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Fri Jul 6, 2018, 11:12 AM

APS seeks 106 MW of batteries to pair with large-scale solar

Solar is a good fit as an energy provider as it generally produces power when AC usage is at its highest. The problem is obvious - it's output declines as the sun lowers on the horizon and it's clearly not going to produce anything when it goes down. Here's a step to extend that output to meet peak demand (the most expensive power). It's only a RFP (request for purposal - which would be followed by a RFQ - request for quote) but it shows that we are stepping in the right direction.

The Arizona utility has issued a request for proposals (RFP) for battery projects to allow its utility-scale solar fleet to meet evening demand, as part of a plan to add up to 500 MW of storage over the next 15 years.


It seems everyone is doing batteries these days. From Massachusetts and New York to California and Hawaii, regulators and utilities are seeing the benefits of battery storage to the grid, particularly where paired with solar.

As the latest in this trend, last week Arizona Public Service (APS) issued a request for proposals for 106 MW of battery storage projects to pair with its existing fleet of large-scale solar projects. The projects will need to be in operation by June 2020, and will be used to shift output from these plants from daytime to evening.


APS notes that it already has three grid-scale batteries in operation, as well as another 50 MW battery project which is scheduled to come online in 2021.

This concept of retrofitting existing solar with batteries appears to popular lately. Last week Hawaiian regulators also approved rules to allow the state’s 60,000+ behind-the-meter PV system owners to add batteries to their existing projects without violating their net metering agreements.


Interesting - I wonder how many utilities have rules like Hawaii that prohibit the use of batteries in their net metering agreements?

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Reply APS seeks 106 MW of batteries to pair with large-scale solar (Original post)
Finishline42 Jul 2018 OP
hunter Jul 2018 #1
caraher Jul 2018 #2
Finishline42 Jul 2018 #3
hunter Jul 2018 #4

Response to Finishline42 (Original post)

Fri Jul 6, 2018, 05:31 PM

1. In places where air conditioning is a significant load...

... it seems to me it would be easier to store cold water or ice.

Solar inputs peek mid day, air conditioning loads lag by a few hours.

Many battery types have severe environmental impacts, most especially lead, nickel, cadmium, or lithium cobalt batteries.

Maintaining batteries is also a pain in the ass.

An insulated tank of icy cold water is a lot less trouble.

Or imagine we built household refrigerators that were satisfied to run on six hours of electricity every day, that could be disconnected from the grid whenever electricity demand was high, or connected to the grid whenever there was a surplus of solar energy.

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Response to hunter (Reply #1)

Fri Jul 6, 2018, 10:24 PM

2. I know this is done to some degree already

Harder to implement at a single-home/residential level, but when there are multiple buildings with a single large-scale chiller this is not an unusual thing to do. They'll run the system when the electric rates are cheapest and during the day dump heat into the stored-up ice.

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Response to hunter (Reply #1)

Fri Jul 6, 2018, 11:09 PM

3. Sure storing excess energy as ice works for HVAC

Sure storing excess energy as ice works for HVAC but how does it work for utility scale electric storage?

I put in bold the fact that the utility already is using batteries. Their request is based not on some theory or some purported expert in a related field but on past experience. My assumption is that the people in the accounting dept have run the numbers and it's cheaper to buy and use batteries.

For no telling how long utilities have been running plants (mostly burning coal) on the ready waiting for demand. They have to keep the boiler heated up, the turbines warmed up, just to be in a position to generate the steam needed to generate electricity. This is a function that batteries can provide much quicker without the energy loss just to be ready.

The hazard of batteries is mainly with disposal. If there are enough of them there will be somebody that will recycle them.

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Response to Finishline42 (Reply #3)

Sat Jul 7, 2018, 06:03 PM

4. The goals of a utility company may not coincide with the goals of a healthy society...

... or a healthy natural environment.

We all might be better off dealing with the problem on the demand side rather than the supply side. Expanding markets for the dirty metals used in many battery technologies might look good on a utility accountant's spreadsheet, but it's not necessarily the best solution to the problem.

For example, the hidden cost of cobalt mining...


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