Hybrid inverter, what to buy?

[Fingers]

Hello, Can anyone recommend a good hybrid system (not sma) for my UK house?
There are so many out there and I have so little time, so if you could point me in the right direction I would be grateful.

I'm looking to lower my electricity bill

What I require:
The ability to use off the shelf lifepo4 batteries.
Not require specialist BMS.
Mains as a backup when batteries & solar are low.
Use solar on a sunny day when the batteries are charging.
No exporting to the grid.
Wire direct to the house fuse box, and without running new sockets in to the house (this would be nice, but doubt it).
It must be able to power my house & charge from solar in a power cut.

I have tried SMA but it's requirements are way too expensive and it doesn't do what I want.
I'm holding off buying new solar panels until I know what the requirements of the inverter are.
I can fit 6 panels 2.4kw total with minimum 9amp, or 5 panels 3.2kw total with minimum 17.2amp (big panels, big amps).



While I'm here, I'd like to ask another question.
Some inverters require separate earthing from the UK house earth. Apparently this is due to some UK electric companies grounding neutral at some substations? Do I install an earth rod? Include the earth rod with all earths, mains and inverter? Keep separate the existing earths from the inverter's.
I'm hoping technology has rolled on to avoid this problem, but doubt it.

Thank you for your help.

 

[houseofancients]

sunsynk... ( AKA sol-ark and deye )
mpp mpi series

to name a few

 

[newbostonconst]

The neutral in all US houses are tied to ground so not sure why a transformer being ground would be much different? I researched UK wiring and honestly from my background of being an electrical engineer, a licensed builder, and master mach, don't see how the neutral can't be tied to ground at multiple places so that the voltage is "referenced" to ground. If the voltage isn't referenced to ground then you could potentially have voltages that drift far from ground and can create a very dangerous voltage. Not only the safety shock hazard but also components not being able to handle large voltage differences causing large potential for internal arching. I am sure I am missing something.

I would love to help more but not sure what is available where you are at. Maybe give us a couple options that you are trying to decide between.

Outback, Victron, Sol-ark, Midnight all are very good components but cost a lot. How much is your budget? There are cheaper options like Growatt.

Good Luck...

 

[Fingers]

Thanks guys.
Am I allowed to l ink to the very popular auction site, or is that a no no on this forum?

Anyhow I'm looking at an Epever 5kw, and the photo says it all, as underneath the unit is "AC in" and next to it is "AC out".
Which means mains in, and house hold circuits out? Which is exactly the same as all of the inverters that I have looked at, or am I missing some thing?
The grid tie that I have is mains in, that's it, simply wire one cable to the fuse box. Really that is what I was hoping for..... But not SMA.

Looking forward to your input please chaps

Edit: I see Growatt has to use a specific battery type and brand, so that's them out

 

[Gezmondr]

Hey @Fingers how far did you get with this? I have similar requirements and also in the UK. I'm looking at a Givenergy system but am happy to do the work myself so I can't get that system unless I pay though the nose.

I can fit 8 x 400kw panels on my south facing garage roof and drop it down into a battery, all in the garage where there is a consumer unit to connect it to. The key thing for me which you don't mention is that I want the battery to be charging from the grid during off peak hours (0200-0600) when there's not enough solar so he charge can be consumed during peak hours.

Edit: just watched the guy presenting his Sunsynk system, looks like it could be the one!

 

[Fingers]

I can fit 8 x 400kw panels

I take it that you meant to say 400w panels? If so 3.2kw?
I can only get 2.4kw, as although the larger 3.2kw panels could physically fit, no doubt the neighbors would complain to the council and that would be the end of all of my solar
I'm also planning to fit panels to the back of my house 90 degrees east facing, but that will only be any good in the summer. It makes me laugh as a neighbor has panels 40 degrees east on his roof and paid a fortune for it. It can't be making more than 300watts at it's best.

What size cable runs from your garage consumer unit, to the house main consumer unit? The inverter will probably only require a 6mm2 cable but a larger cable would be better, as who knows what your going to use your garage for or what system you can fit in the future. Toolstation do 25 meters 16mm2 for about £200.

Ah yes, as far as I know, and I did look into it, cheep off peak electricity does not exist, it's the same price.
Also, Economy 7 or 10 is ok for vampires, doing their washing up, laundry, vacuuming and everything else in the night; but it's no good for people who are awake in the daytime as the price goes up in the day, so it may be cheaper in the night. They give nothing away.

Charging batteries from the mains, hummm, yes this would make your house "power cut" ready, but unless you do get cheap mains electricity, I can't see the point.

Do you have a link to Sunsynk system?

 

[Gezmondr]

I've not looked into cabling, it will be a very short run and I can source that easily enough but yes 3.2kw is what I can fit on that roof. I already have an old feed in PV system on my main roof so leaving that alone.

Yes cheap off peak electricity does exist; I am on a tariff where I get 4 hours per night for 5.9p per kwh because I have an electric vehicle to charge, I also schedule the washing machine and dishwasher for these times. The vampire scenario you mentioned is the entire point of the battery system by charging them up at night and consuming it during the day, the ultimate aim being that we consume zero peak time electricity, just solar + off peak via the batteries.

Sunsynk 3.6 kW Bi-Directional Hybrid Inverters

www.Sunsynk.com Call 0151 832 4300 and ask for TOM +44 (0)7707237414 for more information on this amazing machine. 7 kW MPPT ✔ 3.6 kW Charger ✔ 3.6 kW Inverter ✔ Can Run Both On and off Grid ✔ Can parallel ✔ Can control a Generator ✔ Sunsynk UI and platform ✔ Compatable with Octopus Agile ✔ Top...

www.sunsynk.org

 

[brum]

Anyhow I'm looking at an Epever 5kw, and the photo says it all, as underneath the unit is "AC in" and next to it is "AC out".

A month or two ago EPEVER didn't have a grid-tie inverter. Can you please share the picture and the model of what you were looking at?

If I'm going for a cheap brand that would definitely be EPEVER. All I've heard of their products is positive. The build quality is decent from what I have looked at.

 

[brum]

Found it. There is a UPower series that I've missed last time. I was looking at the UPower HI series which explicitly states that it is an off-grid inverter.

 

[Fingers]

Yes cheap off peak electricity does exist;

Whoo, what suppler do you have? Is this a new option? Can we get this if we don't have an electric vehicle?
I bet it only applies if you buy a brand new electric car, right?

 

[brum]

Checked again - both UPower and UPower HI series are off-grid inverters.

Here comes the question - what power do you need? If you use an off-grid inverter with the grid as a backup then you are limited to the power that the inverter can provide. If you use an on-grid inverter with an export limiter then the peak power consumption is what the grid provides and the inverter will reduce that with what it can get from the batteries or the panels at that moment.

I was looking initially for an off-grid inverter, but my peak power consumption is like 7-8kW. So I decided to go with an on-grid inverter.

 

[Fingers]

On grid hybrid is what I'm looking for, but really don't want to export anything to the grid.
I have an 8kw electric shower and that is the highest demand. We use 600 - 700 watts continuous until the evening and then it drops to 400 watts.
Of course we have the kitchen white goods run at one at a time the max we will need is about 2 to 3kw for three or four hours a day.

If I can get cheap electricity then I'd be a happy bunny as space for the solar is very tight. Charging at night would be brilliant and would take the guess work out of how many batteries to buy. Still a little in the dark about that, was thinking 8 200ah batteries or 12 100ah. But the price is a killer.

 

[Gezmondr]

Whoo, what suppler do you have? Is this a new option? Can we get this if we don't have an electric vehicle?
I bet it only applies if you buy a brand new electric car, right?

I'm with Bulb - I was already one of their customers so switched tariff on my profile, most suppliers do it. Bulb ask for no evidence of EV ownership.

 

[Fingers]

no evidence of EV ownership.

Sounds good, is the electricity the same price in the day as it was before you got the new tariff?

 

[Gezmondr]

Here comes the question - what power do you need?

The only real high consumption product we have is the car (which we would just charge off peak from the grid), next after that it's probably the kettle and oven. An invertor which can output at 3.6kw like this sunsynk can would be fine for us, but I would hope and expect these systems to flip to the grid when there is a large power draw.

I can only find one battery model on Sunsynk and it's 5.12kWh so would need a few of those as we average around 15kwh per day throughout the year (not including the ev). Obviously in the Winter this is far higher like 30kwh+ and less in the summer.

 

[Gezmondr]

Sounds good, is the electricity the same price in the day as it was before you got the new tariff?

No, the standard rate went up by just under 5p a kWh which switching.

 

[Gezmondr]

By the way, for UK folks this as just announced in the budget

• VAT will be scrapped on home energy-saving measures such as insulation, solar panels and heat pumps

 

[newbostonconst]

Edit: I see Growatt has to use a specific battery type and brand, so that's them out

I don't think that is correct....Most people now use LifePo4 batteries....you can make your own or buy them complete...

 

[brum]

The only real high consumption product we have is the car (which we would just charge off peak from the grid), next after that it's probably the kettle and oven. An invertor which can output at 3.6kw like this sunsynk can would be fine for us, but I would hope and expect these systems to flip to the grid when there is a large power draw.

Then consider this when you are looking for an inverter. You need an on-grid inverter with a power rating above the solar panels.

Regarding the Growatt - it can work with DIY LiFePo4 batteries in two ways. Either open-loop (the battery BMS is not communicating with the inverter) or close-loop (the battery BMS must support the Growatt inverter communication protocol, there are options for that).

 

[Gezmondr]

You need an on-grid inverter with a power rating above the solar panels.

Yes it will be - 3.2kw panels feeding a 3.6kw inverter.