Monocrystalline were typically more expensive and produced in larger numbers for a residential house or industrial applications. This is no longer the case and the costs aren't that different so consideration could be made regarding the purpose, site, installation, orientation to the sun etc for a year-round yield benefit. There are always differing opinions in this debate but if your panels aren't going to be mounted at 90 degrees to the sun then a wider sunlight collection method should be considered. In which case Monocrystalline may give a better year-round energy gain.

Polycrystalline, however, performs better in direct sunlight so if mounted at the correct angle facing directly north (if in the southern hemisphere) then your peak daylight yield will be greater. If this is matched to discharge cycles then performance could be measured in usable power during collection rather than stored energy which has to allow for electronic equipment conversions and losses and chemical conversion losses in turning DC energy into battery stored energy. Most small panels which are 36 cell under 200w are Polycrystalline so the decision of which is best suited to your installation might become a whole lot easier.

Most of what's discussed here is our own opinion as this topic has so many variables from manufacturing materials, cell connections, place in the world, installations, angles, colour, strength, quality, performance over years (25 year warranty on some panels) and rated output after 20 years.