Can I hope for some kind of indication the earth proposal is in fact SAFE 

It certainly look sensible in principle to me. At this distance I can't guarantee it's SAFE (there could be all sort of minor looking details that could get in the way that I can't see - such as arrangements for ADS) but I can see nothing in the earthing arrangements per se to object to so far.

... on second look at the diagram I notice it seems to be proposed to locate the battery storage system in the loft .... there have been some very recent discussions about that .. and a new standard published (PAS 63100 I think) which might have potentially moved the goal posts a bit on that score. (Who said cutting edge technology wasn't exciting (or even infuriating)?)

  - Andy.

My kit is entirely commercial off-the-shelf (COTS).  It's 18 Shűko panels, which are now totally obsolete as they are only rated at 190Wp each.  Then a more modern Solax inverter and an LG Chem battery*.

The exact details of how it all works together is dependent on the inverter and the battery management system in the battery box.  I don't know exactly what's going on.

Loosely speaking, it works like this:-

Are the panels generating more power than the house is using?

  Yes...

    Does the battery need charging?

      Yes...  Generate enough AC power to match what the house is using, and charge the battery with the rest.

      No...  Just generate AC.  The excess will go to the grid.

  No...  (and this includes at night)

    Is there any charge left in the battery?

      Yes... Use that to generate more AC.

      No... Tough, you're using grid power.

In practice, it's more complicated than that.  Charging the battery needs to slow down when it gets near 100%.  The inverter is limited to 3.6kW (and the panels to 3.4kWp).  The battery won't discharge more than about 2kW.

I'm relying on the battery management system (BMS) to protect the battery from over charging the battery or letting it go completely flat.  The BMS lies to the inverter.  When the inverter thinks the battery is completely flat, there's actually about 10% left.

*Luckily, the battery hasn't caught fire yet, even though it's made by LG Chem.  Their batteries are noted for their ability to spontaneously combust.  Last time I checked, the pack I have wasn't on the recall list.

That's why off-gridders always have batteries.

Indeed. And in a conventional grid-tied system, the consumer in effect uses the grid as a battery - sometimes exporting spare power to the grid, other times drawing power back. The need to balance supply with demand is quite a difficult problem if you don't have instantly accessible storage.

On the supply side, as mentioned power can reduce very significantly at a moment's notice. This is from my PV monitoring system from a couple of days ago  (yellow is PV generation, blue is consumption, light blue where they overlap):

then on the other side of the equation, remember that loads aren't nice constant things. Motors need extra "starting" current, even simple heating elements will draw more current when they're switched on - things that are often not clear from ratings plates.

   - Andy.

guys   AJ Simon and all sorry delay  : conclusions 

Proposed alternative solution to standard grid tie solar.  Partial off grid with independence 

I want to do this Believe viable alternative Sadly remain on my own .

Taken a long time to reach at least no objection to proposal is actually safe. For which  I thank all you guys for help 

Confidence to proceed hits another stumble  Volatile Lithium batteries in your house. 

Thought long and hard.  Given what we now know. I dont think I could sleep with those inside  Even with a fire canister next , 

The solar industry chooses again to ignore:  No solutions on hand 

I have not given up . Another hurdle I will find a way and prove  all my my doubters wrong  

All best  thanks again  to so many here in this forum who got me at least this far  Earthing. 

ciao Ms O 

If you don't like lithium ion, then you could go old-school and get lead acid batteries.  There are batteries that are specifically optimised for off-grid use.

Or the newer technology is lithium iron phosphate (LiFePo or LFP).  These are still lithium, bur are much less flammable than lithium ion.

Simon Barker said:

These are still lithium, bur are much less flammable than lithium ion.

I understand from the experts that investigate battery fires there are risks associated with the off-gas vapour from LiFePo or LFP igniting. A difference from lead-acid, though, is that the off-gas vapour might be heavier than air.

simon  Andy  G:k   

Thanks again : Lead acid  might have to lift the roof and crane them in  LOL  

Read PAS Is  it pointing to building fire regs  inclusion  soon ?  

Thinking place inv / batteries  on outside wall  Perhaps we just need a larger computer case with a fan  in it ?  Global warm maybe high temp is the enemy to life time Not cold .   None is addressing. 

None of this would be needed if I could simply place the thing in the garage . Foiled again by the the regulatory conspiracy to forbid  DC cables beyond 5 cm !   No protection technology available .  Though my solar supplier had no qualms about it over 20 m  Just wont guarantee .... 

The small print taketh away.  

Not given up yet but time runs out.

Andy "in a conventional grid-tied system, the consumer in effect uses the grid as a battery " 

 Really pull the other one ?   Buy hey 

all the best 

Ms O 

I think what was meant was

in a conventional grid-tied system, the consumer in effect uses the grid as a battery place to dump excess power into and then later to take power from to tide over whenever  the demand exceeds local generation.

 Perhaps more like a savings account at the bank, than a battery but for kilowatt hours, not money.

Well, and money too - depending on the contractual details

Mike

 Hmm   Can we just be clear 

The grid does NOT store energy :  If you want  it  ( even what you have regenerated) you wail have to pay for it ? 

Intrigued to know how this savings account  works ?

So all the solar grid tie ads had to be taken back to reflect : If your are out all day you will have to pay standard  tarrif  (because your solar has gone   somewhere and its dark  Never mind  Should have read the small print . 

Grid is not a public utility : It is a private business run for private profit  Like Thames Water. with Turds 

Love details of proposed  grid "savings account" 

 Convinces me more to go at least partially off grid .

Ms O 

Better get the batteries installed before they change the rules!  Building regs aren't retrospective.

well maybe tthe grid is more like a payday loan then.

My point is that banks don't store your money either - its not like they have a shoebox per customer stuffed under a big bed out the back (its not really like the bank in this sketch)

Rather they actually lend your money out to someone prepared to pay more for it who uses it there and then, and then when you ask to take your  money out, actually you some get money that someone else recently paid in.

The grid is much the same. The excess electricity you put in supplies someone else's load at that moment , and you get paid for that. The electricity you take out at other times when clouds cross your solar panels, you pay for in the normal way

A real example a colleague of mine uses https://octopus.energy/smart/intelligent-octopus-flux/

and that system charges the batteries in his garage  from solar panels when it can, and when solar power is weak, then charges from the grid when it is cost effective to do so, and he exports to the grid at times of high demand and gets paid over the odds for it - usually early evenings. So far on average over any one month the company have been paying him more than he pays them, even in the winter....

Mike.

well maybe tthe grid is more like a payday loan then.

My point is that banks don't store your money either - its not like they have a shoebox per customer stuffed under a big bed out the back (its not really like the bank in this sketch)

Rather they actually lend your money out to someone prepared to pay more for it who uses it there and then, and then when you ask to take your  money out, actually you some get money that someone else recently paid in.

The grid is much the same. The excess electricity you put in supplies someone else's load at that moment , and you get paid for that. The electricity you take out at other times when clouds cross your solar panels, you pay for in the normal way

A real example a colleague of mine uses https://octopus.energy/smart/intelligent-octopus-flux/

and that system charges the batteries in his garage  from solar panels when it can, and when solar power is weak, then charges from the grid when it is cost effective to do so, and he exports to the grid at times of high demand and gets paid over the odds for it - usually early evenings. So far on average over any one month the company have been paying him more than he pays them, even in the winter....

Mike.

Mike Andy  Thank you both  I dont get your visual that somehow there is an energy bank you can just tap into Like Banks ? 

They only want to lend  you money(  at at profit . Your house as guarantee ?   Fail payback your on the street ? 

" I'm forever blowing bubbles ?  In the air . Pay day loans ? 

Energy regenerated back to grid is like a puff of smoke wafting down the line somewhere . Actually On the grid If someone wants it They will pay grid price  No doubt more than you were paid  to put it there. I reckon that person on sole grid tie  who took your regen had not idea at all they were doing that .  Just  grid Auto  

They paid your  bill. 

Intrigued by your example Octopus energy    I cant imagine a private company selling its goods at a loss ?  Nor break even. Tell me more please ? How do I sign ? 

I can understand using off peak electricity at night    Octopus scheme ?  Had understood you need a smart meter that works for that  Sadly  seems nationally most smart meters dont  work 

Thought Octopus had with withdrawn from scheme . Certainly another national failure that no other is offering off peak rates.? I have one that works I had to fight for but alas EDF not interested in off peak supply .

Back to my scheme Partial off grid No intrigues  No Blowing  bubbles in the air .. 

I know where energy is going and I know where its come from  Yes with battery losses .    Sadly the rules are against me . But I will do it

ciao Ms O 

Intrigued by your example Octopus energy    I cant imagine a private company selling its goods at a loss ?  Nor break even. Tell me more please ? How do I sign ? 

I can understand using off peak electricity at night    Octopus scheme ?  Had understood you need a smart meter that works for that  Sadly  seems nationally most smart meters dont  work 

Thought Octopus had with withdrawn from scheme . Certainly another national failure that no other is offering off peak rates.? I have one that works I had to fight for but alas EDF not interested in off peak supply .

They're not selling at a loss - quite the reverse - there's a formula but roughly they sell at around twice what they buy it for. The point is that wholesale electricity costs vary wildly. When there's plenty of wind and sun and low demand it's cheap as chips, when demand is high and low (fuel) cost generation is low, so they have to burn lots of expensive imported gas (or worse coal) to generate electricity the price rockets. What the Agile tariff does is base the customer price per unit on the wholesale price at that moment (with a markup) - so if the customer is able to time shift some of their consumption to times when the wholesale price is low, they can make a significant saving. It also helps keep the grid in balance - and 'peak lops' the most expensive generation, so making some contribution to keeping prices down for everyone. Likewise it reduces the amount of high emission generation needed - so win win overall. Octopus have a Dashboard Page which gives the import and export prices.(and emissions) for the current period (you can adjust the boundaries of the summary chart in the middle to expand the range and see about a weeks worth, or change the date to look further back). Typically if you avoid the 1600:1930 peak you'd be onto a winner, but you'll likely need be pretty dynamic to optimise things fully,

As far as I know Octopu's Agile tariff is still going. Being linked to the wholesale prices it's not got the safety net of the domestic 'price cap' though. So when wholesale prices skyrocketed after the recent Ukraine invasion and suppliers were having to sell in effect at a substantial loss to domestic customers to keep within the government's price cap (purely a political problem - the government could have devised a scheme that provided an equivalent level of support to variable rate tariffs if they'd thought about it) - people would have been substantially worse off on the Agile tariff than an ordinary fixed tariff - so Octopus were recommending that people didn't switch at that time. AFAIK, it's all back to (relatively) normal now though.

What's obvious from Octopus's charts (and others - e.g. Drax's https://electricinsights.co.uk/#/dashboard ) is that wholesale prices no longer follow the traditional pattern of cheap overnight and expensive during the day - solar contribution often means that supply is abundant during the middle of the day, pushing prices down, and wind varies unconnected with the time of day. Hence many suppliers aren't keen on the traditional fixed time-of-day E7 or E10 off-peak tariffs that encourage overnight consumption. The future is much more dynamic - hence smart meters. Smart meters get a bad press. The vast majority work perfectly well, its just the few that have problems that get all the headlines. Yes the 1st generation had some silly design problems (like being tied to the supplier that installed it, so sopped being smart when someone switched suppliers), but they've mostly been resolved with the 2nd generation ones. I think a lot of the remaining problems are down to poor administration/installation/support (not paring the meter with the in-home display properly, errors with the back office systems and gormless customer support) rather than the technology of the meters themselves. Not helped by everything being done in a rush to meet arbitrary government targets.  

  - Andy.

andy thanks  Looks interesting  to switch  Do we just keep away from  4 'til 6 or must we analyse the dashboard daily to  keep abreast of off peak. ?

How is easy is this to manage ?  Do you watch the daily ? 

Perhaps very useful along side my off dual grid  thought     Ponder why no other supplier is offering this . Do you have a reasonably independent review for this tarrif  ?

thanks

PS Dont share your optimism  for roll out of smart meters. Mine  SM 1 installed by B gas then stopped:  Never told me  Ignored my requests to reinstate. Had to find out alleged .gov guides m'self 

Switched to edf  who advertised smart meter  Nope  Had to wait 2 years before I finally forced them to change my meter  Threatedn them with ombudsman and .gov  sell by dates.

Many same experience just unheard. Still with Bletchley Park memorial smart meters. 

ciao Ms O 

Do we just keep away from  4 'til 6 or must we analyse the dashboard daily to  keep abreast of off peak. ?

To do it properly - and guard against peaks in prices at other times which will inevitably happen sometimes, yes you need to pull down the price data every day. I think most people have it automated though - (grid tied) battery systems will no doubt have a small computer embedded, so often it can be configured to fetch the data over the internet and, given knowledge of your typical usage and likely on-site generation (possibly pulling down weather forecasts too) it can work out a likely optimal way of how much to import when to meet your needs at the lowest cost. I dare say some will roll their own using an Aduino or Rasberry Pi or the like.

I don't do any of this myself (yet) - this is just the result of my research. I'm actually with a different supplier at the moment and rather hoping that they'll come up with something along similar lines soon. Octopus do have reputation for being a bit bleeding-edge technology wise, and do say the agile tariff is experimental, even for them,. so it might be a while yet before the old fuddy duddy suppliers see the need.  When more people have home battery systems and start switching in noticeable numbers, I dare say it'll happen.

Never told me  Ignored my requests to reinstate. Had to find out alleged .gov guides m'self 

...   Had to wait 2 years before I finally forced them to change my meter  Threatedn them with ombudsman and .gov  sell by dates.

So most of the problems were with the people, rather than the meter?

    - Andy.

I have booked a smart meter for Monday. In fact, I asked how big it would be and whether it would fit in the available space, but they just booked me in.

I foresee a complete disaster, but you never know.