What is Solar Inverter Sizing?

Solar inverters are available in all shapes and sizes.  They are rated in watts (W) or continuous watts. Continuous watts refer to the number of watts an inverter can support indefinitely. The watts rating for an inverter must be almost if not equal to your system’s watts for it to be right. For this reason, solar inverter sizing is crucial.

Using the wrong inverter will affect your solar energy efficiency. If your solar is rated at 2000 watts, the inverter should also be at 2000 watts or more in rating. However, it should not be too much to avoid affecting the system. We are going to look at solar inverter sizing in more detail. Let’s begin.

All You Need to Know About Solar Sizing

solar panel inverter

Definition of Inverter Sizing

As stated above, sizing refers to choosing the right solar inverter for the energy system. Getting the most suitable one is an essential part of the solar design process. When it comes to sizing an inverter for a solar system, the installer looks at three main factors. These are geography, the size of the solar array, and specific conditions of the site. Let’s look at these factors in detail.


Geography will affect your solar energy system production. For this reason, it plays a significant role in sizing solar inverters. For example, properties located in Arizona have larger amounts of solar radiation (Solar irradiances) than those in places such as Vermont. This will mean that the same-sized rooftop solar system in Arizona will have a higher output than one located north.

When you consider the varying DC electricity production by the two systems, you will need different sizes of inverters for each. The chosen inverters should handle the load from the PV modules.

The inverter sizing may be closer to the actual solar panel’s voltage for areas that experience more sunshine with moderate temperatures. With such sizing, it can handle the maximum production of electricity from the solar array at any point. 

However, solar panel efficiency is significantly affected in areas with high temperatures and low solar radiation. In such places, it is less likely to have maximum output according to the defined DC rating. For such areas, using a smaller inverter can still be effective.

The Solar Array Sizes

Experts consider this to be the most critical factor when conducting inverter sizing for the solar system. The inverter needs to handle the DC electricity the solar array produces in its full capacity. 

Generally, the main rule is that the inverter’s size needs to be the same as the DC rating indicated on the solar panels. For example, when installing a 6-kilowatt solar energy system, the chosen invert should be about 6,000W, give or take a few watts. 

The manufacturers usually indicate the sizing instructions on the product sheet for inverters showing which array capacity they can handle. Remember, if you use the wrong size, it is a ground to void the warranty.

Specific Conditions of the Site

Another important factor relates to the site. The specific design of the solar array and the installation space will affect solar PV inverter sizing. Solar panels’ azimuth and tilt directly affect the inverter as it impacts the amount of electricity produced. 

Other environmental factors of the site, such as dust or shade, will also affect electricity production. The main reason for this is because it affects the amount of sunlight that will reach the array. 

When installing the array, the installers always account for such conditions. They also look at equipment efficiency because it affects your solar energy system’s overall capacity or derating factor. Derating factor helps to determine your solar panels’ output in a real-life scenario.

If your solar panel has a higher derating factor, the installer can use a smaller inverter- mainly because the array will not reach its maximum production.

How to Calculate Solar Inverter Sizing

To a certain extent, your solar inverter sizing can be larger or smaller when you compare it with the solar panel’s DC rating. Ideally, you calculate the array-to-inverter ratio by dividing the array’s DC rating by the maximum inverter AC rating. Most of the installations have a ratio ranging between 1.15 and 1.25. 

You can use higher ratios mostly when you don’t expect maximum array output because of the factors listed above. Oversizing is beneficial because lower wattage inverters are less expensive in comparison to larger ones. However, oversizing is most likely to cause clipping.

When the solar panels produce excess DC electricity, overwhelming the inverter at any given time, it is referred to as clipping. In these cases, the inverter limits the amount of energy conversion, resulting in power losses. For this reason, oversizing is not recommended.  

Inverter Stacking

Sometimes, you may find people connecting more than one inverter to get more power. Mostly, stacking happens when you have several smaller inverters, and you want to make a bigger one by joining them together. When your inverter demands increase, mostly from buying more solar panels, you can purchase a bigger inverter or wire smaller inverters into one.

Inverter stacking provides you with a higher voltage or more power. When two compatible inverters are joined together in a series, they double the voltage.

Sizing inverter for solar panels is vital in increasing efficiency and preventing malfunction. Through careful evaluation, an installer can recommend oversizing where you can maximize harvesting energy, mostly in the morning or afternoons. Proper sizing also prevents clipping.

The best way to make sure you get the best size is to work with highly skilled and qualified professionals. They can advise when you require another inverter in cases where increased energy production is necessary. Reputable installers will come armed with a service warranty, which holds them liable if any issue arises from human errors.

Dynamic SLR has helped numerous homes and businesses in Texas to go solar. We do correct solar inverter sizing to prevent warranty voiding and also guarantee the system’s durability.