What are my options for a 20kwh+ battery?

[Andeh]

18 hours ago, Dillsue said:

If the cable was correctly sized to carry 7 kw from the house to the garage for the charger then it will be large enough to carry up to 7kw in the other direction ie from the battery inverter to the house. 

 

FIT rules changed a few years ago and you can chop and change a system like adding batteries and probably change the inverter for a hybrid if that suited you better

 

 

Thank you for all that, now that you say it... It makes perfect sense... If a cable can carry electricity in one direction... Spooky that it can do it in reverse!! 🤔😂

[Andeh]

How easy are these frogstar type units to install? Is this default job for an electrician, or does it need someone who has specialist knowledge? 

 

I'm very tech literate (but entirely new to home energy) , so would research the right combination of inverter to suit my needs... But could my normal sparky install it in a few hours? 

[-rick-]

AFAIK it's electricly simple. You do need an inverter that supports the battery. The tricky bit is configuring the inverter to talk to the battery. That will likely be outside of a non-solar installers wheelhouse. Equally, while simple if an electrician is not used to working on 48V stuff they may not be the right person.

 

The assumes the inverter is already installed. Installation of the inverter is a bit more complex, again something for an electrician used to doing solar related installs.

[crispy_wafer]

https://www.fogstar.co.uk/products/fogstar-energy-16kwh-48v-solar-battery

 

There’s a vid on this page, the guy uses a sunsynk inverter with the fog star battery, this almost makes a shopping list quite easy to assemble.  

[Dillsue]

2 hours ago, Andehh said:

How easy are these frogstar type units to install? Is this default job for an electrician, or does it need someone who has specialist knowledge? 

 

I'm very tech literate (but entirely new to home energy) , so would research the right combination of inverter to suit my needs... But could my normal sparky install it in a few hours? 

Fogstar have a list of inverters that are compatible with their battery kits so probably best to stick to one they know will work.

 

Install from scratch is probably the best part of a day. With the kits you need to balance charge the cells which would take a bit of time to assemble and disassemble. Charging may take a few hours or maybe days. This is all on their Web site.

 

For install you got the following to do-

Batteries need assembling into the pack enclosure

Battery pack DC cabling needs connecting to the inverter together with a Canbus comms cable

Mount inverter and connect up AC connection to consumer unit

Connect up solar if its a hybrid inverter

Install meter/CT by service meter and connect up supply to the meter

Run comms cable between inverter and meter

 

If you're going for an inverter with a backup output for when the grid goes down you've got to install another consumer unit and move the backed up circuits over to the backup CU. Then run a supply cable between the inverter and the new CU. Could be best part of a day just for the backup CU!

[-rick-]

I don't tend to think the assemble at home options from fogstar are that worthwhile. For the units we were discussing above, the preassembled version is 25% more and for that you get higher grade battery cells, the work done for you and less chance of assembly errors. I'm sure their factory has occasional issues but the odds of a DIYer making a mistake, eg, not getting the torque right on a bolt and causing overheating issues is much higher IMO.

[Dillsue]

A follow up on this thread. I bought a fogstar 16kwh DIY kit and Solis 5kw hybrid inverter back in March. Inverter installed and set up fine but the inverter I bought needs a DC supply to operate so without a battery or generating PV it's dead. With a faulty battery that becomes a problem leading me on to.....

 

Fogstar kit went together OK following 3rd party YouTube videos.....the Fogstar documentation isn't the best. I had problems balance charging and after a couple of weeks Fogstar tech agreed I could build and use the battery. Had problems with a couple of cells which Fogstar were reluctant to replace and accounted for the struggle to balance charge them. Not long after I started using the battery there were a couple of instances of the battery collapsing and dropping to 0% charge in front of my eyes. After weeks of back and forth with Fogstar tech and stripping the pack for balance charging a further 2 times, Fogstar took the battery back for 'test and proper set up'. 3 weeks later I got the battery back and 2 days later it collapsed again so went back for a refund.

 

In the months I had the battery Fogstar stopped selling the kits and the cells that go in them so I guess I wasn't the only one with problems.

 

Spoke an installer who sells Fogstar kit on ebay and he convinced me the product is good so I bought a factory assembled battery through him and it's run perfectly for the last 2 months. There's another one on the way to help with the winter load.

 

I'm happy to recommend fogstar kit but just be aware that after sales can be lacking!

[Andeh]

Thank you! What's the Comms between battery and inverter?

 

I installed cat6 cable alongside my armoured cable, between house and garage, where I want batteries installed .

 

Is there any system which uses cat6 for the Comms?

[Dillsue]

The comms between our solis inverter and the fogstar batteries is over  CAN bus. The cable came with the inverter. I'm sure you'll be able to run CAN over a cat 6 cable with the correct connectors, but....

 

If you want to use your cat 6 to link the battery and inverter then aren't you going to run into the issue discussed up thread of needing massive cables between the inverter and battery if you have them separate??

 

 

[Nickfromwales]

2 hours ago, Dillsue said:

The comms between our solis inverter and the fogstar batteries is over  CAN bus. The cable came with the inverter. I'm sure you'll be able to run CAN over a cat 6 cable with the correct connectors, but....

 

If you want to use your cat 6 to link the battery and inverter then aren't you going to run into the issue discussed up thread of needing massive cables between the inverter and battery if you have them separate??

 

 

Not an issue if it’s feeding AC into a CU in the outbuilding? 
 

On the current project we’ve put a 3ph CU (DB2) into the ‘garage’, and that’ll have full LAN and WiFi access hard wired from the house.
 

DB2 will feed back into Henley blocks at the DB1 location, and there is where the meter resides for CT’s. 
 

Will likely be a hybrid inverter, as all of the solar PV is going on the outbuilding.

 

I don’t actually know of any installs where DC was exported long distances, is this actually ‘a thing’?  

 

Assuming a tri-input inverter (batts + Pv + genny) if one (or more) turbines are a possibility (exposed site which is windy as feck all winter, when solar is at its worst).

[Dillsue]

7 hours ago, Nickfromwales said:

Not an issue if it’s feeding AC into a CU in the outbuilding? 
 

I don’t actually know of any installs where DC was exported long distances, is this actually ‘a thing’?  

I took it that @andeh was looking to put the battery in the garage and inverter in the house hence the query over comms between the 2. Probably doable but would need some hefty cables between the 2

[Nickfromwales]

3 hours ago, Dillsue said:

I took it that @andeh was looking to put the battery in the garage and inverter in the house hence the query over comms between the 2. Probably doable but would need some hefty cables between the 2

@Andeh, wha’s the deal?  

[Andeh]

Yeah, unsurprisingly I'm still learning my way through how the system all sings together.

 

We have a single garage next to the house, and the only cables between the two (in ducts, buried) are 2 x 7kw armoured and 2 x CAT6A.

 

In the house we have an inverter and 4kw of solar panels, in the same utility room as the fuse box where the CAT6A and 2 x 7kw cables terminate.

 

Tieh solar panels are tied to an old school 80p/kw FIT which we do not want to lose (!) hence being ok with 2 x inverter for solar and battery.

 

I'm trying to work if there is any blockers to installing battery and inverter in single garage, making use of the 7kw cable and if any other ancillary control cables can use the CAT7A... Current clamps etc?

 

Fogstar batteries very much looking at the size and price point is like, of around 16-20kWh storage.

 

Hopefully this is clear!

 

 

 

[Dillsue]

8 hours ago, Andeh said:

I'm trying to work if there is any blockers to installing battery and inverter in single garage, making use of the 7kw cable and if any other ancillary control cables can use the CAT7A... Current clamps etc?

Your battery inverter will likely need a meter on the incoming house supply and you may need one to monitor solar generation if you want to charge your batteries off PV. A typical meter connects to the inverter over RS485 comms which will almost certainly work over your cat6 cable. Our meter is connected to the inverter over a 25m run of cat5. Power cabling has been discussed earlier but get your spark to confirm reuse of the SWA.

[Andeh]

Thank you! That clear and helpful - that's good to hear, as I ran CAT6A to the meter cabinet just in case I ever needed something in there.

 

Now I just need £10k for a decent setup!!

[Dillsue]

£10 grand??

16kwh fogstar battery £1850 on ebay

Solis 5kw hybrid inverter incl meter, battery cables and WiFi dongle £700

Install £500-1000. Maybe less with cables already in place??

Edited 10 hours ago by Dillsue

[JohnMo]

2 hours ago, Andeh said:

Now I just need £10k for a decent setup!!

You don't need anywhere near that much, if that's what being quoted look elsewhere.

[SteamyTea]

8 hours ago, Dillsue said:

kwh...kw

 

6 hours ago, JohnMo said:

You don't need anywhere near that much

Are talking cash or capacity?

[JohnMo]

3 minutes ago, SteamyTea said:

 

Are talking cash or capacity?

That would be cash, I would cram as much KWh capacity in you can afford/have space for, then play with tariff import (and PV generation) I'll and export rates, got a 23p export slot coming up which runs for a couple of hours, so good to have plenty of capacity then you can export and run your heat pump also.

 

So no point having a small inverter either.

[DamonHD]

A large inverter will likely have higher overheads/losses at lower loads: probably don't size to cover your biggest load, but maybe 95% of the time.

 

I have what is now a quite weedy inverter (~1.25kW, 6kWh) but only import/leak ~0.3kWh/d in summer, in part because low overnight loads are covered effectively.

[JohnMo]

By constant we have a 6kW inverter and it will provide the house with all power 95+% of the time, which means no expensive imports when battery is supplies the house, is great for exports also. So we can heat the house and cook the tea at the same time if we want.