Similarities and Differences of photovoltaic cells and solar heating panels?

Similarities and Differences of photovoltaic cells and solar heating panels?

Similarities and Differences of photovoltaic cells and solar heating panels?

Photovoltaic cells are smaller, individual wafers, about as big as your hand, that go into photovoltaic panels. But I’ll assume that the question is to compare photovoltaic (solar electric) to thermal (solar heating) panels.

Both need the sun to work, so mounting schemes are designed to have the sun shine on them as much as possible.

Neither works at night, so some sort of storage or backup is generally used. For solar electric, this could be charging batteries, or reverting to grid electricty at night. For solar hot water, this could be a big insulated tank, or reverting ot electric or gas heat at night. An exception would be in tropical climates, where the “cold” water is still no colder than a swimming pool, and someone would be willing to bathe without hot water if they had to.

Solar electricity is expensive, and the panels are light, so sometimes a motorized mount is used to track the sun across the sky. Because solar thermal panels are cheap, such tracking is generally not worth it – people just get enough panels to serve their needs.

For solar electric, the panels are more efficient when cool, so they are mounted for good airflow. For solar heat, the goal is to get as hot as possible.

Solar electric is expensive enough that one would consider sizing a system to produce less than one’s full electrical needs. Solar hot water is cheap enough that a system is usually sized for 100% of hot water needs.

Photovoltaic prices have dropped about two orders of magnitude (100x) in the last 30 years. Solar thermal is still about the same price.

A solar heating panel can be made at home. People have posted YouTube videos about how they did theirs. It is not practical to make photovoltaic panels at home.

Lec 28 | MIT 3.091 Introduction to Solid State Chemistry

Heating For Home

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