While developing the Engineering Specifications sheet, it became clear that an appropriately rated solar panel would be essential to the success of the project, but that without knowledge of how solar panels perform behind a car windshield, there was no way to determine what panels to buy. An experiment was devised which would compare the output of two solar panels. One would be kept under the windshield, while the other would be placed on top of the windshield. The voltage and current of each solar panel would be measured periodically over the course of a day. The group decided that this test would be performed on the same day as the prototype testing. Two cheap, small solar panels were purchased. They are each 130x130mm, rated for 2.5W at 5V/500mA. These are shown below.
The group planned for testing beginning at 11:00 AM on Sunday, 10/2/2022. Modifications to the device were discussed due to Daniel's preliminary findings. This included the need for the Peltier cooling device to be mounted on the window so that the hot side can be insulated from the interior of the car. This would also enable the cold side to be insulated from the exterior, making full use of the heat pumping capabilities.
We conducted both experiments within the same window of time. The solar panel test data is shown below.
The second test's purpose was to test the efficacy of the Peltier cooler in the vehicle over a 6 hour period. The primary issue was that the Peltier would not stay cool, as it could not transfer enough heat to the radiator. The radiator and fan seemed to be too small to cool the water enough before being pumped back to the water cooling block. As a control, we used Ian's car (Blue Hyundai Elantra Hatchback) to monitor temperature over the same time period.
Ventilation was also discussed. When the car is first parked, the aim is to keep as much cold air in the car as possible, so ventilation must be kept at a minimum. Once the interior air has heated up to the same temperature as the exterior, maximum ventilation becomes desirable. Some form of automated opening and closing vent could be used for the final design.
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