Solar install with two consumer units

[Lamentable]

My mains incomer is split after the meter to feed two consumer units A & B.

A supplies: bedrooms, office, kitchen, utility room
B supplies: reception rooms, a fridge freezer

Unit B is closer to where I could install the battery / inverter etc.

If my solar system feeds into unit B, can unit A receive any of that energy?

As a side note, how does the electricity from the solar install override the mains electricity? Is it as simple as it being a slightly higher voltage or something? I have in my mind two water tanks, one at a slightly higher pressure than the other. I've never tried this but I guess a tap with a feed from both would draw more from the higher pressure tank 1st.

Thanks in advance.

 

[flameport]

If my solar system feeds into unit B, can unit A receive any of that energy?

Yes it can

Is it as simple as it being a slightly higher voltage

In a simplified way, yes.
Voltage from the inverter is higher than the grid supply, energy from the inverter will be used before anything is taken from the grid.

 

[Lamentable]

Thanks.

I have an electric shower twin & earth cable running through the loft for an 8kw shower. It runs near to the proposed solar panel location.

I would guess this is 6mm cable which runs from the loft, down a stud wall and through some ceiling joists to the consumer unit.

The electric shower will soon be decommissioned. Could cable this be repurposed to supply the inverter from the panels ?

I would probably be installing a 2.3kWp system but I'm not sure on the voltage output from the panel array to plug into the P / V = I calculation.

 

[SUNRAY]

Thanks.

I have an electric shower twin & earth cable running through the loft for an 8kw shower. It runs near to the proposed solar panel location.

I would guess this is 6mm cable which runs from the loft, down a stud wall and through some ceiling joists to the consumer unit.

The electric shower will soon be decommissioned. Could cable this be repurposed to supply the inverter from the panels ?

I would probably be installing a 2.3kWp system but I'm not sure on the voltage output from the panel array to plug into the P / V = I calculation.

Your installer will be very happy to reuse the existing cable, as long as it's suitable which I imagine it is.

 

[bsr]

I think you said panels to inverter rather than inverter to CU?

Sunray is a pro and I'm not but I would have expected a proprietary DC rated cable to be used not T&E. Something like this:

Search results for: 'most popular solar 1m to 25m solar pv cable 6mm solar panel pre crimped mc4 connectors'

Whether You Need Solar Panels or Solar Power Systems, We Have Them Here. Contact Us Today. From Solar Panels to Power Systems, We Have Them Here. Contact Us for Any Inquiries. LED Street Lights. Batteries & Storage. Protection & Monitoring.

voltaconsolar.com

Panels run at 40v DC so a string will often exceed the voltage rating of twin and earth.

 

[SUNRAY]

I think you said panels to inverter rather than inverter to CU?

Sunray is a pro and I'm not but I would have expected a proprietary DC rated cable to be used not T&E. Something like this:

Search results for: 'most popular solar 1m to 25m solar pv cable 6mm solar panel pre crimped mc4 connectors'

Whether You Need Solar Panels or Solar Power Systems, We Have Them Here. Contact Us Today. From Solar Panels to Power Systems, We Have Them Here. Contact Us for Any Inquiries. LED Street Lights. Batteries & Storage. Protection & Monitoring.

voltaconsolar.com

Panels run at 40v DC so a string will often exceed the voltage rating of twin and earth.

Oh my apology, I read that as to re-used for the mains connexion.

My Solar contact has been minimal (3) but to date I've only encounterd 5 panels in series and saw less than 200V on 270V maximum controller.The others are 150V max & 3 panels in series. I have no idea how typical these systems are.

Under 300V the T&E will be within voltage rating and there will be no technical or regulation reason for it not to be used for the DC path. The moral thought may be different.

 

[flameport]

String voltage depends entirely on the installation, but voltages of 500V+ are not uncommon.
T&E is not suitable for connecting panels to an inverter. It's not suitable for MC4 connectors either.

 

[SUNRAY]

String voltage depends entirely on the installation, but voltages of 500V+ are not uncommon.

Thank you, as I wrote I haven't have much contact with such.

T&E is not suitable for connecting panels to an inverter.

As long as voltage and current ratings are not exceeded, what it the reasoning behind this?

It's not suitable for MC4 connectors either.

 

[Lamentable]

I would also be interested to know why T&E would not be suitable.

However, I think now due to project constraints it may be worth me running appropriate cable in place now rather than destroying walls to run it in the future.

With that in mind, if string voltage can be 500V+ (DC?), are these cables subject to the same regulations as running T&E? e.g. in the safe zones?

 

[JohnW2]

With that in mind, if string voltage can be 500V+ (DC?), are these cables subject to the same regulations as running T&E? e.g. in the safe zones?

As far as I am aware, any/all cables buried <50mm deep in walls etc. are subject to the requirement to run in 'safe' zones, unless they are in (metal) conduit, armoured or have some other earthed outer metallic sheath.

Kind Regards, John

 

[Lamentable]

Not saying you're wrong but surely, for example, 12v alarm sensor cables are not subject to this requirement.
Hope not!

 

[JohnW2]

Not saying you're wrong but surely, for example, 12v alarm sensor cables are not subject to this requirement. Hope not!

Well, yes, but I was talking in the context of your question about your PV system, and assumed it was taken as read that, as you imply, ELV (SELV or PELV) cables are excluded from the 'safe' ('dangerous' for someone with a drill, screws or hammer/chisel in their hands!) zone requirements [per 522.6.204(v) of regs].

As you will presumably understand, the point I was making was that, apart from the specific types of 'protected' cables I mentioned, the requirements do not differ for different 'types' of cable.

Kind Regards, John

 

[Lamentable]

I assume it is best to run them safely.
Not sure what happens to someone who bridges a 500v DC battery. I guess it depends on the current which could be high given the cables linked above are 6mm2?
What sort of protection do solar systems have if someone was to introduce themselves to the circuit?

 

[JohnW2]

I assume it is best to run them safely.

It's best to do everything safely.

Not sure what happens to someone who bridges a 500v DC battery. ....

I'm not sure that any "500V batteries" are likely to be involved.

I'm also not sure what you mean by someone "bridging" such a battery. If you're talking about situation in which current from such a battery was flowing through their body (because they were touching things connected to the 'two sides' of it), they may well die.

Kind Regards, John

 

[JohnD]

IIRC my cables from the panels to the inverter are some kind of low-emission fire resisting grade. I think it is "shotgun" cable