so thinking about some sort of emergency electric supply if electric goes out

[CalvinHobbes]

Hello, so we have just under 12kw of panels on roof, an 8kw inverter and on Monday 5.12kw x 2 batteries are being installed. All this talk of Putin and war is making me think of putting in a few sockets next to the inverter. What is the least expensive way of doing this, can it be an automatic switch? I just don't know what to ask for.

 

[JohnMo]

Does your inverter with the battery, not supply the house in a power cut? We went AC coupled for that reason, grid off makes no difference, house runs as normal, PV string inverters don't see and difference so keep producing.

 

We also have a geny with change over switch should battery run flat - need to get more petrol.

[nod]

I heard that Putin is about to Nuke us before Christmas 

Im out buying a Turkey now 😂

[-rick-]

Looks like this inverter only has an EPS output for when the grid is down. So needs to be separately wired to circuits that need to be protected by the battery. It's a beefy inverter though so could probably power your whole house from the EPS output in all but the most unusal situations.

 

If you want to do this properly you would ask for some of your house circuits to be moved to a separate consumer unit and have that wired via changeover switch to both the EPS output of the inverter and your normal consumer unit. Big change at this late stage though.

 

Your idea of a few sockets near the inverter is a good one. You will likely need a small consumer unit with an rcbo in it to liimt the current to that circuit, not a big job but maybe one that the installer doesn't want.

 

Oh, and if the shit really hits the fan with Putin, this system is unlikely to really help. But emergency backup would be good for less extreme emergencies. Putin is like all bullies, take as much as he can until he gets real push back then he'll stop. He was talking to Xi about living to 150, someone who has that ambition isn't going to commit suicide.

Edited September 21 by -rick-

[JohnMo]

9 minutes ago, -rick- said:

you want to do this properly you would ask for some of your house circuits to be moved to a separate consumer unit and have that wired via changeover switch to both the EPS output of the inverter and your normal consumer unit. Big change at this late stage though

That's what I liked about the GivEnergy AIO, once you find a home for the gateway, it does it all out the box, no house changes needed.

[G and J]

I’m going for a split board with a battery that can run in island mode supplying one side of the board. 
 

I’ll run lights, internet, WiFi, MVHR and a set of charging sockets off the battery backed side, but I like the idea of a couple of sockets in the utility room that I can plug stuff I didn’t think of protecting into.  Fab addition to the plan. 

[BotusBuild]

We should all build an Edison Generator 😁

[JohnMo]

43 minutes ago, G and J said:

I’m going for a split board with a battery that can run in island mode supplying one side of the board. 
 

I’ll run lights, internet, WiFi, MVHR and a set of charging sockets off the battery backed side, but I like the idea of a couple of sockets in the utility room that I can plug stuff I didn’t think of protecting into.  Fab addition to the plan. 

For the small uplift in AC coupled battery cost, why would you add the extra complication to just let your house limp? I get the full 6kW available from inverter plus what ever PV is generating. So heat pump runs, can cook the tea etc. power cut just go unnoticed.

[G and J]

2 hours ago, JohnMo said:

For the small uplift in AC coupled battery cost, why would you add the extra complication to just let your house limp? I get the full 6kW available from inverter plus what ever PV is generating. So heat pump runs, can cook the tea etc. power cut just go unnoticed.

We’re going for a 10kWh battery. I’m guessing (without doing any numbers so it’s all guy feel) that that’ll be good for several days of the bits I plan to protect. If I did the lot I would expect it to be a day max. before the battery disconnects itself due to low charge.  Or is my gut feel an order of magnitude out?
 

We’re having a woodburner for warmth and we’ve a campervan for warming food up if needed.  So I’m thinking we would keep things ticking over for three or four days…

[Beelbeebub]

56 minutes ago, G and J said:

We’re going for a 10kWh battery. I’m guessing (without doing any numbers so it’s all guy feel) that that’ll be good for several days of the bits I plan to protect. If I did the lot I would expect it to be a day max. before the battery disconnects itself due to low charge.  Or is my gut feel an order of magnitude out?
 

We’re having a woodburner for warmth and we’ve a campervan for warming food up if needed.  So I’m thinking we would keep things ticking over for three or four days…

excluding cooking and heating the average home is pretty low powered these days.  10kwh would do you a day without any issues.  2 or 3 if you were little frugal

 

If you cook or heat with the elec, you'll chew through the energy pretty fast.

 

if you're really concerned about off grid run time, get bigger batteries 

 

don't forget your panels will provide some energy in all but the crappest of weather

[BotusBuild]

4 hours ago, Beelbeebub said:

crappest of weather

Heehee - when most electricity cuts happen 🙂 

[Roger440]

5 hours ago, Beelbeebub said:

excluding cooking and heating the average home is pretty low powered these days.  10kwh would do you a day without any issues.  2 or 3 if you were little frugal

 

If you cook or heat with the elec, you'll chew through the energy pretty fast.

 

if you're really concerned about off grid run time, get bigger batteries 

 

don't forget your panels will provide some energy in all but the crappest of weather

 

If you need the extra power, rather vheaper to buy a generator than bump up battery size. Plus can be used indefinetely in the event of an extended power cut. 

[CalvinHobbes]

21 hours ago, JohnMo said:

Does your inverter with the battery, not supply the house in a power cut? We went AC coupled for that reason, grid off makes no difference, house runs as normal, PV string inverters don't see and difference so keep producing.

 

We also have a geny with change over switch should battery run flat - need to get more petrol.

No, tbh we initially put the panels on just because the scaffolding was up and it seemed silly not to. It wasn't in the budget (what's a budget *manic laughter) So it wasn't that planned.

[CalvinHobbes]

11 hours ago, Roger440 said:

 

If you need the extra power, rather vheaper to buy a generator than bump up battery size. Plus can be used indefinetely in the event of an extended power cut. 

Yes but you need fuel for the generator, that can be an issue too.

[JohnMo]

5 minutes ago, CalvinHobbes said:

Yes but you need fuel for the generator, that can be an issue too.

5 gallon jerry can, would keep generator running a few days, running full time. But you wouldn't run while you were asleep or out and about, only when needed. The fuel doesn't go off in sealed container. So why an issue?

[CalvinHobbes]

3 minutes ago, JohnMo said:

5 gallon jerry can, would keep generator running a few days, running full time. But you wouldn't run while you were asleep or out and about, only when needed. The fuel doesn't go off in sealed container. So why an issue?

Fair, I am probably catastrophising. Putin has wound me up.

[JohnMo]

42 minutes ago, CalvinHobbes said:

Fair, I am probably catastrophising. Putin has wound me up.

Build a bunker - not house

 

Diesel generator and an oil boiler tank to feed it.

[sgt_woulds]

Bunker

 

Compost bio reactor for heat, hot water and cooking gas. 

 

Small solar panel and battery for lights and USB charging and CB radio

 

Underground food store and a lifetime supply of mason jars.

 

An AI chatbot for when everyone around you is gone.

 

And a gun with at least one bullet?

 

 

[-rick-]

3 hours ago, CalvinHobbes said:

Fair, I am probably catastrophising. Putin has wound me up.

 

Yes. Putin is outside your control so don't worry about it. It's sensible to plan for the occasional power cut, but beyond that focus your attention on things you can control.

[Roger440]

14 hours ago, CalvinHobbes said:

Yes but you need fuel for the generator, that can be an issue too.

 

So buy fuel?

 

Petrol can degrade over time, so use diesel. Will pretty much last forever.