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Techy Question - Can a domestic EV charger accept a variable wattage?


Kurt Barlow

Question

I have mentioned this before but solar panels are getting very cheap and we have just bought a house with a big roof. Downside is the FIT has gone. 

I have been thinking about buying a cheapo Nissan leaf as a potential energy dump and as our local runaround. The best set up would be charging through something like  this that diverts suplus power (in 240v AC) to a resistive load to heat water cylinder.

https://solarimmersion.co.uk/

Now ideally water heating should be last resort. These units have two outlets that work in priority order and match the output to the equivalent of what would otherwise be exported. 

Outlet 1 (max of 3.6KW) when this is full or not available it switches to:

Outlet 2.

I was think you could use outlet 1 to charge the car and if the car was being used or battery full it would switch to 2 to heat water

Only thing is can one these below take a variable wattage? 

https://shop.evchargersdirect.co.uk/products/nissan-leaf-2017-and-earlier-nissan-e-nv200-ev-home-charger-charging-cable-10amp-evse-5-meters-long-uk-to-type-1?variant=3775621333020&currency=GBP&gclid=CjwKCAjwkenqBRBgEiwA-bZVtujiyGL1p1J0lKSk-kEoR66EffUV-ugE7D5C3rHMKqiI_Ypn2DfxyBoCPW4QAvD_BwE

I can't see that trickle charging the battery would damage it  but I am not sure how the controller would behave. 

The other option would be to put the car on charge from say 11am to 3 pm every day however that would inevitably result in more import of electricity. 

Any thoughts from the electrically minded Dosbodders? 

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The charge rate will be controlled by the car, or if using the granny lead they often allow the selection of different charging rates.

You could build your own variable charger but its easier to just buy a zappi:

https://myenergi.com/product/zappi/

Or do the sums and see if its better to just set the charge rate to low (typically 5A, perhaps 10A) and keep an eye on the weather forecasts.

 

 

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Some further thoughts - now that the FIT is gone, on the plus side you don't have to worry about using MCS approved kit. Big batches of second hand panels sometimes pop up on ebay, same for inverters. If you have a big garden and fancy a new big shed or workshop then cover the roof of that with PV. From memory the permitted dev rights for ground mounted PV are rather stingey at 9m2 but you can build a shed pretty much as big as you like, although check the latest rules about distance from boundries to avoid getting caught out. Ground mounted will be cheaper and can be mostly DIY with a sparky doing the new consumer unit. Don't forget G83 notification to keep it all in order.

Personally, I would go for a PV diverter that just does hot water (also consider the iBoost+) and for the car set it to charge at low rate and plug it in on sunny days. It will depend on what sort of mileage you will be doing as well. Come the gloomy winter months you will be mostly using grid electric but even then it works out at around 4p per miles vs around 12p per mile on petrol/diesel.

As an added bonus your neighbours (and you) will get to breathe slightly cleaner air.

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1 hour ago, null; said:

Some further thoughts - now that the FIT is gone, on the plus side you don't have to worry about using MCS approved kit. Big batches of second hand panels sometimes pop up on ebay, same for inverters. If you have a big garden and fancy a new big shed or workshop then cover the roof of that with PV. From memory the permitted dev rights for ground mounted PV are rather stingey at 9m2 but you can build a shed pretty much as big as you like, although check the latest rules about distance from boundries to avoid getting caught out. Ground mounted will be cheaper and can be mostly DIY with a sparky doing the new consumer unit. Don't forget G83 notification to keep it all in order.

Personally, I would go for a PV diverter that just does hot water (also consider the iBoost+) and for the car set it to charge at low rate and plug it in on sunny days. It will depend on what sort of mileage you will be doing as well. Come the gloomy winter months you will be mostly using grid electric but even then it works out at around 4p per miles vs around 12p per mile on petrol/diesel.

As an added bonus your neighbours (and you) will get to breathe slightly cleaner air.

Thats exactly what I'm planning. Cheers for the Zappi link. 

I though I would just hire a decent mobile elevated work platform to get he job done. I have also designed my own dirt cheap fixing system using gagble end restrains and stainless steel builders strap. 

I am also going to put in a large solar water heating system and large cylinder. This will work well as my house is full of people over summer. MIL comes to help with child care. Step daughter on long visits and at least 2 (seems like an hour ) shower each day. 

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1 hour ago, null; said:

Some further thoughts - now that the FIT is gone, on the plus side you don't have to worry about using MCS approved kit. Big batches of second hand panels sometimes pop up on ebay, same for inverters. If you have a big garden and fancy a new big shed or workshop then cover the roof of that with PV. From memory the permitted dev rights for ground mounted PV are rather stingey at 9m2 but you can build a shed pretty much as big as you like, although check the latest rules about distance from boundries to avoid getting caught out. Ground mounted will be cheaper and can be mostly DIY with a sparky doing the new consumer unit. Don't forget G83 notification to keep it all in order.

Personally, I would go for a PV diverter that just does hot water (also consider the iBoost+) and for the car set it to charge at low rate and plug it in on sunny days. It will depend on what sort of mileage you will be doing as well. Come the gloomy winter months you will be mostly using grid electric but even then it works out at around 4p per miles vs around 12p per mile on petrol/diesel.

As an added bonus your neighbours (and you) will get to breathe slightly cleaner air.

You can get 6.5 KW of Panasonic solar panels for 2150

https://www.ebay.co.uk/itm/22-x-295w-Panasonic-Solar-Panel-MonoCrystalline-High-Efficiency-Mono-6-5KW/254327860876?hash=item3b371f2e8c:g:qt4AAOSwk1hcve1O

My roof is East and West plus I have a south facing sloped garage roof that I could get 600-800w of panels on. 

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2 minutes ago, null; said:

East West is great for better use of generation vs highest annual generation for FITs.

Please keep us posted on how you get on.

I have to paint the entire interior first or risk a divorce so thats this year tied up. 

I will stick another 200mm of loft insulation in. 

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Chewing Grass
10 hours ago, Kurt Barlow said:

I have mentioned this before but solar panels are getting very cheap and we have just bought a house with a big roof. Downside is the FIT has gone. 

I have been thinking about buying a cheapo Nissan leaf as a potential energy dump and as our local runaround. The best set up would be charging through something like  this that diverts suplus power (in 240v AC) to a resistive load to heat water cylinder.

https://solarimmersion.co.uk/

Now ideally water heating should be last resort. These units have two outlets that work in priority order and match the output to the equivalent of what would otherwise be exported. 

Outlet 1 (max of 3.6KW) when this is full or not available it switches to:

Outlet 2.

I was think you could use outlet 1 to charge the car and if the car was being used or battery full it would switch to 2 to heat water

Only thing is can one these below take a variable wattage? 

https://shop.evchargersdirect.co.uk/products/nissan-leaf-2017-and-earlier-nissan-e-nv200-ev-home-charger-charging-cable-10amp-evse-5-meters-long-uk-to-type-1?variant=3775621333020&currency=GBP&gclid=CjwKCAjwkenqBRBgEiwA-bZVtujiyGL1p1J0lKSk-kEoR66EffUV-ugE7D5C3rHMKqiI_Ypn2DfxyBoCPW4QAvD_BwE

I can't see that trickle charging the battery would damage it  but I am not sure how the controller would behave. 

The other option would be to put the car on charge from say 11am to 3 pm every day however that would inevitably result in more import of electricity. 

Any thoughts from the electrically minded Dosbodders? 

Forget the leaf, fit solar panels with battery storage and an invertor, remove your domestic lighting circuit from the mains and replace all bulbs/fittings with LED ones.

Light your entire place off sunlight, just size it so it produces enough stored power to cover winter evenings.

If I remember rightly the power has to be clean enough and powerful enough (kW) for the leaf to accept charge which is why they won't charge off small generators.

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4 minutes ago, Chewing Grass said:

Forget the leaf, fit solar panels with battery storage and an invertor, remove your domestic lighting circuit from the mains and replace all bulbs/fittings with LED ones.

Light your entire place off sunlight, just size it so it produces enough stored power to cover winter evenings.

If I remember rightly the power has to be clean enough and powerful enough (kW) for the leaf to accept charge which is why they won't charge off small generators.

As a second car we have my dads old Auris which for short journeys does about 25mpg and costs 210 a year to tax. Otherwise cheap to run. The car will largely be for running jnr to school, picks up and other about town travel. For longer distances we would use the Hybrid as much better fuel economy. (60mpg vs 42-43mpg) 

That first link I posted is ideal for a time switch set up as its 10 amp so 2.4 KW. I could easily stick 3KW on each roof (east and west ) and another 600-700W on the garage roof (south). Timeswitch to charge car between 11am and 3pm. 

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5 hours ago, Kurt Barlow said:

I have mentioned this before but solar panels are getting very cheap and we have just bought a house with a big roof. Downside is the FIT has gone. 

I have been thinking about buying a cheapo Nissan leaf as a potential energy dump and as our local runaround. The best set up would be charging through something like  this that diverts suplus power (in 240v AC) to a resistive load to heat water cylinder.

https://solarimmersion.co.uk/

Now ideally water heating should be last resort. These units have two outlets that work in priority order and match the output to the equivalent of what would otherwise be exported. 

Outlet 1 (max of 3.6KW) when this is full or not available it switches to:

Outlet 2.

I was think you could use outlet 1 to charge the car and if the car was being used or battery full it would switch to 2 to heat water

Only thing is can one these below take a variable wattage? 

https://shop.evchargersdirect.co.uk/products/nissan-leaf-2017-and-earlier-nissan-e-nv200-ev-home-charger-charging-cable-10amp-evse-5-meters-long-uk-to-type-1?variant=3775621333020&currency=GBP&gclid=CjwKCAjwkenqBRBgEiwA-bZVtujiyGL1p1J0lKSk-kEoR66EffUV-ugE7D5C3rHMKqiI_Ypn2DfxyBoCPW4QAvD_BwE

I can't see that trickle charging the battery would damage it  but I am not sure how the controller would behave. 

The other option would be to put the car on charge from say 11am to 3 pm every day however that would inevitably result in more import of electricity. 

Any thoughts from the electrically minded Dosbodders? 

I'd have thought it will just stop charging as soon as it detects anything untoward with the input supply. I thought there was charging circuitry within the vehicle also.

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