PV Array Layout

Owned by Jessica Lin
Last updated: Dec 02, 2017



RequirementsTypeNotes
Leave at least 1mm spacing between each moduleTechnical

This is to allow some room for thermal expansion between the modules

Leave space for brake lights, hinge (and rear camera (question))WSC
Leave space for front (and back (question)) name plateWSC

Maximum 324 Cells

Maximum 326 Cells (According to footnote)

WSC


Max array area: 5 m^2.


SunPower C60 Solar Cells: 0.01534 m^2. (info)

Type: MONO CRYSTALLINE SILICON

Total number of cells = Max area / Cell Area = 5 / 0.01534 = 325.9452411994785 ~ 324.

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(info) Note that 0.015333 m^2 is an estimation provided by WSC and adhered to by the ASC in their 2018 Regulations (Rev. A) in footnote 3, page 24 of 77.


Note that a more accurate calculation has been done here:

Each string should consist of around 32 cells

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Technical

We will have two stacks of 5 MPPTs in series, in parallel with each other, make 10 MPPTs in total. Thus 5 MPPTs in series should make up the battery voltage (151.2V - Battery Pack Design Proposal).

Each MPPT outputs 30.24V regardless of input (as long as it's between 10V - 30V), thus 5 MPPTs in series makes 151.2V.

The efficiency increases as the input voltage is increased, therefore to get the max efficiency, we want to spread out the voltage as evenly as possible to get the maximum input voltage between all the MPPT strings and get the most efficiency.

We can have a maximum of 324 cells on the car and there are 10 MPPT strings in total, there should be about 324/10 ~ 32 cells per string.


Each string should consist of around 27 cells

Technical

We will have two stacks of 6 MPPTs in series, in parallel with each other, making 12 MPPTs in total. The 6 MPPTs in series should make up the battery voltage (151.2V - Battery Pack Design Proposal).

Our MPPTs have variants then can output between either 23 - 37 V or 18 - 33 V (info). We will use the 18 - 33 V variant, setting each MPPT to output around 25.2V would make up the 151.2V needed to make up the battery voltage.

This option replaces the 5 MPPTs in series design since it improves flexibility for array layout and arrangement. Also, dividing by 27 is easier since modules could come in 1x3s, 2x3s, and 3x3s. This makes it easier to replace cells in the likely case of damages.

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(info) From the Nomura Co MPPT Manual

  1. Midsun Proposal: 324 cells
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  2. Gochermann Counterproposal 
  3. Midsun Proposal: 326 cells
  4. Midsun Proposal: half cells


Excel sheet for array output analysis: