Hi everyone,
I have a quick question if I may? I'm thinking of adding a second PV system to my existing rooftop PV & battery setup.
As the parts will be second hand due to lack of FITS & poor export prices, I'd like to install as much as I can myself to save money (I've already bought the inverter). I think I have a friendly local electrician lined up who will finish things off, but the less I involve him beforehand the less it'll cost, plus I'd like to do things properly (I seem to have had a few issues over the last few years, with the EV and battery installs).
The new PV array will be on a ground mount in the back garden, only 2kWp, with the inverter in an outbuilding which doesn't have any electrics.
Just so I've got everything clear in my head, the array is a DC circuit with DC extension leads back to the inverter. Am I OK to bury the DC cables in an underground duct? If so how deep to they need to be? Googling suggests at least 600mm deep, but is it the same for DC cabling? Or am I better off running them over on a catenary wire?
I'm assuming I'm allowed to connect up the DC side of things on my own?
At the inverter, as it's a SMA model with their ESS Electronic Solar Switch, so I don't need a DC isolator next to the inverter?
From the inverter there will be a 4mm SWA AC cable run back to the house's meter cupboard, about 33 metres.
Now we get to where where I'm wondering what's best practice.
There is an AC insolator in the meter cupboard for the existing PV system, I guess as it's connected to an MCB is inside the house, so I don't need another one of those?
Also in the meter cupboard, there are already two small additional distribution boards, one for the battery system and one for the EV charger, which both go into a henley block. I would think that the best thing to do would be to add yet another mini DB, with an RCD/mains switch and MCB, bring the the SWA from the inverter into it and wire that into the henley block.
However, this will cause a problem with the battery system, as the power from the new array won't be going through the battery inverters "solar CT" sensor.
Now, could the SWA be unsheathed and the live cable fed through the CT before it goes into the new DB? The cable/CT could be boxed up, would it be OK?
Or perhaps better, rather than using 16mm/25mm tails (seems overkill?) to the henley block like the other DBs use, could it use 4mm T&E (or maybe 10mm?) to the henley block? It's only going to have 2kW on it after all?. This would be more flexible/manoeuvrable, splitting the outer sheath, putting the live through the CT which could be put inside an enclosure? The 4mm/10mm conductors then put into the henley block, and there should only be a minimal single insulated conductor under the henley block.
Or would you recommend something else?
Another thought that has occured, is there likely to be an earthing issue with the outbuilding? Will that need an earth rod?
Lastly, if I buy and bury the SWA cable and get it into the outbuilding and into the meter cupboard, any rough idea about how many hours work we're talking to install the new DB, connect it up to the SWA and the henley block (about 2 feet away), connect up the inverter and sign it off?
Many thanks,
James
I have a quick question if I may? I'm thinking of adding a second PV system to my existing rooftop PV & battery setup.
As the parts will be second hand due to lack of FITS & poor export prices, I'd like to install as much as I can myself to save money (I've already bought the inverter). I think I have a friendly local electrician lined up who will finish things off, but the less I involve him beforehand the less it'll cost, plus I'd like to do things properly (I seem to have had a few issues over the last few years, with the EV and battery installs).
The new PV array will be on a ground mount in the back garden, only 2kWp, with the inverter in an outbuilding which doesn't have any electrics.
Just so I've got everything clear in my head, the array is a DC circuit with DC extension leads back to the inverter. Am I OK to bury the DC cables in an underground duct? If so how deep to they need to be? Googling suggests at least 600mm deep, but is it the same for DC cabling? Or am I better off running them over on a catenary wire?
I'm assuming I'm allowed to connect up the DC side of things on my own?
At the inverter, as it's a SMA model with their ESS Electronic Solar Switch, so I don't need a DC isolator next to the inverter?
From the inverter there will be a 4mm SWA AC cable run back to the house's meter cupboard, about 33 metres.
Now we get to where where I'm wondering what's best practice.
There is an AC insolator in the meter cupboard for the existing PV system, I guess as it's connected to an MCB is inside the house, so I don't need another one of those?
Also in the meter cupboard, there are already two small additional distribution boards, one for the battery system and one for the EV charger, which both go into a henley block. I would think that the best thing to do would be to add yet another mini DB, with an RCD/mains switch and MCB, bring the the SWA from the inverter into it and wire that into the henley block.
However, this will cause a problem with the battery system, as the power from the new array won't be going through the battery inverters "solar CT" sensor.
Now, could the SWA be unsheathed and the live cable fed through the CT before it goes into the new DB? The cable/CT could be boxed up, would it be OK?
Or perhaps better, rather than using 16mm/25mm tails (seems overkill?) to the henley block like the other DBs use, could it use 4mm T&E (or maybe 10mm?) to the henley block? It's only going to have 2kW on it after all?. This would be more flexible/manoeuvrable, splitting the outer sheath, putting the live through the CT which could be put inside an enclosure? The 4mm/10mm conductors then put into the henley block, and there should only be a minimal single insulated conductor under the henley block.
Or would you recommend something else?
Another thought that has occured, is there likely to be an earthing issue with the outbuilding? Will that need an earth rod?
Lastly, if I buy and bury the SWA cable and get it into the outbuilding and into the meter cupboard, any rough idea about how many hours work we're talking to install the new DB, connect it up to the SWA and the henley block (about 2 feet away), connect up the inverter and sign it off?
Many thanks,
James
- TL;DR
- Best way to get new PV live cable through existing battery CT?
