Solar Power Plants - 10 most FAQ

1. How big of a solar power plant is required for a four-person household?

According to the statistics gathered by Slovenian electrical distribution companies on power consumption for a family of four and based on the assumption that a well-designed solar power plant produces 1119 kWh/kW /year, a solar power plant with 3.5 kW to 4 kW of power is required to meet your need for electricity. Families with above-standard needs, require a solar power plant with approximately 7 kW of power.

But at the same time, we should clarify that solar power plants are usually not meant for our own consumption of electricity, since we would need batteries to store energy due to the dynamics of "production". Power plants are connected to the grid and all the energy they produce is "sold" to the network at a subsidized price, while the energy that we require is simply drawn from the network and we continue to pay a "normal", non-subsidized, market price for it.

2. What kind of roofs are appropriate for solar power plant placement?

A solar power plant can be constructed on any roof, regardless of its shape and type. Naturally, we have to adapt to the laws that affect the optimum operation of solar power plants. For this reason, we recommend roofs and surfaces that are facing south, that have no shadings on the surface itself or in the vicinity and that are covering buildings with unquestionable static integrity. The roofing also has to be in the condition to hold the additional weight of the photovoltaic system.

3. What is the lifespan of solar power plants?

The lifespan of a solar PV power plant is 30 years and more, which makes it a very reliable and long-term investment. The safety of the investment is, along with feed-in tariffs, also further guaranteed by long-term income from produced electricity, since after the period of reimbursing the invested funds ends, the produced electricity brings nothing but net profit to the investor.

4. How high is the income from solar power plants?

The income from solar power plants depends on their size, on the optimization of the entire system and on their operation. The average amortisation estimation is 12 years with an average rate of return between seven and nine percent. With a properly set plan and a favourable ratio of your own investment and an external source of financing, the personal investment is reimbursed in six to eight years, and the entire investment in 12 years. A solar power plant is an investment in renewable energy sources, which contributes to mankind's sustainable development and to the reduction of greenhouse-gas emissions.

5. What needs to be considered, before we decide to invest?

Optimal placement and operation of a solar power plant and consequently the maximum energy yield largely depend on the following key elements:
  • choosing the right location,
  • choosing quality components for the plant, especially photovoltaic modules as the generators of electricity, and inverters,
  • choosing experienced, professionally qualified and verified contractors, who will know how to design a solar power plant with optimal system configuration, how to install it and how to obtain all the necessary consents and permits,
  • an optimal ratio between the value of the investment and a specific yield, which is guaranteed by the contractor (this ratio determines the cost of producing electricity, which must be as low as possible).

6. What kind of maintenance do SPPs require?

A solar power plant is a system that incorporates numerous elements and is intended for permanent and reliable operation. The investor's greatest loss of income is the time, when the power plant is not producing electricity due to various reasons, since the contract on leasing electricity applies nevertheless. The top priority is to continuously monitor the system  and its efficiency, and to detect reduced efficiency and act immediately.

7. How are solar power plants insured?

Insurance for a solar power plant is approximately 0.2 percent of the investment value per year. It is around 100 € a year for a10kW plant. The individual insurance value depends on the size of the power plant, on the number of policies on which we insure it, and on the specific offer made by an insurance company. Good insurance for a solar power plant should cover the following risks: fire, (in)direct lightning, explosion, natural hazards (storm, hail and flood), mechanical damage, theft and robbery, and third party insurance.

8. Which documentation is required for connecting a solar power plant to the grid in Slovenia?

A conceptual design project (IDZ), an execution project (PZI), a project of executed works (PID), connection consent, contract on connecting to the distribution network and a contract on the purchase of electricity.
  • The IDZ is the introductory part of the project documentation, the purpose of which is to obtain design conditions or connection consents from competent consent authorities.
  • Adequacy of the PZI is checked by the distribution company operating in the area where a solar power plant is being constructed. If it is deemed appropriate, you may start assembling the plant: otherwise the distribution company sets project conditions. Installation may begin when they are met.
  • After the installation of the solar power plant, a visit is made by the electrical inspector and the representative of SODO, the electricity distribution system operator.
    The designer and the contractor are present during the inspection, with all the documentation for the project works. The power plant owner can sign a contract for connection to the distribution network and the SODO may issue a consent for the connection.
  • The owner of the power plant then has to obtain a declaration for production machinery from the Energy Agency of the Republic of Slovenia, and finally, he/she enters into a contract on the purchase of electricity with the BORZEN, d. o. o. company, the organizer of the electricity market, which operates the support centre - the operational operator of support schemes for electricity production from renewable energy sources.

9. How does the government support solar energy?

The Republic of Slovenia supports the construction of solar power plants by ensuring the purchase of produced electricity at set purchase prices or by providing operating support if the power plant owner is selling electricity on the market on his/her own.

The feed-in tariffs that are determined in the Regulation on Supports for the Electricity Generated from Renewable Energy Sources are lowered each year in accordance with governmental provisions and the starting position from 2009. Prices are somewhat higher for integrated photovoltaic systems and a little lower for solar power plants which are located as separate objects on the ground. A contract for the purchase of electricity is signed for 15 years, which means that you are selling the produced energy at the same price for the entire contract period.

10. What do we do with the generated electricity after 15 years?

Government subsidies in the form of feed-in tariffs in Slovenia are favourable for investors. You enter into a contract for the purchase of produced electricity for 15 years (the subsidy remains the same for all 15 years), and in this period it has been depreciated. This means that after 15 years the investor earns money by selling green electricity and becomes active in the electricity market, because of the right to choose a provider of electricity. It is important that the investor selects the best provider, since his earnings depend on this.

Plan-net Solar d.o.o.

Kamnik pod Krimom 8B
  1352 Preserje
+386 1 363 31 31

Feb 9, 2016
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