• Hi all and welcome to TheWoodHaven2 brought into the 21st Century, kicking and screaming! We all have Alasdair to thank for the vast bulk of the heavy lifting to get us here, no more so than me because he's taken away a huge burden of responsibility from my shoulders and brought us to this new shiny home, with all your previous content (hopefully) still intact! Please peruse and feed back. There is still plenty to do, like changing the colour scheme, adding the banner graphic, tweaking the odd setting here and there so I have added a new thread in the 'Technical Issues, Bugs and Feature Requests' forum for you to add any issues you find, any missing settings or just anything you'd like to see added/removed from the feature set that Xenforo offers. We will get to everything over the coming weeks so please be patient, but add anything at all to the thread I mention above and we promise to get to them over the next few days/weeks/months. In the meantime, please enjoy!

Solar PV and power storage

M

misterfish

New Shoots
Joined
Jul 22, 2014
Messages
68
Reaction score
5
Location
Chichester, West Ssussex
I had a cold call yesterday from what appeared to be a Bournemouth phone number trying to interest me in buying a battery based storage system to attach to our existing PV system! He first wanted to confirm we had a PV system and then started talking about lithium batteries to provide storage of the PV generated power.

I do not react positively to cold callers so quicky and politely terminated the call. But it got me wondering just what is currently available that is 'proven' for storage and usage of PV generated power. My thoughts were wahat was the cost and capacity of such a system. Although interesting I do not want to be a guinea pig tester for such systems.

Anyone know anything about this sort of thing?

Misterfish
 
Jeff,

You need to get some hard data from them if they call again.
1)What is the capacity in kWh of the battery? - you only be able to use about 50-60% at most without over stressing the batteries from that you can get a figure for the price per kWh stored. Then what is the battery life in charge-discharge cycles.
You can then start to work out the value of the power stored over the lifetime of the battery compared to the cost of replacement batteries. This answer may well surprise you!
2) What voltage will the system create? it might have an inverter to create 240 ac or if not you might need to add a low voltage lighting circuit to use the stored power.
3) What sort of switchgear and wiring is needed? what ever circuits (lighting, tv, computer say) will have to disconnect from the grid and instead connect to the battery derived supply.

Something to think about?

Bob
 
I can't see how this makes sense for a single home unless it's not on the grid or has very unreliable line service. It might make more sense if your power company varies the price by the demand on the grid, so that you can avoid the most expensive periods. Even then you'd have to have some controller that detects the line power costs so it can cut in the battery instead at a certain threshold.

I presume you have some kind of setup where you sell your excess power back to the company. If you don't this might make some sense too, but still the payback period would be long unless you've really oversized your panel setup.

Kirk
 
Having a rather large plot of land. I had the idea of getting couple of large submarine batteries charging them up with via the PV then via another inverter with transformer into a Briggs & Stratton secondary mains isolator which disengages the house supply from the mains.
This is needed so if there is a fault on grid supply your secondary power supply doesn't leave your property.
The only problem that stopped my venture was the weight of the submarine cells.

Richard
 
As you get a bonus payment for half of the total generated which is considered as supplied to the grid. There is equipment that can recognise the export and use it to power a immersion heater for your hot water and you still get the bonus payment. This arrangement would be much more cost effective but does not give any standby power.Its also worth mentioning that standby power would have to be changed over manually so as not to feed back to the grid on a power cut and hurt someone fixing it.
 
Sorry about the blank posting - I tried to post last night but my mobile phone decided to throw a wobbly!

As Bob says I really need more details of their system - but I have an aversion to cold calling and nearly always terminate such calls quickly. If I had been in a 'normal' frame of mind I might have asked more questions but following my mother's death last month I'm preoccupied with solicitors and probate!. Also, as we all know problems always seem to be i threes and at the same time I'm frequently in contact with my brother and sister-in-law that live in France - my sister-in-law slipped on ice at the local supermarche and broke her leg so has been limited in mobility while my brother (her husband) has been going through a mid life crisis and run off to Spain a couple of times - it turns out that he is suffering from encephalitis and is about to be transferred to a Valencia hospital for further scans/treatment.

Anyway - back to PV - our mains supply is usually pretty reliable (underground rather than overhead) so any storage system would not offer much. If we had (ir)regular protracted power outages then I would consider a backup generator but it's not really worth it. Kirk is right - our PV supply pays us about £0.45 per killowat/hour subsidy guaranteed for 25 years, linked to inflation and not liable to income tax. Also it is deemed that 50% of our generation is considered as fed back into the national grid for which we get a few pence per kilowat hour. We have to have a separate meter to measure the amount of electricity generated (we can't have meters that run backwards when electricity is exported!)

So I think what they are trying to sell is really a non starter. I looked at the cost of gel batteries and they are expensive so I reckon a useful system would come in at many thousands of pounds. My wife found a cost when she did a search - it was something like £6,000 for a small system installed!

On a related subject it turns out that the mains supply to our property is (unusually) for the uk is 3 phase. Our property on one phase and the attached granny annex on a second phase - the shared/linked sun room has supplies from both phases (lighting on one phase and power sockets on another). I suppose ther is no simple (safe) way to run three phase motors using just two phases. I was unaware of the supply until the electrician mentioned it in passing way after having provided a single phase supply to my workshop!

Anyway if I hear any more about the PV backup system I'll add to this thread.

Jeff
 
misterfish":7xifir5v said:
On a related subject it turns out that the mains supply to our property is (unusually) for the uk is 3 phase. Our property on one phase and the attached granny annex on a second phase - the shared/linked sun room has supplies from both phases (lighting on one phase and power sockets on another). I suppose ther is no simple (safe) way to run three phase motors using just two phases. I was unaware of the supply until the electrician mentioned it in passing way after having provided a single phase supply to my workshop!

Jeff
Click to expand...

Jeff, do you have two single phase meters on your supply or one three phase meter at the point of entry?

This will affect the range of possibilities.

Bob
 
My parents house had 3 phase supply but you couldn't have a 3 phase feed from it. One phase did their house, another disappeared through the party wall for the house next door and the third was unused.

When we were first married we converted 2 rooms into a self contained flat. I did a rewire for it and had it connected to the third phase on its own meter after inspection and test by the electricity board. things were simpler then :)

Just thinking this sounds similar mains supply in this thread.
 
misterfish":2ejf8b6b said:
One phase is connected to our supply and a second phase conneced to the granny annex supply (tis is an economy 7 type supply with two meters and a time switch. The 'blue' phase is not connected to anything

http://www.drosera.f2s.com/3phase.JPG shows the incoming supply.

Jeff
Click to expand...
OK so you can't connect three phase kit simply.
Trying to do anything with just two phases might cause you to be billed twice - I think (?)

so single to 3 phase converters/inverters are the best options.

hth

Bob
 
Thanks Bob

That's what I thought - I think there's only a single phase armoured cable that goes to the workshop and on to the garage so any upgrade to a proper 3 phase supply would be awkward - not to mention actually getting a 3 phase meter fitted would no doubt be awkward and expensive. If I do acquire any three phase equipment I'll use a converter/inverter.

Jeff
 
You must log in or register to reply here.
Back
Top