Systems for small stables and agricultural buildings

1803 Often in the case of small stables and agricultural buildings all that is required is lighting and perhaps the occasional use of electrical hand tools. In this case a smaller system can be used. stables supply The Marlec range of wind chargers is well suited to such applications.

Size of wind turbine

In this case the electrical output of the wind turbine is stored in a battery bank to provide energy and power on demand. The size of the wind generator required now depends directly on the average electrical energy consumed. The size of the battery bank will depend in part on the peak power required and also the degree of dependence on the wind energy source. It would be unwise to rely solely on wind power since calm periods would require excessively large battery banks, In very light energy and power requirements wind is often supplemented by photovoltaic panels. Let's look at a simple exampleProviding lighting for a small stable.

Storage of electrical energy is done by batteries. The size of the battery bank is determined by the reserve of energy required.

Battery capacity is specified in ampere hours, Ah. The life of a battery is quoted in terms of charge / discharge cycles. Deep cycle lead acid batteries should be used rather than the standard car battery which is designed to supply very large peak current for starter motors. The batteries should not be allowed to discharge fully as this will reduce their life- 50% discharge is a reasonable guideline. The control system should take care of this automatically,

Lighting is required for a small stable consisting of two loose boxes and a tack room. The maximum daily use of the lighting will be 3 hours and 4 x 15 wattt energy saving lightbulbs will be used.

Total daily electricity demand: 3 x (4 x 15)/1000 kWh = 0.18 kWh

energy draw from battery: 0.18/0.8 kWh = 0.225 kWh (assuming Inverter efficiency 80%)

Losses in battery 20% battery capacity used: 0.27 kWh

We will restrict the discharge to 50% and have 5 days reserve capacity. Size of battery bank needed: (0.27 X 5)/0.5 kWh = 2.7kWh which is equivalent to approx. 196 Ah. So two 100Ah batteries would be sufficient.

The power required is simply given by the number of lights powered on at any given time. Peak power is then 4 x 15 W or 60W. An inverter rated at 100W would be adequate for this. In a real life situation a larger inverter would probably be chosen to give the possibi;ty of operating electrical hand tools such as clippers.

Essential requirements

a survey - average wind speed and presence of obstructions such as trees etc.
planning permission from your local council