silicon watts

ws9876ws9876 Solar Expert Posts: 404 ✭✭✭
do squares of silicon have the same voltage no matter what the size??? or does the voltage
go up with the size of the square or circle..?? providing the silicon is the same..

Comments

  • mike95490mike95490 Solar Expert Posts: 9,358 ✭✭✭✭✭
    Re: silicon watts

    All PV material shares a common voltage, about 0.55V. As the size (surface area goes up, the amps produced, increases. To get more voltage, cells are wired in series.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • BB.BB. Super Moderators, Administrators Posts: 32,005 admin
    Re: silicon watts

    All silicon PV material has the ~same voltages. Different materials can have somewhat different voltages.

    For example, if I got this right, gallium arsenide solar cells run Vmp~2.1 volts per cell (company: www.spacequest.com).
    Solar Cells: Triple Junction GaAs with Protective Covering
    Protection: Individual diodes on each cell and attached to each string
    Bus Bars and Interconnects:
    1 mm cell-to-cell spacing; 3 mm string-to-string
    Over 90% coverage per panel area
    UV-protected Fiberglass
    Substrate: Printed Circuit Board
    Honeycomb or other flat substrate material
    Efficiency: 26% nominal
    Panel Size: 10” X 9”
    Mass: As low as 10 grams/cell
    Peak Power Voltage: 2.1 Vpp/cell at 28°C
    Open Circuit Voltage: 2.5 Voc/cell at 28°C
    Current: 420 mA/cell
    Output Power: 880 mW/cell
    Operating Temperature: -90°C to +90°C
    Storage Temperature: -100°C to +100°C

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Dr. StrangeloveDr. Strangelove Solar Expert Posts: 49
    Re: silicon watts

    The voltage produced by any PV cell is based on the energy band gap of the PN semiconductor junction. Silicon junction bandgap is around 0.55V, while other materials like GaAs or CdTe/ZnTe have different band gap potentials. A bigger cell is like many smaller cells of equivalent total area in parallel, hence more current but same potential (voltage). Because of quantuum mechanics, a photon must have the same or higher energy than the band gap to create an electron/hole pair. Photon energy is proportional to wavelength (or color). So a multi-junction cell can be built, stacked on top of each other, to harvest more photons of different energies. In Bill's extremely expensive satellite PV cells, there are three junctions stacked, with different concentrations of In and P to create different band gaps. While they are very efficient, you don't want to know what a panel of those babies are going to set you back, trust me.
  • nsaspooknsaspook Solar Expert Posts: 396 ✭✭✭
    Re: silicon watts

    The quantum efficiency in first/second generation solar cell is limited by photon to electron/hole conversion but there is another way that deals directly with the EM fields.

    http://www.nrel.gov/docs/fy03osti/33263.pdf
    http://ecee.colorado.edu/~moddel/QEL/Papers/EliassonThesis.pdf

    Improvements in MIM diodes for direct optical rectification.
    http://onlinelibrary.wiley.com/doi/10.1002/adma.201002678/abstract
  • mike95490mike95490 Solar Expert Posts: 9,358 ✭✭✭✭✭
    Re: silicon watts
    BB. wrote: »
    All silicon PV material has the ~same voltages. Different materials can have somewhat different voltages..... gallium arsenide solar cells run Vmp~2.1 volts per cell....... -Bill

    But is anyone actually installing / affording any of the NEW panels ??
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • ggunnggunn Solar Expert Posts: 1,973 ✭✭✭
    Re: silicon watts
    mike90045 wrote: »
    But is anyone actually installing / affording any of the NEW panels ??

    Define "new". Multijunction Si modules have been around for a while, but the cost of them is still prohibitive for most applications. There are a lot of "new" thin film modules being made, but their efficiencies are generally significantly less than Si modules, but they are cheaper, so if space is not a problem, they may be the way to go.
  • mike95490mike95490 Solar Expert Posts: 9,358 ✭✭✭✭✭
    Re: silicon watts
    ggunn wrote: »
    Define "new". Multijunction Si modules have been around for a while, but the cost of them is still prohibitive for most applications. There are a lot of "new" thin film modules being made, but their efficiencies are generally significantly less than Si modules, but they are cheaper, so if space is not a problem, they may be the way to go.

    new = gallium arsenide solar cells $$$$ thin film hybrids are reasonable, but still only .5v
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

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