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I hadn’t considered solar until yesterday when I got chatting by chance with some people selling systems at IKEA in Milton Keynes yesterday – the numbers seem compelling.
One limitation I have is that my house has a hip roof, so the largest single roof surface (which fortunately is best for south orientation) is quite small in relation to the size of the house. Without doing any detailed sums, I think that might limit me to as little as a 2.1kW system (unless of course I use more than one of the four surfaces available).
I realise this is almost a noddy level question but if I charged my Fluence on such a system on a reasonably bright day, would some current be drawn from the grid, or would the system alone normally deliver enough to do the job?
I’ve blogged about my experiences of solar – see the Solar category.
The short answer is probably not – I have a large array and I certainly can’t produce enough to charge the ZOE. I’ll try to reply in more detail tomorrow.
With a Zoe, the supplied charger is 7kW, so a 2.1kW solar PV system would not provide enough. However, assuming that you generate about 2MWH over the year, that would probably be more than the total used by the car throughout the year.
I’ve got a 4kW system which is spread between two roof sections. One is South facing, the other West facing. I’ve got 10 panels facing South (2.5kW) and 6 facing West (1.5kW) – see image attached. My peak output record is just over 3.6kW in the middle of the summer. Yesterday when it was sunny, generation peaked at about 0.8kW so As @andyfras says, you will not get close to the 7kW that a Zoe can consume (not sure what a Fluence can charge at). For me, the Solar generation was partly an environmental decision (like the Zoe since I’m a low mileage driver) and partly a financially driven decision. The system basically cost me an annual ISA allowance, and even allowing for the fact that ISAs are tax free, the return I’m getting is significantly higher so therefore a better investment!
I also have solar panels and they do not generate enough electricty to cover the zoe charging.
your best best is getting an economy 7 tariff and charging your car overnight or charge out and about for free!
A more complete follow-up: the rating of a solar array is the maximum theoretical peak (p) output and in the UK on a sunny summer day we may get close to that, so my not-quite 7kWp system can produce about 5kW, and as nick says his 4kWp system can produce about 3.6kW. Most of the rest of the time you could get about half the rating, in the winter you’ll get a much smaller fraction. On a bad day it might seem like it’s not working at all!
Taken ‘in the round’ across a year a 2kWp system could produce about as much power as you need to run an EV depending on your mileage, but a solar array certainly couldn’t charge a ZOE directly at 7kW unless it was very big. If you tried you might get half ‘free’ from the PV and half from the grid. That’s still not a bad situation, but in my case it is still cheaper to charge overnight since Eco 7 is only about a third the cost of in the daytime.
However, the question was about the Fluence and that is a different story. If it only needs 2-3kW to charge then in theory a 3-4kWp system could power it completely on a sunny day. You would get it then for free, and then you could calculate at what point in the autumn and spring to swap between daytime solar charging and nighttime Eco7 charging.
Although everyone historically recommended south facing roofs have you considered west facing? West will typically produce more useable electricity than south (i.e. in the early evening when you want it) even though it produces slightly less overall, and there is an increasing fashion to ‘go west’ in many countries as the FIT diminishes.
My second array is actually north facing as that was the only space left, and I didn’t want to go without!
Thanks for the replies – the picture is already quite a bit clearer.
I think going for solar looks like a good bet financially, with somewhat greener charging being a bit of a bonus!
Hi, ElectricDream and Merry Christmas to you. Theoretically your solar array almost exactly matches the current the 10A “brick” cable supplies so your charge rate would be similar. What you have to consider, however, is whether having the car on charge for 7 – 8 hours DURING DAYLIGHT HOURS to replenish a threequarter used battery would be feasible – unless you work nights – or, like me, you don’t use the car for a daily commute.
I didn’t think it made any difference with the FIT, because you are simply balancing out, using the grid, what is above or below your immediate consumption, and the ‘presumed’ rate of your own use is not calculated directly.
The charge rate versus evolved power is purely theoretical, no?
I was wondering if anyone looked at the possibilty of using a solar panel,say 20volt o/p,(off load) at around 20watts to charge the 12 volt battery,these days amorphos panels seem the way to go,and the panel could travel with the car.
To consider an expensive home system,feeding into the grid through an inverter in order to charge the 400v LI-on car battery seems to me to workout at nearly the price of another car and I think keep it simple.
It may be foolish to mess with the 12v battery system without permission from the manufactures,almost certainly invaladating the warranty though?
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