Southern California Edison shares gained knowledge

by Ernie Hernandez on August 18, 2013

Electric Meter

We look at their study in this two part series

It turns out the sky isn’t falling after all. Many electric vehicle (EV) naysayers talk about the inability of the electrical grid nationwide to keep up with the increase in EV charging over time. Southern California Edison (SCE) says otherwise, based on a recently released study that evaluated EVs, customers, and grid reliability.

Let’s first take a look at why this study is relevant, and try to determine if it will it provide any useful information for other utilities, or potential EV owners. We feel that the study is relevant because roughly ten percent of all plug-in electric vehicles (PEVs) sold in the US are within SCE’s market. By anyone’s measure this is a pretty significant concentration. These PEVs include fully battery electric vehicles (BEVs) such as the LEAF, but also plug-in hybrid electric vehicles (PHEVs), such as the Chevrolet Volt and Toyota Prius Plug-in hybrid. Currently almost two-thirds are PHEVs while the remaining thirty five percent are BEVs. One of the biggest areas of concern was the cost to upgrade the grid to service all of these plug-in vehicles. According to SCE’s study, of the nearly 400 upgrades made in areas that service PEVs since 2010, only one percent of the work was actually due to the increased potential load of the PEV. That amounts to only three or four transformers in about three years. In other words, the vast majority of replacements were due to normal maintenance and replacement. Let’s take a closer look at why this might be the case.

The study shows that about seventy percent of PEV owners commute forty miles or less daily. This correlates with data provided by the Federal Highway Administration (FHA) regarding commuters in general. According to the FHA, the average annual mileage in the US is 13,476 (found here). This equates to just under thirty seven miles per day. In Southern California one might expect that average daily commutes would be higher. For a certain segment of the population this is true. It is not true of the population in general as supported by SCE’s study, at least of PEV drivers. Many PEV owners recharge their vehicle overnight when more grid capacity is available, with many of those charging using Level 1 (120 volt) charging. This equates to about four or five plasma television sets (found here). SCE found that transformers needed to be resized with the uptake in plasma tv use, but we didn’t hear a public outcry against plasma television sets.

One recommendation made by the study is that PEV owners use their vehicle’s charge timers to set a charge end time. Most charge timers have a start and end time capability. With some PEVs using Level 1 while others use Level 2 (240 volt) this will help even out the load on the grid. If all charge timers start at midnight for instance, there will be a significant initial draw which will fall over time as vehicles attain their required charge and stop charging. By setting an end timer, there are multiple benefits. Staggered start times will even out the demand on the grid as the vehicles will have driven various distances with unique driving styles. Also, if charging to 100 percent, it is best to complete the charge as near to your departure time as possible to optimize battery life.

Our next article will take a look at some of the other findings in SCE’s study.

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