Spherical solar cells were developed in the early 1990s by Texas Instruments using a large number of silicon globules, 1mm in diameter, with a concentric p-n junction (see Figure 3.45). These globules are placed near each other and pressed together in double-layer aluminium foil with insulation between the layers. The globules are ground in such a way that one layer of the foil abuts the n-layer and the other the p-layer. With the aluminium foil being placed between the globules, the aluminium generates additional diffuse light, which likewise ramps up current production.
The advantage of these solar cells lies in their mechanical flexibility and the fact that, due to a relatively simple manufacturing process that lends itself to mass production (i. e. no monocrystals, casting or sawing), they can be made using relatively impure silicon. Texas Instruments repeatedly announced over a lengthy period that the product was slated to go into pilot production, but no effective product appeared on the market. Spheral Solar Power (SSP) recently brought out initial products of this type from pilot production (module with 200 Wp and zM up to 9.5%).