3"x3" or 78x78mm Polycrystalline Solar Cell with 1BB
78x78 mm (3x3 inch) polycrystalline solar cell rated about 1.15 Wp with 1 busbar. Nominal values: Vmp 0.544 V, Imp 2.10 A, Voc 0.64 V and 18.7% efficiency.
A compact square format for mini photovoltaic modules, prototypes, models and STEM labs. This is a bare cell and requires ribbon, soldering, support and encapsulation.
The 78x78 mm 1BB polycrystalline solar cell produces approximately 1.15 Wp in a compact square format for mini panels, electronic prototypes and educational activities. Each cell supplies a nominal 0.544 V and 2.10 A at maximum power.
It is not a finished panel. Practical use requires compatible ribbon, mechanical support, insulation and encapsulation against moisture, impact and bending.
What projects suit the 78x78 mm cell?
The 3x3 inch size supports compact modules with a regular layout and lower current than full-size cells. It is useful for small solar supplies, models, sensors, demonstrators and series/parallel experiments.
For repairs, dimensions, technology, current, busbar design and polarity must match the original module. The single busbar requires a specific ribbon layout.
SC1P1-78x78 technical specifications
| Reference | SC1P1-78x78 |
| Technology | Polycrystalline silicon |
| Rated power Pmax | About 1.15 Wp |
| Vmp | 0.544 V |
| Imp | 2.10 A |
| Voc | 0.64 V |
| Isc | 2.48 A |
| Efficiency | 18.7% |
| Busbar | 1BB |
| Dimensions | 78x78 mm, about 3x3 inches |
| Thickness | 170 ± 20 µm |
| Weight | About 4 g |
What do 12, 24 or 36 cells produce?
Series connection adds voltage while current remains about 2.10 A. These are theoretical nominal values before temperature, mismatch, soldering and encapsulation losses.
| Cells | Vmp | Voc | Approximate power |
| 12 | 6.53 V | 7.68 V | 13.8 Wp |
| 24 | 13.06 V | 15.36 V | 27.6 Wp |
| 36 | 19.58 V | 23.04 V | 41.4 Wp |
Choose the cell count from the voltage required by the load or charge controller. Connect only complete matched strings in parallel, with suitable wiring and protection.
STEM projects and educational photovoltaic kits
The compact size is easy to handle in laboratories. Students can measure voltage and current as light changes, compare series and parallel connections and study shading, angle and temperature.
Discover The Sun in the Classroom and MR WATT educational photovoltaic kits
How to solder a 1BB cell
The single busbar is the main collection line. Use compatible ribbon and flux, a clean tip and short contact times. Do not bend the wafer, and check continuity, polarity and voltage after every string.
Read the MR WATT solar-cell soldering guide
Frequently asked questions
Is this a complete solar panel?
No. It is one approximately 1.15 Wp cell requiring interconnections, support, insulation and encapsulation.
What does 1BB mean?
It means one main current-collection busbar. Ribbon and soldering layout must match this geometry.
How many cells are needed for a small 12V module?
Twenty-four cells provide about 13.06 V nominal Vmp; 36 provide about 19.58 V. The correct choice depends on the load and controller.
Is it suitable for school experiments?
Yes. It makes voltage, current, series, parallel and light-response measurements straightforward.
Can it be used outdoors without protection?
No. The bare cell must be encapsulated and protected from moisture, impact and bending.
