Solar inverter input voltage from 2KW series connected grid tied

Most folks are pretty familiar and comfortable with how a battery works. A battery (for example) outputs 12 volts pretty steady until it is dishcarged or a load pulls more current than the battery can supply.

Solar panels are not voltage sources (batteries), they are current sources. At full noontime sun, a panel can output (for example) can output 5 amps between zero volts and ~18 volts... It is a (more or less), constant current. When the load voltage rises above ~18 volts, the current starts to drop down to zero amps at ~21 volts (this is a "12 volt" solar panel specification, and it would be a (Vmp*Imp=PM; 5 amps * 18 volts = 90 Watt panel).

Note that Pmp, Imp, and Vmp are specified at 25C/75F. And the numbers do change with temperature.

You need to "match" the solar panel to the load... For example, we generally match a 12 volt solar panel (Vmp~18 volts at 25C) to charge a 12 volt battery bank which runs between ~10.5 volts (dead) to 16 volts (equalization charge). And we would use a PWM (Pulse width modulation) type charge controller (just switches on/off.. The longer the on cycle, the more average charging current. The longer the off cycle, the less charging current.

Note that the Battery bank is what "regulates" the battery bus voltage. Charge controllers are there to prevent the batteries from being damaged by overcharging.

And we have MPPT (Maximum Power Point Tracking) type charge controllers. These use switching power supply principles to (usually) drop the output voltage of the array and increase the output current (almost the DC version of a variable transformer). The switching supply is not that complex (uses an inductor to store energy, and a transistor "switch" to control current flow through the inductor, and a diode -- This allows upwards of 95% efficiency. The ability to take (for examples) 100 volts and 12 amps (1,200 Watts) and "down convert" to 12 volts and 100 amps (still 1,200 Watts) to charge the battery.

More or less, think of the MPPT controller to be a computer controlled variable ratio transmission between the solar array and battery bank. And the computer monitors the performance curve of the array (i/V curve in electronics, RPM and Torque in mechanical), and finds the best "match" to deliver the proper voltage and current to the battery bank.

An AC inverter--A little more difficult to describe simply.. But basically, you have 4 transistors (switches) or an "H Bridge". Each leg of the H leg is a switch. The top two are connected to the positive bus, and the bottom two are connected to the bottom bus. If the Upper left and lower right is turned on, current flows left to right in the center bar. If the Upper right and lower left switches are turned on, the current flows right to left (opposite direction). If the center bar is a winding on a 12 volt to 120 volt transformer, you have your "AC" 12 VDC input, and the secondary winding is your 120 VAC output.

Anyway, here are some good links to read:

https://forum.solar-electric.com/discussion/5458/two-strings-in-parallel-with-unequal-string-voltages (this is very basic on solar cells)

https://en.wikipedia.org/wiki/Switched-mode_power_supply (generally MPPT solar controllers are "buck type")

https://en.wikipedia.org/wiki/Switched-mode_power_supply (buck mode specific wiki)

https://en.wikipedia.org/wiki/Power_inverter (general DC to AC inverter wiki)

I will stop here... This is a big subject matter, and I think you have specific questions you want to ask about. If you can tell us what your area of needs are (off grid solar + charge controller + battery bank + AC inverter or Grid Tied Solar + GT (AC) Inverter used on homes to reduce their energy costs).... Otherwise this gets into the realm of how does a Diesel Big Rig work. And why you went to college for 4+ years to get your engineering degree.

-Bill