There is different aspects about PV based storage in houses or grids: In Germany most PV based battery storage systems are mainly used to increse self consumption of the electricity derived from the PV systems instead of feeding the electricity into the grid. This leads economically to an increased profit for the owner of the systems since there is an incentive system for self consumption in place in Germany. Talking about the grid, this leads to lower energy rates being fed into the grid, since the control scheme tries to minimize energy beeing fed into the grid. Which lowers grid extension costs, since less energy has to be transported. From the technical standpoint most of the systems being offered in Germany are connected to the grid like a PV inverter, thus not helping fequency or voltage stability directly. Never the less, it would be possible to at least directly influence the voltage at rural feeders by use of such battery storage systems.

@ Armin : Thank you for your response. What are all the practical constraints you consider in Germany for modelling of PV system to analyse grid power flow, static voltage stability and control, dynamic rotor angle stability and voltage recovery and short

circuit breaker duty, protection design and coordination, control interaction, and

harmonics, etc.

I am agree with @Armin. PV based battery system is mainly used for standalone system not for grid connected system. One more thing, it is also not economical. Solar based power generation is very good if you thrown the generated power into the grid(river).

PV based generation of 100 kW and above is considered for grid interconnection.   However the owner of PV generating unit has tp provide on grid equal amount of diesel or alternative source readily available conneted online.   This obviously means a higher investment and so a higher cost of generation.   However encouraging through subsidies for installing such systems and assurance to buy the excess power pumped back at competitive price will definitely encourage such installations.   Baically the reuirementen forced is only to ensure reliability and stabiliy of the system.  This kind of installation doesnot require storage systems since they are directly connectd to the grid.

Hi Balaji - these two reports from the University of NSW (which I am not affiliated with) might be useful for providing some insight into question: 

• A review of the potential benefits and risks of photovoltaic hybrid mini-grid systems
• PV integration into Australian distribution networks

Hi Balaji,

maybe the following papes help to answer your follow up questions.

Armin

Conference Paper Generic Photovoltaic System Models for WECC – A Status Report

Article Twilight of the Grids: The Impact of Distributed Solar on Ge...

Conference Paper Grid planning and operation with increasing amounts of PV st...

Conference Paper CONTROLLABILITY OF WIND POWER PLANTS CAPABILITIES REGARDING ...

Conference Paper Simultaneity of PV- and wind power-generation from distribut...

Article Approach for ancillary service provision by decentralized en...

Conference Paper PV-Benefit: A Critical Review of the Effect of Grid Integrat...

@ Armin: Thank you for your response. I will get back to you once i gone through...

@ Dylan :Thank you for your response. I will get back once I have gone through those articles...

@ Rajagopalan :  Thank you for your response...

PV storage in grid would be beneficial to increase grid inertia. you can refer to paper ·         Vaclav Knap, Rakesh Sinha, Maciej Swierczynski, Daniel Stroe, Sanjay Chaudhary, “Grid Inertial Response with Lithium-ion Battery Energy Storage Systems”, IEEE International Symposium on Industrial Electronics (ISIE 2014) to be held in Istanbul, Turkey, June 1-4, 2014

There are other several advantage of battery storage  connected to grid in order to increase reliability and stability.

it can store energy when the production from renewable source connected to grid is surplus and would release energy during peak

would be helpful for providing inertial response during sudden disturbance in grid,

can be helpful for peak shaping if managed properly: ·         Sinha, R.; Rodriguez Moldes, E.; Zaidi, A.; Mahat, P.; Pillai, J.R.; Hansen, P., "An electric vehicle charging management and its impact on losses," Innovative Smart Grid Technologies Europe (ISGT EUROPE), 2013 4th IEEE/PES , vol., no., pp.1,5, 6-9 Oct. 2013

In general storage system can help in peak power shaving which means to store energy during non-peak period to share it during peak-period. It also used to mitigate the fluctuation effects of the renewable energy systems as PV and wind sources.

@ Yousry : Thank you for your response. Can we a vision towards effective Power Market?