Autonomous photovoltaic systems
The purpose of an autonomous photovoltaic system is to provide electricity to a house or any other place (e.g. the holiday home, the boat, etc.) using energy from the sun, without dependence on the PPC network, so there are no bills , fixed, line transmission cost (clock) etc., only "free" energy from the sun.
Now autonomous electricity supply with autonomous Photovoltaics is not only economical but also reliable. The electricity supply is uninterrupted and capable of supplying any load as long as the proper study has been done by a specialized engineer for autonomous Photovoltaics.
Also another way to cover our energy needs, are the hybrid systems that take advantage of solar & wind energy at the same time, which have photovoltaic collectors and wind turbines.
The stand-alone system is similar in its basic structure to the back-up backup system, only it is installed on permanent bases and is of course larger in size.
With the autonomous system we can cover the electricity needs of the place where we install it and they cannot be covered by any other form of energy.
Depending on our needs, the total cost of an autonomous system ranges from a few hundred to a few thousand euros.
The maintenance required by an autonomous system is minimal and mainly concerns a periodical (a few times a year) cleaning (dusting) of the surfaces of the solar collectors and checking the accumulators (batteries).
Aenaos Energy Systems has been specialized for decades in autonomous photovoltaic power supply systems and with experience of hundreds of installed projects, throughout Greece, guarantees a reliable study, immediate supply of materials and an efficient and economic autonomous photovoltaic system.
The use of photovoltaics in autonomous systems can cover the electricity needs of homes located in hard-to-reach areas or remote from the D.E.H. network. and it proves many times to be a profitable option compared to the cost of connection to the D.E.H., or even to the use of conventional means of power generation that have high operating costs and prove to be much more expensive in the long run.
The direct production of electricity offers relative independence from D.E.H. resulting in a large number of private individuals installing photovoltaic systems aiming to avoid higher prices in the future or the effects of sudden power outages.
A huge variety of consumer products with a wide variety of uses can be exploited and leveraged by photovoltaic applications. In general, photovoltaics can be used wherever the autonomous production of electricity for small consumptions is deemed necessary. More specifically, the following applications can be mentioned:
- Pocket computers
- Portable electrical appliances (lamps, TVs, refrigerators, etc.)
- Mobile homes - Mobile homes
- Prefabricated Houses
In terms of telecommunications, radio and television repeaters, telephone systems and autonomous telephone booths, control and remote management systems, weather stations can be supported. Photovoltaics are an ideal solution for areas where the installation of such telecommunication systems is necessary and it is not possible to connect to the electricity grid.
The application of photovoltaic elements is an ideal solution for the production of electricity in remote rural areas where there is no connection to the electricity supply network. Therefore a large category of agricultural applications can be supported such as:
- Water pumping
- Greenhouse heating
Photovoltaic technology is an excellent solution for outdoor lighting. Avoiding an electrical installation connected to the power supply network, which for safety reasons must be watertight, proves to be a significant benefit. With the use of photovoltaics, a continuous supply of electricity is ensured during the day which is accumulated in order to be consumed at night. Such an outdoor lighting system includes the photovoltaic element, the accumulator, as well as a photocell for the automatic operation of the luminaire at sunset. A wide variety of application coverage can be achieved such as:
- Street lighting
- Bus stops
- Telephone booths
- Signaling systems
- Security lighting systems.
The basic equipment of an autonomous photovoltaic system is:
Photovoltaic panels (photovoltaic panels) which collect solar energy and convert it into electricity. Photovoltaic panels are current sources and produce direct current and voltage. The two main types are monocrystalline and polycrystalline panels. A photovoltaic panel is characterized by its power in ideal conditions (Wp). In a stand-alone PV, special attention must be paid to the orientation and tilt of the PV panel.
The charge regulator or charge controller (solar charge controller) is the "brain" of the autonomous photovoltaic system and is the subsystem that takes charge of charging the batteries. It takes as input the output of the photovoltaic panels and converts it into suitable current and voltage levels for charging the batteries. It also monitors the charge level and accordingly makes the decision to stop it when the batteries are full. We have two charge controller technologies MPPT (synchronous-intelligent) and PWM. Now in modern autonomous photovoltaics we always choose MPPT regulators.
The batteries or accumulators (batteries) of an autonomous photovoltaic store electricity for when solar energy is not available (evening or cloudy).
The most commonly used PV batteries in stand-alone PV are lead-sulfuric acid deep discharge and in recent years lithium PV batteries.
They are divided into open type or closed type and are divided according to their voltage usually into 2 volts, 6 volts and 12 volts. Photovoltaic batteries are characterized by their voltage (V), their capacity (Ah) and their charge-discharge cycles.
Attention needs to be paid to the temperature of the room in which the batteries of an autonomous photovoltaic are located and to adequate ventilation, especially when it comes to open-type batteries.
In autonomous photovoltaic systems with high requirements, you recommend the use of 2V cells.
The inverter converts the dc voltage of the batteries into alternating current. It is characterized by its power and indicates the set of simultaneous loads that an autonomous photovoltaic can "lift". There are pure and modified ("dirty" current spectrum capable of damaging electronic equipment) sine wave inverters. The inverter is characterized by its power (kVA), the starting power it can provide for a short period of time, the operating battery voltage and whether it can charge batteries or not (simple inverter or inverter/charger). In modern stand-alone photovoltaics we only choose pure sine inverters.
The wind generator converts wind energy into electricity and is usually used as a supplement to photovoltaics. It is usually chosen in autonomous photovoltaic systems that require operation in the winter as well.