Solar day parking with AC charging
Posted: Mon, 02 Sep 2019, 10:14
A few thoughts on the increased evening/overnight grid load with growth of EVs, and a possible way of minimising the impact. Let me know what you think.
- Soon, most people driving EVs will have 200-300km ranges or higher. They will not necessarily need to charge every day.
- AC destination charging may become less popular as ranges increase and DC charging locations increase. (People will be less inclined to "get some charge now, just in case", the effort of plugging in may not be worth it for some - maybe for overnight while on holiday, but not for an hour at the local shops)
- EVs plugging in at "home time" - 5-6pm - can be mitigated by offering off-peak tariffs which start later in the evening. However as the number of EVs grows, there may be a new "peak" in the evening, as people start charging at 9-10pm (whenever off-peak starts) and then they are all completed by 11pm-midnight.
- At typical commuter car parks (either all day car parks, park and ride car parks, train stations, etc) - cover them with solar, and install AC chargers in every spot (or most spots). This is a pretty standard concept.
- Do not guarantee a particular rate of charge, or volume of energy to be supplied.
- Using Zappi-like monitoring, only charge the EVs using excess solar energy which was otherwise destined for grid export. This can be done by either reducing the charge rate per unit (down to the minimum of 1.4 kW) or by alternating which chargers are active (as some cars finish charging, other stations will start up).
- Alternatively, use the grid connection and a Reposit-like system to purchase cheap energy during the day if the wholesale price drops low enough, and use this energy to charge the cars.
- At the end of the day, the commuter will (most likely) have a bit more energy in their car battery. Possibly not full.
- Solar generated during the day is self consumed - reverse the duck curve.
- There may be fewer cars needing to charge in the evening
- If the cars have added more energy than what they used in a typical day, some may not need to charge at home at all
- An option for those without home charging
- Energy used did not affect the grid - and is 100% renewable.
- Basically - match renewable generation with consumption.
- Who pays? The vehicle owners are not guaranteed a charge so this would have to be free or very cheap to them. The car park operator could bundle it in to their own costs. The main beneficiary of this is the grid operator.
- There may be a physical limit to the amount of solar that can be installed on a site. The solar needs to be physically on the same grid connection to get the benefits of minimising grid demand.
- A certain level of EV penetration is required for this to have a noticeable effect.