2kw DIY Solar PV Install Questions

[Johnny Jekyll]

I'd like to understand a little more about how to wire together our solar pv system? Would you mind filling in some gaps for me? Thank you.

 

CURRENT POSITION

• Self-build already up and water tight. Doing most of the work myself.
• 6 panel 2kw integrated Marley (Viridian) pv solar panels already installed as part of the 45 degree south facing roof looking good.
• Two end cables with MC4 PV connectors through the roof and inside the cold loft.
• No other system parts have been purchased or installed yet.
• Inverter will be installed in cold loft onto fibre cement board.
• No battery required.
• Not interested in exporting to the grid so no MCS required.
• We are looking to DIY install, my boy is an electrician but not experienced in PV, I'm doing some research to help.

 

INTERNAL INSTALLATION

• Panel cables to
• DC isolator to
• Inverter to
• Generation meter to
• AC isolator to
• Consumer unit

 

QUESTIONS

1. Good quality inverter recommendations for 2kw system?
2. Is generation meter needed?
3. What cable would be used to run from the Inverter down to the consumer unit?
4. How best would the cable be connected to the consumer unit? RCD v RCBO v MCB?
5. Anything else needed to connect to the consumer unit? Or does the electricity simply come down and get used by appliances (sorry for simplistic question)?
6. Do I need to notify DNO (UK Power Networks) about the install, being only a 2kw? 
7. Anything obvious I'm missing or helpful comments?

 

Many thanks everyone.

[ProDave]

I think currently Solis is a recommended make of inverter.

Fit a generation meter for your own use, so you can see how much you have generated.

2.5mm twin and earth from inverter to CU

How to connect to CU, post a picture of your CU first, that is possibly the hardest bit to get right.

You need to notify the DNO under G98  that will need some paperwork, but nothing too complicated.  you notify after connection.

 

And as a separate thing without export payments you want to be load shifting to self use as much as possible, so washing machine etc only on in the daytime one at a time close to mid day, and fit a solar PV diverter to sent excess power to your immersion heater, that will pretty well guarantee nothing significant gets exported.

 

Oh and respect those DC cables, they will be live now.

[Radian]

12 minutes ago, ProDave said:

Fit a generation meter for your own use, so you can see how much you have generated.

 

Solis also have a modbus port that can be freely used to get at generation data. The connector is a bit unusual though. I cannibalised an old Garmin satnav cable with a similar plug on the end of it to interface to the inverter. How you handle the data depends on how deep you want to dive into the world of home automation.

[Johnny Jekyll]

Thanks very much guys.

Stupid question... Should we be looking at a 2kw inverter for a 2kw system?

[joth]

6 hours ago, Johnny Jekyll said:

Thanks very much guys.

Stupid question... Should we be looking at a 2kw inverter for a 2kw system?

Yes. While you can use a smaller inverter than the panel capacity, 2kW is already at the small end so can't see any savings from going smaller still.

You could consider a 3.68kW inverter, if you think you may ever want to add more panels somewhere, or a DC coupled battery 

[Dillsue]

Plenty of clarification so far. I would install a larger than 2.5mm cable if theres a chance you or someone else might expand the system in the future. You also need to consider the no load voltage in the house. If its already high you don't want a smallish cable creating too much of a voltage rise and pushing the inverter voltage over the 253v limit. Your lad should be able to calculate cable size for you.

[Johnny Jekyll]

Great info everyone. Any more tips are very much appreciated.

[Jenki]

37 minutes ago, Dillsue said:

 I would install a larger than 2.5mm cable if there's a chance you or someone else might expand the system in the future.

 

2.5MM t&e will handle around 26A (6KW), way past the 3.6KW load. Any bigger is a waste of money. 

[Dillsue]

3 hours ago, Jenki said:

2.5MM t&e will handle around 26A (6KW), way past the 3.6KW load. Any bigger is a waste of money. 

Would that be buried in insulation? What would the voltage rise at the inverter be if the house was running at 250vac and the system was upgraded to 3.68kw? Without us knowing install characteristics its probably prudent to let the OPs lad size the cable.