Rural homes, like our permanent residences, require electricity to operate the equipment and household appliances they contain.
A rural home, due to its nature as a residence, has the following characteristics:
– It is not inhabited all year round
– It may be located in a very remote location compared to the existing electricity network
– It may be located in a place with an unstable network or frequent interruptions and faults
– It may be a large modern residence with complex and energy-intensive systems
– It may be a small simple residence with basic consumption needs.
– In some cases, it cannot be electrified as an arbitrary construction
However, what are the appropriate ways to supply electricity to a rural residence, apart from connecting them to the electricity network of the Public Power Corporation (PPC) or even more economically with private electricity providers (e.g., PROTERGIA), which in some cases is difficult to impossible to implement due to the above reasons?
By analyzing their particular characteristics and considering alternative solutions for providing electricity with modern RES systems, we will examine the best possible way to power them.
The philosophy of RES in the production and provision of electricity has the opposite logic from the provision of electricity through the grid and its sale based on consumption. In the above RES systems, we have an initial cost of procurement and installation of equipment, which varies according to consumption and energy needs, and then we enjoy “very cheap” electricity. In contrast, in the provision of electricity through the grid, the initial installation is relatively cheap (for areas with a network) but then we are burdened with consumption charges and regulated charges related to the transmission network, public benefit, etc., which tend to increase continuously in recent years. Also, through electricity bills, we are obliged to pay other entities (Municipalities, ERT, etc.).
The systems we will examine are: Standalone Photovoltaic (Hybrid) Systems and Grid-Connected Self-Generation & Energy Aggregation Systems (Net Metering) via photovoltaics.
Autonomous Photovoltaic (Hybrid) Systems
The owner of a rural residence using photovoltaic panels, wind turbines, and even a combination of conventional electricity generation systems (e.g., diesel generators), becomes independent of the public grid and produces cheap electricity to meet their needs (when visiting their rural home) with the help of energy storage systems (batteries).
Grid-Connected Self-Generation & Energy Aggregation Systems (Net Metering)
With the Ministerial Decision of 30/12/2014, the energy aggregation of produced-consumed energy, known as NET METERING, allows consumers, through the installation of photovoltaic systems, to independently produce cheap electricity and cover (aggregate) a significant portion or all of their electricity consumption.
In NET METERING systems, the generated solar energy can be consumed directly by the owner. If there is no generated electricity (e.g., at night), the consumer continues to source their electricity directly from the grid at prevailing rates. If the total generated energy fed into the grid exceeds the consumed energy, the owner is not entitled to any compensation.
The aggregation of total generated solar energy fed into the grid with the energy consumed by the consumer is done on an annual basis (12 months). The 12-month aggregation particularly benefits the Greek territory, as the surplus energy generated during the summer will cover the reduced production during the winter months.
- When is it appropriate to install a RES system:
Autonomous Hybrid Systems: These systems are ideal in cases where the electrical grid is at a long distance or there are no other interested new residents nearby to share the high cost of installing energy transmission columns and wires. They are also suitable in cases where there are arbitrary constructions or legalization issues, resulting in them not being supplied by the Public Power Corporation. In other cases where the country house is connected to the grid, we need to study the characteristics of the house and its consumption and decide through a documented study-assessment whether it is worth installing an autonomous system or a Net Metering system. All consumptions need to be calculated in detail, including the frequency of visits and the number of guests, as well as the geographical and climatic data of the residence. Daily consumption and solar energy intensity in the area are the key factors for effectively studying a photovoltaic system, so it perfectly meets the owner’s requirements. Given that autonomous systems have more expensive equipment (due to the cost of accumulators), making the initial investment more expensive than Net Metering systems, we must seriously consider the initial investment cost versus its usefulness and the alternative solutions available to us. Large autonomous systems, to meet demands such as heating, cooling, can also collaborate with solar thermal systems and in the near future with solar cooling systems, so as not to overload the system with energy-intensive electrical loads. In any case, a properly dimensioned system becomes future-proof and expandable. Therefore, an owner can start with a smaller and cheaper autonomous system and then, according to their needs, gradually expand it. Indicative Equipment for Autonomous Systems: Photovoltaic Panels, Small Wind Turbine in case of a hybrid system, Inverter, Energy Manager or Charge Regulator depending on the technique, Deep discharge batteries, Mounting bases, Control Panel, Electrical equipment, and optionally a Generator (Photovoltaic Generator Pair H / Z) for backup.
The charge manager ensures the coverage of the loads required in consumption up to the maximum load for which the system was designed. Depending on the available production from the photovoltaic system and other alternative energy sources that may have been adapted to the grid, it deflects energy appropriately either to cover the demand in consumption or to charge the batteries, and ensures the diversion of energy from the generator whenever necessary.
Indicative Costs of Autonomous Systems. Small Country House from €3,000 to €6,000. Medium Country House from €6,000 to €15,000. Large Modern Country House from €15,000 to €60,000+++
Connected Self-Generation & Energy Balance Systems (Net Metering)
The consumer, after a relevant application, enters into an agreement with the Public Power Corporation and one with their energy provider for 25 years, pays approximately €369 to the Public Power Corporation for connection works, and when the work is completed, the new bidirectional meter is connected. Based on the above, we conclude that a country house, which is legal and connected to the grid (and depending on the frequency of visits and annual consumption), if we dimension a Net Metering system of such power that will produce almost as much energy as consumed, essentially will not need to pay for electricity again, due to the energy balance that will take place. This system has a lower initial investment cost compared to the autonomous system, has no restriction on the instantaneous power required by electrical consumption, and is not instantaneously affected by weather phenomena like the autonomous system. In areas where the grid is unstable and there are frequent outages-faults, resulting in problems with vulnerable electronic and electrical appliances, depleting the backup systems (cameras, alarms, etc.) and going out of operation, there is the possibility of combining the Net Metering system with a Backup system. Backup systems consist of accumulators for energy storage, an inverter to provide alternating current 230V – 50Hz, and an automatic switching system from the grid supply to the backup system and vice versa. In case of power outage, there is an automatic switch to the installed backup system, which provides energy directly from the photovoltaic if there is sunlight or provides the stored energy to cover energy needs. When power is restored from the grid, the system recharges the accumulators from the photovoltaic until full charge.
What distinguishes these systems is their enormous autonomy capabilities, from a few hours to several days depending on the dimensioning of the accumulators and consumption loads.
Indicative Equipment for Net Metering Systems: Photovoltaic Panels, Inverter, Mounting bases, Control Panel, Produced Energy Meter, Electrical equipment
Indicative Costs of Net Metering Systems. Mixed Country House from €3,000 to €6,000. Medium Country House from €6,000 to €10,000. Large Modern Country House from €10,000 to €20,000 or more.
Useful Tips. Proper study and dimensioning of the system, as well as the selection of reliable branded equipment and specialized installation companies, are very important, as the performance and longevity of the system depend on them. Preventive maintenance and technical support from a specialized company in RES throughout the system’s life are also essential factors for its smooth and effective operation. PVMAINT IKE, certified according to ISO 9001:2008, is staffed by specialized engineers with many years of experience in the study, installation, and maintenance-technical support of photovoltaic systems and RES systems. With a network of partners throughout Greece, it is your ideal partner and responds promptly to the needs of any photovoltaic system. Contact Information: PVMAINT IKE, AG. SARANTA 22, 18346 MOSCHATO, PHONE: 2104810045-2104810041, FAX: 2104810096, EMAIL: info@pvmaint.gr, URL: www.pvmaint.gr, Contact Person: Filippos Lazarakos.