How many solar panels do you need?: A 2021 Guide
While determining how many solar panels do you need, you should first look for your electricity needs.
Most people want to generate enough energy to eliminate their electricity bills while others just want to cover their partial usage.
It is always best to keep your electricity consumption in mind before installing PV panels.
No need to worry if you do not know it!
People are often confused while deciding the number of PV panels they should install either it is for home or utility purposes.
In this blog post, I will cover all the factors that you should not forget to consider before adopting solar power.
I will guide you with the stepwise approach, so that, at the end of this post, you will get the exact number of solar panels you will need to install.I think the future of solar energy is bright🔆…Make the sun work for you! Click To Tweet
Let’s start with the factors you should look over before the installation of panels-
- What factors decide your panel requirement?
- Know your Energy Consumption
- How much wattage should your system produce?
- How many Solar panels will you need?
- Best Angle and direction for your solar panel
- Which solar panel to choose?
What factors decide your panel requirement?
✔️The amount of energy consumption.
✔️Your geographical location.
✔️The direction of the roof.
✔️Best angles and directions for your solar panel.
✔️ The amount of wattage or energy the solar panel you purchase can produce.
Considering the above factors will conclude your total panel count.
So, without further delay, Let’s move forward to know how to analyze these factors?
Know your Energy Consumption
To find your energy consumption, let’s follow the following steps:
#1 Get Your past Utility Bills
To know what amount of electricity will you need, first, get your past electricity bills.
Your electricity bills should be the most recent, that is, the last 6 to 12 months bills.
#2 Look for your Monthly Usage
Once you get your bills, collect your usage from each bill. Note this number down for each bill you have.
It is typically shown in the kWh or kiloWatt-Hours.
**If your bill doesn’t show kWh usage, then subtract ending meter readings to the previous one.
#3 Calculate your daily kWh usage
Now, take an average of all those numbers and calculate the average daily electricity consumption.
Let say you have your past 6 months bill and the usage for the same is 300 kWh, 200 kWh, 275 kWh, 125 kWh, 250 kWh, 350 kWh respectively.
Then, the average monthly electricity consumption is
Likewise, the average daily electricity consumption is
=(average monthly consumption/30)
Now, you got the values of how much daily electricity you will need.
How much wattage should your system produce?
The average daily usage you got is your full day usage, that is day and night. But, you only get the sunlight during the day time.
To deal with this you need a battery backup system so that you can store solar energy for later use.
But, you have to spend extra for battery backup.
Thanks to Net Metering! By doing your house or firm net-metered, you do not need to spend money on the battery backup.
If you are installing a battery backup, your system should be able to produce enough energy that you will be able to use at night time.
So, how to get the energy production that your panel needs to produce every hour?
It depends on the peak sunlight hours you are getting in your area.
How many hours of sunlight can you expect at your location?
Peak Sunlight hours describes the intensity of sunlight in a specific area.
Generally, panels get 7 hours of sunlight. But, the intensity of the sunlight is highest for 4-5 hours only.
These hours are the peak hours for your panels to absorb the maximum solar energy.
Below is the peak sun hours map by UnboundSolar, indicating the average solar insolation (full sun hours) for these zones.
Suppose, you have 4 peak hours of sunlight at your location.
Multiply the average hourly kWh requirement by the number of peak sunlight hours.
Average hourly wattage your system should produce
= Hourly energy requirement × Peak sunlight hours
= (50 kWh /24 hours) × 4 hours
= 8 kW (approximately)
or 8000 Watts
Now, you know how much your system should produce every hour to fulfill your daily requirement.
How many Solar panels will you need?
When you purchase solar panels, you should first ask for the wattage of that panel.
To determine the exact number of solar panels, divide your average hourly electricity requirement by the wattage of 1 solar panel that you want to purchase.
Number of solar panels = Average hourly wattage requirement /Wattage of 1 Solar Panel
As a rough estimate, let’s assume that you purchased 310 Watts solar panel.
And, your average hourly wattage requirement is 8000 Watts.
Then, the number of solar panels
= (8000 /310)watts
= 26 solar panels (approximately)
You would need 26 panels if you want to completely eliminate your electricity bill.
Also, if you want to cover your electricity usage partially with solar energy, then you would need fewer panels.
Best Angle and direction for your solar panel
PV panels perform at their best when sunlight is falling straight at its surface.
However, the sun is never stable and thus, it is not possible for us to get the sunlight falling straight on the surface of panels all day.
So, what’s the mid-way?
You can tilt and face your panels to an appropriate position to help them to produce maximum energy as they are exposed to the highest intensity of sunlight for the greatest period of time.
In short, the general rule for solar panel placement is that solar panels should face true south (or geographical south).
in the second place, the general rule for optimal annual energy production is to set the tilt angle of your solar panel equal to your geographical latitude.
Let’s say If you are living in Brussels, a city having a latitude of 50°, then you have to tilt your solar panel 50° from the ground.
Above is the data from EIA showing U.S. utility-scale fixed-tilt solar photovoltaic capacity tilt angle.
Also, you can do seasonal adjustments to get more electricity production. We have also covered it in our previous blog.
Which solar panel to choose?
The total energy production by your solar panel is also affected by the type of panel you will choose.
Solar panels are made of semiconductor materials like Silicon.
The efficiency of the solar panel varies depending on the purity of semiconductor material used in the manufacturing of solar panels.
Monocrystalline solar panels are considered the most efficient panels in terms of electricity generation.
Polycrystalline panels are also used to get the budget-friendly installation of solar panels.
Q. What is Net-Metering?
Ans. Net metering is a kind of billing mechanism that allows you to transfer your excess electricity to the grid.
When your total electricity generation is greater than the electricity you consume. Then, you can also earn by transferring the extra electricity to the grid.
Q. Do my solar panels produce power when the sun isn’t shining?
Ans. Since there is no access to sunlight at night. Thus, solar panels do not produce electricity at night.
However, these do produce electricity on cloudy and rainy days but with less efficiency.
Q. How long will my solar panels last?
Ans. Generally, the solar panels last about 25-30 years.
Q. Which battery should I use for battery backup?
Ans. The most commonly used batteries are:
1. Lithium-Ion Batteries
2. Lead Acid batteries
Lithium-Ion batteries have a longer expected lifespan in comparison to the Lead Acid batteries.
Q. What are the different types of solar panels?
Ans. There are various types of panels available in the market.
The three main types of solar panels are:
1. Monocrystalline solar panels
2. Polycrystalline solar panels &
3. Thin-film solar panels
I have discussed all the factors that determine your solar panel requirement. I hope you have got the answer to how many solar panels do you need.
Even, if you contact a solar power provider to install the system, you have enough information to ask the right questions to your provider.
Also, you should not forget to test your solar panels before installing them. By doing this, you can ensure that you don’t waste your time installing panels that you’ll have to take down and fix.
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