How do i connect storage battery's to my existing system.

[Spats]

HI guys / gals

Got a 4kw PV system fitted with a Growatt 3.6 mtl-s inverter in the loft, my house faces South.
System is only just over 1yr old.

My question is can i fit storage batteries to my existing system in the loft and connect it to the Inverter for nighttime use instead of importing from the grid, and if so how, What would i need.

Regeneration meter is downstairs where the Main Board is.

would appreciate some feedback please

Thanks guys

EDIT: Forgot to mention it was fitted with an MSC installer who at the time says i don't need batteries, but with prices rocketing for Leccy, i am looking at battery storage to call upon at night.

I don't get anything for exporting as its not feasible, so i try and use as much leccy when it generates.

 

[johnb2713]

I dont believe the Growatt 3.6 mtl-s can have batteries attached to it directly. You would need to install an AC coupled battery or change the inverter for a Hybrid inverter.

 

[Spats]

Thanks for that , it didn't say in the manual but needed confirmation.

I can't change the inverter to hybrid as i would probably need the installers to change over at cost.

now what if i went the AC coupled battery, would that just connect into the existing inverter?.

Thanks

 

[johnb2713]

Thanks for that , it didn't say in the manual but needed confirmation.

I can't change the inverter to hybrid as i would probably need the installers to change over at cost.

now what if i went the AC coupled battery, would that just connect into the existing inverter?.

Thanks

AC coupled connects directly to your mains supply.

 

[Spats]

Thanks
That would mean the AC coupled battery would have to be at main board level and not in the loft as where i would like it to be.

what kind of typical price am i looking at here and what is involved, thanks

 

[binky]

Thanks
That would mean the AC coupled battery would have to be at main board level and not in the loft as where i would like it to be.

what kind of typical price am i looking at here and what is involved, thanks

you can still fit the battery in the loft, but you will need a new cct for it. It's a bit if a Catch22 siutation, you could change your existing inverter for a hybrid, but you may find output limited by the existing cable supplying that. It would also possibly invalidate any MCS cert you may have, although as there is no longer a FiT to worry about, that may not be a concern, unless you want to go on a fexible tariff from the likes of Ocotpuss.

 

[MHarv]

Thanks for that , it didn't say in the manual but needed confirmation.

I can't change the inverter to hybrid as i would probably need the installers to change over at cost.

now what if i went the AC coupled battery, would that just connect into the existing inverter?.

Thanks

If you change out for Hybrid inverter you will have to notify DNO first; legal obiligation in the ENREC G98 document, Form D and apply again for G98 with the new G98 application.. easier to contact DNO before buying and installing batteries to get prior approval confirmation from them so they can verify the local area for Connecting extra Generation.

Most DNO’s have G99 Fast Track application <7.36kWh limit for G98 and G99 Type Tested ENA Register manufactures Reference Number to add Battery Storage to existing G98<3.68kWh capacity.

For larger inverters on G99 Fast Track requires the Full G99 application Form
Will still require E100 ELS Form (Export Control) Declaration for Type Tested ENA Register Approved Inverters for both both G99 Fast Track and Full G99.

You yourself can apply and fill in the Application Form for G99 Fast Track


Check out ITS Technologies website very competing prices depending on budget

 

[Spats]

Thanks guys,
@binkyWith Scottish Power, I don't want to invalidate my system, hence the reason for inquiring bud.

@MHarv do i need to swap out my inverter, as i would want to keep as is, and install batteries as an addon if you know what i mean.

Will check out ITS Technologies bud
what would be the battery output for the system I have.

Thanks again guys

 

[MHarv]

Thanks guys,
@binkyWith Scottish Power, I don't want to invalidate my system, hence the reason for inquiring bud.

@MHarv do i need to swap out my inverter, as i would want to keep as is, and install batteries as an addon if you know what i mean.

Will check out ITS Technologies bud
what would be the battery output for the system I have.

Thanks again guys

I am with SP Energy , MSC certified G98 <3.68kWh Solax X1 Boost 3.68kWh inverter with split PV Array East/West 2.56kWh each total 5.2kWh Array seperste Mini CU split tails from Henley block with iBoost+install plus Hypervolt 2.0 EV Charger again on seperate Mini Single 40A with split tails from Henley block (Henley block prior was just 2 split tails to Main Consumer Unit now totals 6 split tails after Solar Pv and EV Charger.

Solax HV (High Voltage) Battery System consisting of 1 Main Master LFP Battery 5.8kWH and 1 Solax Slave 5.8kWh total capacity 11.6kWh but Only 10.4kWh Useable due to DOD (Depth of Discharge)
90% by Solax.

SP Energy do G99 Fast Track for adding Battery Storage with G98 and G99 Type Tested ENA Registered Approved Inverters
within 2 weeks, my application which I did
Includes providing details of Existing Generation Installs plus the New additional
Generation or Battery Storage which in my case Solax X1 AC-3.6kWh G98 & G99 Type Tested ENA Registered Approved inverter and Battery Capacity; DNO more interested in the Inverter, all done prior to purchasing as stated by the G99 EREC document to get Approval Confirmation to go ahead with Install.

SP Energy did say Hybrid Inverter was possible with Batteries, but DeCommissiong Form would have to made for Solax X1 Boost 3.6kWh inverter (plus Qualified Electrician cost) to update their records, legal obligation under ENREC G98 document for home owner and start New Application for Hybrid requiring MSC Certified install again and new application for SEG plus inform Electric Energy Provider
Of the Changes as well to be totally Legal.

Easy and quickest route was apply for G99 Fast Track approval first with DNO, purchase Battery AC System (48volt LV or >100volt Battery Configuration)
That’s another topic to consider for discussion.

Battery installation does not need MSC certificate, a CPS qualified Electrician is legally required to fulfil the connection and Commissioning for the relevant Forms to be filled as required by the DNO.

I fitted the Battery System together, fitted Inverter to wall all cables 6mm2 to AC Isolator left rest for Electrician to Connect to Mini CU and Commission system and fill in the parts of forms printed out he is required for DNO.

IMHO I would Keep your setup inverter and install AC system unless you go through all the bureaucracy of Decommissioning, Re-Applying with DNO and SEG for Export EXPAN number with Energy provider again
which requires DNO Approval letter or email and new MSC Certificate (Has your Inverter type on it)

Very long winded but has to be done to keep DNO records correct, upto date as well as the records for your Energy Provider.

Your Installer can do all this but is reflected in price you pay, you need to discuss with installer what he is happy with and go from there, some installers will only do the install fully again reflected in the price, mine was happy to do what I could but not Connection, even the wiring for AC inverter and AC Isolator were left undone so he could verify the wiring and torque check before attaching AC cable to inverter and putting on AC Isolator Cover back on and securing.

But you can save some expense in the process. Hope this helps

 

[Bob Smith]

@MHarv do i need to swap out my inverter, as i would want to keep as is, and install batteries as an addon if you know what i mean.

Hello

I missed this conversation. I am in a similar situation. I already a PV system (4kWp) and intend to add batteries. However as I have FiT. I have no choice but to have AC couple batteries.

Since your inverter does not seem to be compatible, then as others suggested, I would simply keep the system as is (no change, no new application) and have AC coupled batteries.

If you want to learn more about DC and AC couple batteries maybe you'll learn something from here

https://www.cleanenergyreviews.info/blog/ac-coupling-vs-dc-coupling-solar-battery-storage

 

[binky]

have no choice but to have AC couple batteries.

Bob, you are looking to add additional solar arrays, including your rear roof space. Fit a hybrid inverter for that and the batteries will still pick up surplus leccy from the existing array, and anything you put on micro-inverters. The only limitation from using a hybrid is possibly limited output from the battery governed by the hybrid inverter.

 

[Spats]

Hello

I missed this conversation. I am in a similar situation. I already a PV system (4kWp) and intend to add batteries. However as I have FiT. I have no choice but to have AC couple batteries.

Since your inverter does not seem to be compatible, then as others suggested, I would simply keep the system as is (no change, no new application) and have AC coupled batteries.

If you want to learn more about DC and AC couple batteries maybe you'll learn something from here

https://www.cleanenergyreviews.info/blog/ac-coupling-vs-dc-coupling-solar-battery-storage

Cheers Bob,

I don't have FiT or SEG as i would only get pence back.

Hence the reason of just wanting batteries for storage as an addon but my problem is that i would want AC couple battery system in the loft out of sight, but doesn't look like that can happen as it's got to connect to main board.....Nightmare

cheers guys

 

[MHarv]

Why not attaching to new additional AC Isolator and Mini 4 or 6 Way CU MCB or RCBO appropriate ampage suitable for AC Battery inverter.

Considerations:

What size cable is present in the loft for the solar Pv inverter 2.5, 4 or 6mm2?

How far from Main CU to loft?

Run new appropriate cable size (larger to have lower voltage drop depending on distance) to run both inverters on their own seperate AC Isolators solar Pv and AC battery systems in new Mini CU in loft

Do you have Mini CU already in loft solely for the existing solar Pv setup? If Yes

Any spare slots if no upgrade to 6 Way Mini CU

Just info to consider if going to

 

[Bob Smith]

Cheers Bob,

I don't have FiT or SEG as i would only get pence back.

Hence the reason of just wanting batteries for storage as an addon but my problem is that i would want AC couple battery system in the loft out of sight, but doesn't look like that can happen as it's got to connect to main board.....Nightmare

cheers guys

One thing the installers I met had in common is that they were all OK with my additional kits (inverter, batteries) to go along my existing inverter in the attic.

 

[MHarv]

Great choice’s, choice’s

 

[Spats]

Why not attaching to new additional AC Isolator and Mini 4 or 6 Way CU MCB or RCBO appropriate ampage suitable for AC Battery inverter.

Considerations:

What size cable is present in the loft for the solar Pv inverter 2.5, 4 or 6mm2?

How far from Main CU to loft?

Run new appropriate cable size (larger to have lower voltage drop depending on distance) to run both inverters on their own seperate AC Isolators solar Pv and AC battery systems in new Mini CU in loft

Do you have Mini CU already in loft solely for the existing solar Pv setup? If Yes

Any spare slots if no upgrade to 6 Way Mini CU

Just info to consider if going to

@MHarv something to consider bud,

This is the setup in my loft (not a very good photo taken from an angle)

Anyway the two strings from the panels goes into bottom of Inverter, and approx. 15m of 4mm2 drops down to CU in cupboard downstairs where it connect to mains isolator then goes into a fuse in DB.

I do have a couple of spare ways in the DB.

Thanks guys

 

[MHarv]

If you are going to locate batteries in loft, the existing cable 4mm2 in loft to CU downstairs, imho will not cut it, for both Inverters and Batteries, probably would need 6mm2 twin and earth upgrade... there are tables that you enter details of cable size, and distance to get
a known voltage drop, you need to be within 1.25% could be less, can't remember exactly.... if replacing the existing cable.

You could lay another new cable 6mm2 just for the Battery system... then need to know are there any vacant slots on Main Consumer unit downstairs, PV & Batteries should be in own Mini CU (where at loft or near Main DB, not in Main DB, Inverter specs for AC size cable needs to be known... what inverter.. but 6mm2 is not much more expensive... than 4mm2 if inverter battery specs, AC isolators at loft and Consumer Unit for battery system for electrical safety and maintenance would be required.
No doubt you have to 2 x AC isolators for the existing system from loft to Main Consumer Unit for safe practice and emergencies.

Food for thought, on designing your battery system.. very doable...

Is there an specific reason not to locate the battery system near the Main Consumer Unit... lack of space, downstairs cupboard not big
enough. All consideration to be taken into account when planning, designing your battery system

Could you yourself lay new cable save some expense, along with the AC Isolators, mount inverter and possibly Mini CU,

 

[Kot]

My loft gets very hot in the summer, and I wouldn't dream of putting many kg of batteries in the loft or even an inverter for that matter. Garage or utility room etc etc not such an issue with AC and correct csa of cable. Some batteries are suitably IP rated and can be installed out side.

 

[Bob Smith]

I have had my inverter in the attic since January 2016 and so far no issue.
It has a built-in thermometer and I saw last summer that the temperature had reached 64 (while the operating limit from the spec is 60) at some points

I am considering adding extraction fans when I will add my new system as I think it will get hotter and hotter the more stuff I have up there.

I have no garage and my utility room is full!! so I do not have much choice and I will not do like you see in the marketing material, install the kits in my living room lol.

 

[Geoff1946]

My inverter is in the loft, and for the limited number of hot days we get, I lashed up a fan just to increase the airflow over the heatsink. I put it on an ordinary room thermostat to cut in at about 40 degrees.