PV systems are divided between two main technologies of using energy: on-grid systems that are based on constant connection with energy grid and off-grid technologies that use batteries to accumulate energy from PV modules.
Thanks to set of batteries connected to such systems they are able to accumulate whole energy from your PV system in your building. Those systems also called stand-alone power system (SAPS) give us full autonomy with no need of connection with electrical grid.
In the other hand, in case of any malfunction of our system we don’t have access to energy from electrical grid at all. What is more despite all advantages of off-grid systems they are still relatively expensive. High cost of batteries makes total cost of off-grid systems even 40% higher than typical price of on-grid solutions.
If you want to read more about storage systems check our previous article.
Nowadays it is the most popular technology of PV systems. On-grid provide you constant connection with electrical grid. In case of such systems whole additional energy from PV systems is going to the grid. Thanks to that you can sale that additional energy and take it from the grid in case of lack of energy from sun.
No need of battery packs and support mechanisms like Fit-in-Tariff make on-grid systems much cheaper then off-grid system.
What system should we choose?
Unfortunetally in most cases the answer is simple: on-grid. High price of battery packs and undevelopment technology cause that off-grid solutions are uneconomic.
In the other hand it doesn’t mean that it will be permanent situation.
Constant growing prices of energy, low quality of electrical grid and development of modern technologies can cause that off-grid systems will be in the future more and more popular. Many experts predict that in the futere autonomic systems will be a standard in household solutions. Thanks to that we will be completely independent and we will don’t have to rely on support mechanism or large energy suppliers.
Even now in countries like Australia, USA or South Africa it is in some cases cheaper to install off-grid systems rather then developing electrical grid.