Help with all the kit I need for connecting Batteries to home

FlorayG

You get your fully qualified and certified electrician to advise and procure the parts you need. Buying them yourself and then saying " Fit these, please" means you will have no comeback on the electrician if it doesn't all work properly

TroubledTarts

QrizB said:

TroubledTarts said:

QrizB said:

Is your garage CU the main one serving the property, or is it a sub-circuit from a CU in the house?

I only ask because you're likely to need a current clamp on the main incomer, immediately after your meter, so the battery inverter can sense your household energy use and then try to balance it at zero. And most of those current clamps are wired, so you'll need to get a run of twin low-voltage cable (bell wire, most likely) from your meter to the inverter.

Sub circuit from the main CU in the house.
Interesting as the garage is not attached to the house so that could be a stumbling block.

The next question, if you're dead set on putting the battery in your garage, is can the cable from the house to the garage support whatever loads the storage inverter is going to impose?

You mentioned in a previous post that you were thinking of an 8kW inverter. That's 35 amps at 230v. What's the rating on the MCB/RCBO serving your garage?

If eg. the connection's only good for 16A, you'll be limited to a 3.6kW inverter and might want to restrict it further.

A quick check says we have a 20ah so that's 5kw I think so might take that down a bit below 5kw for the inverter

Heedtheadvice

I think you might be confused or have made an error? 20Ah does not equate to 5kW.

Do you mean a 20A breaker in the consumer unit, is that the main house unit feeding the garage or the mini unit you have in the garage? Has that garage feed been pro installed I.e. can you be certain that the breaker(s) are correctly rated for the cable carrying capacity?

Your electrician should check for you in case you need a rewire of that feed.

Notwithstanding that, the rating for an battery inverter is not a straight forward continuous power basis for calculation. It will surprise many that the breaker needs to be of higher current rating. Consider the Lux  3600acs a nominal 3.6kW inverter. The max input from the grid is rated at 6kW and the spec for the AC isolator [edit] is 40A minimum!

Similarly there can be very high battery currents flowing ( well above nominal) and the expected 60 or 70 amp current requires a DC side100A isolator.[edit]

Scale all that up to 5kW to give you a guide!

EDIT: 'breaker' changed to 'isolator' where indicated.

Dave_Fowler

Assuming you are not VAT registered, AIUI if you buy all the necessary parts yourself you'll be subject to 20% VAT.  A VAT registered installer can claim back the VAT and pass on the saving to you.

TroubledTarts

Heedtheadvice said:

I think you might be confused or have made an error? 20Ah does not equate to 5kW.

Do you mean a 20A breaker in the consumer unit, is that the main house unit feeding the garage or the mini unit you have in the garage? Has that garage feed been pro installed I.e. can you be certain that the breaker(s) are correctly rated for the cable carrying capacity?

Your electrician should check for you in case you need a rewire of that feed.

Notwithstanding that, the rating for an battery inverter is not a straight forward continuous power basis for calculation. It will surprise many that the breaker needs to be of higher current rating. Consider the Lux  3600acs a nominal 3.6kW inverter. The max input from the grid is rated at 6kW and the spec for the AC breaker is 40A minimum!

Similarly there can be very high battery currents flowing ( well above nominal) and the expected 60 or 70 amp current requires a DC side100A breaker.

Scale all that up to 5kW to give you a guide!

That's the fuse supplying the garage the main fuse is 100ah

Happy to learn what type of inverter I could spec and how so thankyou

michaels

Heedtheadvice said:

I think you might be confused or have made an error? 20Ah does not equate to 5kW.

Do you mean a 20A breaker in the consumer unit, is that the main house unit feeding the garage or the mini unit you have in the garage? Has that garage feed been pro installed I.e. can you be certain that the breaker(s) are correctly rated for the cable carrying capacity?

Your electrician should check for you in case you need a rewire of that feed.

Notwithstanding that, the rating for an battery inverter is not a straight forward continuous power basis for calculation. It will surprise many that the breaker needs to be of higher current rating. Consider the Lux  3600acs a nominal 3.6kW inverter. The max input from the grid is rated at 6kW and the spec for the AC breaker is 40A minimum!

Similarly there can be very high battery currents flowing ( well above nominal) and the expected 60 or 70 amp current requires a DC side100A breaker.

Scale all that up to 5kW to give you a guide!

Probably worth thinking about what loads you plan to support with the battery, given that we have access to the mains, it may be worth accepting that for example the battery powers the continuous load from the heat pump but that if someone then puts the kettle on you accept that you will have to import at peak rate?

Qyburn

Heedtheadvice said:

Similarly there can be very high battery currents flowing ( well above nominal) and the expected 60 or 70 amp current requires a DC side100A breaker.

The battery is rated for 200A charge or discharge. But I note it has an integral 250A DC isolator, is an external isolator also required.

Qyburn

TroubledTarts said:

That's the fuse supplying the garage the main fuse is 100ah

What's the size, type and length of cable between house CU and garage DB?

TroubledTarts

Qyburn said:

TroubledTarts said:

That's the fuse supplying the garage the main fuse is 100ah

What's the size, type and length of cable between house CU and garage DB?

Looking at getting under the kitchen cabinets where it runs in the next few days to check that out.

michaels

TroubledTarts said:

Qyburn said:

TroubledTarts said:

That's the fuse supplying the garage the main fuse is 100ah

What's the size, type and length of cable between house CU and garage DB?

Looking at getting under the kitchen cabinets where it runs in the next few days to check that out.

Is it not visible at either end?