EG4 18kPV Q+A general thread

[Markus_EG4]

Here it did change it takes about 5 min for it to display.

 

[Luxpower_Gilbert]

I'm planning to add some panels to my AC coupled 18kpv (waiting for delivery) and I have a couple of questions regarding the MPPT inputs and adding panels to the PV inputs.

I'll be adding 8 south facing ground mount panels, and I am leaning towards running 4s2p because I will get some AM/PM shading as the sun moves over trees to hit the panels. They will be in the same area, and all the same panels facing the same direction.. But the shading will move across both mounts slowly and can take an hour or so to clear.

I worry about the ~155v that a string of 4 is too close to the lower end of the MPPT rating during those shading hours...Should I?

Also, should I worry less if both of these strings go into the MPPT 1 port and are paralleled at the inverter? I don't know enough to know if that will help me stay inside the MPPT range or not?

I can easily put these in 8s and will keep that as a backup plan... But if I shouldn't waste my time experimenting with parallel to try to help my shading situation when I'm that close to the lower end of the MPPT range I would like to know ahead of time!

Thanks!

I recommend 200v+ pv input. Lower will be getting pv input error or will delay your production.

 

[y0bailey]

I recommend 200v+ pv input. Lower will be getting pv input error or will delay your production.

Thanks for the response. 8s it is.

 

[ajalger]

I changed that and didn't see a difference. I restarted the inverter through the menus too

View attachment 168164

Well nevermind.. it started working again. Super odd. Hopefully it was just a long delay after changing that setting. Thanks again!

 

[zanydroid]

I worry about the ~155v that a string of 4 is too close to the lower end of the MPPT rating during those shading hours...Should I?

If you’re worried about shading impact on voltage you probably should be just as worried about voltage vs temperature coefficient knocking the string out of range.

 

[Brucey]

This most likely expected with off grid applications, if the load is not stable. High surge load will affect sometimes the frequency.

What does high surge load mean? Going beyond the sustained output rating momentarily?

 

[y0bailey]

If you’re worried about shading impact on voltage you probably should be just as worried about voltage vs temperature coefficient knocking the string out of range.

I'm in NC so you are referring to heat driving voltage down? Yep another reason for 8s I guess?

 

[zanydroid]

I'm in NC so you are referring to heat driving voltage down? Yep another reason for 8s I guess?

Yup.

There's actually a thread on here recently about somebody that got screwed by their installers by a mistake in string voltage calculation. On hot days that string drops out when it's too hot.

 

[Systems Planet]

Can I use the EG4 18kpv inverter AC loads without batteries?

My AC loads are not live, even though PV is powering the inverter.

 

[timselectric]

Can I use the EG4 18kpv inverter AC loads without batteries?

My AC loads are not live, even though PV is powering the inverter.

I believe that you have to have a grid input for it to work batteryless.

 

[Luxpower_Gilbert]

What does high surge load mean? Going beyond the sustained output rating momentarily?

Anything with an inductive or high startup current draw. Like well pump, ac central, or a air compressor.

 

[cs1234]

What does high surge load mean? Going beyond the sustained output rating momentarily?

Anything with an inductive or high startup current draw. Like well pump, ac central, or a air compressor.

Wouldn't something like that only affect the frequency for a very short time, a few seconds at most? Does it not go back to a nicely maintained frequency immediately after the startup surge?

 

[timselectric]

Wouldn't something like that only affect the frequency for a very short time, a few seconds at most? Does it not go back to a nicely maintained frequency immediately after the startup surge?

With a generator, it affects frequency. Because it lugs down the generator speed.
With an inverter, it drops the voltage to an unusable level.

 

[cs1234]

With a generator, it affects frequency. Because it lugs down the generator speed.
With an inverter, it drops the voltage to an unusable level.

So, if he's offgrid, why would @Luxpower_Gilbert say surges are affecting the frequency? Were they talking about a generator as input source being lugged down?

Looking back on the thread.. they were maybe discussing 3rd world situations, where a generator is being used as the "grid power" and being lugged down maybe? I'm lost.

 

[Markus_EG4]

So, if he's offgrid, why would @Luxpower_Gilbert say surges are affecting the frequency? Were they talking about a generator as input source being lugged down?

Looking back on the thread.. they were maybe discussing 3rd world situations, where a generator is being used as the "grid power" and being lugged down maybe? I'm lost.

He’s talking about using PV only for loads

 

[cs1234]

He’s talking about using PV only for loads

Oh wow. No batteries and high surge loads? Ok, I can't fault the inverter for freaking out on something like that.

 

[timselectric]

So, if he's offgrid, why would @Luxpower_Gilbert say surges are affecting the frequency?

He didn't say anything about frequency.
You did.

 

[cs1234]

This most likely expected with off grid applications, if the load is not stable. High surge load will affect sometimes the frequency.

@timselectric

I was referring to this post. Maybe I misquoted in my other post? I'm getting all out of order.

 

[timselectric]

@timselectric

I was referring to this post. Maybe I misquoted in my other post? I'm getting all out of order.

I see.
I don't know why it would affect frequency of an inverter. There's no rotating mass to slow down. It's all electronically created frequency.
Unless the surge induced low voltage changes the timing of the electronics. Which I guess could be possible. If the voltage went extremely low.

 

[Mesquitemonkey]

The last 2 days my batteries shutdown because of high voltage. My 18kpv has worked great up until this point. I've read that clouds could cause a voltage spike that might throw the batteries over 100%. I use the inverter off grid. How do I lower the charge cut off to say 97%. The only cutoff % I see are ac cutoff and force charge cutoff %.