A 50 watt solar panel that a friend recently bought to charge to his battery once connected up only produced 35 watts. He was feeling cheated because the sticker on the solar panel clearly said it was a 50 watt solar panel.
But I explained that he was not conned, but just not fully informed.
You see the solar panel retailers often do not take the time to explain, or worse still they try to avoid mentioning the following vital facts about solar panels.
A solar panel must be producing power at its MPP . The MPP is the maximum power point. This is where the voltage and current flow produce the most power. Most solar panels once connected up will be operating off their MPP depending on the system load resistance. The load is a technical term for the total power used. In an ideal system only the device that you want to power is the load, for instance a battery you want to recharge, but in practice all the components that make up the system, such as connections and wiring and voltage regulation devices, use some of that power and contribute to the total load on the system. When the system load moves away from the optimum load then the PV module’s voltage and amps will move away from the MPP and the solar module becomes less efficient, thus produces less power.
The solar panel must be fully bathed in direct sunlight. Most of the time the solar panel will not be facing directly into the sun, there may be clouds or shadows obscuring the sun and there may be debris on the solar panel obstructing the sunlight. In a 100% efficient solar module the sun falling on an area of one square meter of solar panel would produce 1000 watts but the average PV panel is about 15% efficient and produces about 150 watts per square meter of area.
The solar cells temperatures must not exceed 25°C . Excessive heat has the greatest effect on the voltage generated by the cells. Don’t be fooled by the ambient temperature, because when the air is about 10°C, the solar cell will be at about 40°C. Solar cells don’t like heat, when the temperature rises then the cell produces less voltage. At 40°C a cell is producing 10% less voltage than at 25°C so on a typical summer day the cell may be at 65°C. and producing 80 watts instead of 100 watts.
All of these factors add to the total energy loss of the solar generating system so when you measure the actual usable power it will be less than the panel’s rated output. For more details and diagrams see this article covering how to get the most out of your solar panel on our website at Ecopia Portable Solar
50W solar panel was only 35 watts
A 50 watt solar panel that a friend recently bought to charge to his battery once connected up only produced 35 watts. He was feeling cheated because the sticker on the solar panel clearly said it was a 50 watt solar panel.
But I explained that he was not conned, but just not fully informed.
You see the solar panel retailers often do not take the time to explain, or worse still they try to avoid mentioning the following vital facts about solar panels.
All of these factors add to the total energy loss of the solar generating system so when you measure the actual usable power it will be less than the panel’s rated output. For more details and diagrams see this article covering how to get the most out of your solar panel on our website at Ecopia Portable Solar