Post by riobob on Nov 6, 2024 14:22:07 GMT -5
So this is an easy task using a multi meter. I have a digital one and it speeds the process. You need a meter to handle 10 Amps DC current (assuming 100 or 150 Watt panels, larger panels be sure your meter handles the label current needs for Isc).
Your panel will have 2 leads out of the block on the back. It also has a label indicating the specifications. You are interested in 2 numbers. Open circuit voltage (Voc) and Short-Circuit current (Isc) Voltage is referenced with a V and Current with an I. Most panels have a rated power characteristic on that label which is displayed in watts.
Place your panel in direct sun with NO SHADE
You will first place your meter on voltage and a range that is near or above the labeled voltage. Connect your positive lead to the positive output of the panel (usually has a red washer on the connector) and the meter negative lead on the other connector.
Take a reading and Note it: depending on your sun intensity and panel angle your voltage will vary.
Next on your meter move the red positive lead to the 10A current socket (or the range for your panel and meter) and again connect the red lead to the panel plus and the negative lead to the other connector (panel negative) note the reading.
Wattage will be found multiplying voltage by current. Of note, your panel may not be at the ranges on the label. this is typically an angle issue and with the leads connected, angling the panel can positively and negatively impact the output.
Solar panel glass is not always clean and this too impacts output. I clean surfaces with Plastic polish of a good name brand.
Realize most chargers have a differential above the battery before they output. My victron needs 5v above battery voltage. When the battery is 14.6 my panel needs 19.6 before any impact. this means very limited generation time for solar. So to combat this, I have 2 panels in serial and parallel this pair. Panels in serial are additive of the voltage, panels in parallel are additive of current. Your solar charger will convert excess voltage to output current. therefore if my 2 panels in lower intensity sunlight output 10 volts each, that adds to 20 volts and my charger works in lower light. adding other pairs in parallel, increases current available to the charger. I have oversimplified and am sure the EE's out there are going to roast, but this simplification allows better resource utilization for RV solar and means that the angle to get perfect sun to each panel is no longer necessary to increase a days output from your panels.
Your panel will have 2 leads out of the block on the back. It also has a label indicating the specifications. You are interested in 2 numbers. Open circuit voltage (Voc) and Short-Circuit current (Isc) Voltage is referenced with a V and Current with an I. Most panels have a rated power characteristic on that label which is displayed in watts.
Place your panel in direct sun with NO SHADE
You will first place your meter on voltage and a range that is near or above the labeled voltage. Connect your positive lead to the positive output of the panel (usually has a red washer on the connector) and the meter negative lead on the other connector.
Take a reading and Note it: depending on your sun intensity and panel angle your voltage will vary.
Next on your meter move the red positive lead to the 10A current socket (or the range for your panel and meter) and again connect the red lead to the panel plus and the negative lead to the other connector (panel negative) note the reading.
Wattage will be found multiplying voltage by current. Of note, your panel may not be at the ranges on the label. this is typically an angle issue and with the leads connected, angling the panel can positively and negatively impact the output.
Solar panel glass is not always clean and this too impacts output. I clean surfaces with Plastic polish of a good name brand.
Realize most chargers have a differential above the battery before they output. My victron needs 5v above battery voltage. When the battery is 14.6 my panel needs 19.6 before any impact. this means very limited generation time for solar. So to combat this, I have 2 panels in serial and parallel this pair. Panels in serial are additive of the voltage, panels in parallel are additive of current. Your solar charger will convert excess voltage to output current. therefore if my 2 panels in lower intensity sunlight output 10 volts each, that adds to 20 volts and my charger works in lower light. adding other pairs in parallel, increases current available to the charger. I have oversimplified and am sure the EE's out there are going to roast, but this simplification allows better resource utilization for RV solar and means that the angle to get perfect sun to each panel is no longer necessary to increase a days output from your panels.