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Solar with IREA in Colorado

A PowerWall does NOT require a new meter set. So, IF you have been a customer since Jan. 1, 2016, and you install PowerWall, the load factor adjustment will NOT apply to you.

However, If you add solar, you will receive a new "two-way" meter set. The installation of that new meter set will cause the load factor adjustment (LFA) rider apply to you, even if you've been a long time customer.

The LFA is a three part rate rider, where a demand charge "triggers" when your load factor drops below 9%-10%. Load factor is equal to your average demand divided by peak peak demand during each billing period. Normal residential load factors are in the 19%-20% range. Adding PV generation on your home will reduce the amount of energy you will purchase from IREA, and therefore will may reduce your average demand. This is because your average demand (see the equation above) is equal to your total energy (during the billing period) divided by the number of hours in the billing period.

That's all the math you need to calculate your load factor. To summarize; (LF= Avg Dmd / Pk Dmd) and (Avg Dmd = Energy / hours). If your L.F. during a billing period ends up below about 10% (9% for IREA's City Residential rates), then the LFA will kick in and charge you a either $4.04 or $4.13 per kilowatt (kW) of peak demand (depending on your rate). Suppose this happens, and your peak demand was 7 kW. In that case, your bill for that period will be the service charge ($12.50) plus your total energy x energy charge (roughly $0.12/kWh) plus $4 x 7kW (i.e., around $28 to $29).

The charge is assessed every month, so there may be some months where you might see it and others where you won't.

Don't let the LFA stop you from going solar or installing the PowerWall. But, absolutely factor it into your calculations. There is a 30% investment tax credit (ITC) that will apply to your solar purchase, provided you do that before the end of this year. Beginning in 2020, that drops to 20%, and then, in 2021 it drops to 10%. The ITC will not apply to the cost of the PowerWall (to my knowledge).


New Member
Apr 26, 2021
Key point for Tesla Gateway users, “site import limit” can be set to prevent the inevitable 8kW spike and let your powerwall manage all demand above the site limit. My LFA has been fixed at 1 kw ($4) since November, and I’ve used plenty of IREA ’trons during snow storms.
So you have your gateway set to limit max draw from IREA to only 1kW? Sounds like a good idea as long as you have power in reserve in the Powerwall. Since you're getting hit with the LFA charge, your average draw from IREA must be 100W or lower, right? I'm curious what the total power of your arrays are, and how much Powerwall capacity you have to reach such low a draw from the grid. Have you ever run out of battery reserve? Thanks!

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