Sizing an Off-Grid Power System 

Let’s delve into the process of sizing an off-grid power system. 

For most residential customers, reaching out to a solar company is a lot easier. They usually begin by requesting a copy of your electric bill and conducting a remote assessment of your roof using satellite imagery. This helps them estimate your solar potential and calculate potential energy savings. However, it’s important to remember that even in this scenario, maintaining a utility connection is essential. Think of it as your backup battery. It allows you to utilize the solar energy you generate and even sell excess power back to the utility.  

But when the utility goes down, your solar panels won’t produce power for your home, even on sunny days. This is the standard approach offered by most residential solar installers, and it’s straightforward and cost-effective. 

Complexity of Off-Grid Systems 

On the flip side, off-grid power systems are a different beast. Here, we need to consider all your power needs, what you intend to run, and for how long because a connection to the utility is either not available or because the client wants to minimize purchasing power from the utility. 

Solar energy is only available during daylight hours, typically providing three to six hours of solar irradiance per day, depending on the season. However, you require power 24/7 for various tasks, whether it’s watching TV at night, brewing coffee, or running an air conditioner. To size the system correctly, we must estimate what you want to power and for how many hours each day. Take a microwave, for instance. We can easily calculate its power consumption while in use. The real question is how many minutes a day you use it. An average home might use a microwave for 10 to 15 minutes daily. Other devices, such as well-pumps, consume a substantial amount of power but run for short periods. We need to determine how often they operate throughout the day and add all these factors together to ensure we have sufficient energy storage. 

Off-Grid Challenges 

Off-grid systems significantly differ from their grid-connected counterparts. Some off-grid customers may still have a utility connection, but it might not be adequate or cost-effective. Let’s consider an example: a recent project involving a client looking to establish a commercial bakery in a remote area. They needed three-phase electricity, but the local utility quoted a staggering half a million dollars to provide it to their rural location. Instead, we proposed a more affordable solution combining solar, batteries, and enough inverters to provide three-phase power. The existing single-phase utility connection can provide backup power to recharge the batteries if ever needed. 


To sum it up, sizing an off-grid system boils down to understanding your unique needs, crunching the numbers for each load, and designing a system that ensures uninterrupted power. Unlike residential installers who rely on utility bills, our approach is highly customized. We aim for a precise fit that minimizes costs while guaranteeing dependable power. 

Monitoring and Adaptation 

Post-installation, we closely monitor your system’s performance. We collect data on consumption, solar generation, battery status, and many other parameters. If necessary, we can make adjustments remotely based on your usage patterns to keep your system running optimally. 

In conclusion, sizing your off-grid power system involves understanding your specific requirements, calculating load demands accurately, and crafting a system that provides the necessary amount of power you need.