That isn't exactly true when it comes to grid feed inverter setups. You wiil find with most if not all grid feed inverters the panels are wired up in series and you end up with anywhere between 300-600vdc at the inverter input. You aren't allowed to touch it unless you're a licenced electrician and there are also requirements as far as panels go in that they need approvals in order to be connected to a grid feed system so your home made panels could not legally be used in such a way.