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You are quite welcome, sir.
Actually, the Wiki descrption is not quite accurate and a bit confusing. Grid tie inverters can still be limited to 12/24/48 VDC inputs, and many are. The way it evolved is this:
When it became possible and legal and profitable to tie a solar or wind power to the grid, many folks were excited because the battery requirement was effectively eliminated. In other words, if you have the national power grid available and you can get paid for pumping into it when you are not using all the power you produce, it becomes your effective "battery". You can take out and put in whenever convenient. It has unlimited "storage" capacity in effect.
Once this whole idea started to catch on, the 12/24/48 volt constraint was removed for inverter makers. It is generally easier and more efficient to design power conversion devices at the higher voltages because losses are lower as current goes down. A 5KW inverter that uses 12VDC nput will draw 417 Amperes! The same inverter designed for 300VDC input power will draw a mere 17A.
Since losses in circuits and copper wiring (anything with any resistance at all) follow the I-squared X R rule, you can see that I-squared gets enormous in low voltage systems. Just think of the difference in wire sizeneeded to keep the losses low between 417 Amps and 17 Amps! Same idea applies to the MOSFETs, transformer primaries, etc. in the inverters.
So, grid-tie inverters are actually defined as inverters that can synchronize the output AC to the grid and that have been approved for doing that. A side benefit of this syncronizing ability is that they can be tied together at the output (and input) in parallel, so they can be modularized easily in affordable increments. A grid-tie inverter may still be designed only for 12/24/48 volt DC input. But the higher input voltage types of grid-tie inverters have become popular, partly because no one really wants to use 400 pounds of giant fat wire to get 12V at 417A down from the solar panels on the roof!
So-called "string inverters" are pretty much all higher voltage DC input and are a sub-group of grid-tie inverters. If you don't have grid access or don't want to sell-back to the grid for some reason, you pretty much need the batteries. Or if your grid is unreliable, as in third-world countries. There may be string inverters that don't have the grid-tie feature, even.
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Topic: Converting DC to AC: Open Discussion - All methods (Read 5592 times)
