Could someone explain, in layman's terms, what the difficulty in building a smaller inverter is? I unfortunately paid less attention in high school Physics than I wish I had.
The output of a solar array is a DC voltage (constant over time). Our homes are fed by an AC voltage (varying sinusoidally over time at a frequency of 60Hz).
A circuit is needed to convert the DC to AC. There is a loss in energy due to the functioning of the circuit. The circuit size and complexity depends on the specifications of the DC to AC inverter including the maximum power capability desired.
Traditional converters operate at low frequencies and lose a lot of energy due to the technological limitations of the semiconductors switches used. The switches essentially chop the DC input into a square-wave type output of a frequency in the low kHz range. This square wave output needs to be low pass filtered to allow only the 60Hz to propagate through to the inverter output. For low kHz type square wave, the inductors and capacitors used to make the low pass filter are large.
New semiconductor technology has resulted in switches that can operate at MHz frequencies. The inductor and capacitors used to make the low pass filters can be much smaller for MHz frequencies. These switches also have much lower conduction losses than the previous silicon-based switches but they need to be used in more novel topologies in order to minimize what are called switching losses.
To see a real-world example of what improvements can be made with the new semiconductor technology, compare the brick power supplies that come with our laptops to the much touted FINsix Dart (http://finsix.com/dart/). The latter uses new GaN switches that operate in the MHz range AND a novel topology that minimizes switching losses.
