I'm having a hard time finding a news article with links to the actual standard, and secondary sources like this Bloomberg article are omitting important details. Does this represent the standard that was adopted:
In particular, I wonder what the minimum system size is, in kilowatts. Reporting household system size in "dollars" is a poor metric because PV dollars-per-watt is changing rapidly.
The source that I linked above says "Minimum PV sizing by code will rely on results from the energy consultant’s Title 24 compliance calculations." Can anyone explain what's required to comply with Title 24? I'm looking for answers in physical units rather than currency units.
FWIW, Germany and Australia have fully-installed residential rooftop solar costs-per-watt less than half of that in the US. I'm not sure where the big cost gap comes from -- Germany and Australia have decent wages for labor and safety codes too. The hardware is commoditized and globalized. If California could match Australian costs-per-watt then this proposal would add significantly less to the initial cost of a new house and significantly increase lifetime cost savings vs. using only power from the grid.
EDIT: it looks like the final adopted proposal is 17-BSTD-02, rather than the earlier 17-BSTD-01 that I linked above. Here's the final one:
> Can anyone explain what's required to comply with Title 24?
I help write software that implements calculations related to Title 24 compliance, so I'll give answering this a shot.
It's described in this[1] 289 page document (only like a fifth of it applies to residential construction). It covers a lot of things, to say the least.
At a very simplified and high level, it works like this: There are two overall ways of meeting the energy efficiency requirements. One says "meet these material specs" (prescriptive). The other says "be at least this efficient" (performance).
The prescriptive approach has requirements describing things like all walls must be at least this well insulated and any heating/cooling system fans must be at least this efficient.
The performance approach does a performance simulation for both the proposed house design and for that same design, but built to the prescriptive spec. The design passes if the proposed design uses less energy in the simulation.
The document you've linked says both approaches will now require solar panels (so you can't "just" be energy efficient).
My guess is that you'll have to add at least as much solar as the current minimum required to get credit for doing so, which is described in section 2.2.3 in this document[2].
14. Photovoltaic Requirements. All low-rise residential buildings shall have a photovoltaic (PV) system meeting the minimum qualification requirements as specified in Joint Appendix JA11, with annual electrical output equal to or greater than the dwelling’s annual electrical usage as determined by Equation 150.1-C:
kWPV = (CFA * A) / 1000 + (NDwell * B)
Where:
kWPV = kWdc size of the PV system
CFA = Conditioned floor area
NDwell = Number of dwelling units
A = Adjustment factor from Table 150.1-C
B = Dwelling adjustment factor from Table 150.1-C
(I'm not going to try to copy the table into this comment.)
I also found this document digging around recent additions to the public docket site:
It says "The specific minimum size of the system is based on the size of the building and number of dwellings and can vary between 2 and 7 kilowatts output per dwelling..."
Which is less specific, but it's nice to see upper and lower minimum capacity requirements without having to consult a table.
http://docketpublic.energy.ca.gov/PublicDocuments/17-BSTD-01...
?
In particular, I wonder what the minimum system size is, in kilowatts. Reporting household system size in "dollars" is a poor metric because PV dollars-per-watt is changing rapidly.
The source that I linked above says "Minimum PV sizing by code will rely on results from the energy consultant’s Title 24 compliance calculations." Can anyone explain what's required to comply with Title 24? I'm looking for answers in physical units rather than currency units.
FWIW, Germany and Australia have fully-installed residential rooftop solar costs-per-watt less than half of that in the US. I'm not sure where the big cost gap comes from -- Germany and Australia have decent wages for labor and safety codes too. The hardware is commoditized and globalized. If California could match Australian costs-per-watt then this proposal would add significantly less to the initial cost of a new house and significantly increase lifetime cost savings vs. using only power from the grid.
EDIT: it looks like the final adopted proposal is 17-BSTD-02, rather than the earlier 17-BSTD-01 that I linked above. Here's the final one:
http://docketpublic.energy.ca.gov/PublicDocuments/17-BSTD-02...
The final version says even less about minimum system size. I suppose that detail is hidden in one of the 14 documents it incorporates by reference.