Both are great names, one for obvious reasons which negates any value to an end user or a smarter-than-average domainer from a reseller point.
SolarPowerInverter is a super name but suffers from two things: First, being a dot info. Secondly, being a very small market. Anyone who is thinking of installing or using Solar power will need an inverter. Problem is, that product in itself is a niche market withing a niche market. Typically the inverter is included as a compliment to the package of panels, installation, etc.
Naturally, there may be a market for off-brand inverters that have greater capacity or as a replacement.
It is a good name that the market needs to catch up to. Usually any of these tech names or devices are out ahead of the rush and someone just needs patience to sit on them while the rest of the world discovers them.