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A Definitive Guide to Hybrid Solar System Sizing (How to Size a Hybrid Solar System?)

Homeowners in the United States have started to prefer installing hybrid solar systems for various reasons. These systems pair traditional grid-tied solar systems with battery storage and offer several benefits over conventional solar systems.

To begin with, they provide a reliable source of backup power during outages, reduce dependence on the grid, and even lead to lower electricity bills. With the increasing popularity of hybrid solar systems, it’s more important than ever for homeowners to understand how to size their systems properly. A poorly sized system can lead to poor performance and increased costs.

This is what this article aims at—it is a comprehensive guide to sizing a hybrid solar system correctly. We will discuss the key factors to consider, how to calculate the size of your system, and common mistakes to avoid.

First, a discussion on what factors to keep in mind while sizing a hybrid solar system.

Key Factors to Consider When Sizing a Hybrid Solar System

i. Energy usage

Your daily and monthly energy usage is a key factor in determining the size of your hybrid solar system. A detailed analysis of your energy usage patterns, including peak usage times and appliances that consume the most energy, can help you determine the optimal size for your system.

Calculate your average monthly electricity consumption. You can do this by dividing your annual electricity bill by 12. Calculating your daily average for both summers and winters would be best. This average must include your peak energy usage—the time when most of your appliances are turned on. Usually, this is the night as your lights, television, air conditioners (in summer), heaters (in winter), refrigerators, etc., draw the most power.

Your system should be big enough to provide electricity to you during peak hours. You can evaluate your daily peak usage by multiplying the power rating of all the appliances with the number of hours they would be on and then adding them up. Power ratings are usually mentioned on the devices or their data sheets. You can also use a power meter to know the power rating of different appliances used at your home.

ii. Location

Location plays a significant role in the size of your solar system, irrespective of whether it is a hybrid system, on-grid, or off-grid solar system. It is because location determines the number of peak sun hours your home receives on a typical sunny day. Sun hours, in turn, impact the size of your system.

For example, if your region receives 4 hours of peak sunlight, you would need a bigger system than an area where peak sunlight stands intact for 5 hours. You can note how much sunlight your roof—or ground if it is going to be a ground-mounted system—receives from the National Renewable Energy Laboratory’s maps here.

iii. Shading

The next thing you need to keep in mind is shading on your rooftop. Conducting a shading analysis to determine how much shading your system will receive throughout the day and year is crucial. Shading can cause a decrease in the overall energy production of the system, which can result in a smaller system being required to meet the household’s energy needs.

Additionally, shading can cause a decrease in the performance of individual solar panels, which can lead to uneven energy production and decreased overall system efficiency. To ensure that your hybrid solar system is appropriately sized, it’s important to take shading into account and adjust the system design accordingly.

iv. Energy storage

Energy storage is an essential component of any hybrid solar system. The amount of energy you would like to store in the battery will depend on your energy consumption and the backup power you require during outages. A larger energy storage capacity will allow for more power to be stored for a longer period of time, which can be beneficial for households that consume a lot of electricity or those located in areas with frequent power outages.

However, it is important to keep in mind that a larger battery storage capacity will also increase the overall size and cost of the system. The larger the energy storage system, the more charge it would demand from solar panels, thus increasing the size of your system. The energy storage should be sized so as to strike a balance between the desired battery storage capacity and the budget for the system.

v. Budget

Lastly, how much are you willing to spend on a hybrid system? If your budget is limited, the system you install may be smaller and only adequate for offsetting only a few of your energy needs. In contrast, if budget is not an issue, you can have a more extensive system.

Is there any way to reduce the cost of solar panels? Yes, many solar incentives, tax breaks, and financing options available may help you offset the cost of a hybrid solar system. When planning and budgeting for your system, these options should be researched and considered.

For example, the Federal Income Tax Credit (ITC) is a tax break that puts 30% of the whole system’s cost into your pocket. Other solar incentives available in your state may reduce your system’s cost by up to 50% when combined with the ITC.

Did you know?

Hybrid solar systems are typically more expensive than traditional solar systems, but they provide greater energy security and independence.

Now that we know the basics and got some key determinants, let’s move to size your hybrid system.

Sizing a hybrid system

To size a solar system, we need your average monthly electricity average, daily peak consumption, and peak sun hours. But when it is a hybrid solar system, we add another element—batteries. In this section, we will estimate

  • Your solar system’s size
  • Inverter size
  • Energy storage size

Let’s start with your solar system’s size.

Estimating the size of your solar system

To begin with, let’s assume some parameters. These parameters could vary depending on your electricity consumption, the amount of sunlight your roof receives, and the capacity of your solar panels. But for the sake of simplicity, we will keep the solar panels rating as 300, monthly consumption as 1000kWh, and peak sun hours at 4.5.

Multiply 300 by 4.5, and this is the energy one solar panel would produce in a day. This turns out to be 1.35 kW. In one month, one solar panel would produce 40.5 kW. Since your monthly consumption is 1,000 kWh, we would divide this figure by 40.5, and we would get the number of solar panels you would need, which is 25 in this case.

One solar panel was 300 watts, so your whole system size would be 7.5 kW.

This system will be enough to meet your energy demands during the day. For the night, you will switch to the grid electricity, which doesn’t put caps on consumption.

Sizing your battery bank

Unlike sizing the energy storage of an off-grid system, battery sizing for a hybrid system is relatively simple. It is because you do not have to install a huge battery bank for your night needs. You only need storage that can supply power when there is an emergency.

The size of your battery bank depends upon which appliances you would run on batteries and for how long. For example, if you would run only lights, a TV, etc., for a couple of days, then even a single medium-size battery would suffice. You can size your battery by multiplying your daily consumption by the number of days the battery is required and dividing the figure by the battery’s depth of discharge (DoD).

Say you want to get 5kWh power per day for two days from your lead acid battery, the battery required would be: (5*2)/0.5=20 kWh battery (or 833 Ah). If the battery’s DoD is 80%, then the battery size would be 12.5 kWh (or 520 Ah). The first type of batteries would be lead-acid and the latter lithium-ion.

Sizing the inverter for a hybrid solar system

Now the last part. Note that hybrid solar inverters are different from other types of inverters in the sense that they are smarter and quickly navigate between solar panels, the grid, and batteries. When sizing a hybrid inverter, note that your inverter’s capacity should ideally match your system’s size. For example, we estimated the solar panel system to be 7.5 kW, which means the inverter must be at least 7.5 kW.

But since solar inverters lose some of the power during operation, we recommend installing a bigger inverter to ensure that your hybrid system runs smoothly and efficiently. A 9 kW (or 11.25 KVA) inverter would be suitable for the above system.

Installing the system

This was all about how to size a hybrid solar system. It is now time to install the system. You can do it the DIY way or let a professional installer handle the whole process. Since installing a solar system is a complex mechanism, we recommend handing over the process to a certified solar installer. There are too many intricacies involved, and a small misstep could backfire, costing you more than saving you.

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Call us today to get a quote on solar panels, inverters, and battery packs. We're sure we can beat any other quote you have!.

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