Can you dual-wire a house, part AC and part DC?
I have been doing a bit of research lately on solar power, grid-tied and backup systems. As we plan to build a house to Passive House standards, is there any way to get around building it exclusively with AC power systems? I would like to build it with at least the lights running on a straight DC system to prevent waste from the inverter and again at the light source. This would also allow for smaller wire to be ran to the actual light bringing forward some cost savings. Is the National Building Code moving towards allowing people to do this or is it still set for AC power only with plug in every twelve feet?
We have seen that people dual wire a house for solar panels so there's no technical problem with it, but to know if you're allowed you'd need to check with your local building authorities to be sure it doesn't violate Building code.
Our two cents - there is for sure losses due to the inverter, but for a load as small as lighting, it may not be worth the added effort to wire it for DC, particularly if you use LED lighting. Since you’re going to install an inverter anyway, it really boils down to the amount of lights you think you’ll need, what that draw is, and how much cost and effort is required to run DC as well.
Please let us know what you finally decide, that's a great question and a great ide, thanks!