Siemens Solar published short application notes: where the system was, who installed it, the climate, the component list and a comment. They are the closest thing to field experience in Siemens’ own documentation, so we converted the lists into tables and checked the arithmetic. A handful of numbers in the notes do not add up; we say where.
How to read the notes
Treat them as vendor case studies, written in the late 1990s to sell modules. The component lists are useful and mostly self-consistent. The performance statements are the vendor’s. Where we compare with other numbers (for example the 1,730 kWh per kWp at Sacramento), those are our calculations from the stated array size and energy, not independent measurements.
Module names in the notes (M50, M55, M65, M75, M55VJ) differ from the SM, SP, SR and ST names on the datasheet pages, and the source does not say how they relate. The notes imply 48 W for an M75 and 50 to 55 W for an M55 (53 W wherever a module rating is given); they do not say how those ratings were determined, so they may not equal the 55 W STC rating on the SM55 datasheet.
A sixth group: traffic and street lighting
Siemens’ traffic and railroad page names solar power for flashers, warning signs, call boxes, message boards and railroad safety equipment, and lists the SM6, SM10, SM50, SM55, SP36 and SP65/70/75. Its one installation note describes Solight street lights from Engcotec, Stuttgart, in Saxony-Anhalt, Germany: since 1992, 40 municipalities have installed lights with a programmable microprocessor that balances charging, storage and drain against the community’s real-time lighting needs. Each light is listed with two M55 modules and one 80 Ah battery. Two modules of roughly 55 W give about 110 W against a battery of about 0.96 kWh at 12 V, a small array for a night-long load, which is why the controller manages energy use. The note does not state the voltage, the lamp power or the hours.