Yash
Nowadays, the 400-watt solar panel has become the standard size for most solar installations, I look around.
A solar panel is an interface between solar energy and the electricity produced to run the appliances.
The right solar panel size can meet energy demands and provide smooth electricity for decades.
The 400-watt solar panels when connected make an array that can meet your energy needs. Let us discuss more about 400-watt solar panels in this complete guide.
The power produced by 400-watt solar panel
A 400-watt solar panel produces this amount of power when certain conditions are met.
These conditions are called Standard Test Conditions when:
- The sunlight intensity is 1000 W/m²
- Wind velocity of 1 m/s
- Cell temperature 25 degree Celsius
- The air mass index is 1.5
- The Right tilt of the solar panel is given based on the latitude of the location.
The voltage and current produced by 400-watt solar panel
Before knowing what can we run with 400-watt solar panel.
Let us know the voltage and current produced by it.
We know that power is the product of voltage and current.
A 400-watt solar panel has a Vmp (voltage at maximum power) of 42 volts and Imp (current at maximum power) of 9.5 Amperes
Which makes P(max) = Vmp X Imp
= 42 volts x 9.5 Amperes
= 400 watts under STC.
It has a Voc (open circuit voltage of 49.8 volts) and Isc (short circuit current) of 10.36 amperes.
The energy produced by 400-watt solar panel
There is a relationship between the power of the solar panel and the energy produced by it.
Energy = Power x Time
When a 400-watt solar panel is placed under the sunlight for 1 hour.
It will produce 400-watt hours (400-watt x 1 hour) of energy.
But the condition is that for 1 hour the sunlight intensity must be 1000 W/m².
Which is called Peak Sun Hour (PSH).
- 1 PSH = 1000 W/m²
I can re-write my equation as:
400-watt x 1 PSH = 400-watt-hours of energy.
People mistook PSH for the sun shining in the sky.
They assume if the sun is there for 10 hours, then their 400-watt solar panel will produce 4000-watt hours (400 x 10) of energy.
This is not true.
Because the sunlight intensity is not the same throughout the day.
The intensity is less in the morning and in the evening when compared to the noon.
The sun might be half as intense in the morning or evening as it is in the noon time.
Therefore, in the morning, it might be producing 400 x ½ PSH = 200 watt-hours of energy. The variation in the PSH in a day depends mainly on the rotation of the earth.
While the value of PSH depends on the latitude of the location.
The latitude value tells the angular distance of any location from the center of the earth.
Any place which is near the equator will have less value of latitude and receive more sunlight intensity (PSH) than a place that is situated away from the equator.
Examples:
- New Delhi (India): latitude 28.61ᴼ North: 5.35 (PSH)
- Kerala: latitude: 8.50ᴼ North PSH: 5.64
- Arizona (USA): Latitude 34.0 North: 6.44 (PSH)
- Delaware (USA): latitude 39 ᴼ North PSH: 4.57
- Maryland (USA): Latitude 39.0ᴼ North: 4.54 (PSH) Alaska (USA): latitude 64.0ᴼ North: 3.08 (PSH)
These PSH values are averaged over the 12 months. I mean in some months you get more than the average while in others you receive less than the average.
You see that the average PSH for the 12 months is 4.57
And
December is the worst-performing month with an average PSH of 2.41.
When I consider the average PSH then my 400-watt solar panel would produce: 400-watt x 4.57 = 1828-watt hours of energy per day.
My 400-watt solar panel will produce an average of 1828 watt-hours of energy when it is installed at Delaware with a tilt of 39ᴼ facing southwards.
(The similar solar panel will produce 2576 watt-hours of energy when placed in Arizona with a tilt of 34ᴼ with the ground).
The energy produced by 400-watt solar panel in real conditions
But in real life, the 400-watt solar panel produces less than what is mentioned in the datasheet.
In real conditions, we have a number of losses in the system.
Let me highlight them:
- Dirt losses
- Shading losses
- Transfer losses
- Conversion losses
- Degradation
- Age-related losses
- Efficiency losses
When I consider all the losses then a 400-watt solar panel may lose up to 30% of what it is producing.
We saw that it is producing 1828 watt-hours of energy when it is installed at Delaware with a tilt of 39ᴼ facing southwards.
Considering the losses.
It will produce 1828 x (1-30%)
= 1280 watt-hours of energy
We can use this energy to run various electrical appliances.
Moreover, we can store this energy in the battery to run the appliances at night.
Battery sizing
Assuming we are looking for a 24 volts battery in the market.
Let us calculate the capacity of the battery which can store 1280 watt-hours of energy.
Before sizing the battery, let us understand some basic features of the battery.
I assume we are using the lead-acid battery for storing the energy produced by the solar panel.
Read: Lead Acid vs Lithium ion: Which is better?
In a lead acid battery, you cannot withdraw all the charge stored in it.
A certain percentage of charge must remain in it for its effective working.
It is decided by its DOD value.
If I say that a battery with a capacity of 1800 W-hr has a DOD of 80%.
It means I can withdraw 1440W-hr (80% of 1800 W-hr).
And the remaining 20% remains inside the battery.
Therefore, an 1800 W-hr battery with 80% DOD gives me 1440 W-hr of energy.
I assume that my lead acid battery has a DOD of 50%.
And I need 1280 watt-hrs of energy from it.
Then I should look for a battery with a capacity of 1280 x 2 = 2560 watt-hours of energy.
Further, there are losses when the energy is converted from one form to another.
If my battery is 90% efficient.
In that case, the new capacity is: 2560/0.9
= 2844.44 W-hrs
Therefore, I need 2844 watt-hrs of the capacity of the battery which can provide me 1280 watt-hrs of energy.
In the market, you see batteries in terms of Amp-hrs.
Which can be found as follows:
In Ampere hour = {Energy/ (DOD x voltage x efficiency)}
DOD = 50%
Efficiency = 95%
= 1280/50% x 24 volts x 90%
= 118.5 A-hr
Therefore, the battery specification would be 24 volts, 118.5 A-hr, and 50% DOD.
In case, I need 2 days’ backup then in that case, the ampere rating would be:
2 x 118.5
= 237 Amp-hr.
Sizing the solar charge controller
As there is a difference between the solar panel voltage and the battery voltage.
Therefore, we should look for MPPT solar charge controller.
It has the ability to convert the voltage difference between the solar panel and the battery into an equivalent amount of amperage.
The first rating would be the output voltage it will produce.
It is equal to the battery voltage which is 24 volts in this case.
The second rating of the MPPT solar charge controller is its input voltage.
The voltage it is getting from the solar panel.
Take 1.1 times Voc to get the input voltage rating of the MPPT solar charge controller.
It should be: 49.8 volts x 1.1 = 54.78 volts
The third rating is its output current which it can produce for charging the battery.
It can be found as:
Power of the solar panel/battery voltage
In our case, 400 watt/24 volts = 16.67 amperes.
What the battery can run?
The battery will produce 1280-watt hr of energy.
It will run the following appliances:
- A 10-watt led bulb for 128 hours
- A 100-watt fan for almost 13 hours
- A 10-watt led and 100-watt fan for almost 12 hours continuously {1280 watt-hours/ (100 watts + 10 watts)}
- 2 x 100 watts fans for 6.5 hours
- 2 x 100 watts fans and 1 x 10-watt LED for 6 hours {1280 watt-hours/ (100 + 100 + 10)}
You can use as many combinations as you want by using the following formula:
Number of hours of running = 1280 watt-hours/ (Combined load in watts)
Weight and dimensions of 400-watt solar panel
We all have space constraints.
Therefore, it is important to know the dimensions of the 400-watt solar panel.
To get an idea of the space it will occupy if you plan to install it on the roof of your house.
Along this, the weight of the solar panel is of important consideration to know whether it is compatible with the roof structure and design.
Also, the installation cost has an element associated with the weight of the solar panels.
More weight means more labor is required to install a solar panel.
There is no exact value that we can say.
But yes, there is a range of values in which 400-watt solar panels lie.
So, let us know these values by looking at the similar solar panel of different brands.
1. Jinko Cheetah
In the case of Jinko, it is 22.5 kg heavy and has dimensions of
1.979 m x 1.002 m x 0.04 m
These are length x breadth x depth
We need to know the area of the solar panel to know how much space it will occupy on the roof.
Therefore, we will take the length and breadth values only.
In this case, the area is: 1.979 m x 1.002 m = 1.983 m²
2. REC Alpha
Let us take another company REC Alpha Series with a 400-watt solar panel.
In this case, the REC 400-watt solar panel has the following dimension:
- Weight: 21.5 kg
- Dimensions: 1.73 m x 1.118 m x 0.03 m
- Area: 1.934 m²
Its area and weight are less than that of the Jinko Solar 400-watt solar panel.
3. LG NeON
Let us take the 3rd brand of similar capacity.
- The weight is 20.3 kg and the dimensions are:
- 2.024 m x 1.024 m x 0.04 m
- Area: 2.024 m x 1.024 m = 2.07 m²
Let us compare these dimensions in one picture:
We can summarise our findings about the weight and area of a 400-watt solar panel in the following form:
Efficiency and cell type
The efficiency of any solar panel is its ability to convert sunlight into electricity.
Or
What amount of 1000 W/m² of input sunlight intensity is converted into electrical power is defined by the efficiency of any solar panel.
It is measured in percent (%).
It can be written as:
Let us look at the efficiency and the technology of 400-watt solar panels under the above-mentioned three brands (Jinko, REC, and LG).
The efficiency of Jinko Cheetah 400-watt solar panel: 20.17%
Its technology is Mono-PERC and has an efficiency of 20.17%
In Mono-PERC technology a passivated layer is pasted at the back of the monocrystalline solar cell.
This layer traps the bypassed light, reflects it again, and makes it available for photo-electric effect.
This technology improves the efficiency of the solar panel.
The Efficiency of a 400-watt REC solar panel: 20.7%
It has the technology of half-cut solar cells with heterojunction technology embedded into it.
This technology gives it an efficiency of 20.7%.
It is slightly more than the Jinko 400-watt solar panel.
LG-400-watt solar panel efficiency: 19.3%
Its cell type is Monocrystalline/N-type with an efficiency of 19.3%.
Let us summarize the efficiency of the 400-watt solar panel in the following chart:
REC Alpha 400-watt solar panel has the highest efficiency of 20.7% amongst the three solar panel companies we discussed.
As the 400-watt solar panel is big in size therefore monocrystalline cells are used for making the solar panel.
It is not that we can not use polycrystalline solar cells.
But
If we use the polycrystalline solar cell, the overall size will increase if we want the same efficiency from the solar panel as that of a monocrystalline solar panel.
Price of a 400-watt solar panel
The 400-watt solar panels generally have better technology and higher efficiency than their smaller versions.
When you go for big-size and high-power solar panels. Then You need fewer solar panels to meet your energy needs.
The monocrystalline 400-watt solar panel price is Rs. 28 to Rs. 33 per watt.
Whereas polycrystalline 400-watt solar comes in Rs. 22 to Rs. 27 per watt.
Important specifications you look for in a 400-watt solar panel
When you consider solar for your home, office, or factory.
Look for certain specifications in solar panels which can make your solar installation a great experience.
1. Warranty
A warranty is a product quality and performance assurance that a solar manufacturer gives to its buyers.
In solar panels, we see two types of warranties:
Product warranty: In this warranty, the manufacturer assures the buyer about the quality of the solar panel for a certain period. The manufacturer assures that in case the solar panel suffers any premature wear and tear, damage to the diode, or leakage within a specified period. He will repair or replace the solar panel.
We usually see product warranties for 10 years.
Performance warranty:
The manufacturer assures the buyer that after the purchase, the solar panel is going to produce a certain percentage of Pmax even after 25 years.
For example, a 400-watt solar panel with 80% of Pmax after 25 years means that it will produce 360-watt (80% of 400-watts) under standard test conditions.
2. Efficiency
As we discussed above, efficiency is the ability of the solar panel to convert sunlight into electricity. A highly efficient solar panel produces more power in a limited space. Therefore, people with space constraints must look for efficient solar panels.
3. Strength
Once you install the solar panels on the roof or outside your house. They will remain there for decades. Therefore, they must be strong enough to withstand the weather extremities such as rain, snow, and high wind pressure.
The strength of any solar panel is defined by 2 ratings:
One is the wind load rating and another is the snow load rating.
The wind load rating often called rear load rating defines the ability of the solar panel to withstand wind pressure.
And it is expressed in Pascals.
While on another hand, the snow load rating (front load rating) is the capacity of the solar panel to bear the snow load.
It is also expressed in Pascals. The higher the values of both ratings, the stronger is the solar panel.
4. Temperature co-efficient of power
This specification defines the performance of the solar panel at high temperatures.
The power output of any solar panel reduces as its cell temperature rises beyond 25ᴼ C.
How much power any solar panel will lose is defined by the value of its temperature coefficient of power.
It is written in negative which defines the power loss and expressed in %/ᴼ C.
The lesser the value, the lesser the power loss.
5. PID resistant
As the system voltage increases, the chances of originating the leakage also increase.
The high voltage difference between the solar panel and the mounting frame causes some current to flow from the solar cell to the mounting frame.
This leakage current instead of going to the electrical appliances is leaked to the ground.
Hence the house gets less current than what is produced.
Therefore, the solar panel must be PID-resistant. IEC 62804 is the certification that shows that the solar panel is PID-resistant.
6. Salt and Mist resistant
When the solar panel is outside.
The water content in the air may corrode it and affects its performance.
Also, solar panels installed near the water bodies are more prone to deterioration.
Because the salt content in the water bodies evaporates and meets the solar panel along with the air.
The salt has a more corrosive effect and can degrade the solar panel faster.
Therefore, the solar panel must be salt and mist resistant.
The IEC 61701 ensures that the solar panel is resistant to salt and mist.
Let us look at the value of all 6 specifications of 400-watt solar panels of different companies (Jinko, REC, and LG) in tabular form.
References:
Conclusion
The energy produced by the 400-watt solar panels depends on many factors such as:
- Location
- Time of the day (morning, noon, or evening)
- The tilt of the solar panels
- Losses in the system
- Efficiency of the system
The same 400-watt solar panel when placed at 2-different locations may not produce the same energy due to the above-mentioned factors.
Therefore, the amount of energy produced by the 400-watt solar panel is specific to a particular location.
Further, it is better to consider the losses to understand the real working of the solar panel. When you do so, your estimation will be very close to the real energy produced by the solar panel in the practical world.
