A 12kW solar system can power most things in your home, but how much power can it really produce?
Let’s break it down and find out.
First, we need to understand kilowatt-hours (kWh) to calculate the power a 12kW or 10kW solar system can generate.
Factors that Determine Solar Panel Output
Sunlight Change In the Day
From 6AM to 6PM, the amount of sunlight your solar panels receive changes due to the Earth’s rotation.
Early Morning (6AM - 9AM): The sun is lower in the sky, meaning sunlight arrives at a shallow angle. Panels receive less direct sunlight, resulting in lower power output. The intensity of sunlight gradually increases as the day progresses.
Midday (12PM - 2PM): The sun is at its peak, directly overhead or close to it, providing the most direct sunlight. This is when your solar panels generate their maximum output due to the high intensity of sunlight.
Afternoon (3PM - 6PM): As the sun begins to set, its angle decreases, reducing the intensity of light hitting the panels. Solar output starts to drop again, and by 6PM, there’s very little sunlight left for energy production.
Throughout the day, the position of the sun and the intensity of sunlight vary, significantly affecting how much energy solar panels can generate at different times.
Shading and Angel
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.
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.
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.
Calculate Solar Panel Output
There're several ways to estimate how much the 12kw solar system produces: 1. Use a national average amounts 2. Use our solar calculator.
Using Averages
The national daily power usage in the states is around 30kWh.
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.
For residential solar systems, 300-500 watt panels offer higher energy conversion efficiency, providing more power output in a smaller area. 
In real circumstances during the DC to AC conversion, there're 5% to 20% power lost. Say we choose 400W panels and consider 20% power lost, then each panel can generate 360W instant power. To supply 6kW AC output, the number of panel we need is:
6kW / 360W = 16 Panels
Using Solar Calculator
If we're using 400W panels to supply our 12kW solar system, we get 30 panels. That means we can get 12kW peak power output. If we receive 5 hours sunlight everyday, we can produce:
12kW x 5 Hours = 60 kWh
to supply our house power requirements.
The actual solar system power model should consider the actual house appliances usage pattern, the charging and discharging of solar battery, and the peak consumption hour when the system draw extra power from the grid.
To quickly estimate how the number of panels affect the solar system power usage, you can use our Solar Calculator to make a detailed plan.
The steps to use our calculator:
1. Select your electricity rate, house appliances with quantity and working hours per day: this step will estimate the power peak demands (kW), total power requirements (kWh) and electricity bill each month.
2. Select Solar Panel and Solar System Parameters: this step will simulate the power input by the array of panels, power consumption by the appliance, power storage by the battery, and the peak power hour when the system draw extra power from the grid.
Example Case:
Without solar: We select $0.18/kWh as our electricity price rate, and system selected appliances by default. This preset contains major appliances by a house.
With 12kW solar system and 5 panels: We select 12kW inverter and 20kWh battery, with 400W x 5 solar panels. Let's see what happens.
The result shows a $100 bill savings by simulating 30 days solar working behavior. The problem is: the quantity of solar panels are far less from supplying a 12kW solar system. To protect battery from depletion, the preset SOC is 20% which means the system will switch to grid without solar panel input and battery supply at this threshold.
With 12kW solar system and 20 panels: We select 12kW inverter and 20kWh battery, with 400W x 20 solar panels. Let's see what happens.
We saved $300 electricity bill each month. That's a big saving. The quantity of solar panels can match the 12kW inverter and 20kWh battery capacity. The power drawn from the grid comes from the peak power load by the house cause we have a 7kW load electric vehicle.
Final Thoughts
In conclusion, a 12kW solar system offers a reliable way to power your home while reducing reliance on the grid. The amount of power a system generates depends on factors like sunlight, shading, panel angel, and system losses. By understanding these factors and using tools like solar calculators, you can accurately estimate the power your solar setup will produce and how many panels are required.
It’s important to consider the unique characteristics of your home, such as appliance usage patterns and the presence of a battery for energy storage. While a 12kW system can meet the energy needs of most households, achieving optimal performance requires careful planning and the right equipment, such as the right number of panels and an efficient inverter.
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