If a home will run on 100% solar electricity, is it still wise to spend extra $$ to make the home LEED or Passive certified?
If a home I plan to build will run on 100% solar electricity from PV panels on its roof, is it still wise to spend extra $$ to make the home LEED or Passivhaus certified?
The house will be in southern Oregon.
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First of all, there is no direct connection between either of the certifications you mentioned (LEED and Passivhaus) and solar electricity. Many LEED homes and Passivhaus homes don't include solar panels.
It's also true that many PV-equipped net-zero homes aren't LEED-certified of Passivhaus-certified. So there is really no connection between PV power and these two types of certifications.
You may, however, want to pursue these certifications for other reasons; that's up to you.
Concerning your plan to build a home that "will run on 100% solar electricity from PV panels on its roof," it's worth pointing out that there are two ways to do this. Your house can be grid-connected or off-grid.
Most such homes are grid-connected. If you choose this route, you need to understand that you will be buying power from your local utility to run your house at night and when the weather is cloudy. So this approach doesn't really result in a house that runs on 100% solar electricity. Instead, you'll have a house that uses some grid power, but which balances your electric bill by selling electricity to the power company when your PV array is producing more electricity than you need.
If you want to build an off-grid home, it's also hard to build a house that "runs on 100% solar electricity." That's because it's extremely expensive to buy batteries that are large enough to power your house during cloudy spells in November, December, and January. Most off-grid homes rely on a gasoline-powered generator or a propane-fired generator for the dark days of winter.
Finally, if you want to build a net-zero energy house, it always makes sense to reduce your electric usage to a bare minimum. This can be done by following a design procedure that emphasizes energy efficiency and by choosing very efficient appliances.
For more information, see Net-Zero-Energy versus Passivhaus.