Syonyk's Project Blog: Why a Typical Home Solar Setup Does Not Work With the Grid Down - And What You Can Do About It
Behavior of solar panels: MPPT: Maximum Power Point Tracking
September 17, 2018 at 3:19:40 AM GMT+2
" So, going back to the curve: If I try to draw more than whatever the peak power of my panels are (in current conditions), the voltage (and power) collapses. If I tried to pull 2A out of my morning panels when they were facing east and only able to source 1.3A, the voltage would collapse to 0V and the power would drop to zero. What if I try to pull 2A out of them when they're swung out and able to produce 7.4A? Well, I can pull 2A for as long as I want."
"A typical grid tied solar system is built with microinverters. These are a combination MPPT tracker and inverter for each solar panel, normally in the 280-320W range, though that's creeping up with time as panel output increases. The output from these synchronizes with the grid - typically 120VAC and 60Hz, in the US. However, they're very simple devices. They don't have onboard frequency generation - they can only work when given a voltage waveform to synchronize against. They also only work at maximum power point - that's their whole point, and when the grid is up, they're connected to what is, from the perspective of a microinverter, an infinite sink. So they sit there, finding the maximum power point, and hammering amps out onto whatever waveform the grid is feeding them."
And, batteries are expensive.