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I already know what a MPPT is supposed to do. It's basically a buck/boost converter connected to a solar panel that finds the ideal power output by changing (boosting or lowering) the voltage of the panel. That's all well and good, however, this is where I get confused.

Once you connect the load to the MPPT, let's say our solar panel voltage gets boosted to 50V, and we then want to charge a car battery with it, which is currently at 12V.

Once we connect the MPPT to the battery, the voltage will drop to the battery's 12V...so...why did we boost the voltage in the first place? Is there now more current available now that we're using MPPT since there's more power? Is it the same as just connecting the solar panel directly to the battery?

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    \$\begingroup\$ There are two voltages. The solar panel voltage and the battery voltage. The MPPT adjusts the solar panel voltage to maximize battery charging current, basically. If we assume the efficiency of the DC-DC converter is constant, then maximum charge current will always occur at the maximum input power point. The DC-DC converter keeps input voltage and output voltage separate. \$\endgroup\$
    – user57037
    Apr 20, 2021 at 18:44
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    \$\begingroup\$ Most MPPTs can't boost, they can only buck to a voltage lower than teh panel voltage. \$\endgroup\$
    – user16324
    Apr 20, 2021 at 21:07
  • \$\begingroup\$ @user_1818839 grid tie MPPT can usually boost or buck as needed. \$\endgroup\$
    – user57037
    Apr 21, 2021 at 1:21
  • \$\begingroup\$ @mkeith fair enough, but I didnt' get the impression this Q was about grid tie inverters \$\endgroup\$
    – user16324
    Apr 21, 2021 at 10:49
  • \$\begingroup\$ @user_1818839 I agree. But people find these questions by web search. They tend to rank high in search results. So I just wanted to throw that in there for the benefit of other people who come along later. \$\endgroup\$
    – user57037
    Apr 21, 2021 at 16:02

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