Upgrade a Grid-Tied Solar PV System with battery. Solis RAI

[Thebeeman]

I would also venture that you may find the Pylontech US 5000 too small. We started in May last year with 7.1 kWh of Pylons but by November it was obvious that even with a modest life style they were too small and I added a third module as in the sig. Now there is enough capacity to survive most winter days, and two whole days without sun if we are away.

Spot on there. We have 3x 3.5 pylontechs which with luck should see us through as cheaply as possible.
During summer there "should" be no import, and during the winter we can top-up if needed via an E7 tarrif.
Currently I'm charging to 70% overnight which with a bit of sun sees us through to next cheap period, 3 to 5Kwh ish per charge. One day we did export about 1.5Kwh, too much sun that was not predicted.

[sharpener]

Currently I'm charging to 70% overnight which with a bit of sun sees us through to next cheap period, 3 to 5Kwh ish per charge. One day we did export about 1.5Kwh, too much sun that was not predicted.

That's what I've defaulted to, having said which I have just turned it down to 50% in the expectation of a bit more sun tomorrow, we will see. Fortunately I can use the immersion heater as a balancing load, any shortfall in the h.w. is made up by the oil boiler which costs about the same per kWh as E7 electricity.

[Bignose2]

Hi,

As I say I don't even get the few P feed in as no smart meter so batteries have to be the way but not at any cost.
As quite a few have advised to change to a Hybrid inverter instead, little more expensive but should save some work & notification to DNO so I am concentrating on this.

Looking I really hope I can do myself, if any one can advise, fairy confidently.

From what I can glean from the manuals the Solis Hybrid inverter has almost identical connections to the non-hybrid inverter.
Just a single plug for mains/grid side, so assume that goes to my CU the same as the existing grid tied one, same meter which does have a Imp & Exp written on the window so assume can record import & export etc.

So as far far as I can tell it would be a simple change over, unplug old & plug the new one in.

My only thought & don't see why it would make any difference is the mains/grid cable going to the meter & CU on the existing grid tied inverter is really just one way at the moment, power from solar & inverter going INTO the house whereas the hybrid would take power from the grid to charge the batteries (when there is no Sun, or however it is programmed) Of course the cable does not care which way the electricity flows and must be big enough for the Amps required anyway but just noting.

Just the extra battery connections & I think more comms.

So do I need the solar guys in? they want about £2k for this so making me think there has to be a lot more to it.

Does anyone know if this really is a like for like swap.

[MrPablo]

It should be pretty straightforward to do a DIY swap if you wanted to.
Much of the hard work is already done (PV wiring, mains wiring) so it should be pretty simple.

I think it'd be a case of:
- establishing space by the inverter for the battery
- fitting a DC fuse for the battery
- remove the existing solar inverter
- fit the new hybrid inverter in the same location
- connect mains and PV cables to the new inverter
- connect batteries via the fuse to the new inverter

Depending on where you're located then it's a job I'd be happy to help out with.
If you can, take some pictures of the various bits of your existing setup (inverter, connections, meter, etc).

[Bignose2]

Very many thanks MrPablo

I'm live near Farnham, Guildford, Surry, down south, GU10 2

I am pretty confident in doing this sort of this thing, from what you say it does seem can be a relatively straight swap apart from the meter.

Have plenty of space around and very happy to place, mount & connect any of the physical stuff.

Had not thought of "- fitting a DC fuse for the battery"
From a few videos I have not seen any mention of a fuse, they just connect the two cables + & -

I think the main issue for me is the installation video show's a Solis Meter & a RS465 cable connected back to the inverter.

My meter is completely different, It does look like that is essential to connect the CT to.

I am happy to do all the rest but assume need a qualified sparky to do that part & then wonder if this might need DNO notification even though no real change.
This is still a good option as Sparky for half a day, a few hundred £'s at most as opposed to the £2k the original install guys want.

[sharpener]

From what I can glean from the manuals the Solis Hybrid inverter has almost identical connections to the non-hybrid inverter.
Just a single plug for mains/grid side, so assume that goes to my CU the same as the existing grid tied one, same meter which does have a Imp & Exp written on the window so assume can record import & export etc.

So as far far as I can tell it would be a simple change over, unplug old & plug the new one in.

I am a bit alarmed by this talk of plugs. All connections should be hard wired. If there are any plug/sockets involved apart from (possibly) sockets for the UPS output then they have not done a proper job. There are various other key points that should be checked also for a battery ESS e.g.

• Any UPS capability will require you to have your own earth electrode less than 200 ohms

• inverter should have its own MCB or RCD not shared with any other circuits

• inverter should have its own lockable double pole isolator

• a system with UPS capability needs to have anti-islanding relay(s) and neutral-earth link relay, incorporated in the inverter or externally

and quite a few other things that are often missed and not mentioned in the generic instructions with Chinese imports.

[nowty]

I believe the OP is simply talking about the AC connector on the actual inverter as it is a special plug / socket on those inverters.

[sharpener]

Ah, that makes sense and something of a relief. But I stand by my other comments as they have been discussed before at some length on this board and installation of an ESS is considerably more complicated than a simple PV system.

[Bignose2]

Hi,

Yes I am the OP.

I had hoped I had made it clear, the pictures show the isolation switch etc. as it was all professionally installed & commission & DNO paper work etc.

So all the plugs into the inverter are the same & simply unplug one & pug into the new one.

Just the meter to consider but still a single convection into the CU.
Not sure why attaching a battery to the inverter would complicate the issue so much.

I cannot image that the inverter sold into mainstream the UK does not have those protections build in on the backup circuit.
In the case of power failure from what I read it immediately isolates just that one circuit so no way it can feed back to the grid.
Its not as if trying to do the whole house on UPS.

[MrPablo]

When I installed my Solis hybrid inverter, I didn't have sufficient space for the meter in the main CU so I just put a separate enclosure next to it, dedicated to the meter.
It needs connecting to a mains circuit for the AC voltage reading, so I just took that from a lighting circuit.



Perhaps you could do something similar? That way you may not need to directly connect to the consumer unit if you don't want to.

Regarding the EPS capability, if you don't have the local earthing then only connect class 2 appliances to the EPS circuit.
That should be fine if you want backup for things like routers, but not a freezer, etc.