The BLK12S Thunderbird Solar Electric Fence Energiser is capable of powering up to 10km of normal fencing wire, or 200m of ele. Therefore this model is a good starter energiser for those who want a portable energiser with enough power to suit a medium fencing application.
The BLK12S is very similar to the Thunderbird S75B in terms of performance. Please note that it does not come with an AC adaptor. Therefore you will need to charge the energiser directly from the solar cell rather than using mains power.