Short on Time? Here’s The Article Summary

The article explores the factors affecting the output of a 12kW solar system and provides methods for calculating its power production. Factors like shading, irradiance, and panel orientation impact a system's efficiency. The article suggests using monocrystalline panels for better efficiency and ensuring all components are included for optimal performance. To calculate output, one can use national average power usage and irradiance values. For example, with 5 peak sun hours per day, a 12kW system might produce around 15kW of DC power. After considering conversion losses, this could equate to about 17,500kWh per year.

Alternatively, the article discusses Ohm's Law for calculating power output using resistors. For a 12kW system, using 200W panels, one might need 75 panels to achieve the desired output. The article concludes that regardless of the method used, understanding these factors and calculations is crucial for determining the potential power output of a solar system, whether it's 12kW or smaller.

Introduction

A 12kW solar system can power almost anything in your house, but exactly how much power can such a system produce?

Join us as we calculate and help you answer that question.

Before we can begin to figure out how much power a 12kW or a slightly smaller 10kW solar system can produce, we need to understand kW hours in general.

Factors that Determine Solar Panel Output

We need to understand a few key factors before we can determine how much power a 12kW solar system produces.

These factors also let us know what a 5kW solar system can run or any other smaller system.

Shading and Irradiance

The location of your solar system and its surroundings affect what appliances a 12kW system or a smaller 5kW solar system can run.

If your solar panels are blocked by trees or buildings and spend most of their time in the shade, you won’t have an efficient solar system.

Irradiance can be determined by looking at an online solar map. This allows you to determine how many sun hours you are receiving per day.

if you’re in an area that doesn’t receive a lot of sunlight, your system won’t reach its full potential.

This also means that certain weather and climate conditions such as heavy snowfall and harsh storms will cause a drop in performance. 

The worst-case scenario is that these weather conditions end up damaging or breaking your solar panels.

The Tilt Angle

Orientation is key when it comes to achieving the best solar results. If you want the best performance, your solar panels should face towards the south.

Your solar installation team will recommend orientations based on where you reside as well as where you want the panels to be installed.

The tilt of the solar panel however remains constant throughout any placement. You want to ensure that the angle of your solar panels sits anywhere between 30 and 45 degrees.

If you have a flat roof, you’re going to need brackets so that your panels can stand and be slanted at the right angle.

You also want to ensure that your roof is well-maintained and reinforced to withstand the weight of solar panels.

Other Factors

Some other factors that play a role in decreasing solar efficiency are the type of solar panel you’re using and whether or not you have all the components needed in a system.

Monocrystalline solar panels are more efficient than polycrystalline and thin film solar panels so you want to ensure that these are the ones in your system.

As for the components, you want to have all the necessary components of a solar system. Outside of the solar panel, you should have inverters, resistors, a solar generator or battery, and good wiring.

How to Calculate Solar Panel Output

There are two ways to figure out how much a 12kW solar system produces. The first is using national average amounts and the second is through manual calculations.

Using Averages

The national daily power usage in the states is around 30kWh. The first step is to take this value and divide it by the irradiance value from earlier.

Let’s say you receive around 5 peak sun hours per day.  

So, if we take 30kWh and divide it by the 5 sun hours, we’re left with a value representing the amount of KW needed in your household.

In this example, you would need 6kW, but today, we’re working with a 12kW system.

The modern solar panel produces around 250W of power during peak conditions, but as we stated before, certain factors prevent that number from being the true output amount.

The power in your home that’s being supplied to appliances is AC, but solar panels produce direct current (DC). 

During the conversion process that occurs in your solar system, almost 80% of that power is lost. So, if we have our 12kW system and divide it by 80%, we get 15kW of DC power.

Based on average amounts, you can determine anything from how much a 75kw solar system produces to what exactly such a system can power.

Number of Panels

To figure out how many solar panels we need, we take the DC amount of 15kW and divide it by the solar panel’s rating.

If we’re using 200W solar panels in our 12kW solar system, we get 75 panels. This means our 12kW solar system contains 75 200W solar panels within it.

If we have a 12kW system, that receives around 5 hours of sun per day, for 365 days, we get around 17,500kWh of energy per year. Divide this value by 12, and your 12kW system produces nearly 1,460kWh every month.

If you want to know how much power a 3kW solar system produces, you can use the same method to figure it out. Considering you’re still using 200W solar panels, you end up with a system producing 6,850KWH every year.

Ohm’s Law

This law states that the voltage of a system is equal to the current multiple by the resistance. We also use the wattage, which equates to the current of a system multiplied by the voltage. In our 12kW solar system, we’re going to assume that it’s made up of multiple 200W solar panels.

A panel reaches peak power when connected to a certain value of the resistive load. You want to ensure that the resistor hooked up to your system is significantly higher than the solar panel.  

Resistors for such a system are typically the wire wound 15kW braking resistors. These are measured at around 10,000 ohms.

If you want to know how much power a 7kW solar system produces per day, you can use a smaller resistor. Connecting a volt meter across the resistor in the system, and in direct sunlight, you should get a reading of no more than 100V.

If we want to calculate the current we would take the voltage of 100 and divide it by the resistor's measurement of 10,000. All these values are interchangeable and the calculations can become complicated if you aren’t keen on mathematics. 

However, whichever path you choose, you end up with the same or similar value.

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