual system operation time. A 30kW PEP in Bulgaria produces between 35 and 40mWh per year, which is within the permissible production for purchase at a preferential price. 0.03 x 1,406=42.18 mWh This production generates for the investor between 6,500 and 7,000 BGN per year. These revenues vary on a monthly basis, according to the season and the intensity of sunshine in the given month.  The only costs under the FEC are fees and taxes on these additional revenues. The system does not require any technical support. Solar panels need regular cleaning to ensure maximum efficiency in their operation. On this page < /a>you can view a financial analysis of the investment in a system with a power of 30kW, the validity of the purchase preferential price is until 01.07.2023, and the validity of the value of the equipment is one week from the publication of this analysis (08.07.2022) .