Home solar output throttling

My PV system is some distance from my house so I use a home-grown system that utilises a cheap wireless remote control system to power a relay wired in parallel with the HWS's off-peak switch in the house switch box. The off-peak switch is normally disabled as the inverter's load management facility has an option for daily minimum on-time that I can configure if there's been a run of cloudy days.

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Originally Posted by edddo

There is a product on the market that deals with this problem

EdgeIQ | Edge Electrons

Pricey but may well be worthwhile very soon. I dont understand how these work?

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It’s not that simple - while that device will show the system the grid voltage is lower - in reality it isn’t and unless that device is breaking the law it can’t allow a higher voltage back into the grid - which is what your system needs to do to push its power in there - with it without that device. It says up to 15% more - but 15% of 0 is still 0. If the grid voltage is too high to allow any input from the PV system, this won’t help. I’m only on my phone at the moment but will post a better explanation at some point.

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Originally Posted by edddo

@Homestar

This is my system Solax Power Station | Sunshine Coast Solar Power

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Thanks - not much technical data there - do you have anything on the ‘throttling’ you are describing? Is that something above and beyond what the inverter would normally do once the local voltage reaches its peak voltage or something else?

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Originally Posted by Homestar

It’s not that simple - while that device will show the system the grid voltage is lower - in reality it isn’t and unless that device is breaking the law it can’t allow a higher voltage back into the grid - which is what your system needs to do to push its power in there - with it without that device. It says up to 15% more - but 15% of 0 is still 0. If the grid voltage is too high to allow any input from the PV system, this won’t help. I’m only on my phone at the moment but will post a better explanation at some point.

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It appears that this device can allow the PV system to provide more of the household consumption when the grid voltage is unnecessarily high, saying as much as 15% more is produced by the PV system and therefore less drawn from the grid, but it doesn't appear to claim to increase export.

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Originally Posted by Graeme

It appears that this device can allow the PV system to provide more of the household consumption when the grid voltage is unnecessarily high, saying as much as 15% more is produced by the PV system and therefore less drawn from the grid, but it doesn't appear to claim to increase export.

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Could be the case but that’s not how I read it. The standard inverters don’t need help to supply the household they’re connected to.

They would if the grid voltage is already above the inverter's upper limits or close enough to severely limit the inverter's o/p. However the electricity supplier then has to reduce the voltage back to within their allowable limit.

Not that simple and there’s quite a bit to consider and understand but I don’t seem to be making anyone understand - probably my fault for not explaining clearly enough, so I’ll not continue with this - I work with the grid and the supply authorities and with how solar interact with the grid so I’ll stick to actually doing that rather than this. I am trying to help the OP not have an argument about this.

My take on that device is that it will stop your inverter seeing the high grid voltage and shutting down.
It won’t help with the solar harvest being fed back into the grid, but will reduce your power consumption as the household continues to be powered from the solar rather that the solar inverter going offline and resulting in 100% of your consumption coming from the grid while its offline.

Steve

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Originally Posted by steveG

My take on that device is that it will stop your inverter seeing the high grid voltage and shutting down.
It won’t help with the solar harvest being fed back into the grid, but will reduce your power consumption as the household continues to be powered from the solar rather that the solar inverter going offline and resulting in 100% of your consumption coming from the grid while its offline.

Steve

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I've been trying to figure out how it works, and the only think I keep coming up with is it's some form of switched converter which can take anything > 225VRMS and regulate it down to 225VRMS. Certainly possible, but it seems like a completely mental solution to a "problem". It'd also theoretically and necessarily completely block any supply *to* the grid. I'm sure it has a bypass to allow that when the grid voltage is low enough to allow in-feed.

I'd love to get some technical information, and some real efficiency numbers because I can't for the life of me think of any other way to achieve what it purports to achieve.

I'd also love to see what distortion it presents to the grid.

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Originally Posted by Homestar

What make and model inverter do you have - that’s different from any other system I’ve heard of - usually you use what you want and any you aren’t using goes back to the grid if it is available to take it (ie the local grid voltage not being too high). Grid power is only used when you are consuming all of the available solar or it’s dark, etc.

Why would a system be designed to not give the grid power OR you power - that doesn’t make any sense.

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If the inverter could differentiate like that, why doesn't it keep supplying the house when the grid power is off? I've no technical backup at all, but I'd say it just shuts down if the grid supply is out of spec (ie too high or too low...)??