Limiting factors of PV Modules and Thermal Collectors

[says]

What limits the efficiency of a PV Module and a Thermal Collector?

PV efficiecy is limited more by temperature in summer than by illumination in winter.

Thermal Collector efficiency is limited by temperature and illumination in winter. The lower the temperature a thermal collector will be less efficient, and in winter there will be less illumination, and lower illumination means less efficiency.

 

[anorlunda]

It sounds like you are asking about effectiveness rather than efficiency.

Efficiency should be defined as the percentage of illuminating power that gets converted to useful electricity or heat.

Also please clarify, are you looking for theoretical or practical limits?

 

[says]

Both theoretical and practical limits.