Solis Inverter - Battery Charge & Discharge

[Hogan]

I have a 6.8 kW solar pv system with 2 x 5 kW batteries (and I'm going to add another 5 kW battery at the beginning of April). I do get paid for exporting to the grid.

The installer set it up so that I charge the batteries at night from 12 to 4 a.m. I'm happy with that. The issue is that my heating kicks in at 6.30 and the battery starts to discharge. I don't want that as my cheap rate runs until 8 a.m. Ideally, I dont want the batteries to discharge until 8 a.m.

The other wrinkle I have is that I have an EV. Currently I have it set up to charge from 4 a.m. to 8 a.m.

What are the most efficient settings for my inverter so that I maximise the cheap rate (which runs from 11 p.m. to 8 a.m.?

 

[jgh]

It'll depend what rate(s) you get for export.

Consider just setting the from-grid charging period as 23:00 - 08:00 (and you might as well put the current limit on that just low enough
that an empty battery gets totally filled). Come summer, if you consistently get enough PV to top off AND have enough battery to last you until next sunrise, turn off the from-grid charging.

This assumes your house isn't limited by your grid connection capacity. What does the EV draw?

 

[Hogan]

I think I get about 21p per kWh for exporting. The EV draws around 7 kW.

I'll give that a go to see how it works out. Thanks for your reply.

 

[rpdom]

I agree that setting your charge times to match the cheap rate is best. Any load during that time will run from grid directly so won't have the conversion losses from battery charge/discharge.

You can prevent your battery being used by setting a discharge time slot with a current of 0A.

 

[Hogan]

You can prevent your battery being used by setting a discharge time slot with a current of 0A.

I saw that stated elsewhere but it confuses me the way the UI is set up. If I set a discharge period with the current set to 0A, I'm assuming once that period is over then normal discharge will resume? I think it's the fact that there are multiple charge and discharge lines, but only one box for discharge current? My fear was that even after the period expires the discharge current will be set to 0A and it will never discharge.

 

[rpdom]

I think it's the fact that there are multiple charge and discharge lines, but only one box for discharge current? My fear was that even after the period expires the discharge current will be set to 0A and it will never discharge.

The current setting works for all three time slots only. It doesn't affect the inverter outside those time slots.

Any time slot which has the same start and end time is considered disabled and won't be used. Usually you set them to 00:00 to 00:00 to disable them.

 

[Hogan]

Ok, one last question before I configure the inverter.

I have attached an image from section 6.6.6.4 from the manual. I've also attached the manual just in case.

The charge time here is set to 10 p.m. to 8 a.m. Let's say the battery is full by 1 a.m. Given that the discharge time is set from 8 a.m. to 10 p.m., won't that prevent any load between 1 a.m. and 8 a.m. from discharging the battery?

 

[jgh]

It would, and would thereby maximize your cheap-rate grid use (modulo your preferred 23:00 start, and leaving your battery full at 08:00).

But I'm not understanding why you want to fully-discharge your battery, at a pretty high rate, starting at 08:00 (per that image)

 

[Hogan]

It would, and would thereby maximize your cheap-rate grid use (modulo your preferred 23:00 start, and leaving your battery full at 08:00).

But I'm not understanding why you want to fully-discharge your battery, at a pretty high rate, starting at 08:00 (per that image)

I think this main issue is I'm very new to this and really don't know how it works I only want to discharge the battery to cope with the load. Maybe my best bet is to just set the battery to charge between 12 midnight and 8 a.m. and then not set any discharge time?

 

[jgh]

Yes. These periods are only for when you want to override the usual "self-use" behavior (charge from PV when possible and not-full;
discharge to supply house loads while there is still energy in battery; emergency charge from grid if battery gets really low).

Over here in England, I'm charging from grid 2-5 AM and doing a trickle (just enough to be more than typical house loads) discharge 4-7 PM (which is a higher-rate than normal, on my tariff). I might change that for summer.

 

[rpdom]

The discharge settings are for discharging your battery to the grid. For normal use (discharge to load) you leave them all at 0:00.

 

[SeaGal]

here is a useful guide...

Solis Hybrid Inverter: charging from the grid

How to configure your Solis Hybrid Inverter to charge from the grid on schedule.

blog.jonsdocs.org.uk

 

[Hogan]

Yes. These periods are only for when you want to override the usual "self-use" behavior (charge from PV when possible and not-full;
discharge to supply house loads while there is still energy in battery; emergency charge from grid if battery gets really low).

Over here in England, I'm charging from grid 2-5 AM and doing a trickle (just enough to be more than typical house loads) discharge 4-7 PM (which is a higher-rate than normal, on my tariff). I might change that for summer.

Thank you. Your first paragraph taught me more than the manual ever could! Really appreciate it.

 

[Hogan]

The discharge settings are for discharging your battery to the grid. For normal use (discharge to load) you leave them all at 0:00.

Cheers. I didnt get that from the manual at all, but now that you've explained it, it makes a lot of sense.

 

[Hogan]

here is a useful guide...

Solis Hybrid Inverter: charging from the grid

How to configure your Solis Hybrid Inverter to charge from the grid on schedule.

blog.jonsdocs.org.uk

Thanks. That guide is very useful. I wish the manual explained it like that.

 

[SeaGal]

That's Chinglish for you

 

[rpdom]

Cheers. I didnt get that from the manual at all, but now that you've explained it, it makes a lot of sense.

It's something that catches most of us out the first time. When I first set up a timed charge test I wondered why my batteries were draining again straight afterwards until I realised what the discharge times really mean.

 

[Broadlands]

Yes. These periods are only for when you want to override the usual "self-use" behavior (charge from PV when possible and not-full;
discharge to supply house loads while there is still energy in battery; emergency charge from grid if battery gets really low).

Over here in England, I'm charging from grid 2-5 AM and doing a trickle (just enough to be more than typical house loads) discharge 4-7 PM (which is a higher-rate than normal, on my tariff). I might change that for summer.

How did you do that, can you help me? It sounds exactly like you've done exactly what I want to do.

 

[Broadlands]

Thanks. That guide is very useful. I wish the manual explained it like that.

Is there a way of doing all that online?

 

[jgh]

How did you do that, can you help me? It sounds exactly like you've done exactly what I want to do.

(mailed response)