Photocells and modules

 

 

In 1875, American, G.R. Carey invented the photo tube. The light-sensitive photo-cathode consist of a thin film. Under illumination, low work-function metals, such as cesium, will release energetic electrons from the cathode.

 

This photoelectric relay was made by Central Scientific Inc. and sold by the Chicago Apparatus Company. The photocell signal produced by illumination is amplified by a tetrode vacuum tube. The amplified signal drives a small relay, which, in turn drives a larger relay.

Bergmann improved selenium devices in the 1930’s. These proved superior to the cuprous- oxide based devices and became the commercially dominant product.
Above, a popular, linear response: “Weston Photronic Cell Model 594”.

In 1954, the PV effect in CdS was reported. The primary work was performed by Rappaport, Loferski and Jenny at RCA.
In the left, a CdS-based thin film solar cell made at Institute of Energy Conversion in the seventies

A Schotky barrier CdTe based solar cell made by me in the 1980's. At that time it probably was the largest CdTe based device around. Now this is an antique!

 

This solar cell made from an 11/2 inch diameter silicon ingot probably belongs to the first generation of solar cells made by Bell Atlantic. Looks more like a detector than a solar cell. The efficiency ~6% is outstanding. Has antireflection coating and the front surface buss bar is a ring of solder at the edge of the device.

Early amorphous silicon module by Arco. High expectation from this technology. Stability problems plagued developments since the beginning. Apparently, this type of thin film module can not compete with CdTe based and CIGS modules

A early solar module made by Silonex module made with 3 inch solar cells.

In the 1970s, CdTe-based and amorphous- silicon thin-film solar modules start the journey towards the large-scale application of photovoltaics.

Cupper-indium-gallium-arsenide thin film solar cells made on plastic foil. A glimpse into the future.

An early, four inch diameter ingot produced by Chocralsky method. The 111 seed (the square bare above) are deepen in high purity silicon melt and then slowly goes out while rotating. Amazingly, the crystallographic structure in the seed is preserved and the whole ingot grows "single crystal". The chunk on top is a piece of metallurgical silicon.

A photometer by Photo Volt. Obviously is previous to the above one. The meter is more sensitive and elaborate probably to compensate for small output for the cell.