Here's an interesting take on the latest APS earning's call.  

CEO Jeff Guldner said the integrated resource plan (IRP) for utility Arizona Public Service Co. (APS) filed in June called for 2,500 MW of power supply from 2020-2024 via a mix of renewables, demand response, energy efficiency and storage.

Between now and 2035, the APS territory is expected to see steady growth even as 1,400 MW of coal capacity is retired and 1,600 MW of gas-fired generation purchase agreements expire. Overall, APS by 2035 still would need another 6,000 MW of capacity, Guldner said

Those of you who don't live in AZ will not be surprised by a headline that says "Statute Trumps ACC Rules."  After all, don't laws always trump rules?  Not in Arizona.  The Arizona Corporation Commission is a Constitutional body and has long argued that it has sole authority over Public Service Corporations, so its rule making authority with respect to the companies that it regulates trumps Statute.  

The Supreme Court disagrees.

Here's the key paragraph.

¶30 However, when there is a conflict between a Commission
regulation and a statute, the legislature’s police authority is “paramount,”
meaning it has the authority to override the regulations of the Commission.
Pacific Greyhound, 54 Ariz. at 176–77 (stating that apart from the
Commission’s ratemaking authority, “under the direct language of the
constitution and the police power inherent in the legislative authority, the
paramount power to make all rules and regulations governing PSCs not
specifically and expressly given to the[C]ommission by some provision of
the constitution, rests in the legislature”); see Ariz. Const. art. 14, § 2 (stating
that all corporations doing business in Arizona may “be regulated, limited,
and restrained by law”); see also State v. Harold, 74 Ariz. 210, 215–16 (1952)
(holding that the legislature has a duty to exercise its police power to enact
laws “reasonably necessary for the preservation of the public health, safety,
morals, or general welfare of the public”).