During Steffes’ two dozen pilots and trials over the past five years, Steffes confirmed that residential electric space and electric water heating in many regions in North America are major segments of residential load demand – usually amounting to 50% for space heating and 30% for water heating as percentages of the entire total residential electrical load.

As one would expect, total load is generally characterized by a ramp beginning around 7:00 a.m. followed by a mid-day trough followed by yet another sharp ramp into 7:00 p.m., and any ability to flatten that curve optimizes operations. The shape and pitch of that load profile varies but the characteristic “double hump” appears time and time again.

GETS Optimizes Operations in Eastern Canada

To help optimize operations, a key Steffes learning outcome across those pilots is that electrical space and water heating will best support the smart grid by altering the tradition of – generation follows load – to precisely the opposite – load follows generation.

That idea was convincingly proven during field trials in Eastern Canada known as PowerShift Atlantic. During that pilot, hundreds of disperse GETS space and water heaters were aggregated into a single high speed controllable asset under the command of a Virtual Power Plant or VPP. This large and very ambitious multi-year field trial sponsored by Natural Resources Canada (NRCan) which involved a number of Canadian Provinces.
The Steffes Portal screenshot from that trial (directly below) shows the 5 MW shift of water heating and space heating load altered so that it coincided with and followed wind generation. The chart also clearly illustrates the very tight and highly accurate GETS System load response of those aggregated electric space and water heater resources along with a very highly correlated response to VPP power requests.

Steffes GETS successful pilots in Hawaii

In addition to this massive Canadian trial, Steffes has run a number of pilots in Hawaii where over the past eight years rapid growth of renewable generation significantly altered typical system load demand patterns throughout the day. As shown below beginning at sunrise Solar PV energy handles much of the system needs, but when the sun begins to set it triggers rapid and dramatic increases for alternative generation.

  • In Hawaii, 40% of a typical residential electricity bill is for water heating
  • As you would expect (and like the rest of the U.S.) immediate demand for that hot water is concentrated in the early morning and the early evening
  • A surge of electrical generation handles those two periods of immediate demand
  • Yet end users only care that they have hot water not when it is made

Altering the timing of water heating so it is timed to availability of PV generation not only absorbs more solar energy but also dampens minute-to-minute solar volatility. This simple change from the tradition of heating to meet immediate demand greatly optimizes the grid while simultaneously flattening the high needs for power in the morning / evening peak.

In Hawaii they have proven that flattening and optimizing this residential load (or demand) curve lowers the costs across the entire system. Using cost-effective behind-the-meter (or grid-edge) assets like GETS water heaters to create a very flexible load also eases the burden and challenges of renewable integration. It also provides a very effective tool to deal with mid-day over generation of PV solar which is the number one challenge in Hawaii today.

This key of enabling load to follow generation is why GETS is so important.