5 Other Key Takeaways

There are several key things to remember when using a solar panel with a battery charger. First, the OCV of the panel must be less than the OVP of the charger selected. When the solar panel is connected in low light or nighttime conditions, the solar panel voltage rises to the OCV. Keeping the OCV below the OVP allows for proper operation of the battery charger.

Second, there is a balance needed between sweeping the VINPDM of the battery charger and sticking at the last found MPP. Take the example of Figure 1-1. From a 14V to 16V solar panel output voltage, the solar panel output power is fairly linear from 0W to 6.5W. Assuming equal time at each step and a perpetual sweep to the MPP, the average power is about 3.25W as shown in Equation 1. However, if the sweep is done for only 25% of the time with 75% dedicated to the 14V/6.5W operating point, then the average power goes to about 5.69W as shown in Equation 2. That equates to a best case of 43% reduction in total average power if the sweep is constantly run. Therefore, this is important to evaluate how long the panel is swept versus how long the panel is kept in a steady state.