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.

oh answers ??   ok  Can you be our Martin Lewis for real solar data ?  Can you calc for me ? 

Thought summer Boil kettle run washing machine ... u wave    other bonus : Dare I think oven ? Not all same time of course  

Batteries expensive  Extend life   As summer to autumn  switch  in one battery /  autumn to winter  switch  in another  ( x 2 )  

I will be reliant on grid  in the dim months .. and other times for sure .

But I would  have real time know of where it comes from and directing day to day to where it is being used.  Proposal is plug and play  My choice . You have an algorithm ?

Ms O  

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.

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