Home  5  Books  5  GBEzine  5  News  5  HelpDesk  5  Register  5  GreenBuilding.co.uk
Not signed in (Sign In)

Categories



Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
These two books are the perfect starting place to help you get to grips with one of the most vitally important aspects of our society - our homes and living environment.

PLEASE NOTE: A download link for Volume 1 will be sent to you by email and Volume 2 will be sent to you by post as a book.

Buy individually or both books together. Delivery is free!


powered by Surfing Waves




Vanilla 1.0.3 is a product of Lussumo. More Information: Documentation, Community Support.

Welcome to new Forum Visitors
Join the forum now and benefit from discussions with thousands of other green building fans and discounts on Green Building Press publications: Apply now.




    • CommentAuthorrevor
    • CommentTime5 days ago
     
    Having failed to get an EPC in time to gain from FIT, pressure now off, so in position to do a DIY installation. Don't really want to give the grid the benefit of my investment (Claire Perry seems to be dragging feet on this one) so thinking of a battery back up off grid system. Am also in the market for an electric vehicle and wondered whether I could use the battery on the car to serve both purposes. Guess possible but expect the specifying will be critical bit.

    Anyone got any thoughts.
    • CommentAuthorbhommels
    • CommentTime5 days ago
     
    Recently somebody told me the Mitsubishi i-MiEV has an emergency mode that allows it to power devices from its battery. The gizmo is available in Japan, where they have 100V mains voltage.
    The Wiki page on V2G has a few references to Nissans and Mitsubishis being capable of it. Nothing off the shelf (outside Japan) though. Electricnation.org.uk has some information on their 2018 trial.
  1.  
    A subject that I'm very interested in but also a bit confused about.

    Getting excess PV generation into your car seems pretty easy. Zappi car chargers seem to be well reviewed and have solar divert functionality.

    If you want to go the next step and get electricity stored in your car battery back into your home via a vehicle to grid or vehicle to home system it all seems to get more confusing (to me at least). I think we are basically in trial stages here in the UK. I believe you need a pretty new electric car too that can support charging your house (so you can't pick up a cheap old Leaf for example).

    Robert Llewellyn (Scrapheap Challenge, Red Dwarf) runs a YouTube channel about EVs and renewables called Fully Charged. He's having one of the trial systems installed in his house soon and said he'll make an episode about it so could be worth looking out for.
    • CommentAuthortony
    • CommentTime4 days ago
     
    I have an electric car and can charge on solar

    Battery charging is inherently inefficient so although it can be economic for an individual overall in energy terms it wastes some energy
    •  
      CommentAuthorfostertom
    • CommentTime4 days ago
     
    That matters less, if at all, if the energy source is abundant and 'renewable'. The imperative for 'efficiency' is vital when the source is fossil, for reasons of greenhouse gases and other toxic pollutants - but that reason doesn't apply to renewables.
    •  
      CommentAuthornigel
    • CommentTime4 days ago
     
    I am going down the full EV shortly and I am going to extend my PV from 3kWp to 7kWp.

    Zappi and EDDi will be used to use as much as practical and then you can export the excess using someone like octopus energy who will pay 5.5p per Kw.

    They also do an agile tariff that uses half hour rates so you pay the market rate and therefore charging at night is cheaper.

    So most of the daytime use is covered by PV and night time at reduced rates on Agile tariff and the EV can be topped up at night at times when there is insufficient solar. At times the night time tariff can be as low as zero and more often than not no more than the export rate your are paid.

    Battery technology is too expensive at the moment and I think its better to use the grid as your battery store.
    Batteries are also energy intensive to make so consider the embodied energy in their manufacture and later recycling.
    • CommentAuthorbhommels
    • CommentTime4 days ago
     
    Posted By: tonyI have an electric car and can charge on solar

    Battery charging is inherently inefficient so although it can be economic for an individual overall in energy terms it wastes some energy


    True, although for Li batteries the round-trip efficiency can be as high as 90%. And the electricity grid is not 100% efficient either.
  2.  
    If someone stores solar by charging a car, then discharges it to power a house, will that charge/discharge cycle use up a bit of the lifecycle of the car battery and hence of the car itself? IE they buy an expensive car but it has only a short useful life before the battery gives up. How will the financial/environmental cost of that compare to the solar energy value?

    Alternatively could you buy an old/bashed electric car, park it in the garden and use it as a home battery?
    •  
      CommentAuthordjh
    • CommentTime4 days ago
     
    Posted By: WillInAberdeenAlternatively could you buy an old/bashed electric car, park it in the garden and use it as a home battery?

    That's what a Tesla Powerwall is, AIUI. Other manufacturers are also moving in that direction.
  3.  
    Posted By: WillInAberdeenIf someone stores solar by charging a car, then discharges it to power a house, will that charge/discharge cycle use up a bit of the lifecycle of the car battery and hence of the car itself?


    I'm not dismissing this as a concern, but I'm not sure how big an issue it is. Car batteries are lasting longer then people expect. All of the car manufacturers quote prices for replacing batteries but I heard 4/5 months ago that none of them had actually ever done a replacement. There are some pretty old Nissan Leafs out there. I've also read reports of an electric taxi in Cornwall that had done 150,000 miles and had 90% of its battery capacity left. As this is such a new area, more research is probably required.
    • CommentAuthorCWatters
    • CommentTime4 days ago
     
    One way I can see this being useful is to mitigate the evening peak surge in demand. eg people arrive home and plug in their car, instead of charging the car helps the grid over the evening peak. Then later the car starts recharging.

    If that's what happens in practice then I guess the effect on the battery is slightly deeper charge/discharge cycles rather than more cycles. Deeper discharge cycles are known to reduce the life of some li-ion cells.

    Will lease/rental companies allow such use if it wears out their asset faster?
    • CommentAuthorphiledge
    • CommentTime4 days ago edited
     
    <blockquote><cite>Posted By: fostertom</cite>That matters less, if at all, if the energy source is abundant and 'renewable'. The imperative for 'efficiency' is vital when the source is fossil, for reasons of greenhouse gases and other toxic pollutants - but that reason doesn't apply to renewables.</blockquote>

    Whilst solar energy may be abundant, the PV electricity isnt abundant and we're still totally reliant on fossil fuels. Only time renewables may be abundant is in the dead of night when wind may be enough to meet base load demand and maybe have some spare for car charging.
    •  
      CommentAuthorfostertom
    • CommentTime3 days ago
     
    That's true for now - I was just encouraging clarity as to precisely why efficiency is vital now, so that we can keep an eye open for it getting less important.

    Certainly, reducing demand due to efficiency will shorten the time to when its curve crosses the curve of rising abundance of renewable electicity, esp solar, tho wind is taking the headlines at present.
    • CommentAuthorrevor
    • CommentTime2 days ago
     
    Thanks everyone found out lots today particularly from mentions by nigel. Been on Octopus did not know anything about them but it looks just up my street. followed the Zappi mention and came across this Robert Llywellyn video fully charged mentioned earlier by richardelliot
    https://www.youtube.com/watch?v=0EtegQfZQRw. Made me think of a small wind turbine also as have plenty of wind where I live would not have to be particularly powerful when combined with all the other stuff.
    This followed from the first video https://www.youtube.com/watch?v=nWLzlrGGuxQ.

    Interesting concept buying and older EV for the battery could have mileage.
  4.  
    Posted By: revorInteresting concept buying and older EV for the battery could have mileage.


    I'm not an expert, but I'm not sure an older EV will give you what you want? You can definitely divert excess generation into a car battery and get some 'free' driving miles, but I think you'd struggle to get the electricity back out again (especially when it is an older car) to create a backup off grid system.
Add your comments

    Username Password
  • Format comments as
 
   
The Ecobuilding Buzz
Site Map    |   Home    |   View Cart    |   Pressroom   |   Business   |   Links   
Logout    

© Green Building Press