Berserkerboy
Well-known member
I know what you mean about the quoting company. Some sales teams are keen to the point of being rude, whereas others are more relaxed knowing that they win some and they lose some.
Additional solar array and addition of a battery
- Thread starter Ronski
- Start date
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The company doing the quote was quite happy for me to send the G99 application off, and just put their name as the electrician, so we'll have to wait and see how that goes.
As this is being installed in a detached garage, and the existing power cable is useless, we'll need a new cable or two run in. I say two cables as I presume to use the backup feature of an inverter/charger we'd need a second cable run back for the circuits to be used in a backup situation when the grid goes down, which is very rare here, but seems silly to have batteries and be unable to use some stuff in a power cut. Presumably the backup power would need to feed a CU for just those back up circuits (fridges/freezers, lights, and two ring mains excluding the kitchen which is on a separate circuit)?
Actually I've just realised it gets a lot more complicated than that, as ideally in a power cut both solar arrays would need to keep running, using the backup feed as detailed above would mean both solar arrays stop working - suggestions please on how this is accomplished?
I'm considering using Victron Multiplus-II 48/5000/70-50 for the battery inverter/charger, which has a maximum output of 4.4kw. PV inverter will likely be 4kw, so a total of around 8.5kw.
The existing house consumer unit, and meters is under the stairs, now in the middle of the house since we extended. There are ways to route a new cable, but there are obstacles, the easiest route would be underground to the house and come up in the corner, there is the gas meter here (no idea if that’s an issue), then the cable could come into the kitchen and along the wall under the cupboards, the gas pipe also runs here. Then there is the oven and the other side of the wall a floor standing boiler, so the cable would I suspect have to go up the wall behind the full height cupboard (not shown in the drawing below) next to the oven (presumably as its not directly behind the oven this won't be a problem?) then around the top of the utility room, there is a false ceiling, but also heating pipes (the ambient temperature probably gets high due to the boiler and heating pipes), then it can drop down into the under stairs cupboard. I calculate this cable would need to be 21 meters long, would 16mm SWA be sufficient?
As this is being installed in a detached garage, and the existing power cable is useless, we'll need a new cable or two run in. I say two cables as I presume to use the backup feature of an inverter/charger we'd need a second cable run back for the circuits to be used in a backup situation when the grid goes down, which is very rare here, but seems silly to have batteries and be unable to use some stuff in a power cut. Presumably the backup power would need to feed a CU for just those back up circuits (fridges/freezers, lights, and two ring mains excluding the kitchen which is on a separate circuit)?
Actually I've just realised it gets a lot more complicated than that, as ideally in a power cut both solar arrays would need to keep running, using the backup feed as detailed above would mean both solar arrays stop working - suggestions please on how this is accomplished?
I'm considering using Victron Multiplus-II 48/5000/70-50 for the battery inverter/charger, which has a maximum output of 4.4kw. PV inverter will likely be 4kw, so a total of around 8.5kw.
The existing house consumer unit, and meters is under the stairs, now in the middle of the house since we extended. There are ways to route a new cable, but there are obstacles, the easiest route would be underground to the house and come up in the corner, there is the gas meter here (no idea if that’s an issue), then the cable could come into the kitchen and along the wall under the cupboards, the gas pipe also runs here. Then there is the oven and the other side of the wall a floor standing boiler, so the cable would I suspect have to go up the wall behind the full height cupboard (not shown in the drawing below) next to the oven (presumably as its not directly behind the oven this won't be a problem?) then around the top of the utility room, there is a false ceiling, but also heating pipes (the ambient temperature probably gets high due to the boiler and heating pipes), then it can drop down into the under stairs cupboard. I calculate this cable would need to be 21 meters long, would 16mm SWA be sufficient?
I’ve been watching more of Andy’s off grid garage journey, and it occurred to me at the weekend, from a simplicity and cost point it view it would be better to use four MPPT 150/35 charge controllers, with three panels on each string. Whilst this won’t work as well as SolarEdge optimisers with regards to shading, it probably wouldn’t be far behind, problematic panels could have Tigo optimisers fitted if need be.
This approach would reduce maximum usable power, as the new array and batteries would be just through the Multiplus II, which unless I went up a size (a lot more expensive) would be limited to 4kw output, but it’s not often we’d exceed that anyway.
The existing array could be run in to the critical loads output, and thus both arrays would keep running in an extremely rare power cut, supplying power and charging the batteries. The fridge freezers (on their own circuit already), lighting and perhaps some emergency sockets could be run off the critical loads circuit. This would of course require two new cables from the garage.
Would the Multiplus II be able to handle the existing 4kw array on the critical loads circuit and would we be able to use say 7kw of solar if both arrays was producing 3.5kw?
What's you're thoughts on the above?
This approach would reduce maximum usable power, as the new array and batteries would be just through the Multiplus II, which unless I went up a size (a lot more expensive) would be limited to 4kw output, but it’s not often we’d exceed that anyway.
The existing array could be run in to the critical loads output, and thus both arrays would keep running in an extremely rare power cut, supplying power and charging the batteries. The fridge freezers (on their own circuit already), lighting and perhaps some emergency sockets could be run off the critical loads circuit. This would of course require two new cables from the garage.
Would the Multiplus II be able to handle the existing 4kw array on the critical loads circuit and would we be able to use say 7kw of solar if both arrays was producing 3.5kw?
What's you're thoughts on the above?
Who the firk is Andy? A Youtube 'expert' by any chance
. The Victron unit is more expensive than Solaredge and will not work as wellI know the MPPT chargers won't work as well, the question is how much worse, 5%, 10%, 50%, obviously it's not an easy or exact answer.
Who's Andy? He's clearly an expert at YouTube, but certainly does not claim to be an expert at solar and battery storage, he will also admit when he's made mistakes, not many that will do that. it's been very interesting watching his journey.
https://youtube.com/c/OffGridGarageAustralia
Who's Andy? He's clearly an expert at YouTube, but certainly does not claim to be an expert at solar and battery storage, he will also admit when he's made mistakes, not many that will do that. it's been very interesting watching his journey.
https://youtube.com/c/OffGridGarageAustralia
every device fitted has an electrical inefficieny, whereas a single inverter will have a single inefficiecy, plus you have shading issues which will be much better dealt with with solaredge rather than 3 panels on a single MPPT, Solaredge moves the MPPT to the individual panels.
Photon international did a shade comparison test beck in 2011, so the gear will have improved since then.
Had a watch of a few videos, interesting, but the guy is reinventing the wheel, so to speak. That's great if you are retired and want a project to work on.
Photon international did a shade comparison test beck in 2011, so the gear will have improved since then.
Had a watch of a few videos, interesting, but the guy is reinventing the wheel, so to speak. That's great if you are retired and want a project to work on.
@Ronski
I finally find someone with a very similar project. You seems to be head of me though.
I got a 4kWp installed in 2016 facing south. All good. I have additional space (not as much as you though) for 9 panels 3 facing south, 4 facing west and 2 facing south west. Originally the company said I could have 3.5kW. However, after looking at what the same PV provider (JA Solar) offers, I have found that I could combine (with a Tigo optimiser) different panels and reach 4.75kW. In addition to this, I am planning to have 10kWh batteries (for now) to be charged by the new panels and the existing 16 panels. This part has been sorted even if this means some losses in order to keep my FiT
I am struggling to understand what I need with regard to DNO. I did ask the company to inquiry and they have done it however I think they went asking for the 3.5kW while I am keen to have 4.75kW (or even more if I find panels more powerful that still fits).
How far are you with your project?
Cheers
Bob
It's not so much the array your DNO is interested in, it's the inverter and what's being backfed the grid, if anything.
As Binky has said, what the DNO is looking for is the maximum power you could export. So the total of the installed inverters, and battery if that has its own inverter. I have an application in with my DNO, but am awaiting a reply.
My project is still in the planning stage, I'm waiting on a quote from a local supplier who did a site visit two weeks ago, failing that I'm going to be phoning some electricians.
@binky The inverter I'm likely to use has a constant output of say 8kw, and a peak of 15, would the DNO go by the constant power or the peak?
Thank you to both of you.
The maximum power to be exported... That's is interesting. Is that based on the theoretical max power?
The reason of my asking is that as mentioned the plan is:
Existing system: 4kWp all panels facing south + Iboost that heat the water when there is an excess of electricity
Additional system (not yet installed): 3 Panels facing south, 2 facing South west, 4 on a wall facing west. Some of panels 4.7kW. with a inverter for those 9 panels. There will also be 10kWh battery (expected to expand later to 15) that will be charged by my existing panels + the new one.
As you can see, The panels will never, ever provide all at the same time their maximum power. However, the real max power could be difficult to calculate though.
On the other hand, I am not interested in exported if this creates more hassle. I am willing to lose my export tariff (from my existing system).
Could the solution be a system that charge the batteries and when they are full, instead of exporting the electricity, sometime shut it off. So in essence, my panels are only use for my own use and produce electricity fed back to the grid?
Thanks
The maximum power to be exported... That's is interesting. Is that based on the theoretical max power?
The reason of my asking is that as mentioned the plan is:
Existing system: 4kWp all panels facing south + Iboost that heat the water when there is an excess of electricity
Additional system (not yet installed): 3 Panels facing south, 2 facing South west, 4 on a wall facing west. Some of panels 4.7kW. with a inverter for those 9 panels. There will also be 10kWh battery (expected to expand later to 15) that will be charged by my existing panels + the new one.
As you can see, The panels will never, ever provide all at the same time their maximum power. However, the real max power could be difficult to calculate though.
On the other hand, I am not interested in exported if this creates more hassle. I am willing to lose my export tariff (from my existing system).
Could the solution be a system that charge the batteries and when they are full, instead of exporting the electricity, sometime shut it off. So in essence, my panels are only use for my own use and produce electricity fed back to the grid?
Thanks
Your panels will be connected to an inverter, or if they are DC connected to the battery you will have an inverter to covert the battery to 240v, what is the rating for the inverter? That is the figure you need, add that to your existing inverters rating.
Are your batteries AC or DC connected, if the battery pack produces AC then that will have a kw rating, and will need to be added to the other two.
In my case the batteries will be DC connected to the inverter, so I take the rating of that inverter and add it to the existing inverter, and that's what the DNO wants to know. On the form I used it had a box for existing, and then additional.
Are your batteries AC or DC connected, if the battery pack produces AC then that will have a kw rating, and will need to be added to the other two.
In my case the batteries will be DC connected to the inverter, so I take the rating of that inverter and add it to the existing inverter, and that's what the DNO wants to know. On the form I used it had a box for existing, and then additional.
Thanks Ronksi for your quick response
My existing inverter is a 3.6kW
So far the new inverter was to be also a 3.6kW however as I am optimizing the space I have and mix panels I could eventually have 4.7kW of panels. However as they are facing 3 different directions (West (4 panels mounted on a wall), South (3 mounted a roof) and South west (2 mounted on a flat roof) )they will never provide at the same time their max power. It could be that the 3.6kW is still OK.
So if I understand DNO will do 3.6kW + 3.6kW (or eventually 5kW if it had to be for the 4.7kW total panel power).
Are we here talking about the form G99. Believe it or not I have not been able to find it to download it and actually see by myself the questions they ask.
As for the battery. I seem to recall they are DC because they wanted to connect my existing panels to it and bypass my generation meter (and de facto make me lose my Fit).
This is what they proposed
My existing inverter is a 3.6kW
So far the new inverter was to be also a 3.6kW however as I am optimizing the space I have and mix panels I could eventually have 4.7kW of panels. However as they are facing 3 different directions (West (4 panels mounted on a wall), South (3 mounted a roof) and South west (2 mounted on a flat roof) )they will never provide at the same time their max power. It could be that the 3.6kW is still OK.
So if I understand DNO will do 3.6kW + 3.6kW (or eventually 5kW if it had to be for the 4.7kW total panel power).
Are we here talking about the form G99. Believe it or not I have not been able to find it to download it and actually see by myself the questions they ask.
As for the battery. I seem to recall they are DC because they wanted to connect my existing panels to it and bypass my generation meter (and de facto make me lose my Fit).
This is what they proposed
Well what they proposed would certainly invalidate your FITS system. If your two inverters are both 3.6kw, then total power is 7.2kw, even if you increased the number of panels on the new array it would still be a 3.6kw inverter, only if you go for a larger inverter would that value change. It's the size of the inverters that matters, not the panels with regards to the DNO.
For the FiT, it will depend on how the my existing panels will be connected to charge the batteries. If they are connected before the existing inverter then yes, I will lose the FiT. However the battery can be charged from the output of the inverter. In that case it is OK for the FiT. I have checked that with my FiT supplier.
Now, this would mean converting the electricity twice (DC -> AC -> DC) because the DC from the existing panels will go through the inverter and its output is AC, then the batteries needs DC.
Nonetheless, now I am wondering why not having AC batteries directly.
I need to learn more the pros and cons between AC and DC batteries......
Now, this would mean converting the electricity twice (DC -> AC -> DC) because the DC from the existing panels will go through the inverter and its output is AC, then the batteries needs DC.
Nonetheless, now I am wondering why not having AC batteries directly.
I need to learn more the pros and cons between AC and DC batteries......
If you have AC batteries, then that will be another Inverter to add to your DNO application. Also if you have AC batteries, then the output from both arrays will be converted DC -> AC -> DC. If you DC connected batteries to the new array, so directly charging the batteries by DC via a SCC (solar charge controller), then it is only the old FITS array that is doing DC -> AC -> DC (you'd need a suitable inverter to make use of the excess power from FITS array) and you can't get away from this without modifying the original system.
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No need to lose the FiT, which is nothing to do with the DNO. Put in a G99 application for the second system a describe it as set for zero export or capable of being set to comply with whatever they will allow you to back feed to the grid.
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