Hi,

Does anyone know if it's possible to input rectified AC into the PV input on the Axpert MKS ii. So the rectified AC would probably be around 300VDC smoothed, the issue I'm concerned about is that pv- would be essentially be connected to neutral.

Thanks Andrew 

Jy soek vir kak... I'd say if you want to try this kind of stunt, you would have to use a 1:1 transformer and maybe a fuse or similar current limiting/disconnection device in line with the AC side or the rectified DC end, certainly would not suggest you rectify from mains and try this... why do you want to do this anyway?

1 hour ago, Kalahari Meerkat said:

why do you want to do this anyway?

Due to the excessive KWH price, I want to reduce importing from the grid and exporting from my solar system to the grid.

I have 4kw PV array going through a grid tied Sunny Boy inverter which feeds through a generation meter generating the feed in tariff. So I want to use a solar Immersion heater booster to dump any excess solar power into some lead acid batteries rather than export it. Then I can use battery power overnight to reduce importing. I was thinking of putting a bridge rectifier and a large capacitor on the output of solar Immersion heater booster and feeding into the PV input of the Axpert.

I think, you are playing with fire literally. 

Much cheaper ways to destroy an inverter. The machine was not designed for this type of use. There are better ways to get more efficiency. However, please let us know the results, it will be very interesting to see what happens. 

 

Edited August 29, 20223 yr by Steve87

3 hours ago, AndrewM314 said:

Due to the excessive KWH price, I want to reduce importing from the grid and exporting from my solar system to the grid.

I have 4kw PV array going through a grid tied Sunny Boy inverter which feeds through a generation meter generating the feed in tariff. So I want to use a solar Immersion heater booster to dump any excess solar power into some lead acid batteries rather than export it. Then I can use battery power overnight to reduce importing. I was thinking of putting a bridge rectifier and a large capacitor on the output of solar Immersion heater booster and feeding into the PV input of the Axpert.

This is an interesting project. It might work provided you also limit the current from the rectified DC.

This type of project I would only do with YOUR inverter or a sponsored R & D unit.

Rather get the cheap China 1kW grid tied inverter that won't export to the grid but will work from a source like a battery.

Why would one rectify the AC and feed it into the DC input?

Why not just feed the AC power into the AC input side of the MKSII and use it as a UPS? Else a DC transfer switch to divert the panel output into the solar input of the MKSII? Also possibly useful for loadshedding. Just my 2c.

 

Edited August 30, 20223 yr by GreenFields

14 hours ago, AndrewM314 said:

I have 4kw PV array going through a grid tied Sunny Boy inverter which feeds through a generation meter generating the feed in tariff.

Why not feed those PV directly into the inverters MPPT PV input? You may have to change the serial/parallel setup to adapt to the MPPTs input voltage allowance. But that would be still less costly and safer.

10 hours ago, GreenFields said:

Why not just feed the AC power into the AC input side of the MKSII and use it as a UPS

thanks for the reply, that's actually how I'm using it at the moment, but I wanted to stop importing from the grid to the batteries and only use excess solar that would have been exported. Due to the cost of importing and the lead acid batteries only being 70/80% efficient.

 

10 hours ago, GreenFields said:

Else a DC transfer switch to divert the panel output into the solar input of the MKSII

Capturing excess energy pre generation meter I would lose 20/30% of the feed in tariff due  to the efficiency of the batteries.

Thinking about it, Kalahari Meerkat may have the solution going through an isolation transformer, I could probably step down from 240v to 110v which would give me around 156vdc not referenced to anything, which would surely be the same as the output of the panels 

Edited August 30, 20223 yr by AndrewM314