Inverters

QrizB

uk1 said:

Thanks co-NorthHampshiree …..:)
Asking in case you know to save me reading it all.  If it is G100 does that imply prior approval before installing and commissioning?  

Yes, I think it does. Para 6 says you need to apply, and that the DNO will make an assessment. Para 7 then talks about "witness testing" although it also says the DNO can elect not to witness it. All this indicates to me that you need to apply before commisioning.

uk1

QrizB said:

uk1 said:

Thanks co-NorthHampshiree …..:)
Asking in case you know to save me reading it all.  If it is G100 does that imply prior approval before installing and commissioning?  

Yes, I think it does. Para 6 says you need to apply, and that the DNO will make an assessment. Para 7 then talks about "witness testing" although it also says the DNO can elect not to witness it. All this indicates to me that you need to apply before commisioning.

Many thanks.  I think I can see why my favoured quote includes a Q98 compliant inverter, but oddly the others all have a 5kwh inverters.  

What I find bewildering is if you can set a 5kwh inverter to have a 3.6k clamp during initial install why would they not allow a G98 application and approval. They are both set at 3.68.

TheTwillows

Are SolarEdge inverters the only ones which handle each pannel individually, and this more efficiently. I ask because I've just been told that this is the only invetor which will handle an array where parts of it are in shade for a few hours each day.

QrizB

TheTwillows said:

Are SolarEdge inverters the only ones which handle each pannel individually, and this more efficiently. I ask because I've just been told that this is the only invetor which will handle an array where parts of it are in shade for a few hours each day.

The short answer is no. Any system that puts conversion electronics on the panel - whether optimisers or microinverters - will "handle each panel individually".

Or you can buy panels with the electronics built in.

String inverters (when used without optimisers) are the ones that don't handle shade well.

uk1

TheTwillows said:

Are SolarEdge inverters the only ones which handle each pannel individually, and this more efficiently. I ask because I've just been told that this is the only invetor which will handle an array where parts of it are in shade for a few hours each day.

My understanding is that the Solis does this and is better (I am told) than the Solar Edge.

Magnitio

Alnat1 said:

Unfortunately, my Lux app doesn't have the option to set this by time and I have to manually remember to change the %. Also, there's the risk that the sky clouds up at lunchtime and the batteries don't fill but that hasn't happened yet 

Exactly what happened to me today. Exported this morning and left battery charging to after 1:30 when the rates were lower, then the clouds rolled in! 

[Deleted User]

uk1 said:

Thanks for that …. I’m learning all the time.  I hadn’t realised that a 5k could be restricted in that way and still allow the rest to be used or stored. 

I may have introduced an element of confusion. If you have an AC battery (that is, a battery on the house side of the inverter) it is treated as a house load as is an EV. If your inverter is limited to an output of 3.68kW then that is its maximum output from your solar irrespective of the size of your array. If you had a 10kWp array on a bright sunny day you would just see a long straight output line at 3.68kW.

If the inverter is outputting 3.68kW and your house baseload is, say, 300W then 3.38kW is available to charge your battery. If your battery is at 100% and your baseload is 300W, then 3.38kW will be exported to the Grid. If you increase the home requirement to 5 kW by putting on the washing machine and kettle, then 3.68kW will come from your solar and 1.32kW will come from the Grid.

As I understand it, the situation is different for a DC battery on the array side of the inverter. The DNO is not interested in DC batteries as the total output will be restricted by the 3.68kW solar inverter. That is, the 3.68kW output could be a mix of solar and DC battery.

[Deleted User]

uk1 said:

TheTwillows said:

Are SolarEdge inverters the only ones which handle each pannel individually, and this more efficiently. I ask because I've just been told that this is the only invetor which will handle an array where parts of it are in shade for a few hours each day.

My understanding is that the Solis does this and is better (I am told) than the Solar Edge.

All installers have their preferred equipment. SolarEdge is the system of choice for many installers.

uk1

Dolor said:

uk1 said:

Thanks for that …. I’m learning all the time.  I hadn’t realised that a 5k could be restricted in that way and still allow the rest to be used or stored. 

I may have introduced an element of confusion. If you have an AC battery (that is, a battery on the house side of the inverter) it is treated as a house load as is an EV. If your inverter is limited to an output of 3.68kW then that is its maximum output from your solar irrespective of the size of your array. If you had a 5.7kwh array on a bright sunny day you would just see a long straight output line at 3.68kW.

If the inverter is outputting 3.68kW and your house baseload is, say, 300W then 3.38kW is available to charge your battery. If your battery is at 100% and your baseload is 300W, then 3.38kW will be exported to the Grid. If you increase the home requirement to 5 kW by putting on the washing machine and kettle, then 3.68kW will come from your solar and 1.32kW will come from the Grid.

As I understand it, the situation is different for a DC battery on the array side of the inverter. The DNO is not interested in DC batteries as the total output will be restricted by the 3.68kW solar inverter. That is, the 3.68kW output could be a mix of solar and DC battery.

Thanks for clarifying, but I fear that I'm not as clever as I look because I thought just as I was begining to understand but I am now it seems going backwards.

My understanding was that I'm moving towards a system that looks like it is going to be around a 5.7kwh  array of PV panels on my roof feeding down into an inverter in my garage that will (a) convert the output of the arrrays irrespective of how many I buy because the total downfeed kwh will be reduced in the inverter to a maximum of 3.6kwh irrespective of what it then does with it.

It will then as it's first priority send it to (b) the house to use and then if any is left over as things go on and off from the house it will direct anything below 3.68 that is left over from the house to (c)  the set of batteries that are DC and store it at around 48v DC (which is then converted back to AC when there's nothing coming down from the array) and if any power is left after when the batteries are full and the house is using all it needs anything left  over will be sent up the grid and hopefully give me a few pence to buy some wine gums.   When there is nothing coming down from the array or the batteries I will be using the grid.  Have I misunderstood?

I'm told that in this scenario if I have a 3.68kwh inverter then it throttles back ALL of the power sent down from the PV array but only needs a G98 approval and the work can be installed and commissioned and everyone is happy.  Except me it seems who wants every ounce out of the array and is even thinking of more output. 

I am told however that if I get a 5kwh inverter that has the option to restrict the output to the grid to 3.68 then the DNO's say "No way Jose" you need a G99 or even a G100 (I know not which) and therefore I am being led to believe that if I am sensible I should accept a Solis 3.68 because the number of days in which my 5.7kwh array will exceed 3.68 although counter-intuitive is actually quite small but the larger overly rich array will be better for me because in winter when there is less of the bright stuff it will provide more to keep the lights on.  So it's a bit wasteful in summer and makes you smug in winter.  But I'd like more of the summer stuff to be fed to my batteries.

I have probably totally misunderstoof so has my grasp been a misgrasp?

Thanks again for your patience and sorry if I seem dim.  No pun intended. I have only been going to school for a week or so.

ABrass

10kW of panels on a 5kW inverter? No, that's just silly.

You should be doing G99 and getting a larger Inverter.