Export fee question

GreenBo

kevin6666 wrote: »

The information I've seen suggests the deemed 50% export on <=4kW PV systems is too high. Obviously most people aren't in all day but when they do meter their export for whatever reason it's not good.

Kevin - are you saying that for an average <=4kW system the average household exports a lot less than 50%? what sort of % is more realistic? for a typical home that's empty in the day (at least in the week). My Smappee is telling me my average daily kW is around 100watts through the day. Should I still assume about a 50% amount of my solar kWh will be exported?

EricMears

GreenBo wrote: »

Kevin - are you saying that for an average <=4kW system the average household exports a lot less than 50%? what sort of % is more realistic? for a typical home that's empty in the day (at least in the week). My Smappee is telling me my average daily kW is around 100watts through the day. Should I still assume about a 50% amount of my solar kWh will be exported?

That is indeed what he seems to be saying - but I wish he'd shared that 'evidence' since the consensus on this site is that unless you work very hard at it you'd be very lucky to use much more than a third of what you produce.

Your 'Smappee' is no doubt averaging up what you're generating over the full 24 hrs when of course there's an awful lot of hours per day when you're generating nothing (because it's too dark from 5pm till 7am this week )

pinnks

I have a spreadsheet set up to give a very broad brush guesstimate of what I export.


It looks at what I generate each month and subtracts from that what my usage was for the same month before I had solar but after we had LED'd the lights and otherwise rationalised our use. It then subtracts again what is going through the Immersun.


What is left is that guess of export. In the summer it is of course high, in the winter virtually nil. Overall it suggests 27% exported as I type this, so adjusting for inaccuracies etc I might be at about 35% to 40% export.


I am upgrading to the Immersun 2 soon and that should give me an accurate figure I think. It will be interesting to see how that pans out.

Lei_Chat

Having just had our annual bill for 2230kWh I'm expecting (if we don't get an iBoost) that we'd definitely export more than 50%.

I believe our electricity meter is one of the new ones capable of recording the export. We'll have to figure out whether it's worth having the iBoost.

System

I have a 2.15kWp PV solar system which generates about 1950kWhs a year. For the past 3 years, we have 'consumed' about 60% of what we generate. We looked at diverting unused PV solar to our HW tank but the cost v benefit equation didn't stack up as we have mains gas.

Separately, we came up with a clever plan to change our diesel car for an EV. It made sense as we tend not to wander very far from home. The higher cost of the EV is offset by savings of £800 per year on fuel, tax, maintenance and insurance.

As others have said, the cost of battery storage for PV solar is expensive and likely to remain so for many years. However, with an EV car in the garage, it makes sense to divert unused solar energy to the EV. Last week's sunshine allowed me to charge the car on a standard 13 amp plug at 6 amps/1440 watts which, in turn, has given me over 100 miles of free driving.

Kernel_Sanders

Martyn1981 wrote: »

Upcoming storage boom could ‘revolutionise’ the UK market

What a poorly constructed article that was.
' The timeline fits well with projections conducted by industry analysts, with IHS having previously forecast grid-connected energy storage installations to surpass 6GW in 2017, almost treble the 2GW+ estimate for 2015.'

Are we supposed to know what IHS stands for? Whoever they are, what the hell do they mean by 6GW storage..... GWpeak, GWhours, GWdays?

The 'upcoming boom' they mention when speculating about domestic-sized lithium-ion batteries could well turn out to be the boom of an explosion in some unlucky PV generating household.

Martyn1981

Kernel_Sanders wrote: »

Are we supposed to know what IHS stands for? Whoever they are, what the hell do they mean by 6GW storage..... GWpeak, GWhours, GWdays?

The 'upcoming boom' they mention when speculating about domestic-sized lithium-ion batteries could well turn out to be the boom of an explosion in some unlucky PV generating household.

IHS is an industry and business analyst, they get mentioned in the solar press all the time, though that is only a small area of their studies.

GW of storage mostly seems to refer to GWh, though this is an area that always seems to be sloppy, whether specialist news areas, or just regular reporting such as the Guardian, Telegraph etc. An additional area of interest would also be the rate of storage/supply - you might have 4kWh of storage, but the charge controllers may only be able to store/retrieve 1.5kW max (as an example).

Lead acid batts have been used for this purpose for decades (by of-gridders), and do need a safe storage area, and some level of monitoring. For Li-ion things should be safe, though only time will tell, but remeber that our houses now have many Li-ion batts dotted around, and the larger PV storage is very much partnered to that in EV's (electric vehicles) so it has been tested for many years in a far harder environment than sitting in a cupboard.

Price wise - well, if we look at some of the systems being rolled out in Germany, Japan, US and on offer in the UK, they often seem to be around £3k for a 'plug n play' system. This is very expensive, but strip out the inverter, since one is needed anyway, and the battery element is probably about £2k. Next, keep those fingers crossed as the battery market is currently exploding with the expansion of production. Tesla's gigafactory (under construction) should have a capacity greater than all current Li-ion production put together. It's hoped that prices could halve in the next 5 years.

For myself, a £1k battery with 3 to 4kWh of useable storage each day might reduce my import by 1,000kWh per year, so have a value of about £140 pa. If the battery lasts 10 years then it'll work financially, but only just.

I'm doubtful, but there's also the chance that the UK may offer some form of subsidy for such systems. The reasoning being that reducing peak demand, when electricity is more expensive, could save more than the battery subsidy scheme. No idea if that works out!

Mart.

Sterlingtimes

Hengus wrote: »

Separately, we came up with a clever plan to change our diesel car for an EV. It made sense as we tend not to wander very far from home. The higher cost of the EV is offset by savings of £800 per year on fuel, tax, maintenance and insurance.

I would be interested in this if it costed in. I cover about 5,000 mile a year in mileage and drive a Ford Fiesta Ecoboost. Would there be any credibility on my thinking electric?

Kernel_Sanders

Martyn1981 wrote: »

of-gridders

Thanks for the informative and well written reply (apart from the quoted bit ).

As for the last point, I believe the reason Govt. is pushing smart meters is so that the price per unit can be increased at peak times because I believe peak demand is the Achilles heel of the National Grid. If they can do this then there'd be little reason to subsidize household batteries.

zeupater

Sterlingtimes wrote: »

I would be interested in this if it costed in. I cover about 5,000 mile a year in mileage and drive a Ford Fiesta Ecoboost. Would there be any credibility on my thinking electric?

... only if you've considered where the vehicle spends most of the daylight hours, the relative cost of the purchase (Leaf vs Fiesta), cost of replacement battery packs if you're keeping it for a number of years ... and, the big one - whether you've got access to another vehicle for the long(er) journeys ....

Around here you can't guarantee to find a charging point where you're going, and if you can it's either out of order, decommissioned or normally has a demonstration Leaf or Ampera already plugged in ..... not bad if you're retired and/or never go far or have a particularly accommodating employer willing to provide dedicated spaces around charging points, else it's almost a no-brainer to go for a plug-in hybrid .... MrsZ's is on the drive at the moment having spent a good proportion of a glorious afternoon on a NT car park elsewhere thus taking no advantage of today's generation - I'd almost guarantee it's not plugged in though as it never is when it's here .... just content that we made the right decision ....

HTH
Z