Energy Matters Forums

[offgridQLD]

Yes that is true.

The good thing is with a electric car you have a gas station to fill it in your own garage. Every house has electricity outlet . It's open 24 hrs a day 7 days a week.

You can purchase your food where you like without contemplating the fuel discount on offer.if you run out of charge some place inconvenient .The emergency road side assist has a huge battery or generator and The I-mive accept DC fast charge at 50kw! That will charger 80% from empty in 20mins or 50km range in ten mins.

There are a few examples of this kind of charger. Below is one the NRMA has that they tow behind a BMW motorbike. Though I do remember reading of one that used battery's for DC/DC charging.

Developed by Australian-based international battery swap company Club Assist and destined to be rolled out around the world to up to 70 motoring organizations, the mobile charger can also ramp up the charge from 15amps to 30amps, should the vehicle be capable of accepting the higher rate, to halve the charging time to as little as 15 minutes.

You just need to look at it differently.Im willing to change some thing for the benefits.

Kurt

[bpratt]

I'm not against EV's, but I find it a bit disappointing that there's not more chargepoints available, particulary when there are many dealers that don't provide charging onsite, particulary when the only dealers that I've seen have been Nissan dealers (albeit not all of them).

I agree with the comments regarding the early days of the 'horseless carriage', where petrol was sold in drums and took a while before towns had pumps. The early days of LPG vehicles were dual fuel, so lack of LPG pumps wasn't a real big problem.

One of the best things about EV's is as Kurt said, everyone has their own 24/7 fill station in their own house. If you have large enough PV, then it's pretty much a free fill.

I am pleased to see there's roadside assist available for people to get a roadside recharge if necessary.

[offgridQLD]

The simple fact is you buy the car and know the range each charge can take you and you use it withing that limit and you will never have a problem. you want to drive more than 150km in one day then you don't use your EV.

It simply isn't a issue unless you want to create one.

Again its a interesting experiment to reset you trip meter each day and take note to see how many km you clock up each day. Do it for a week do report back I would be interested to see the numbers. That's what I did before making the choice.

It wont work for everyone. like people living in very remote areas. Or people with above average distances to travel. But for most people it will work even if there were zero charge station and they just charge at home.

The average Km driven each day for Australia is 36km total . Thats (1/3) of the I miev's realistic range on one charge. So you would only need to charge every 2nd day. though most people would just top up while they sleep each night so you always have a full tank.

We average 300km a week (42km each day) but we live between two homes that are 100km apart. We do on average 20km a day over the 5 weekdays and 100km sat & 100km on Sunday. If we were just living in one place the km would be less.

My charge point in the city home is on tariff 33 so I have charging power available all day other than a brief period from 5pm - 9pm so its only 15C kwh to charge or $2.40 in electricity for over 100km of driving.That would only buy me 1.4lt of unleaded petrol in QLD .Or 14km of driving in my petrol car

If I desperately needed to charge in that 4hr peek (5pm-9pm) period I can plug into a normal socket at 22c kwh. The other house its free from pv.

[offgridQLD]

This weekend I want to put together a parts list to upgrade my PV to cover the extra load on the system from charging the I-mievs 16kwh battery.

At the moment I have 4000w of PV facing north east at about 20 deg roof pitch.

I have another roof over my deck that faces north west at about the same pitch thats about 14m long by 5m wide around 70m2 and I have a section of my garage that is 12m long by 3 1/2m wide (42m2) that is facing the same direction on about 25 deg pitch.I already have a large conduit running underground from the shed to the battery room at the house ready for the upgrade.

I could also fit around 2000w of pv under the 4000w that's there now facing north east.

I think an extra 4000w of pv would cover the cars need well . One option is to place 2000w over the deck and another 2000w on the shed. I want to keep some space for two large vac tube solar hot water systems on the house roof though.

Will order another classic 150 charge controller to run in slave mode with the one thats there now.



Now the hard part... what brand of PV what size and what brand of racking and what to pay for it all?

Kurt

[Gordon-Loomberah]

Here's what you need, 20 of these:
http://www.ebay.com.au/itm/321169476221

Located at Eagle Farm, I wonder how many you could fit on the I-miev? If you run out of energy on the way home, just series 10 of them up beside the road to give the battery a quick charge!

[offgridQLD]

That's roughly what I was thinking $1.00 - W. Nice round numbers to work with to Thanks for the link.

I0 of them would weigh 150kw . The I-miev is rated to hold two adults in the back seat. Average adult 75kg each. No problem at all to carry the 150kg in the back. At 1580mm long they might just squeeze in with the two back seats folded down. I know you can fit a full size MT bike in the back.

Or I can just pick them up in our old Holden vectra (little will the car know that is is digging its own grave )

I was thinking Two kits like below for mounting.
http://www.ebay.com.au/itm/SOLAR-PANEL-TIN-ROOF-MOUNT-KIT-Suit-2kW-SYSTEM-Fits-8-x-250W-PANELS-/181127906247?pt=AU_Solar&hash=item2a2c1083c7


I would need a couple of extra clamps (that they sell separately) As the kit is for 250w pv. Makes two racks 10.2m long with all hardware for $222. So $2222 for 2kw mounted each using the Pv linked above. Then I just need DC cable and breakers & isolator. I'm guessing around $5500 including the extra classic 150 charge controller lite. Considering I spend $3000 in fuel each year that's not a bad investment

My thinking is 4000w should have a comfortable 4hrs of sun each day average in my area -16kwh. That's a full I-miev battery. Sure there will be some considerable efficiency losses but I feel I wont be fully charging each day just topping off the days usage. Often I will have spare energy to contribution from the original 4kw.

The one issue is while at times I will effectively have 8kw of charge potential with all the new PV (battery full in 2hrs full sun) I am limited to the on board charger. (it is user adjustable for charge rate 600w - 3300w after a small modification hack)It also depends on how much load I want to put on my homes inverter.

A more likely way of doing it it will be charge the car at a modest rate stock - 2200w while the house battery's are being charged . Typical day I see myself driving the 25km round trip to local town early morning and needing to return 4kwh or so into the I-miev to replenish the pack to full again. With the new North west Pv I could let the house pack reach float- typically 9:30Am - 11Am but will be faster with the extra 4000w of pvso might even be on float as soon as I get back . But lets not count that in because of weather conditions. Then I would throw the I-mieve on charge from 11Am - 2:30pm.

Kurt

[offgridQLD]

I had a good look at all the potential roof area yesterday to place more PV.

small video of potential roof space.
https://www.youtube.com/watch?feature=player_detailpage&v=T4iqtF6psqg

I defiantly thinking the additional PV should all face north east to try and spread the available power over the day. I'm looking at an additional 20x200w panels and initially I was thinking of splitting them up into two arrays of 2000w each. Placing one on the lower section of the shed and the other over the deck on the house.

Measuring up the space yesterday I found I have more than enough room to fit all 20 panels in the one location over the deck. I think having them all in the one location will keep things simpler and cut down on two wiring runs from different locations.

I took note of the small shadow coasted from the eave of our bedroom roof sitting above the deck roof. It doesn't project out over the potential pv location ( last measured at 5pm). SO no issues there.

I will have the shed roof space free potential (2kw) along with another north east section under the current pv for an additional 2kw of pv there to in the future. Though I feel 8kw will be enough to cover the house and charging the EV . Perhaps 12kw if i want to start a aluminum smelter

At the moment I am looking at all the small hardware for the new array. Wire, breakers,racking. Going of the panels specs . I have a run of about 30m from the most distant panel to the new charge controller and will be wiring the pv in a 2 x series 10 parallel 74ish volt arrangement. I don't think the voltage drop will be to bad for 48v system. I would be pushing around 57A max over the 30m so with 6mm2 wire I would have roughly 5v voltage drop over that distance - 69v. I think that's roughly correct.Hmm that's 250w going into just heating the wire.Whats considered an acceptable loss 3-5% ? I could run 10 runs at 2s each carrying roughly 6A max using 6mm2 and parallel closer to the charge controller. hmm that's 300m of 6mm2 $1200 of wire though the avarage length would be closer to 25m.

[Gordon-Loomberah]

Forget the 6mm^2 cable runs, use 16 or 25mm^2. For the 2 X ~20m runs I have from trackers to FM80s I have 25mm for the 2.19kW array and 16mm in the 945W array, which is soon to be upgraded to 2kW and 32mm^2 cable, to keep losses to a minimum.
What is the highest Voc you have seen, does the Midnite CC log that? I reckon you could probably safely go to strings of 3, although then you would need 21 panels.

[offgridQLD]

Looking at the charts for the classic 150 around 70-80 v looks to be the sweet spot for efficiency (output) and perhaps less heat in the controller for a 48v (58.4v) system or I could be reading it wrong.

My current system is wired as 2 series 12 parallel arrangement with very similar voltage to the proposed new panels and seems to be doing very well at this voltage .





I could go to 3 series 21 panels. I will make some more exact measurements of the distance today. Edit: 25m main cable run from deck and also 25m main cable run from shed roof. 5m cable run from below current N/E PV.


If I placed 1/2 - (2000w) under my existing North/East pv the cable run would only be 5m. other 1/2 of the shed. Perhaps that's to much PV facing north east though.

This is the tool I used to calculate it. http://www.midnitesolar.com/sizingTool/index.php

Using the specs of the panels and a min temp of 2 deg C max 40C

Open Circuit voltage Voc (V) 45.6
Short circuit current Isc (A) 5.89
Maximum power voltage Vpm (V) 36.9
Maximum power current Ipm (A) 5.69
System Voltage (V DC) 1000 VDC
Power temperature coefficient -0.40%/K
Operating temperature (C) -40 - +85C
Storage temperature (C) -40 - +85C

[Gordon-Loomberah]

Strings of 3 seems fine with their calculator. How much less efficient is 105V than the 70-80V sweet spot?

I^2R losses in the cable will be cut in ~half by using strings of 3 rather than 2.

If you are losing your calculated 250W with strings of 2, then you'll only lose about 125W with strings of 3. If the controller is say 1% less efficient at 105V, thats only a difference of 40W with 4kW of PV.