Solar panels and battery - any real world reccomendations?

Mercenary Keyboard Warrior said:
One of them damn why did I do this moments
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Exactly this, but I think it was early on a Saturday.

@DRZ They can insist on witnessing it, not sure whether that ever happens though. Once you have your allowance, it's yours and I don't think they can take it away. If the grid is close to collapse then they need to upgrade it. I have heard of several houses all sending in G98 forms to get the local grid upgraded because one was turned down for more than 3.68kW export.
 
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Ron-ski said:
Exactly this, but I think it was early on a Saturday.

@DRZ They can insist on witnessing it, not sure whether that ever happens though. Once you have your allowance, it's yours and I don't think they can take it away. If the grid is close to collapse then they need to upgrade it. I have heard of several houses all sending in G98 forms to get the local grid upgraded because one was turned down for more than 3.68kW export.
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I suppose early on a Saturday morning is as bad as a late one when generation is at stake!

I believe that the local grid they assume that all houses will install solar and thats how they come up with the allowance.
I guess if a load of people who could have been allocated say 5kw just had a 3.68kw installed then you may get lucky and they may grant a little over 5kw.
Suspect not but you never know.
 
You have a legal right to export 3.68kW, anything above that is allocated on a first come first served basis. If someone else wants more than 3.68kW and the local network can't cope, they either pay to upgrade it or settle for the 3.68. If the network can't cope with even 3.68 then the DNO foots the bill to upgrade, as I understand it.
 
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Ron-ski said:
You have a legal right to export 3.68kW, anything above that is allocated on a first come first served basis. If someone else wants more than 3.68kW and the local network can't cope, they either pay to upgrade it or settle for the 3.68. If the network can't cope with even 3.68 then the DNO foots the bill to upgrade, as I understand it.
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Is that for sure?, I've seen it quoted its a first come first served but never seen it written on official stuff.
But yeah I know the cost can be kicked back if you want above what it can handle.
Which is my point, I assume they in effect reserve this for all houses to get solar (at minimum or at an average)
Wonder what actually happens if the net for the whole substation is negative, IE total export is higher than import, does it get back to the grid or what?
 
Mercenary Keyboard Warrior said:
Is that for sure?, I've seen it quoted its a first come first served but never seen it written on official stuff.
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Old document but look at page 24.

When installing generating equipment which can export to the grid, which totals 3.68kW or less your are only required to notify the DNO once it is commissioned, therefore anyone can install and then notify. You only need to get permission prior to commissioning if it is greater than 3.68kW. There are some examples on forums of people complaining they've been told they can't export anything, but the one I just read appeared they already had a system and wanted to add AC connected batteries, thus increasing the export potential, hence it is zero increase, not a zero export.

Binky on the electricians forums is a very knowledgeable retired electrician and solar installer, and this thread makes an interesting read.
 
Ron-ski said:

Old document but look at page 24.

When installing generating equipment which can export to the grid, which totals 3.68kW or less your are only required to notify the DNO once it is commissioned, therefore anyone can install and then notify. You only need to get permission prior to commissioning if it is greater than 3.68kW. There are some examples on forums of people complaining they've been told they can't export anything, but the one I just read appeared they already had a system and wanted to add AC connected batteries, thus increasing the export potential, hence it is zero increase, not a zero export.

Binky on the electricians forums is a very knowledgeable retired electrician and solar installer, and this thread makes an interesting read.
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Interesting but still nothing in both cases about priority for above 3.68 being a first come first served thing.
On commercial they actually publish that and say thats how it works, but for domestic I haven't seen anything, but everyone says its the case.
I was just intrigued because if there is the possibility the DNO may have to upgrade the local network if everyone applied then I can't see any reason they would grant more than 3.68 to anyone at all.
I also wonder if the priority thing comes from the commercial side and its assumed domestic works the same way.

Of course its possible I guess that different DNOs work differently. I believe everyone has the "right" to the 3.68 but anything above is purely discretionary.

Its not a big thing I was just curious really. :)
 
DNO got back to me today and they are happy for me to submit changes to my current application to fit a 4.6kw inverter. Which negates the need for the G100….. sweet.

Wish i could fit bigger, but at least it allows me to fit at least 6 more panels for a 7.2kw pv array and 4.6kw inverter… yes it will clip at peak times, but im ok with that.
 
Welshman said:
DNO got back to me today and they are happy for me to submit changes to my current application to fit a 4.6kw inverter. Which negates the need for the G100….. sweet.

Wish i could fit bigger, but at least it allows me to fit at least 6 more panels for a 7.2kw pv array and 4.6kw inverter… yes it will clip at peak times, but im ok with that.
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Be careful on the overpanelling at that level.
Some manufacturers do allow upto 200% but many are 150% or below, and watch the string limits.

Eg mine allows 10kwp but input limit is 7.5kw* and individual string limit is 5kw.

(5kw inverter btw)

*total of string 1 + string 2.
 
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Mercenary Keyboard Warrior said:
Be careful on the overpanelling at that level.
Some manufacturers do allow upto 200% but many are 150% or below, and watch the string limits.

Eg mine allows 10kwp but input limit is 7.5kw* and individual string limit is 5kw.

(5kw inverter btw)

*total of string 1 + string 2.
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4.6kw growatt allows 9.2kw of panels…… 2 mppts, 1 string per mppt, max voltage 550v

 
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Mercenary Keyboard Warrior said:
Wonder what actually happens if the net for the whole substation is negative, IE total export is higher than import, does it get back to the grid or what?
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I forgot to answer this, the grid was designed for power to flow from the power stations, outwards in one direction, and be consumed by the end user. Apparently some transformers can work backwards, and send power back up the line, although there is losses, others don't work so well in reverse. If there is too much power on the local grid then the voltage will rise, and eventually be out of spec, which means it exceeds 253v, at this point inverters should stop exporting/shut down. High demand will cause voltage to drop, high export will cause voltage to rise (inverters export by raising the voltage), hence the need to balance the export, and also why EV chargers require permission from the DNO to be installed.

I did watch this the other day which sheds some light on some of it, hopefully I'm thinking about the right video!

 
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Welshman said:
4.6kw growatt allows 9.2kw of panels…… 2 mppts, 1 string per mppt, max voltage 550v

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Think the max input of 13.5A (per string) is your issue but it depends how your setting it up.
If your using something like 435w panels in series then you should be on the 9/10 panel limit. They are around 13.5A under standard test conditions.
I believe thats how you measure it anyway.

Anyway just thought I would mention, seems growatt are also at the top end of allowed kwp
 
Ron-ski said:
I forgot to answer this, the grid was designed for power to flow from the power stations, outwards in one direction, and be consumed by the end user. Apparently some transformers can work backwards, and send power back up the line, although there is losses, others don't work so well in reverse. If there is too much power on the local grid then the voltage will rise, and eventually be out of spec, which means it exceeds 253v, at this point inverters should stop exporting/shut down. High demand will cause voltage to drop, high export will cause voltage to rise (inverters export by raising the voltage), hence the need to balance the export, and also why EV chargers require permission from the DNO to be installed.

I did watch this the other day which sheds some light on some of it, hopefully I'm thinking about the right video!

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Thanks will take a look, I do watch some if his vids but sporadically and hadn't seen this one.
Makes sense that the grid is basically expecting to always send to consumers as opposed to receiving from consumers (net)

I guess that maybe newer hardware can handle export just because its more popular now.

Will take a look in my settings to see if I can figure out the export voltage cap one just to see whats in there.
Cant say exactly which houses near me are on the same local, but there is another west of me not far away, so I am guessing only the ones close to me and to my East.
I don't think there is any other house with solar in that direction. Maybe the one with solar to my North could be with me. Its kinda equi distant from the two substations. (assuming the brick buildings roughly half a garage size are called sub stations!)
 
Mercenary Keyboard Warrior said:
Think the max input of 13.5A (per string) is your issue but it depends how your setting it up.
If your using something like 435w panels in series then you should be on the 9/10 panel limit. They are around 13.5A under standard test conditions.
I believe thats how you measure it anyway.

Anyway just thought I would mention, seems growatt are also at the top end of allowed kwp
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The maximum connected PV power is also only a "recommended" maximum also, as it really is for all inverters. PV power isn't forced into a inverter, it chooses to draw it by applying a load and drawing current. As long as you are within the voltage and current limits then the percentage overpanelled doesn't actually matter, the inverter can just clip the DC side if it really wants to by limiting the current draw - just like it does for normal AC side clipping.
 
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Mercenary Keyboard Warrior said:
Think the max input of 13.5A (per string) is your issue but it depends how your setting it up.
If your using something like 435w panels in series then you should be on the 9/10 panel limit. They are around 13.5A under standard test conditions.
I believe thats how you measure it anyway.

Anyway just thought I would mention, seems growatt are also at the top end of allowed kwp
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Panels are 13amps and 10 in series is fine…..as they are 410w panels. Lots of research and questions have been asked to determine my needs.
 
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@Welshman that inverter use 360v to 500v batteries, not 48v, you'd have to use the specific Growatt batteries.

@Mercenary Keyboard Warrior Don't forget power is often distributed on 3 phases, so a third of the houses are on each phase. Not sure if this applies for every where though. This is one very good reason why you shouldn't connect power between different properties, they could be on different phases and that means 415v, 240v is one phase and neutral.
 
Ron-ski said:
@Welshman that inverter use 360v to 500v batteries, not 48v, you'd have to use the specific Growatt batteries.

@Mercenary Keyboard Warrior Don't forget power is often distributed on 3 phases, so a third of the houses are on each phase. Not sure if this applies for every where though. This is one very good reason why you shouldn't connect power between different properties, they could be on different phases and that means 415v, 240v is one phase and neutral.
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Yes i will be getting the growatt specific batteries, when and if i decide to go down that route next year……
 
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