The Brief

To provide an off-grid power source for an eel counter at the Environment Agency site at Teddington Lock, Surrey.

The System

Beco Energy Solutions indentified a PV solar power kit as the most suitable technology.

The system used pumps to draw water from one side of the lock to the other via a chamber where the young eels or elvers were counted. The Environment agency had a requirement to run equipment shown in the summer and early autumn which is an ideal match for solar power.

The system gains its power from the externally mounted PV module which is used to charge the battery. A charge controller regulates the charge current to the battery to prevent the battery becoming overcharged and also disconnects the battery if the battery voltage falls to a level that is detrimental to the battery.

Due to the considerable size of the batteries we designed, constructed and installed a custom made frame to support the weight.

Sizing The System

Running an off-grid power supply is an operator unique experience in that is is critical to know what the anticipated user demand will be.

The estimated electricity consumption of an off-grid user was calculated on a daily basis and matched to  the expected output of a solar PV module on a daily basis during different times of the year (using meteoroidal data from a 10 year average based in Devon).

Batteries are used to store the electrical energy generated by the PV modules so the energy can be used during periods when the PV module is not generating. The battery needs to be sized to allow for periods where consumption exceeds supply over an extended period (i.e. during extended overcast days). It is therefore necessary to allow for an ‘overcapacity’ of battery storage to allow for this.