Solar panels produce electricity from sunlight thanks to the photovoltaic effect.
They perform best under full sun exposure. Consequently, their surface is subjected to high temperatures.
The main active material of a solar panel is silicon. Silicon is what gives the panels their typical dark-blue color, and like any dark object exposed to the sun, they can become very hot.
High temperatures decrease the efficiency of your solar panels.
So, this begs the question: What are the best solar panels for high temperature?
Not all solar panels are created equal when it comes to high temperature. Therefore, in this post I am giving you my pick of the 15 best solar panels for high temperature.
- Renogy 30 Watt Monocrystalline Solar Panel
- SOLPERK 50 Watt Solar Panel
- RICH 60 Watt Portable Solar Panel
- Chafon 60 Watt Portable Solar Panel
- Paxcess 60 Watt 18V Solar Panel
- WEIZE 100 Watt Solar Panel
- TOGO 120 Watt Foldable Solar Panel
- Renogy 200 Watt Monocrystalline Solar Panel
- Renogy 320 Watt Monocrystalline Solar Panel
(See the full list of solar panels below)
Additionally, I will then discuss the effect high temperature has on the power output of your solar system and offer you some advice on how to cool down your solar panels in extremely hot conditions.
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What are the 15 best solar panels for high temperature?
Have a look below at my selection of the most efficient solar panels for high temperature.
I picked panels from 30 watts output to 320 watts. I included panels for camping (foldable), and roof tops (RV, house).
30W Solar panel
Renogy 30 WATT 12 VOLT MONOCRYSTALLINE SOLAR PANEL
SOLPERK Solar Panel Kit 30W 12V
50W Solar panel
SUNER POWER 12V Waterproof 50 Watt
SOLPERK 50W Solar Panel Kit 12V
RENOGY 50 WATT 12 VOLT MONOCRYSTALLINE
60W Solar panel
RICH SOLAR 60 Watt 12 Volt Portable Monocrystalline Solar Panel
PAXCESS 60W 18V Portable Solar Panel
CHAFON Portable 60W Solar Panel Charger
100W Solar panel
RICH SOLAR 100 Watt 12 Volt Portable Monocrystalline Solar Panel
WEIZE 100 Watt 12 Volt Solar Panel
RENOGY 100 WATT 12 VOLT MONOCRYSTALLINE
120W Solar panel
Togo Power 120W Portable Foldable Solar Panel
TwelSeavan Portable Solar Panel Charger
200W Solar panel
RENOGY 200 WATT 12 VOLT MONOCRYSTALLINE
320W Solar panel
RENOGY 320 WATT MONOCRYSTALLINE SOLAR PANEL
How does temperature affect solar panel output?
It might be counter-intuitive to think that high temperature decrease solar panel efficiency. After all, we know that solar panels exhibit their best performances when exposed to full sun.
But, they can become as hot as 80°C, and like any other electronic devices, solar panels suffer from high temperature.
Let’s see why.
This is due to the limitations of their main active material: silicon.
Silicon is a semi-conductor, similar to the one you’ll find in micro-ship in your computer, your phone and all kind of electronic devices.
A semi-conductor combines the properties of a conductor (metal) and a non-conductor (insulant). Its properties are affected by the temperature.
At low temperature, silicon behaves more like an insulant, and at higher temperature, more like a conductor (metal).
In the particular case of silicon, it can produce electrons (electricity) when exposed to the sun (photons), thanks to the photoelectric effect.
Lower temperatures mean that silicon atoms are in a low excitation state, electrons inside the material do not flow that easily, the material becomes insulant.
On the other hand, higher temperatures mean that silicon atoms are more excited, and the material will become more of a conductor (metal).
Therefore, it will be easier for the electrons to flow into the panel. In the end, more electrons will be produced (more current) but at a lower voltage.
For solar panels the relevant figure is the power output in Watt, which is obtained by multiplying the output current (Amps) by the Voltage of the panel (V)
P(Watt) = I (Amps) * V
The increase in current will not be enough to balance the decrease in Voltage, therefore reducing the overall power output of the solar panel.
What is the temperature coefficient of a solar panel?
Knowing that temperature is lowering the power output of their solar panels, manufacturers are looking to quantify this effect. It is easily predictable and measurable.
They created the temperature coefficient that reflects the loss in power for every degree.
The temperature coefficient can be found in the specifications of your panel. It is a linear coefficient which value varies between -0.3%/°C and -0.5%/°C depending on the type of solar panel.
A -0.5%/°C temperature coefficient means that for every °C increase, your solar panel will loose 0.5% of its total rated maximum power.
Power output of your solar panel starts to decrease when the temperature of the panels surface exceed the nominal operating cell temperature (NOCT) which is 113°F (45°C).
Let’s have a closer look at the specifications of a RENOGY 200W solar panel.
The thermal characteristics are provided.
Accordingly to theoretical calculation, it shows that electric current is increasing with temperature (0.05%/°C) and Voltage is decreasing (-0.31%/°C).
The temperature coefficient for this panel is -0.42%/°C.
If the panel reaches 80°C (176°F), which is considered its maximum temperature, the difference with the nominal temperature is 35°C (95°F).
Therefore the decrease in power output due to temperature is 35*0.42= 14.7%.
This 200W panel, will only be able to produce 171W at max.
Every solar panel has a different temperature coefficient, look at the thermal characterisitics for this information.
Which solar panel is best for high temperature?
Not all solar panels are made equal when it comes to temperature coefficient.
Solar panels come in Monocrystalline or Polycrystalline type.
This term describes the type of silicon material used to produce each solar panels.
Monocrystalline solar panels perform better than polycrystalline under high temperatures.
Polycrystalline panels typically show temperature coefficients of -0.5%/°C whereas monocrystalline panels have temperature coefficient between -0.3%/°C and -0.45%/°C.
Monocrystalline solar panels produce on average 20% more power than polycrystalline under high temperature.
Go for monocrystalline panels, but have a look at their thermal characteristics, you might find small discrepancies between manufacturers.
Why monocrystalline solar panels perform better than polycrystalline under high temperature?
The performance of your solar panel under high temperature is all due to the arrangement of atoms in the silicon. Silicon is the active material of your panel.
Mono and Polycrystalline solar panels have the same active material, silicon, however they differ by their level of internal crystal arrangement.
Monocrystalline as they are named are made from a single silicon crystal. Therefore, the arrangement of the atoms is almost perfect compared to polycrystalline silicon.
This enables an easier electron flow through the material, reducing some loss at high temperature.
On the contrary polycrystalline panels have a more messy crystal arrangement. This results in slightly lower performances.
What is the optimal temperature for a solar panel?
When tested in the laboratory, the outside temperature is set at 77°F (25°C). The front window temperature of the solar panel reaches around 113°F (45°C), this is the nominal operating cell temperature (NOCT), at this optimum your solar panel will produce its maximum power.
However in real life conditions, the outside temperature can greatly vary.
In California for example, it can reach up to 86 °F (30°C) on average during the hottest month of the year. Consequently the surface of the panel can reach up to 176°F (80°C) when exposed to full sun.
This will reduce the performance of your panel by up to 15% compared to the optimal temperature.
How do you keep solar panels cool?
We have seen that high temperatures reduce solar panels efficiency. Cooling your panels is a must to minimize the temperature loss.
There are two ways of cooling your panels:
- Passive cooling
- Active cooling
Passive cooling is a simple yet effective way of reducing your panel surface temperature.
It takes advantage of the natural airflow below the solar panel.
For roof-top solar panels (house or RV), allow at least 15 cm of space between the surface of the roof and the solar panel.
For flexible solar panels, never glue them directly on the roof of your vehicle. They become incredibly hot as the temperature will diffuse into the solar panel through the metal surface of the roof.
If you are using foldable solar panels in a camping trip, make sure that you have a stand so they are not in direct contact with the ground.
With passive cooling you can lower the temperature of your panels by 5 to 10 degrees.
If you are looking at a more efficient cooling method, you should consider active cooling.
We have seen that high temperatures lower solar panel power output by 15%.
For larger domestic and industrial installations it can translate into a lot of energy and money loss.
Active cooling is the most effective way to reduce the surface temperature of a solar panel. It is based on water cooling. We can divide it into:
- Front water cooling
- Back water cooling or hybridation
Front water cooling
Front water cooling is the cheapest, yet an effective active cooling technique.
A drip system is installed on the top of the solar panel, water drops flow on the surface of the panel and are collected at the bottom.
Water is circulated by a pump.
Experimental results show that this method is effective to cool and clean the surface of the panel, resulting in a significant power gain, up to 10% yearly.
With front water cooling you can reduce the temperature of your panel by more than 15 degrees in a few minutes.
However, this technique is limited to large scale installation. It requires equipment like a water pump that will also use energy, water tank, pipes… The system is open, therefore water will evaporate and you will have to refill the tank from time to time.
If you are looking to install this type of cooling, I would advise you to perform a serious calculation before setting up your system. You will determine the quantity of water and the power of the pump needed.
Tips for foldable solar panels for camping:
Foldable solar panels are usually set on the ground, therefore easily accessible.
A simple way of cooling your foldable solar panels, is to spray them with water from time to time. You will quickly notice a gain in performance.
Back water cooling or hybridation
Back water cooling is based on heat exchange.
Water is circulated in small pipes right below the surface of the solar panel. Heat from the panel is transferred to the water and could be used directly in the house as warm water or connected to a heat pump to increase its efficiency.
This type of system is named PVT for Photovoltaic Thermal, it is an hybrid system combining the production of electricity from a solar panel, and warm water from the heat exchanger.
Back water cooling is more expensive to set up than front water cooling, however it is as efficient to maximize your solar panel output and in addition you will benefit from the heat of the water coolant for your household use.
Temperature is affecting the power output of your solar panel.
When the sun is at its zenith, you can loose up to 15% of power output due to high temperature.
Choose monocrystalline solar panels, they offer up to 20% more power output at high temperature compared to polycrystalline solar panels.
Have a look at our list of the 15 best solar panels for high temperature, I have carefully selected them for their higher performance in hot weather.
In addition, never mount your panels directly on a surface, allow for 15 cm to provide natural air cooling.
Think about hybrid Thermal and PV solar panels, they maximize the power output and provide warm water to your house. No waste of solar power, no waste of heat!