SK-SU3700E off grid don’t charge battery is EPS is off

Holy_Cheetos

Hi

I am not sure if I posting in the right place. Please let me know.

I have a SK-SU3700E to use off grip in a garden room which I can’t have power from the house.

I bought this hybrid inverter without checking much about the specs and manual because it was a bargain (I think) and I had no time to look for more information as many people were asking the to collect it from the previous owner. The problem is that the inverter doesn’t charge the battery if the EPS is off while off grid.

I also bought the solar panels and 2.4kw/h battery.

I don’t want to keep the EPS on as the self consumption will be higher compared to power generation during the winter. It will supply power to LED lights, 12v for diesel heater and something to power my power tools up to 1.8kw. The EPS is rated to 2KW and I won’t use the powerful tools very often and for long periods.

It is configured for self use. I can switch off the EPS by connecting the pins 1 and 6 or setting the EPS battery minimum voltage to a voltage higher than the battery. In both cases the inverter still on, the EPS turns off and the inverter stop charging the battery.

Is there any way to bypass this issue? (Functional and worthy)

Do all hybrid inverters behave like mine?

Thank for reading.

QrizB

This is a Solax? One of these?

https://www.energy-xprt.com/products/model-sk-su300-sk-su3700-sk-su5000-hybrid-solar-inverter-505781

There are one or two Solax users on this forum, but I'm not sure if any of them have a similar model to you.

I'm not entirely surprised that, when used off-grid, the inverter will only charge the batteries when the EPS is active. But that doesn't help you.

Have you looked at the DIY solar power forum? There are a few threads regarding these inverters over there.

https://diysolarforum.com/

Sorry I can't be any more help.

I bought this hybrid inverter ... because it was a bargain (I think) ... I also bought the solar panels and 2.4kw/h battery.

Out of interest, what spec are the panels and how much did you pay for the kit?

Holy_Cheetos

thank you for your help.
So-su3700e - £50

18 x 250w mono panels - £120

2x Pylontech extra2000 (maybe same as us2000 first gen.) - £50 for both.

One battery is working and changing but I haven’t had the opportunity to check its currently capacity. I managed to charge it to 50% to avoid further damage. The another one has one pack quite bloated. Will check in the future if it is recoverable.

Holy_Cheetos

Mine is one of those but with E at the end which means it has a EPS port.

Holy_Cheetos

https://forums.moneysavingexpert.com/discussion/comment/81955942#Comment_81955942

thank you for your help.
So-su3700e - £50

18 x 250w mono panels - £120

2x Pylontech extra2000 (maybe same as us2000 first gen.) - £50 for both.

One battery is working and changing but I haven’t had the opportunity to check its currently capacity. I managed to charge it to 50% to avoid further damage. The another one has one pack quite bloated. Will check in the future if it is recoverable.

Mine is one of those but with E at the end which means it has a EPS port.

QrizB

On the face of it, that's a very good deal for what you've got!

I would have expected 4.5kWp of panels to be able to keep up with the per-the-datasheet rated 7W background load of the EPS function, even through a typical British winter. Is the drain much greater than 7 watts in practice, or have you only installed some of the panels and not all?

Holy_Cheetos

https://forums.moneysavingexpert.com/discussion/comment/81956092#Comment_81956092

I will only install 7 to 8 panels as I wont have space for all of them. I may sell my panes and buy some more powerful in the future.

I can't install the panels because I have not built the garden room/workshop yet. I only connected 7 panels provisionally on the fence to check if the system is working. At the moment I only powered a few tools and the heaviest so far was my air compressor (1.2kw I think). During a few quick tests I noticed that the self consumption is between 40w and 50w which is quite high specially with my old battery which wont hold much charge.

To be honest with you, I haven't had many opportunities to test them properly due to the weather during my days off and the panels are not properly positioned. I could only get around 500Wp so far with 7 panels due to the way they are placed at the moment. If it was draining only 7w I would be happy and not bothered with it at all.