In most areas, the arrival of solar radiation and the presence of wind are in antiphase (i.e., when the sun is shining brightly, there is usually no wind, and if there is a strong wind, there is no sun). Therefore, to ensure uninterrupted power supply to the stand-alone facility, reducing the required capacity of the wind turbine and solar panel and battery capacity, improving the modes of operation of the station in many cases it is advisable to use a hybrid wind solar power plant.
Types of wind-solar systems
Stand-alone wind-solar electric systems can be of different capacities. To power low-power loads – such as 2-3 fluorescent or LED lights, TV, radio and other low-power DC load, a small refrigerator – the system is built on the basis of low-power wind turbines rated at 200-100W. Such systems are recommended when the average annual wind speed of 3-3.5 m / c. You will not get the most power from your wind turbine, but the price of the wind turbine allows you to get electricity for quite reasonable money.
More powerful systems based on wind turbines up to 5 kW can power detached cottages and small industrial facilities. The cost of such a wind power system is high, its use is recommended when the average annual wind speed of more than 4 m/sec. Otherwise, the payback period may stretch for many years. Use wind turbines with capacity over 5 kW should be used with great care and carefully choose their installation site. Average annual wind speed in such places should not be less than 4 m/s, otherwise you will get from your wind turbine only a fraction of the passport power generation.
Virtually any system of power supply with a wind turbine can be supplemented by a gasoline or diesel generator to power AC loads (lighting, TV, audio system, refrigerator, washing machine, etc.) as an additional source of electricity for the period of no wind or peak load, as well as solar panels.
The advantages of hybrid stations are especially felt in year-round use. In this case, in winter time, the main electricity generation falls on the wind power plant, and in summer – on solar photovoltaic modules.
Currently, offers low-power wind-solar stations with wind turbine capacity of 200 to 5000 watts and the capacity of solar panels from 100 to 3000 watts. All these wind-solar stations are built on the basis of low-power wind power stations. The voltage on the DC side may be 12, 24 and 48 V for wind turbines with capacity from 200 to 5000 watts, or 120 V and above for wind turbines with higher capacity. It is possible to connect solar panels with almost any capacity through an additional charge controller.
It is possible to complete a system to order with the required set of photovoltaic solar modules, the inverter capacity and type.
What the wind-solar system consists of
In general, the hybrid wind-solar power plant consists of the following components:
- A wind turbine, mast, battery charge monitoring and control unit, ballast load
- Photovoltaic solar modules
- Charge controller for the solar panels (can be integrated into the hybrid controller for wind turbine)
- Inverter of required power
- Rechargeable batteries that are well tolerant of deep cycling modes – carbon lead-acid, gel, or even better – lithium-iron-phosphate batteries.
- Connecting cables, other electrical wiring equipment.
- In wind-solar hybrid power plants, we recommend using lead-acid deep discharge OpzV batteries or carbon batteries. It is also possible to use traction batteries with liquid electrolyte. It is best to use lithium batteries, which have a number of advantages over lead-acid batteries (they are not afraid of being in a discharged state, they charge quickly, have more charge-discharge cycles, etc.).
It is not recommended to use conventional batteries (both sealed and with liquid electrolyte), and especially starter car batteries, as they are not designed for cyclic modes of charge-discharge. Try to initially exclude the “weak link” in your autonomous power supply system. Alkaline batteries are not recommended because they cannot be recharged with low currents, and in most cases their charging modes are not provided in commonly available UPSs and chargers.
To ensure uninterrupted power supply, it is also desirable to introduce a small gasoline-powered unit in case there is no wind and no bright sun for an extended period of time. In this case, the inverter should be replaced by a UPS with a battery charging function, or, if large charging currents are needed, use a separate battery charger.
Also remind you to install a mast of sufficient height – the lower edge of the blade must be at least 10 meters above any obstacle within 500 m of the wind turbine. Otherwise, the energy output of the wind turbine is very much reduced, and you will not get the expected effect from the use of the wind turbine. A low mast is the main reason why wind turbines produce less than they are designed for.