Run house off batteries during the day, no solar.

[GRW]

There and back?? That's not how inverters work.

The DC cabling requirment is smaller and cheaper as voltages are higher.

Means AC grid tied.

Not sure what that means but I think you're getting towards talking about hybrid inverters? That have capability to charge/discharge batteries and accept DC from PV. Neither of those inverters are hybrid ones.


Sorry to pick apart your post, it just, to me, reads as really confusing for the OP.

I was involved with off-grid stuff. So we'd aim to get the AC (the generator) as close to the battery & inverter as possible to minimise the (48v nominal) high current DC cabling. Then the distance from the power centre to the buildings would be 230vac - much cheaper, 5x less current.

So... I was suggesting that the building mains could be taken out to the Solar Array, site the Inverter close to the Solar Array, and synch or AC Grid Tie there.

They weren't "Hybrid" inverters, but known as Inverter-Chargers - so yes they could Synch with an AC source and charge battery packs its a seamless changeover from battery supply to AC supply (& vice-versa).

You could also create a network, where the Master Inverter-Charger was hooked up to the battery store. The AC distribution then could link up buildings spread around the property. E.g. you could have the main battery store & Master Inverter on say a Barn, with the house 100 metres away having a Solar Array on it. The solar would have a Slave Inverter locally, which synced with the existing AC supply and fed power into it at that point in the AC network.
You might turn have a Turbine some distance away on top of a 3rd building - same again - a slave inverter converting the DC into AC, and sharing it onto the AC LAN.
The Master Inverter could bring programmed with load parameters and what level of power to contribute FROM the battery store at loads in excess of the generated power, and to put power BACK when supply exceeded demand.

In addition, you could programme the Master to call upon other AC sources (I.e. Generator or indeed Mains AC) when load exceeded set parameters (to utilise the battery storage for lower level, longer duration base loads only - to utilise the batteries best, and protect them from big discharges & excessive Cycling.

You can program the system to call upon AC source to re-charge the battery store with a proper 3-stage charging cycle (& simultaneously support the demand on the AC LAN) if the battery store became depleted.... and indeed set parameters / preferences for just when the system should use an AC Source (e.g. to take advantage of low-tarriff periods, or to set a "quiet time" when a generator would only be triggered if battery store levels got to the lowest override trigger voltage.

I hope that explains.

 

[Gareth J]

Its all confusing.

Still dont fully understand what "grid tied" means?

With DC cabling i would need to puts lots in to future proof. V one 6 or 10 SWA cable. I like the idea of not having 240v equipment out in the field albeit undercover. Its going to get damp, very damp.

So cabling aside, do i have everything to connect this up?

Grid tied just means that the inverter(s) are connected directly to the mains. Don't worry about how but the inverter takes DC from the panels and transforms it into grid compatible electric and squirts it back into your consumer unit/the grid.

Cabling aside, if the amount of panels you have are suitabke for your inverters, you have everything you need.

However, due to the significant cabling distance and plans to upgrade, I think you should use that setup elsewhere/sell and install a design that maximises what the DNO will let you install from the outset.

Have you considered putting your current panels upright on the south side of your big shed?

 

[Gareth J]

I was involved with off-grid stuff. So we'd aim to get the AC (the generator) as close to the battery & inverter as possible to minimise the (48v nominal) high current DC cabling. Then the distance from the power centre to the buildings would be 230vac - much cheaper, 5x less current.

So... I was suggesting that the building mains could be taken out to the Solar Array, site the Inverter close to the Solar Array, and synch or AC Grid Tie there.

They weren't "Hybrid" inverters, but known as Inverter-Chargers - so yes they could Synch with an AC source and charge battery packs its a seamless changeover from battery supply to AC supply (& vice-versa).

You could also create a network, where the Master Inverter-Charger was hooked up to the battery store. The AC distribution then could link up buildings spread around the property. E.g. you could have the main battery store & Master Inverter on say a Barn, with the house 100 metres away having a Solar Array on it. The solar would have a Slave Inverter locally, which synced with the existing AC supply and fed power into it at that point in the AC network.
You might turn have a Turbine some distance away on top of a 3rd building - same again - a slave inverter converting the DC into AC, and sharing it onto the AC LAN.
The Master Inverter could bring programmed with load parameters and what level of power to contribute FROM the battery store at loads in excess of the generated power, and to put power BACK when supply exceeded demand.

In addition, you could programme the Master to call upon other AC sources (I.e. Generator or indeed Mains AC) when load exceeded set parameters (to utilise the battery storage for lower level, longer duration base loads only - to utilise the batteries best, and protect them from big discharges & excessive Cycling.

You can program the system to call upon AC source to re-charge the battery store with a proper 3-stage charging cycle (& simultaneously support the demand on the AC LAN) if the battery store became depleted.... and indeed set parameters / preferences for just when the system should use an AC Source (e.g. to take advantage of low-tarriff periods, or to set a "quiet time" when a generator would only be triggered if battery store levels got to the lowest override trigger voltage.

I hope that explains.

Ah, off grid. Yes, that's all a foreign world to me, island mode, masters, slaves etc, not something I've any knowledge of. I don't think the OP wants an off grid setup though

 

[GRW]

Its all confusing.

Still dont fully understand what "grid tied" means?

With DC cabling i would need to puts lots in to future proof. V one 6 or 10 SWA cable. I like the idea of not having 240v equipment out in the field albeit undercover. Its going to get damp, very damp.

So cabling aside, do i have everything to connect this up?

AC Grid Tied means an inverter synchronises with your AC network and adds its contribution (be it from Solar, turbine or battery store source) onto the network where it is located.
It means that you can have power sources (such as a DC Solar Array) at any point in the AC Distribution... and it can synch and contribute. (Think like several small tributaries all feeding one river or lake of energy).

Older systems did not AC Grid Tie - meaning that all DC charge sources went into a battery store via separate DC cabling and charge controllers all Marshall in one place - and then a single inverter (or bank of synced inverters together in one place) contributed a single DC to AC contribution.

(At least - the stuff I was involved with did it like this)

 

[GRW]

Ah, off grid. Yes, that's all a foreign world to me, island mode, masters, slaves etc, not something I've any knowledge of. I don't think the OP wants an off grid setup though

Given that the OP considered employing his fork lift pack as a store.... then an "off-grid" Inverter-Charger might be just the thing to be able to have seamless management OF that battery store.

That was my reason for suggesting it.

 

[Roger440]

Grid tied just means that the inverter(s) are connected directly to the mains. Don't worry about how but the inverter takes DC from the panels and transforms it into grid compatible electric and squirts it back into your consumer unit/the grid.

Cabling aside, if the amount of panels you have are suitabke for your inverters, you have everything you need.

However, due to the significant cabling distance and plans to upgrade, I think you should use that setup elsewhere/sell and install a design that maximises what the DNO will let you install from the outset.

Have you considered putting your current panels upright on the south side of your big shed?

Quic questions as popping out.

No to the shed. Shaded by the big sitka spruce from about 1pm.

So if i connect it, and having an old spinny wheel meter, is that going to work. OK, i know i wont get paid for anything going the other way, but will it "just work?"

 

[Roger440]

Given that the OP considered employing his fork lift pack as a store.... then an "off-grid" Inverter-Charger might be just the thing to be able to have seamless management OF that battery store.

That was my reason for suggesting it.

I like the idea. But it all seems hideously complicated. There seem to be a million different options. Hence completely baffled.

I try looking for a circuit diagram, because that gives my an idea, but the sheer number of variations is bonkers.

 

[drjim]

It's very simple. Half the panels in series, I'd angle the sets SE/SW, each set connected to the inverter, then inverter wired into mains. DC isolator inbetween the panel string and inverter, AC isolator between supply and inverter.

Found a you tube video, they have surge protectors and meters but ignore those bits and get it wired up pronto!

 

[GRW]

I like the idea. But it all seems hideously complicated. There seem to be a million different options. Hence completely baffled.

I try looking for a circuit diagram, because that gives my an idea, but the sheer number of variations is bonkers.

It's a lot to take in, but in its most basic theory it's not so bad.
If you have a battery pack...

- Pack is connected to inverter-charger (IC) (which has a programmable brain) via dirty great DC Fused Cables.

- the IC either takes battery stored energy & converts it to AC (it can also add this energy to an existing AC voltage already present, like mains), OR it can USE some if that AC power - to recharge/replenish the battery store. It can be programmed via menus/settings with the size, type and voltage, plus charging settings etc and much more... to tailor what it does to suit the battery pack needs and how you want it all to work.

- so an IC simply has a battery store connected to its DC side - and an AC network cable connected to its AC side.

The "clever bit" is in inputting a good base setting for all parameters - to male the best use out of it

 

[GRW]

BTW...I've not seen one of the battery store systems that are the new thing fir properties on Mains to store energy for later use..... but in essence the idea is the same as the off-grid stuff I was involved with 25-years-ago up until pretty recently.
I suspect the Inverter-Chargers such systems employ are pretty much the same, of not identical to the units we supplied and installed off-grid (perhaps they leave out the extras such as the generator start & generator capacity bits as they don't need them).

 

[Gareth J]

Given that the OP considered employing his fork lift pack as a store.... then an "off-grid" Inverter-Charger might be just the thing to be able to have seamless management OF that battery store.

That was my reason for suggesting it.

Newer battery storage systems are relatively simple, you have a grid connected battery inverter that monitors incoming/outgoing via a CT clamp and sorts out what you want to achieve based on the settings you set. Or use a hybrid inverter that is both PV inverter and battery inverter rolled into one.

Quic questions as popping out.

No to the shed. Shaded by the big sitka spruce from about 1pm.

So if i connect it, and having an old spinny wheel meter, is that going to work. OK, i know i wont get paid for anything going the other way, but will it "just work?"

However, this comment makes any battery storage irrelevant.

If you are fortunate enough to have a meter that will run backwards if exporting, you have a zero cost or maintenance, profitable energy storage system connected without even doing anything. If your meter spins backwards when you export, you're effectively selling generated power at the same value it cost you to turn the meter forwards.

If that's the case, get some PV up asap and enjoy it before the meter gets changed.

If you do do it, you should probably not submit meter reads, in summer, that suggest the clock has gone backwards though.

 

[Gareth J]

P.s, when I said south side of the shed, I meant the southest vertical wall. But I guess either way that's going to get a lot of shade.

 

[GRW]

Newer battery storage systems are relatively simple, you have a grid connected battery inverter that monitors incoming/outgoing via a CT clamp and sorts out what you want to achieve based on the settings you set. Or use a hybrid inverter that is both PV inverter and battery inverter rolled into one.

However, this comment makes any battery storage irrelevant.

If you are fortunate enough to have a meter that will run backwards if exporting, you have a zero cost or maintenance, profitable energy storage system connected without even doing anything. If your meter spins backwards when you export, you're effectively selling generated power at the same value it cost you to turn the meter forwards.

If that's the case, get some PV up asap and enjoy it before the meter gets changed.

If you do do it, you should probably not submit meter reads, in summer, that suggest the clock has gone backwards though.

Yes, sounds like a pared-down & updated variant to what we used to use. Hopefully they've got all the battery charging setup and charging regimens that the off-grid ones have so battery mtce is up to snuff.

 

[voipio]

One thing to be aware of is that a grid tied inverter will only provide 240V AC, if there's an incoming mains of suitably low impedance i.e. it won't act as a stand alone off-grid supply.

 

[gaz1]

@Roger440

whats stopping you putting the panels up infront of your unit ?

 

[GRW]

One thing to be aware of is that a grid tied inverter will only provide 240V AC, if there's an incoming mains of suitably low impedance i.e. it won't act as a stand alone off-grid supply.

I've not heard of this regarding low impedance supply.
All the inverter-chargers I've had anything to do with seemed to be really pretty tolerant, with a wide voltage range for synchronising (below 200v to around 260v) and quite a frequency tolerance also (they'll synch happily with a mechanically-governed generators that would vary under load between 53hz & 49hz without complaint.
My old boss ran one as a test bed with mains in the workshops as the AC supply for several months (& it wasn't even a decent full-sinewave unit) with no issues.

 

[voipio]

I've not heard of this regarding low impedance supply.
All the inverter-chargers I've had anything to do with seemed to be really pretty tolerant, with a wide voltage range for synchronising (below 200v to around 260v) and quite a frequency tolerance also (they'll synch happily with a mechanically-governed generators that would vary under load between 53hz & 49hz without complaint.
My old boss ran one as a test bed with mains in the workshops as the AC supply for several months (& it wasn't even a decent full-sinewave unit) with no issues.

Grid tied inverters are essentially current injection devices, feeding alternating current in phase with the mains supply. A low mains supply impedance is a prerequisite. Imagine what would happen if it wasn't. Grid tied inverters tend to spend some time monitoring the frequency and voltage stability of the incoming supply, before applying power to the grid. The mains supply impedance is one of the parameters measured.
Text from the parameter menu section of a Fronius grid tied inverter manual:
"mains impedance ... resistance of mains - parameter for safe power supply to mains" e.g. 0.5 Ohms.

 

[GRW]

Grid tied inverters are essentially current injection devices, feeding alternating current in phase with the mains supply. A low mains supply impedance is a prerequisite. Imagine what would happen if it wasn't. Grid tied inverters tend to spend some time monitoring the frequency and voltage stability of the incoming supply, before applying power to the grid. The mains supply impedance is one of the parameters measured.

Yes, I'm aware of the process & sequence the inverters go through when Synching to an AC Supply - I was just saying that the ones I was familiar with were remarkably unfussy.

I know of one chap running a 20-yr-old, 3kw Trace Full Sinewave Inverter,Charger, off an lpg converted 6.5kva Honda GX390 petrol set converted to LPG. On paper there's no way it'll work... but it does - just about.
(I had to trim back his charge rate to enable the generator to stay within barely-tolerable volts & Hz parameters with the THD off the Inverter low enough to stop the voltage fluctuating.... so it didn't work really well - but it did work).

Off heavier Listers & the like with greater mass 4-pole alternators (but still only 9.2kva, 7.4kw) units - no problems whatsoever.
(These inverters will also synch & provide AC power synched with a generator supply if loads exceed the programmed-in capacity of the generator - e.g. a 7kw genny mated to a 3kw Inverter could if settings permit combine to support a 10kw load).

You wouldn't classify any of these as a low impedance supply compared to any typical Utility feed?

 

[voipio]

A decent sized non-inverter genny will have a low source impedance. Not so sure about an inverter based generator, though, unless they use low impedance push-pull output stages. Simpler inverter circuits might provide a low impedance to a load that's pulling the output voltage down, but not to another connected supply that is trying to pull the generator's output up.

 

[drjim]

This is a simple grid tied inverter that just needs to be connected to the mains. If the mains goes off so does the inverter. Let's start with the array and a suitable cable out to the field.