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Author Topic: Inverter that has export limiting  (Read 253 times)
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« on: November 21, 2020, 09:51:49 AM »

I have a approx. 4Kw of panels with an inverter that limits to 3.68Kw ( 16A )
This system was installed in 2015 and produces around 3000Kwh / year
I receive FITs payments and have no wish to make any mods to it at all.

The main problem is the system very rarely hits max output and from Oct to Feb the output falls dramatically due to lack of sun.

I have worked out that I can mount 3kw of panels on  my garage roof which will help with my consumption.

The easy way of doing this would be to obtain DNO approval to increase my export level however Northern Powergen are almost impossible to deal with.

Without spending large amounts of money on storage another option would be to limit the output of the second inverter when total export is above 16A.
A few posts have described this can be done with SMA equipment and recently SolarEdge has been mentioned.

Could someone point me in the direction of any technical documentation of any equipment I could achieve this with please.


16 X 240W Panasonic panels with a 3.6 ABB ( PowerOne ) inverter
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« Reply #1 on: November 21, 2020, 11:33:53 AM »

I am wrestling with this issue too and so I also look forward to reading the replies.
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SW London

« Reply #2 on: November 21, 2020, 12:16:21 PM »

According to their websites, the current generation of SolarEdge HD inverters have an export limit control built in, and you can do the same with some kit from SMA.

This means you could install 5kWp of panels, with a 5kW Inverter, set the export limit to 3.6kW, and then either self-consume the rest, or just let the inverter bounce off the limit.

Depends on whether you would benefit from the SolarEdge approach with power optimisers per panel (useful if shading is an unavoidable problem, or you have arrays split on different orientations, e.g. E/W)

Plenty of ways you could self-consume - hot water diverter (like an Eddi), a smart EV charger (like a Zappi), a home battery (Powervault or Powerwall), a heat pump, run a server farm at home...

3.06kWp SolarEdge system with a split array:
2.18kWp 10x South facing, plus 4x West facing 880W

Mk1 ImmerSUN DHW diverter
4kW PowerVault Battery

Tesla Model 3 Long Range
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« Reply #3 on: November 21, 2020, 12:25:22 PM »

Note:  In this instance the output from the new panels and their inverter cannot feed through the original inverter and generation meter.  Otherwise the existing system would no longer be eligible for FITs.  Thus a replacement inverter would not work.

I guess the question becomes one of whether anyone produces a 3kW inverter which can export limit based on the total export.  Obviously a 3 kW inverter would never need to export limit if it were the only inverter.

2.1kWp solar PV  PHEV West London
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« Reply #4 on: November 21, 2020, 01:06:38 PM »

It is possible to run many solar edge inverters which are linked via modbus. One of them is the master and determines if others have to throttle back.  Unfortunately it doesnít help you as you donít have one already but I put it out there for others to think about.

The inverter I think asks the optimisers to throttle and can even turn off panels if required.

6.48kw Solar PV JA (300W)Panels, SolarEdge inverter
Borehole -> Nibe F1255 12kw GSHP -> Radiators
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« Reply #5 on: November 21, 2020, 01:17:40 PM »

Hi Roger.

Our 3.9kW system was installed in October 2010, it paid for itself in FIT payments after 8 years.

In 2019 we had an extra 3.1 kW installed. Like you I didnt want change our original system as it has been perfoming extremely well and I didn't want to loose our FIT payments.

Our installer had contacted our local DNO in June about installing an extra system and by October we still hadn't heard back from them. So he just installed it.... I think it was in January this year that we finally got permission.

We had a Solar Edge inverter with power optimizers on the new system. We have 1 Kw facing South East and 2 kW facing South West.

Our installer explained that if we didnt get permission from our DNO then we would have to fit a Solar Edge "Modbus" which is a device that measure's the Solar output to the grid, this can be used to restrict the output from the new Solar Edge inverter. I think they are about £200. So the original system is left in place and only the new Solar Edge system is restricted if the solar output exceeds 16.8 amps.

We also had a Tesla Powerwall with the backup gateway installed. In the summer the battery was fully charged by 10 AM. From the beginning of March until September we only used 8kW from the grid. Before the upgrade we consumed on average 2000 kWh's a year, I think now we should be down to about 400 kWh's a year.

I just recently I installed a Myenergi Eddi to harvest even more energy from our solar for heating our domestic hot water and assist our Navitron solar thermal system.

By my calculation's the new system will be paid for by FIT payments in 4 to 5 years, but the feel good factor is priceless!

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« Reply #6 on: November 21, 2020, 08:04:22 PM »

Solis do a range of inverters with export limitation for a fraction of the cost of SMA and are available from Navitron  Lips Sealed Lips Sealed Well they used to sell them  Cry dunno what happened there They are really good inverters, I've used both SMA and Solis (Ginlong) and the Solis ones are every bit as good as SMA for a fraction of the price.

Cheers, Paul

'Off grid' since 1985,  Proven 2.5kW, Proven 6kW direct heating, SMA SI6.OH, 800ah Rolls, 9kW PV ,4xTS45, Lister HR2 12kW, , Powerspout pelton, Stream Engine turgo, 60 x Navitron toobs and a 1500lt store. Outback VFX3048 and 950ah forklifts for backup,
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