Various different combinations of renewable and other energy sources can be implemented to suit specific requirements. The automatic interaction of these different components can be configured to suit a number of predetermined requirements.
Grid tied Systems with limiter
In many cases, especially in South Africa, feedback into the grid is not allowed. A grid tied limiter will prevent feedback. Since no power can flow back into the network, it would be best to design the system in such a way that most of the generated power can be used directly. Since the limiter prevents feedback, generated power that is not used will simply be lost. If we have a 5 kW solar array but we are only using 3 kW at the time, the extra 2 kW would feed back into the grid with a standard grid tied system. When the limiter is added to prevent feedback, it will tell the solar array to only produce the 3 kW that is required. The extra 2 kW is thus lost. If our power requirement increases to 8 kW, we will get 5 kW from the solar array and 3 kW automatically from the grid. It goes without saying that all this will only happens when the sun shines!
To size and design these systems correctly and prevent over engineering, it is critical that the base daytime load be determined first. Such a load profile can be established through our energy audits.
Limiter systems are perfect for business, commercial and industrial applications where the majority of electricity is consumed during sun hours.
Hybrid grid tied/grid interactive systems
Grid tied systems could be combined with grid interactive systems to create a hybrid system that will still make power available when the grid network is down. Essentially a UPS inverter and battery bank is added to the basic grid tied system. When Eskom is not available, energy will be supplied by the battery bank. Since the battery bank only needs to be big enough to provide electricity for relatively short periods, a much smaller battery bank can be used which would save upfront costs.
Systems using more than one source of renewable energy
Standalone systems, grid interactive systems and even grid tied systems could be designed to utilize more than one source of renewable energy. Solar panels could be combined with a wind turbine or even a hydro turbine if the resource is available.
Specialized hybrid systems
The various systems mentioned could also be combined in many different configurations, depending on available energy resources, load profiles and specific functionality required. Even a standalone, grid tied system can be configured – yes, the description doesn’t make logical sense! We prefer to call it a grid tied system in island mode or a standalone AC coupled system.
For more professional information on the development and design of a hybrid system for your particular application, contact the ALLSOLAR branch nearest to you.