Electrical generation and consumption

As for how much power we plan on being able to generate, it depends on several factors: the type of solar panels used, environmental conditions, the size of the solar system, the energy needs of the heater, and potential power loss throughout the system. Currently, we plan on using a 1,500W infrared heater to warm the bus stop, and if it were to run 24/7, it would need approximately 36 kWh per day, as shown in the equation:

E = P x T (P - power, T - time)

1500 W x 24 hrs=36,000 W

This would require a massive solar panel system to generate the energy required for the heater to run. Running the heater 24/7 would also drastically reduce the heater's lifespan, forcing more frequent replacements and driving up the costs of the project. So, how can we mitigate the amount of power required while maintaining the warmth for commuters?

We know that buses in Lakewood, Colorado typically start running around 4:30 AM and continue until about 12:00 AM, which cuts down the heater's operation time to 19.5 hours per day. This reduces energy consumption as shown in the revised equation:

1500 W x 19.5 hrs=29,250 W

While this is still a high amount of energy consumption, it's more manageable than the previous estimate of 36 kWh. However, to further reduce the power needs, we will implement intermittent heating—a cycle where the heater runs for 30 minutes, then turns off for 30 minutes. This cycle will balance the need to maintain warmth while reducing power consumption and extending the heater's lifespan. With this new approach, the heater will run for about 9.75 hours per day, and the equation is:

1500 W x 9.75 hrs = 14,625 W

This reduction makes it a far more realistic goal for a smaller solar panel setup. We are considering using a 5 kW solar system, which, in ideal conditions for about 5 hours, could generate up to 25 kWh of energy per day. This amount would be sufficient to power the heater and leave some excess energy to contribute to the grid.

But there’s more we can do to reduce the energy consumption further. By installing a thermostat to measure ambient outside temperatures, the heater will only activate when the temperature drops below a certain threshold. If we assume that the heater wouldn't need to run for ~10-20% of winter days due to mild weather conditions, this would reduce yearly consumption by that additional ~10-20% further reducing wear on parts and costs. During warmer periods, as the outside temperature rises, the heater will turn off, relying on natural heat to maintain warmth at the bus stop. This will further reduce energy consumption and prevent unnecessary usage, especially when the temperature is mild.

Although this temperature-based control is difficult to predict with precision due to varying weather conditions and others, it’s clear that this approach will save significant energy.

Another important aspect is storing the energy generated by the solar panels. Since the heater won’t be running 24/7 and will only use power intermittently, we’ll need a battery to store the excess energy for when the heater needs it. At the moment, QOLCO is conducting research on the ideal battery size. A 15 kWh battery seems appropriate to cover the heater's energy needs during cloudy or inclement weather, though these batteries are expensive. We are still looking into affordable alternatives that will allow us to balance costs while ensuring reliable heater operation. We have even considered setting a 15kWh battery max at 10kWh to be able to store energy for low sunlight days whilst maintaining the lifespan of the battery as much as possible so as to not need to replace it.

No matter the battery size, we plan on partnering with Xcel Energy through their net monitoring program to send excess energy back to the grid. When the battery reaches full capacity on warm, sunny days when the heater isn't needed, any additional energy produced by the solar panels will be sent to the grid. This is an important feature because we want to avoid wasting potential energy. By sending excess energy back to the grid, we can contribute to the community’s power supply, especially during times when the city needs it most, such as hot summer days when demand is high.

This initiative has significant positive impacts on the citizens of Lakewood. By integrating our system into the grid, we can help reduce the city's reliance on fossil fuels, provide clean energy during peak demand times, and lower overall electricity costs. This will go on to contribute to the broader goals of sustainability and environmental practice, ultimately benefiting not only the commuters who will have a comfortable place to wait but also the community as a whole. Additionally, by making the system efficient and reducing energy consumption, we ensure that the project remains affordable and sustainable over the long term, while allowing the system to be able to pay itself off over a shorter amount of time, and offer long-lasting benefits to Lakewood's citizens.