There are two types of solar panels 1. Poly-crystalline 2. Mono crystalline 

1.   Polycrystalline are the most proven and time-test technology in solar modules having more than 40 years of the track record. Comparatively cost is lower and suitable for all the weather condition.

2. Mono crystalline PERC modules are relatively new technology and have higher area of efficiency in terms of output. Comparatively cost is higher and in terms of efficiency is slightly higher.   

Note: Residential plant like 3kw polycrystalline is best & efficient in terms of cost and efficiency of the system