Solar day parking with AC charging

Discussion about EV/Battery charging infrastructure, Electric highways etc.
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Chuq
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Solar day parking with AC charging

Post by Chuq » 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.

Initial thoughts:
  • 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.
Proposal:
  • 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.
Result/benefits:
  • 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.
Issues:
  • 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.

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Re: Solar day parking with AC charging

Post by jonescg » Mon, 02 Sep 2019, 10:51

If workplaces and public carparks had charge points, even only 2 kW or so, that would soak up excess solar in the middle of the day which is demand that won't happen in the afternoon. The total generating capacity of the grid is unchanged, but the timing of its use is shifted back to when there's an excess.

Only when we hit ~15 or 20% EVs will we see a need for more generating power, and that can be in the form of large solar carparks. Since it's not going to impact the ramping of large thermal generators of an evening, EVs will effectively buy the grid time.
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Re: Solar day parking with AC charging

Post by mikedufty » Mon, 02 Sep 2019, 11:23

Even with a 90km range i-MIEV the shopping centre carpark chargers seem more of a marketing gimmick than any actual use. You'd need to be really pushing your range to the limit going shopping for it to be a significant benefit to slow charge for an hour.

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Re: Solar day parking with AC charging

Post by jonescg » Mon, 02 Sep 2019, 12:18

mikedufty wrote:
Mon, 02 Sep 2019, 11:23
Even with a 90km range i-MIEV the shopping centre carpark chargers seem more of a marketing gimmick than any actual use. You'd need to be really pushing your range to the limit going shopping for it to be a significant benefit to slow charge for an hour.
Sure - but this isn't so much about EV owners getting a useful charge as it is about making sure they don't need to charge of an evening at 5 pm.
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Re: Solar day parking with AC charging

Post by Richo » Mon, 02 Sep 2019, 12:46

Work places with solar are still unlikely to cover their energy needs - even if the carpark was added.
So having free solar for customers/employees at the employers expense is unlikely to happen.

If it concerns you then get as much solar as you can on your house and store the surplus - preferably 100% off the grid.
If more people did this then the impact on the grid would be minimal.

The only place this won't work is in high rise complexes (Apartments).
This is where public charging becomes useful.
So the short answer is NO but the long answer is YES.
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Re: Solar day parking with AC charging

Post by Chuq » Mon, 02 Sep 2019, 13:51

jonescg wrote:
Mon, 02 Sep 2019, 10:51
The total generating capacity of the grid is unchanged, but the timing of its use is shifted back to when there's an excess.
Exactly it. Storage is one option - but putting the electricity directly into the car at the time it is generated is more efficient!

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Re: Solar day parking with AC charging

Post by Chuq » Mon, 02 Sep 2019, 14:02

Richo wrote:
Mon, 02 Sep 2019, 12:46
So having free solar for customers/employees at the employers expense is unlikely to happen.

If it concerns you then get as much solar as you can on your house and store the surplus
Just to clarify, this concept isn't for the (direct) benefit of employers or for individuals. It's primarily of benefit for the grid company.

Wording it from a business point of view "peak load timeshifting" may be a service that the grid company is willing to pay for, and that a car park operator may be willing to provide. The service involves reducing the load on the network in the late evening, and absorbing the excess generation on the network at peak solar generation times.

And as Chris says, this won't become an issue for some time.

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Re: Solar day parking with AC charging

Post by T1 Terry » Mon, 02 Sep 2019, 14:10

A combined sales thing aimed at those who want to save the planet? Pay for a parking spot that has a solar feed charging facility in a section that is for plug in EV's only. You know that if you drive to that level and that section there will be a parking spot available because those in the ICE vehicle won't want to pay extra to park on say the roof top level.
Eventually there would be express ramps straight to the EV charging level that are only accessible if your EV gives the secret code, like a high voltage sensed on the induction charging plates that opens the boom gate.
All futuristic stuff, but just how far in the future? You can get jet packs and hover boards now so .......

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Re: Solar day parking with AC charging

Post by brunohill » Mon, 02 Sep 2019, 23:27

I would like to be able to plug in at work and be able to charge my car with the excess power my house puts into the grid. Technically feasible, but needs to financially feasible to someone else other than me.

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Re: Solar day parking with AC charging

Post by mikedufty » Wed, 04 Sep 2019, 12:47

May start happening once they move off peak charging times to the middle of the day.

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Re: Solar day parking with AC charging

Post by Chuq » Wed, 04 Sep 2019, 15:28

mikedufty wrote:
Wed, 04 Sep 2019, 12:47
May start happening once they move off peak charging times to the middle of the day.
Where I am off-peak rate is the same for both overnight (9pm to 7am) or daytime (10am to 4pm). If I have the choice, I prefer the day as then it uses my excess solar first if there is any.

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Re: Solar day parking with AC charging

Post by Chuq » Fri, 06 Sep 2019, 13:50

Coincidentally, here is an article that just just popped up on RenewEconomy on a similar theme - https://reneweconomy.com.au/aemo-looks- ... rid-48314/

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Re: Solar day parking with AC charging

Post by HuffnPuff » Sat, 07 Sep 2019, 04:50

Richo wrote:
Mon, 02 Sep 2019, 12:46
Work places with solar are still unlikely to cover their energy needs - even if the carpark was added.
So having free solar for customers/employees at the employers expense is unlikely to happen.

If it concerns you then get as much solar as you can on your house and store the surplus - preferably 100% off the grid.
If more people did this then the impact on the grid would be minimal.

The only place this won't work is in high rise complexes (Apartments).
This is where public charging becomes useful.
A different way of thinking about it is that if We have lots of solar on houses pushing energy into the grid during the day We want a way of utilising it. It doesn’t need to be local specially installed solar for charging, there is plenty of solar feed into the grid.

Utilise a signal on the grid, similar to off peak, that signals ev charge points to turn on when there is excess feed in. Make the grid smart so that it can shift the load around according to the most efficient usage.

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Re: Solar day parking with AC charging

Post by coulomb » Sat, 07 Sep 2019, 07:28

HuffnPuff wrote:
Sat, 07 Sep 2019, 04:50
Utilise a signal on the grid, similar to off peak, that signals ev charge points to turn on when there is excess feed in.
I like that idea. And it could even use the same signal that is already deployed widely to turn on loads as needed, just that those loads were usually at night, and usually water heaters. Well, EV chargers are nice near-unity power factor loads too. Granted, you might want more control than "turn on now"; you might want something a little more fine grained, like "turn on now to 75% load". But I suspect that the existing tones have a lot more capability than "turn on water heaters now", so it might not be much if any extra infrastructure required.
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