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Post by projectatlas on Dec 7, 2014 15:44:29 GMT 11
Location is 4216, Gold Coast. East, north and full west facing roof unblocked.
Two LEAF equivalent EV doing combined 50000 km per year.
Installing solar purely to feed those two EVs.
How big should it be so that I get to drive with just sunlight? Is it possible at all?
Thanks!
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Post by Phoebe on Dec 7, 2014 15:53:50 GMT 11
I have 3kw and that does me in the summer, but I have shade in the winter. I am always able to pick the day I charge, so pick the weather. It really depends how many kms you travel. I only do 25kms a week so don't have to charge often. If you have to charge every day you could never do it only on solar, 'cos there isn't always any sun.
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Post by projectatlas on Dec 7, 2014 20:12:35 GMT 11
Thanks a lot Phoebe! I am still very very new to the solar panel rebate and pricing scheme. Is it possible to install solar panel after the EVSE has already been hardwired?
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Post by hieronymous on Dec 7, 2014 20:15:09 GMT 11
Location is 4216, Gold Coast. East, north and full west facing roof unblocked. Two LEAF equivalent EV doing combined 50000 km per year. Installing solar purely to feed those two EVs. How big should it be so that I get to drive with just sunlight? Is it possible at all? Thanks! Spending $15-20K+ for a large solar array just to charge EV's is never going to be an economic proposition, but that aside, you are looking at: 50,000 km at a conservative 5km/KWh is over 6 hours charging (both cars at the same time of necessity) 7 days a week, using the EVSE supplied i.e. 2.4 KWh for each car at the same time, so your solar would have to provide 4.8 KWh for 6+ hours continuously, probably 7-8kw at least to do that, and only in peak summer months. You would need a fully north facing roof, and optimal pitch for your location. Yes, it's possible, but probably not with your roof except with a very large array, and not many days a year in any case.... |
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Post by projectatlas on Dec 7, 2014 21:44:40 GMT 11
Spending $15-20K+ for a large solar array just to charge EV's is never going to be an economic proposition, but that aside, you are looking at: 50,000 km at a conservative 5km/KWh is over 6 hours charging (both cars at the same time of necessity) 7 days a week, using the EVSE supplied i.e. 2.4 KWh for each car at the same time, so your solar would have to provide 4.8 KWh for 6+ hours continuously, probably 7-8kw at least to do that, and only in peak summer months. You would need a fully north facing roof, and optimal pitch for your location. Yes, it's possible, but probably not with your roof except with a very large array, and not many days a year in any case.... Cool! Thanks for doing the math for me! I always get headache with those numbers. yes, its not meant to get return on investment, Solar is still a money losing proposition at this moment. I will see if a 10kw system can fit on our roof. We get plenty of sun every day. We do not have air con or fan in the house, maybe those panels can shade the house too. |
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Post by hieronymous on Dec 8, 2014 8:12:10 GMT 11
Oh, and just one more small thing - while your 2 cars are sitting happily being charged through the middle of the day they are, of course, both unavailable for use. Solar charging is an attractive notion at first, but most folks do their driving in daylight (peak solar) hours; when do you do your 50,000km/year?
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Post by gabzimiev on Dec 8, 2014 9:28:59 GMT 11
yes it depends how you want to count the electricity, if your happy with offsetting then you just need to buy enough solar capacity to produce more kwh than you consume so your net positive. If you actually want to ensure the electricity created goes "into" the car you need to charging during the day, and slow down the rate of charge. nothing wrong with either way. easier if you just want to be net postive and produce more solar than you consume. 140km/day (at 150wh/km) 21 kwh per day of solar needs to be produced having a look at other systems in the area, pvoutput.org/outputs.jsp?df=20141207&tid=15 you would need at least 5kW of capacity to offset. |
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Post by empowerrepower on Dec 29, 2014 0:45:54 GMT 11
Location is 4216, Gold Coast. East, north and full west facing roof unblocked. Two LEAF equivalent EV doing combined 50000 km per year. Installing solar purely to feed those two EVs. How big should it be so that I get to drive with just sunlight? Is it possible at all? Thanks! Hi, another alternative to getting your own panels, and definitely cheaper, is to work out how many Kwh you expect to use for a car in a year (I've estimated 3000 KwH to drive 15 000 km), and buy certified GreenPower so that an equivalent amount of electricity is sourced from renewable sources. You can purchase it from your electricity retailer, or from C3 GreenPower. The latter is tax deductible, and helps support charities, and all their renewable energy comes from wind power. Buying certified GreenPower is also a way to support Australia's embattled large-scale renewable sector, which is currently suffering the Federal Government's attempts to slash it severely after their RET review.
I do have solar panels, but as I live next to a forest, and have three KwH guzzling children, the panels make about half of our household use. To make up the missing half, I purchase C3 GreenPower to cover the difference. When we get an electric car, I'll just purchase more. Last time I looked, certified C3 Greenpower worked out at 5c per KwH before the tax deduction, so a year of driving a Leaf 15 000 km would cost $144 pre-deduction to keep it green.
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Post by gabzimiev on Dec 29, 2014 1:01:53 GMT 11
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elkarlos
EV Enthusiast
Posts: 25 
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Post by elkarlos on Oct 6, 2015 23:10:16 GMT 11
Just to add to this, I know it is a few months old, but here Western Australia I live just south of Perth, in Jan 2015 got my blue leaf, in feb 2015 has solar fitted to the house, I put on the biggest array they could fit on the roof - 6 kilowatt solar panels with the maximum 5 kilowatt invertor.
Found too inconvient to charge the car off solar, so in Aug 2015 took delivery of my second leaf the silver one.
Now I always have a car charged ready to go off solar.
The solar has reduced our power bill by two thirds and I only pay two thirds of that, so only about $80 to a $100 every two months, on average and that is with running our big air con unit, dishwasher during the day and about 2000 ks in the leafs.
As I say to the guys at work, you can't tell me that these two leafs and solar aren't going to pay themselves off pretty quick.
Don't buy gasoline, that shuts the guys up at work pretty quick.
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Post by EVangelist on Oct 7, 2015 23:21:57 GMT 11
As I say to the guys at work, you can't tell me that these two leafs and solar aren't going to pay themselves off pretty quick. Don't buy gasoline, that shuts the guys up at work pretty quick. A little bit off-topic, but the rate of improvement in solar panel technology is quite remarkable - see Swanson's Law. Since 1976, the $ cost per watt of electricity from solar has halved every 10 years, but the recent rate of improvement is double that, i.e. halving every 5 years. At that rate, new solar power plants will be cheaper than any other form of power (except possibly wind) within a mere 5 years. The bigger challenge is getting enough power out of them - i.e. how many sq metres you need per kW. The best solar panels now are around 20% efficiency and deliver 175 W per sq metre, and in the lab, the best single cell efficiency achieved is now 46%. The rate of efficiency improvement over time is slow compared to price improvement - about 1% per year. But trending that out - when would it be feasible for a house with 8 hours of usable sun per day and battery storage to go completely off-grid, in terms of roofspace and cost? Answer - around 2020, with 14 sq metres of solar panels, and a manufacture cost (not retail price) around $750. Of course you have factor in cost of installation, inverters, batteries, unreliable sunshine, seasonal variation, peak-to-average power usage factors etc but even with a fudge factor of 2x to 5x we are actually very close to a fully economic, single-house, off-grid solution. |
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Post by jeffthewalker on Dec 3, 2015 11:01:33 GMT 11
I am off grid and need to be very active to be able to charge with the solar/battery system(s) installed. Check out my post from this morning where I have charged up at "home" after a 3000km round trip over 2 1/2 weeks. There are severe limitations to avoid over draining the batteries and/or leaving the "household" with too little power overnight. |
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Post by jeffjl on Dec 5, 2015 23:15:55 GMT 11
I am off grid and need to be very active to be able to charge with the solar/battery system(s) installed. Check out my post from this morning where I have charged up at "home" after a 3000km round trip over 2 1/2 weeks. There are severe limitations to avoid over draining the batteries and/or leaving the "household" with too little power overnight. Recharging after a 3,000km trip. That would take about 450kWh. No wonder you are worried about draining your house batteries. |
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Post by EVangelist on Dec 6, 2015 12:07:35 GMT 11
Recharging after a 3,000km trip. That would take about 450kWh. No wonder you are worried about draining your house batteries. It would take 450kWh in one go only if the Leaf battery was that big  Imagine 3000 km range!! |
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Post by jake on Mar 31, 2016 1:17:18 GMT 11
Don't know if this is the best place to put this but I didn't want to start another thread. I signed the papers today on a 4.5kw solar system. My Leaf will now finally be truly zero emission. Won't see any savings for a few years, but it should wipe out my power bill. Then I guess I should charge during the day as much as possible.
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Post by Phoebe on Mar 31, 2016 1:33:49 GMT 11
Yep, BUT I checked the weather forecast and chose the only day in the week that was forecast really sunny all day, to charge my LEAF. It turned out the least sunny day in the week and I used every tiny bit from the sun, everything from my 6kw battery and some from the grid as well. I was not amused  |
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brisbri
EV Tyre Kicker
Posts: 3
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Post by brisbri on May 12, 2016 23:14:46 GMT 11
Hello All!
I charged my new leaf from my solar for the first time today, only got the charging socket installed late yesterday arvo.
I have a 6kw system, it charged the car with no power used from the grid at all! Stoked!
I will have to charge it in the evenings for the school morning run though cos my wife uses it some evenings.
We love the car, it has changed me, not sure I will ever want another non EV.
We also have an I30, lovely car, but its gonna do a lot of just sitting around now though.
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Post by estation on Apr 1, 2018 22:16:34 GMT 11
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Post by Phoebe on Apr 1, 2018 22:33:04 GMT 11
Don't know that I can answer your question but I can tell you I have a 3Kw solar system with a 6.4 kw LG battery and I use it to charge my LEAF. My system produces up to 17kwHrs a day mid summer. This time of the year on a good day it's about 11.5kwHrs. Mid winter it's between 4-6 kwHrs as there is shade over some of my panels. I can include some graphs of what happens if that is any use.
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Post by EVangelist on Apr 2, 2018 12:28:49 GMT 11
The speed at which solar is improving is quite remarkable. I am finally going to add solar early next year (as part of a wider energy-efficiency renovation) and the state of the art now is 360W panels when only a year ago 330W was the bees knees. I can probably squeeze 20 panels on my roof, and using one of the many excellent solar calculators on the web (which take location, pitch and azimuth of the roof, and local weather conditions into account) this 7.2kW system would generate 10.2 MWh per year, with a day peak of 32 kWh in October and minimum of 21 kWh in May.
I hope the other energy efficiency measures (replacing existing crappy windows with double glazing etc) should reduce my electricity consumption by 25-33% or so. And if that is achieved, solar+battery would enable me to go off-grid one year earlier than my prediction higher up in this thread (2019 vs 2020). The payback time of this system (~$30k) would be around 10 years so arguably marginal but who knows what will happen to power prices in that time? Just being totally fossil-fuel free is enough to make me not care about the payback time. I want to make a point!!
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Post by EVangelist on Apr 2, 2018 12:34:34 GMT 11
Sorry I should clarify that the proposed solar system would average 32 kWh per day in October. The actual peak of daily production is estimated to be 44.8 kWh. Wow.
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Post by Phoebe on Apr 2, 2018 15:19:17 GMT 11
Yes, that is a much bigger system than mine, but I do have a separate solar hot water system as well and there is only one of me so I don't need a large system. Even with this small system and charging my LEAF, I still get a refund on my electricity bill instead of having to pay.
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aja
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Post by aja on Apr 2, 2018 20:05:28 GMT 11
I believe that Powercor in VIC limits residential solar systems to 5kW. We have had to install an export limiting device to meet the export restriction. We are still grid connected.
We have a 2x3 kW PV system, each separately connected to its own phase (2 phase power). One phase is entirely dedicated to the hot water heater and the other is for everything else, including induction cooktop, electric oven, Leaf and 6kW battery.
Our main grid import is for the hot water heater, anywhere between 0 and 4 kW/day depending on the sun. I am planning to change out the 4.5 kW water heater element with a 1.8 kW one to eliminate the peak demand.
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Post by rusdy on Apr 2, 2018 23:33:42 GMT 11
Hi estation, You can use any size of solar panel to be used with Tesla Powerwall 2. If you don't produce enough (or use too much on the day), then the PW2 simply not fully charged by the end of the day. Here is my PW2 screenshot on the second day after being installed in the previous evening. Hence, not enough charge to go through the night to charge my Nissan Leaf (see first arrow at around 1am):  As you can see on 'Noon', I charged my EV again and cranked the air-con full blast. You can see the blue graph (home consumption) peaked at 4.8kW. The PW2 gave around 2.5kW instantaneous power around this time, where-as the rest supplied by solar panel. The grid consumption of the above screenshot is not shown for clarity, but I can assure you no grid power (See note 1 below) being consumed around this time. As for "how much solar panel do I need?", is quite a thesis in itself, and I won't bore you to deaths with details. The short answer is to get detailed consumption pattern of your household per day and also by season. I can assure you, it won't be financially prudent to be off-grid using solar PV (and batteries) alone. This is because PV production is lowest in winter, and very likely your household consumption is highest during winter at the same time (true for me as I use electric everything, except hot water). Using my own household as an example, I use 15kWh average per day in summer months, and I produce more than that from my 3kW PV. Hence, since I installed my PW2 late last year, I could go off-grid if I wanted to. However, if I've done this, I wouldn't be getting my meager 7 cents per kWh export (because I still produced too much in summer) from my SWIS network (in Western Australia). Note: - Actually, PW2 consumes a constant 100 Watt from the grid during charging on the daytime (as the AC conversion to DC is lossy). Annoying isn't it?
- More review of my PW2 click here.
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Post by jacky on Apr 3, 2018 20:17:07 GMT 11
Using my own household as an example, I use 15kWh average per day in summer months, and I produce more than that from my 3kW PV. Hence, since I installed my PW2 late last year, I could go off-grid if I wanted to. However, if I've done this, I wouldn't be getting my meager 7 cents per kWh export (because I still produced too much in summer) from my SWIS network (in Western Australia). Are you sure it is worth for you to get the 7 cents / kWh? How much do you pay for the daily connection charge? In Melbourne, I have to pay $1.3 a day for the connection fee. If I only get 7 cents / kWh, I will have to export 18.5kWh ( = 130 / 7) a day on average to get a break even. It is A LOT of electricity. For me, the reasons to stay on the grid are: - I am still on pFIT - receiving 72 cents / kWh; 60 cents from the VIC government and 12 cents from retailer
- My current solar system does not generate enough power for 2 EVs (which I am planning to do)
- My current solar system almost utilised all usable roof space
I will definitely install home battery after my pFIT expired. |
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Post by rusdy on Apr 3, 2018 23:11:39 GMT 11
Are you sure it is worth for you to get the 7 cents / kWh? How much do you pay for the daily connection charge?  You're absolutely right, the export is definitely not worth it, but my other option is to waste the excess by not using it (since the battery is full). I'd rather export that, even for free, to reduce other's carbon footprint. Unfortunately it's both not physically and financially feasible for me to go offgrid (without lifestyle sacrifice), since my winter usage peak (not average) is in excess of 20kWh per day, and my winter production dips to less than 5kWh per day (which means I need at least 15kW solar panel, and I only have space for less than 5kW). Daily charge in WA is a dollar a day (no choice, unlike eastern states). However, we do enjoy lower rate of electricity here in the west. 27 cents flat rate, or ToU 50cents peak (13cents off peak). |
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Post by EVangelist on Apr 4, 2018 16:15:46 GMT 11
As for "how much solar panel do I need?", is quite a thesis in itself, and I won't bore you to deaths with details. The short answer is to get detailed consumption pattern of your household per day and also by season. I can assure you, it won't be financially prudent to be off-grid using solar PV (and batteries) alone. This is because PV production is lowest in winter, and very likely your household consumption is highest during winter at the same time In my house we use roughly the same amount of power in summer and winter - due to ducted air conditioning and a hopelessly energy inefficient house. I'm hoping I can fix the latter and get my daily consumption within the range of what my proposed solar array will produce in winter, on average. But yes there will be times where grid draw is inevitable, so I was exaggerating slightly saying we'd be off-grid. We'll probably come close to generating enough power per year to match what we consume each year, but that is not enough to truly go off-grid due to temporal factors as you note. The power wil sometimes be generated at the wrong time and unable to be stored because the battery is full. |
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sundrive
EV Tyre Kicker
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Post by sundrive on May 24, 2020 19:21:35 GMT 11
Re the title of this topic;
We live off-grid using approx 7kWh per day, have a 4.3kW PV array approx 48kWh gel PbSO4 battery set and autostart generator set (which runs generally less than 30hrs per year).
We also have, since 2016, a separate 10kW PV array for the Leaf with approx 90kWh gel PbSO4 battery set with no auxilliary support.
Doing the sums, 100km per day (return work commute for wife) at approx 180Wh per km, requires 18kWh from the battery, taking in to account system efficiencies (battery coulombic losses and AC coupled PV inverter losses) we need approx 20kWh per day from PV array to give 100km per day driving range. With a 10kW array (facing Nth at approx 35 degree pitch) in SW Victoria we can achieve that all year round, save for maybe three days per year when system battery is unable to deliver that amount of charge without dropping to an unacceptable SOC (it usually sits between 80-100% SOC but occasionally, if desperate and sunshine on the way, will let it drop to 70%, or so).
If in this location 10kW standalone PV will yield 100km per day all year round, you could expect a 5kW standalone PV system would yield enough for 50km per day, just be careful of the battery storage capacity, and if I were installing this system today I would definitely use LiFePO4 battery set not gel PbSO4.
Hope that is helpful.
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