The pros and cons of 1-minute, 15-minute, and 60-minute solar data

Solar data can be gathered in several ways, including satellites, ground-based sensors, weather models, or historical databases. Depending on the source and desired application, this data can have distinctive temporal resolutions, such as sub-hourly (1-, 2-, 5-, 10-, 15-, 30-minute) or hourly intervals. But how are you supposed to know the difference, and why should you care?

Why does temporal resolution matter?

The temporal resolution of solar data can affect simulation results relating to how accurately it reflects the variability of solar irradiance, the complexity of the simulated scene and how useful it is for specific purposes.

When deciding on the most appropriate data, it’s useful to consider what you’re wanting to achieve.

For example, if you want to design a solar installation or estimate its energy output, you’ll want to know how much sunlight it is likely to receive throughout the year. For this, you can use:

1. Historical monthly long-term averages, if early site selection is being performed, or if only a rough pre-feasibility study is prepared,
2. Typical meteorological year (TMY) data, which represents the typical (average) weather patterns at a site, which can then be integrated into a pre-feasibility study,
3. Time-series data with sub-hourly temporal resolution (typically 10- or 15-minute data), covering a long period of time (for bankable studies at least 10 years of data is expected) to accurately capture occurred weather patterns.

Furthermore, if you want to operate or monitor a solar system in real time or forecast its output for the near future, you need to know how much sunlight it will receive in the coming minutes or hours.

For this, you need nowcast or forecast data that has a high temporal resolution (1-, 2- or 5-minute intervals) but covers a short period of time (such as 24 hours). This way you can capture the rapid and unpredictable changes of solar irradiance due to clouds or other factors.

What are the advantages and disadvantages of each temporal resolution?

Each temporal resolution has its own pros and cons depending on the source and application.

Figure 1: Differences in details covered by 60- 15- and 1-minute data

60-minute solar data

Hourly data intervals are still widely used, persisting from the early stages of the data industry. Originally, data collection, processing systems, and PV simulation tools were designed to gather, export and model datasets in hourly intervals, typically across a period of one year. For this purpose, the concept of TMY was introduced to represent the typical weather conditions at a given site. 

Now in an age of significant digital advancements we can move beyond hourly (and TMY) approaches. Instead, modern technologies offer better and faster simulations with high quality data at shorter (sub-hourly) time intervals.

Nonetheless, if they are used, a coarse representation of the average solar irradiance and other weather variables over a longer time scale should be expected. This may be useful for applications that only require lower accuracy and precision such as:

• Assessing the feasibility and potential of solar projects
• Evaluating the long-term performance and profitability of solar investments
• Studying the trends and patterns of solar resources

15-minute solar data

This captures the variability of solar irradiance and other weather conditions over a shorter time scale than above. 15-minute solar data is useful for applications that require high accuracy and precision, such as:

• Detailed assessment of the potential of solar projects
• Detailed evaluation of the performance of solar assets
• Planning and scheduling solar power generation
• Optimizing the operation and maintenance of solar systems
• Forecasting solar power output and demand
• Integrating solar energy into the grid and markets

1-minute solar data

This is the highest resolution available for solar data analysis, as covered by our first blog, “What is 1-min data?”. It provides detailed information on the fluctuations of solar irradiance and other weather variables across a very short time scale. This can help with applications that require an analysis of short-term effects, such as:

• Monitoring and controlling solar power plants
• Evaluating the behavior of PV components and systems during high cloud variability (clipping losses in inverters, variability smoothing)
• Studying the impact of clouds, aerosols, and shading on solar output
• Integration of energy storage systems (batteries)
• Developing and testing new technologies and algorithms for solar energy

Advantages of 1-min compared to 15-min and 60-min temporal resolutions

Since it is the highest resolution, 1-min solar data has several advantages compared to 15-min and 60-min data. These include:

• Providing more accurate and precise information on the variability and quality of solar irradiance and other weather variables
• Enabling more reliable and efficient calculation of solar power output and performance metrics
• An accurate reflection of current weather conditions and events which may affect solar systems
• Providing increased information for optimal control and management of solar systems and grids

The quality of this high resolution information affects the feasibility, performance, and profitability of your project. Having access to high quality solar data is essential in reducing risks and maximizing returns of solar energy investments.

Solargis’ solar data is the highest quality, most accurate and reliable in the market, based on independent comparisons and multiple independent studies.

To find out more about how we can support you with your solar data needs, please get in touch here.

To read other editions of our 1-min data blog series, please click on the links below.

• Solargis’ approach to 1-minute data
• 4 reasons why PV project designers need 1-min data
• Why is 1-minute data essential for solar project financiers?