Optimal Sizing of ESS and PV Systems in the CCHP Milad Tower Complex (MTC) Microgrid Considering Load Management and Carbon Trading

In the modern world, electricity is rarely a simple commodity flowing in one direction. It is a dynamic balance between what is generated, what is needed, and how that energy is stored for later use. As cities grow more complex, the challenge shifts from simply building more power plants to managing a smarter, more flexible grid. This is where the concept of a microgrid becomes essential. Think of a microgrid as a self-contained neighborhood power system that can operate independently or connect to the main national grid. Within these systems, renewable sources like solar panels offer clean energy, but they come with a catch: the sun does not shine at night, and clouds can appear unexpectedly. To make solar power reliable, engineers pair it with energy storage systems, essentially large batteries that catch excess power when the sun is bright and release it when the demand rises. When these elements are combined with advanced planning and financial tools like carbon trading, they can transform how a building or complex consumes energy, turning a simple power user into a smart, efficient energy hub.

Researchers at the Technical and Vocational University in Tehran, Iran, applied these concepts to a very specific and demanding real-world location: the Milad Tower Complex. This massive structure is not just a single tower but a sprawling city-within-a-city, housing a hotel, a convention center, restaurants, and an IT park. It represents a heavy, continuous load on the power grid, with energy needs that fluctuate wildly throughout the day. The team, led by Shahriar Abbasi, set out to determine the perfect size for solar panels and battery storage to serve this complex. They did not just look at how big the equipment should be; they built a sophisticated computer model that simulates the entire year, balancing long-term investment costs with daily operational decisions. Crucially, their model included two powerful strategies often overlooked in simple planning: load management and carbon trading. Load management involves shifting energy use to cheaper times, while carbon trading allows the complex to earn money by reducing its pollution, creating a financial incentive to be cleaner.

The researchers found that simply installing solar panels and batteries was not enough to maximize efficiency. The true breakthrough came from integrating these technologies with a smart schedule for energy use. By managing the load, the complex could flatten its peak demand, avoiding the most expensive hours of electricity usage. In their simulations, this approach reduced the difference between the highest and lowest energy usage times by nearly half. When they added the carbon trading mechanism, the results became even more compelling. The model showed that by earning revenue from selling carbon credits, the complex could justify installing even more solar capacity. This created a virtuous cycle: more solar panels meant less reliance on fossil fuels, which generated more carbon credits, which in turn funded further expansion of the renewable system.

The financial impact of this integrated approach was significant. In the baseline scenario without these optimizations, the complex faced an annual net cost of over 6,305 million dollars. By implementing the optimal mix of solar and battery storage alongside load management and carbon trading, the researchers calculated that this cost could drop to just over 4,107 million dollars annually. This represents a reduction of nearly 35 percent. The study also revealed that the investment in these new systems would pay for itself much faster than traditional methods. The time required to recover the initial investment costs shrank from nearly seven years to just over five years, while the return on investment increased substantially. This suggests that for large, energy-intensive facilities, the most economical path forward is not just buying more equipment, but buying the right amount of equipment and managing it with a strategy that values both time and environmental impact.

Beyond the numbers, the study highlighted how these changes stabilize the entire power network. By smoothing out the demand curve, the microgrid reduces the strain on the upstream power grid, particularly during peak hours when the system is most stressed. The batteries act as a buffer, absorbing excess solar energy during the day and releasing it when the sun sets and demand spikes. This coordination means the complex relies less on purchasing expensive power from the main grid and can even sell its own surplus energy back at profitable times. The thermal side of the equation was also optimized, with the complex's combined heat and power system running more efficiently to provide both electricity and heating or cooling. The researchers demonstrated that a two-layer approach works best: a long-term planning layer that decides how much solar and storage to install, and a short-term operating layer that manages the minute-by-minute flow of energy. This dual strategy ensures that the physical infrastructure is sized correctly for the long haul while the daily operations squeeze every ounce of value from the system.

Ultimately, the work at the Milad Tower Complex serves as a proof of concept for the future of urban energy. It shows that the path to a sustainable and affordable energy supply lies in the intelligent coordination of generation, storage, and demand. The study confirms that when a facility treats energy as a flexible resource rather than a fixed cost, it can achieve dramatic savings and a smaller environmental footprint. The findings suggest that similar large-scale complexes around the world could replicate this success, provided they are willing to adopt a holistic view that combines engineering, economics, and environmental policy. The result is a system that is not only cheaper to run but also more resilient and stable, offering a clear blueprint for how cities can power themselves in an era of climate change and rising energy costs.