Duo to low voltage at PV output, Boost converter is offered. 

All choppers have arround 98% of efficicency. The choice of the DC-Dc converter depends on the desired output voltage of your application. I hope this would helps you.

Topology with uninterrupted current is preferable.

PV-cells are degrading when pulsed current is consumed out of them. Boost and quasy-impedance converters are good for this reason. Most typical solution is a boost converter in combination with resonant converter at constant frequency (when you get full-resonance and almost no switching loss). You can see this in various paper (for example authors with co-operation with J.W.Kolar made the microconverter this way)  and TI solutions are based on this principle.

Why do they use a transformer? You have to decouple the panel from grid(if this is grid-tied solution). Otherwise the common mode current makes it dangerous. Another way to get rid of danger of leakage currents and voltage on panel frames are choppers and current chopping topologies (like H5, HERIC etc.).

You can also use the buck, flyback, forward converter etc. but you have to take in account that you must include a current filter in order to design a good solution. But that negatively affects your overall efficiency and power density.

The answer is you can use almost any topology, but you have to think which is better(on design stage, is this scientific or industrial solution, which type of converters you have built before and which are built by people around you) for you. As any engineering solution you have to deal with a tradeoff.

Thank you all 

SEPIC Converter has the following advantages

1-Continious input current

2-Non Inverting output

3- Buck-Boost Operation

4- Simple topology

5- Low side switch drive

Hope the answer !

Thank you

Thanks !

Hi Saad Motahhir,

For PV applications, the perfect fit or "best" converter depends on your (or users) requirements and the trade-offs which you are ready to accept. Generically, boost derived topologies with very low input current variation (current ripple) are preferred.

Thank you dear Prabhakar, did you already work with boost converter ? 

It depends on the load current and its variation( d/dt)  which is a major limiting factor. SEPIC or CUK converters can be a good choice. Transformer coupled topologies are also preferable but in boost mode of operation.More over it is not preferable to operate the PV panel at large current values. It leads to drop and heating problems and one need to design appr.. heat-exchanger. SO..it your design.. Check all the factors before concluding which one is best suited. All the best.

ABS 

Thanks 

Yes, Saad. You may refer to some of my works and other works - almost all the converters that have been developed will be fit enough for PV applications.

 Thanks dear Prabhakar

Thank you dear shaw 

Thank you for your answer

The following study says;

"The DC-DC buck converter is more suitable for PV arrays connected in series whereas the DC-DC boost converter works satisfactorily with PV arrays in parallel connection. The DC-DC buck-boost converter integrated with solar PV system is found to be the most effective solution in producing maximum PV output power at any circumstances."

Topologies of DC-DC converter in solar PV applications.

Article Topologies of DC-DC converter in solar PV applications