How Much Power Does A Solar Panel Produce — A Breakdown of Power Output & Efficiency
Everything comes down to wattage.
When you buy a solar system, it’ll be priced in dollars per watt ($/watt).
When describing and comparing solar panels, it’s often done with wattage power output — these are more expensive 350-Watt (W) panels… these are more economic 290W panels…
Wattage is a cornerstone term for any conversation on solar panel power output. Let’s start by defining what wattage is before diving into how much power a solar panel produces.
Wattage, Voltage, & Amps — The Terminology of Electricity
Electricity comes from the flow of electrons. Electrons are negatively-charged, subatomic particles that orbit around the nucleus of an atom. The nucleus consists of positively-charged protons and neutrally-charged particles called neutrons.
The charged electron and proton particles create the potential for electrons to flow. When there are two connected terminals with different charges, there is voltage. Voltage is potential energy, meaning that it doesn’t perform work on its own. It creates the setting that allows for work to take place. The higher the voltage, the greater the potential to push electrons in a given direction.
The actual flow of electrons is measured in amperes (amps). The more electrons flowing past a given point over a certain period of time, the greater the amps.
Voltage is the pressure; amps are the current. Multiplied together, we get watts. A thousand (1,000) watts equals a kilowatt (kW).
Watts (W) = Voltage x Amps
For a simple analogy, imagine two different sized hoses shooting out water with equal force. The first hose has a smaller diameter (high pressure), so less water comes through (low current) the opening at greater velocity. The second hose has a larger diameter (low pressure), so more water comes through (high current) the opening at lower velocity.
In the water analogy:
the force of the water leaving the hoses = wattage
the hose diameter = voltage
the flow of water (current) = amps
Household appliances have different wattage requirements.
LED lightbulb ≈ 9 W
Blender ≈ 400 W
Microwave ≈ 1,000 W
Central AC ≈ 3,000 W
Now let’s take a look at the wattage — or power capacity — of solar to determine what solar panels are able to power.
How Much Power Does A Solar Panel Produce
Typical solar panels for residential systems comprise 62 or more solar cells. Each of these solar cells has a small voltage from the charged silicon layers within the cell. Enough sunlight will knock loose a silicon electron. The voltage across the cell forces the electron to move (amps) in a given direction.
Together, the voltage and amps result in a wattage power output.
One solar cell won’t produce much wattage. That’s why solar panels contain many solar cells. Sixty-two (62) cells coming together in a single panel will produce a modest amount of power.
It’s typical for solar panels on the market today to generate between 250 and 400 Watts of power. The most powerful solar panels used in residential systems are the SunPower A-Series panels which have a power rating of 425W.
Looking back at the wattage needed to power everyday appliances, one solar panel — even a premium one — only produces enough energy to run a blender. Clearly, solar systems need a decent number of panels to power a home.
How Many Solar Panels Are Needed To Power A Home?
The average Texas household uses about 14,000 kilowatt hours (kWh) per year. Texas receives a lot of sunlight, averaging close to 5 hours per day of peak sunlight exposure.
Using 350W solar panels under these average conditions, we can determine the rough solar system size needed to power a Texas home.
5 peak sunlight hours a day x 365 days in a year = 1,825 hours of annual sunlight for solar production
14,000 kWh of annual energy consumption ÷ 1,825 productive sunlight hours ≈ 7.7 kW
7.7 kW = 7,700 watts
7,700 watts ÷ 350 W panels = 22 panels
This simplified calculation shows the average Texas household needs 22 350W solar panels to cover its energy needs.
This is, of course, an over-simplification. Other factors to take into account when analyzing proper solar system size include:
your household’s specific energy profile
your arrangement with the electricity provider
the orientation, size, and slope of your roof
the efficiency of the solar panels
your personal budget
How To Calculate The Right Solar System Size For You
This requires that you know your annual kilowatt-hour (kWh) energy consumption. You can get this figure from your electric bills.
It’s also important to understand how your electricity provider manages solar customers. Some solar buyback programs are more favorable than others. This is critical information to determine if you need an oversized system to cover energy costs.
With that information, you are ready to analyze your available space. Some homes will be more space-restricted than others due to shading, steep roof slope, or limited roof space.
If space is tight, you may want to consider high-efficiency solar panels. Higher efficiency panels are typically more expensive, making your budget an important factor.
Why Does Solar Panel Efficiency Matter?
Alongside power capacity, solar panel efficiency is also a significant metric. It is the percentage of sunlight exposure that’s converted into usable electricity. Many notable manufacturers create solar panels with efficiencies between 18% and 20%. The highest efficiency residential solar panels are the SunPower A-Series panels at 22.8%.
High efficiency means more wattage output per unit of space. This makes high efficiency panels a great option for homes with limited space.
Solar Can Power Your Life
Although solar is not for everyone, it is proving effective for many Texas homes. Solar is gaining popularity in Texas because of the state's good sunlight exposure and favorable incentives. Solar panel technology has improved significantly over the past few years, allowing us to use less space to cover more of your energy needs.
To jumpstart your energy independence and explore your best solar options, we invite you to call us for a courtesy consultation.
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