High Level:

Specs allow for 4, 5 or 6 m^2 of Si cells
Si is much cheaper than GaAs
Sunpower is leader in Si efficiency
- Not released to the public (no information for residential users)
- Can't directly buy. Go through supplier:
  - SunCat Solar
    - American
    - Better encapsulation as of a year ago
    - Really good technique
    - Frustrated with Gocherman (marketing)
    - Cheaper encapsulation with better cells pays off usually
    - A little cheaper
    - USD
    - Per module
  - Gocherman
    - German
    - Price based on area
    - Efficient and serious
    - Euros
    - Can get anything (pyramid encapsulation)
    - More rigid less flexible
Get cell number based on spec sheet, space and power.
- Get max number.
- Note the corners are rounded so you can use this to get more cells
A module is a group of cells and they are connected together into a string

Goals

Max cells
1 MPPT per string
Locate each shaded area and group into a string (Logically).
Goal is to separate strings to defend against shadows.
Less cells per string = lower voltage (MPPTs lose some efficiency)
MPPTs have a minimum operating voltage. String sizes need to be calculated based on this. Research the MPPTs to determine strings.
You can design your own MPPTs (Good teams make their own, most buy from Australian Research Labs)
These MPPTs are off 1% - 5% of the time to poll the array
Divide into modules (4x5, 5x5) make as even as possible withing the string. (No bias on bypass diodes).
You could have bonus cells on a separate string (vulnerable) only activate under ideal conditions.
1 bypass diode per module. (Some cells Gocherman, includes these in the modules but if they do get damaged they are hard to repair).

Encapsulation

When cells are raw they have an efficiency of 25 - 29%
Encapsulating (polymer coating) them causes a loss of 1-3% based on dampening/attenuation effects. Used to protect cell from elements
Currently pyramids are used to maximize the efficiency +3% by angling light to 90 degrees.

Procurement

Diodes

MPPTs

Details

Software

Disconnect, MPPTs from the array before shutting them off. Vice versa for turn on

Safety

Grades

Ordered by bin of how well they do, we have bin J. Usually we can get highest or second highest.
Check approvals.

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