This type relies on a single head transformer to which all solar panels are connected directly. The solar panels attached to this transformer are in groups, each group being panels connected in series. If the number of panels in each group is small (3-5 panels), then the voltages are few. We call this method "low voltage", and it is not very affected by the problem of shadow that falls on some of its parts. But its main problem is the high current that needs thick and expensive wires. The other way is "high voltage", in which more solar panels are used per group. This method helps reduce the thickness of the wires a lot, but it is more affected by the occurrence of shade on the solar panels in groups. This type is the cheapest and easiest to maintain and install.
String Inverter: Reliance here is only on one transformer for each group, instead of using a main transformer for all groups, as in the case of a central strain. This type has the advantage of adapting better to sunlight changes on solar panels, meaning that each group has become Independent and not affected by the rest of the groups when the shadow falls on them. Not all groups need to be very close to each other as in the central transformer, as the amount of wires here is less. This type of transformer is smaller in size than before. Also, modern technologies use two or more groups in this converter..
Solar panel adapter
As the name implies, each solar panel has its own transformer. These adapters are the smallest compared to the previous two types. These converters produce the highest possible power all the time (MPP), and it's also easy when adding another set of solar panels. But in general this type is the least prevalent because of its high cost and its great influence on external factors because it is close to the solar panels outside.