New Solis inverter setup with batteries

[Kermitdafwog]

Hi
I have recently had an 8KW system installed which consists of 24 panels, 2 solis inverters and 3 batters (6Kw in total)

The Solis home app is great for monitoring the usage but it looks like everything has to be done at the panel which is not ideal but it is what it is

My energy supplier, Octopus energy, are not able to offer me an off peak tariff so charging my batteries at night during the summer seems a bit pointless so I was hoping to do the following
Charge the batteries from PV whenever there is free power above what is being generated and what is being used (they are currently 100% charged and have been since installation, my current Self Use is below 2%)
The rest of the time, i want to consume whatever is in the batteries before using anything from the grid

I cannot see the point in charging the batteries at all as i am on a flat rate

Does the above sound sensible and how do i set my inverters to achieve this aim?

When i wake up in the morning, my smart meter is already showing we've consumed 40-50p and when i checked earlier, the inverters were not set to Self Use mode - i have since changed this but need to get more understanding of the charge/discharge timings i can set

I have watched a few youtube videos on the subject and read quite a few posts on this forum but still cant get my head around it

I look forward to any replies - thanks for reading!

Sam

 

[RichardL]

Self use mode should do it - no further config than that.
It will supply as much demand as it can from solar and battery,
...when there is less demand charge the battery
...when the battery is full dump it to the grid (some of which you can grab as hot water if you have an immersion gadget)

 

[KentPV]

I have a related issue. Perhaps my understanding of the inverter (Solis) is incorrect, but I have 14 Solar panels capable of 5.5kW of generation and 6.4 kWh of batteries. However, my inverter is only capable of supplying 3.6kW to the grid, so potentially there is a lot of capacity going to waste at peak solar times. My understanding is that the excess could be used to charge the battery, so potentially I could use the full 5.5 kW?

However, by the time the solar panels are able to generate peak output the batteries are already fully charged.

I have been looking at the settings but for the life of me I cannot work out how to setup the batteries so they do not charge until midday. Feed in Priority mode doesn't seem to do anything different to Self Use mode, and if you set the charge times under time of use then the inverter pulls power off the grid to charge the batteries, even though I have explicitly set the option so this isn't the case.

Does anybody have any ideas? Have I misunderstood the capacity of my inverter ?

 

[RichardL]

With your approach I suspect you'll just end up with the morning power going to the grid rather than the afternoon?
i.e. will it make any odds, are you net losing anything by charging them early?

On self use mode the inverter will prioritise feeding your house over charging the batteries - but once they're full, they're full. - doesn't matter if you trickle fill them over hours, or all in one go at a really sunny time.

Am I missing your point?

Watts are watts - you either burn them when they're generated, store them, or give them away to the grid.

 

[KentPV]

Thanks for replying. I am new to this, having just had the installation completed a few days ago. The issue is that the solar panels have a capacity of 5.5kW but the inverter can only supply 3.6kW down to the consumer unit. When the sun is at its peak, say between 12:00 and 15:00 the panels are capable of generating up to 5.5kW, but in practice only around 4 kW is taken because by this time my batteries are fully charged so the inverter is limited by what it can supply down to the CU.

What I want to do, is to delay charging the batteries to midday so that I can use any excess PV generated power over the 3.6kW that the inverter can supply into the house circuit/grid to charge the batteries. Therefore, I am charging the batteries with the excess power than would normally be "thrown" away. Ok, I am not sure what my inverter can do in excess of 3.6kW, but on Saturday I briefly saw the inverter spike above 5 kW whilst it was charging the batteries (I had just had 8 more panels installed - the previous 6 weren't enough to fully charge the battery by this point) around midday. Once the batteries were fully charged, the PV output taken by the inverter fell back to just over 4 kW, despite it being sunny. I believe the output was "clipped".

The problem is that that the time of use mode with regards Charging, overrides the setting to take energy from the gird, so its useless (taking energy from the grid to charge the batteries defeats the point of having PV). However, I've figured out how to do it, I think, by setting a Discharge time, say between 0800 and 1200. This I think will stop the batteries charging until midday. Any excess PV over load during this time will be fed into the grid (I think), so I don't think anything will be wasted.

PS. I saw your other thread, it was quite helpful.

PS2. The Solis inverter manual is worse than useless.

 

[radurus]

I have a neighbour with this inverter 6kw.
First I have envy him because his inverter has what I wanted (instead I have the known Growatt SPF5000ES) but this inverter setup is way more complicated than I imagined.

The energy flow and prio HAD to be simple in "maximize self sufficiency " scenario with battery.
1. Provide energy in the house
2. Charge the batteries
3. Keep the batteries top up and feed to grid the rest of the energy from the panel.
4. Stay on the battery until overload occurs or the battery-to-ac SOC threshold is reached.
5. Keep providing grid energy and charge batteries from solar until AC-to-battery SOC threshold is reached.

Now the batteries (2xPylontech US2000C) provide about 20min of backup and shut down, the inverter pulls some energy from grid despite the fact it is on battery.
Sometimes it just shuts down without switching to grid.

I saw few days ago the inter link comm cable from batteries was wrong and corrected.
I am eager to see if the "wonder inverter" behave how I expect.

 

[RichardL]

Why do you want to delay charging the batteries?

If the inverter is sending juice to them (on self use) its because your house doesn't have any use for it.
I don't think you're losing anything - just an opportunity to increase battery bank size.

Your steps 1-5 are almost exactly what self use does.

If your batteries are taking energy from the grid - theres a 'do not use grid' setting someplace - turn that on and make sure you don't have a schedule setup for charging - any schedule will override the 'do not use grid' setting.

 

[Portugeezer]

Thanks for replying. I am new to this, having just had the installation completed a few days ago. The issue is that the solar panels have a capacity of 5.5kW but the inverter can only supply 3.6kW down to the consumer unit. When the sun is at its peak, say between 12:00 and 15:00 the panels are capable of generating up to 5.5kW, but in practice only around 4 kW is taken because by this time my batteries are fully charged so the inverter is limited by what it can supply down to the CU.

What I want to do, is to delay charging the batteries to midday so that I can use any excess PV generated power over the 3.6kW that the inverter can supply into the house circuit/grid to charge the batteries. Therefore, I am charging the batteries with the excess power than would normally be "thrown" away. Ok, I am not sure what my inverter can do in excess of 3.6kW, but on Saturday I briefly saw the inverter spike above 5 kW whilst it was charging the batteries (I had just had 8 more panels installed - the previous 6 weren't enough to fully charge the battery by this point) around midday. Once the batteries were fully charged, the PV output taken by the inverter fell back to just over 4 kW, despite it being sunny. I believe the output was "clipped".

The problem is that that the time of use mode with regards Charging, overrides the setting to take energy from the gird, so its useless (taking energy from the grid to charge the batteries defeats the point of having PV). However, I've figured out how to do it, I think, by setting a Discharge time, say between 0800 and 1200. This I think will stop the batteries charging until midday. Any excess PV over load during this time will be fed into the grid (I think), so I don't think anything will be wasted.

PS. I saw your other thread, it was quite helpful.

PS2. The Solis inverter manual is worse than useless.

See this thread

Operating Modes on Solis Hybrid Inverter

Hi, I am looking to buy a 5kW solis hybrid inverter, because it seems to be the only model I can find in the UK that will integrate with 48V LiFe Model number is RHI-5K-48ES-5G. I am trying to get my head around the badly worded manual and hopefully someone has this model (or similar) and can...

diysolarforum.com

You can set the invertor to Charge the batteries at certain times

I've done this - my batteries charge from 8-9 am - then on auto mode - then charge from 14.00 to 19.00 - then on auto mode so batteries used when less power from PVs

 

[KentPV]

Forget batteries for the moment. My inverter has a capacity to supply 3.5kW to the grid. My solar panels can supply 5.5kW at peak. However, because the inverter cannot supply more than 3.6kW on very sunny days output from the solar panels is clipped (I think this is the correct term). So between about 1200 and 1600 there is potential output that is lost.

Going back to batteries, currently these are fully charged by about 1200.

What I want to do is delay the start of charging to when the inverter would otherwise clip the output.

 

[RichardL]

If you set the charge schedule, in my experience (others report differently) it overrides the 'dont use grid to charge' setting.
I'd turn the charge schedule off completely, put it on self-use and job's a goodun.

 

[KentPV]

See this thread

Operating Modes on Solis Hybrid Inverter

Hi, I am looking to buy a 5kW solis hybrid inverter, because it seems to be the only model I can find in the UK that will integrate with 48V LiFe Model number is RHI-5K-48ES-5G. I am trying to get my head around the badly worded manual and hopefully someone has this model (or similar) and can...

diysolarforum.com

You can set the invertor to Charge the batteries at certain times

I've done this - my batteries charge from 8-9 am - then on auto mode - then charge from 14.00 to 19.00 - then on auto mode so batteries used when less power from PVs

For the Solis inverter I have, if you set a charging time it will draw power from the grid even if you have the charge from grid option disabled.

I don't ever want to draw current from the grid to charge my batteries. I *think* however, if I set a discharge time, say from 0800-1200 then the batteries won't be charged during this time. At 0800 the batteries are basically discharged (down to 20%) so the only function of adding this is to delay the start of charging to midday, do I make best use of my PV capacity.

 

[KentPV]

If you set the charge schedule, in my experience (others report differently) it overrides the 'dont use grid to charge' setting.
I'd turn the charge schedule off completely, put it on self-use and job's a goodun.

Yes, except when it's sunny I lose loads of potential kWh from the panels because the inverter cannot cope with any PV in excess of 3.6kW because the batteries are typically fully charged by the time the sun is at is strongest. So the inverter will only draw 3.6kW from the panels rather than the up to 5.5kW the panels can provide.

My understanding is that if the batteries aren't fully charged then the inverter can handle more than 3.6kW because it can route the excess into the batteries.

 

[Solar Guppy]

For the Solis inverter I have, if you set a charging time it will draw power from the grid even if you have the charge from grid option disabled.

I don't ever want to draw current from the grid to charge my batteries. I *think* however, if I set a discharge time, say from 0800-1200 then the batteries won't be charged during this time. At 0800 the batteries are basically discharged (down to 20%) so the only function of adding this is to delay the start of charging to midday, do I make best use of my PV capacity.

There are a few ways to address your issues, attached is a document I wrote, for myself to put into words I could understand how the 5G actually works, not necessarily what Solis documentation describes. This may not be any better than the factory information, but for me, it allowed me to understand what the firmware actually does.

If you never want grid to charge batteries, just turn of that option, located within the storage mode setting selected menu, it is a master level setting. You can also select time of use ( grid ) and then change the charge / discharge currents, including a zero value.

 

[KentPV]

There are a few ways to address your issues, attached is a document I wrote, for myself to put into words I could understand how the 5G actually works, not necessarily what Solis documentation describes. This may not be any better than the factory information, but for me, it allowed me to understand what the firmware actually does.

If you never want grid to charge batteries, just turn of that option, located within the storage mode setting selected menu, it is a master level setting. You can also select time of use ( grid ) and then change the charge / discharge currents, including a zero value.

Great. Thanks. Let me take a look.

Unfortunately I do want to charge the batteries, just not from the grid and only from midday onwards. But let me see what your doc tells me.

 

[radurus]

Why do you want to delay charging the batteries?

If the inverter is sending juice to them (on self use) its because your house doesn't have any use for it.
I don't think you're losing anything - just an opportunity to increase battery bank size.

Your steps 1-5 are almost exactly what self use does.
.

It is not a delay.
It is just the priority of the energy use.
(that's how my Growatt works
- 4.5kw available from solar
- 1.7kw load
- what remains goes to batteries.
What's wrong with this?
Probably it was some misunderstanding)

What do you mean "almost"?

 

[RichardL]

It is not a delay.
It is just the priority of the energy use.
(that's how my Growatt works
- 4.5kw available from solar
- 1.7kw load
- what remains goes to batteries.
What's wrong with this?
Probably it was some misunderstanding)

What do you mean "almost"?

Nothing wrong with that - thats 'exactly' how self use mode works on the Solis (my solis anyway)

It really doesn't matter if the batteries are charged before/during or after peak sun - its all the same Watts.
They'll only get juice if the house isn't already using it.

Make sure you dont have any scheduled charge time setup - that will override the above behaiviour.
A Zero watts discharge schedule is useful for stopping the batteries unload during off peak, saving them for on peak - depending on the type of grid contract you have.

Apologies if I appear to be talking cross purposes - I think your inverter does exactly what you need, its just a matter of not worrying which bit of sun went in the batteries.

Scenario
For example - lets say you could use your midday sun to charge your batteries - were they not already full.
The morning sun that charges them at the moment would then be wasted..

Exactly the same amount - your battery capacity 6kWh was it?

If you want to use that sun - be it morning or midday or whenever you need to have more stuff turned on or more battery capacity.
-or- wait for Autumn - at some point the less sun will reach equilibrium with your capacity to use or store in batteries.

 

[KentPV]

It does matter when the batteries are charged!

Consider this scenario.

My batteries are not charged and the solar panels are producing their maximum capacity of 5.5kW. The inverter is able to use all of this power (I think), some goes into the batteries and the rest is exported to the grid/load.

If however my batteries were fully charged then the inverter would only draw enough power to supply 3.6kW to the grid/load.

Therefore, if my batteries are fully charged at a time when my panels are able to produce their full capacity then some of this is wasted.

If I ensure that my batteries are not fully charged at a time when my panels are able to produce their full capacity then I can make use of the full capacity of my panels.

I haven't been able to get sense out of the Solis inverter. In particular, if you disable charging the batteries from the grid, this feature is overridden if you set a Charging time window in Time of use. Perhaps that makes sense if you think this feature is only designed to make use of cheap rate power.

However, I think I can delay the time that I charge my batteries by setting a Discharge time window between about 8am and midday. On fact at 8am my batteries are empty anyway. However, I think I have to set the Backflow power above zero otherwise it doesn't work. So if I set it to +100W then the batteries won't charge (they won't discharge either because they don't have any spare juice). Will give this a go at the weekend.

 

[RichardL]

@KentPV
I'll openly admit don't get the point you are making - my failing.
I honestly think it's a zero sum game - batteries just time shift the sunlight energy.

Good luck!

 

[KentPV]

My point is that if my batteries are fully charged and the solar panels are working at full capacity (5.5kW) the inverter throws away the difference between this power and the maximum output it can send to the load/grid which is 3.6kW.

Therefore, on sunny days in the summer I am not generating as many kWh as is possible.

 

[radurus]

I understand what Kent is referring.

In the spring, I used to keep my offgrid inverter loaded (some sort of diverter with 3x1.5kw electric heater elements in the 1000L heat buffer and 2 sonoff basic) from the morning so that the battery charge takes as day long because the PV could deliver 6kw but the inverter AC out could handle only 5kw.
Keeping the load progressive up to 4.8kw, some energy remained for the battery slow charge.
Around 14 hour I was decreasing the load so that the battery complete the charge at 15:30...16:00

But this is his particular situation because the inverter is able to feed only 3.6kw.
The inverter I am talking about is 6kw so I assume it will feed to grid at full power (7kwp oriented SVV) it is the case.

So... advice for Kent:
Build/improvise some kind of diverter to heat up the DHW tank (150-200L with the heater element as low as possible to heat all volume), run Air conditioning, replenish the watering tank... and keep the inverter loaded so that the battery charge takes longer.
Use some smart plug with schedule or if you get the taste get into HomeAssistant, openHab and other smart IoT.

 

[KentPV]

Being doing some more research and think I have a reasonable understanding of some of the features of the Solis inverter.

First of all, if you select the Export Power Set option and set it to on, then the Backload power setting will determine the maximum current the Inverter will deliver to the Grid, subject to the Inverters hard limit (3.6kW on mine). I had this set to 0W today and as a result once the batteries were charged my PV output was precisely matched to the usage of power in our house (around 0.3kW) and nothing was exported, which was frustrating to see from my desk at work.

If you set a Discharge time window in Time of Use, it will respect the Backload power setting.

Therefore, for myself Export Power Set will be set to off. When I did this and set a Discharge time window and had Time of Use set to Run, it discharged the batteries at around 2.5kW. The batteries are rated at 3 kW. Not sure why there is a difference (PV power was zero), but it isnt something that bothers me.

At the weekend I'm going to experiment with Time of Use again to see if I can delay the start of charging of the batteries to harvest the PV power that would otherwise be clipped. Effectively I will be able to charge the batteries with power that is mostly wasted, so increasing my total yield.

So assuming Saturday is sunny I will be able to determine whether my suspicion is true that many PV installations with batteries are not delivering their maximum possible yield.

(Of course I may have misunderstood how the inverter works. My hypothesis will be disproved if my inverter can't make use of more than 3.6kW even when the batteries are not charged. I don't think so though because I observed PV of 5.5kW just after my extra panels had been installed a week ago which dropped to 4kW when the batteries completed charging)

 

[KentPV]

Update. I called the company who installed my setup yesterday. The customer service chap said that I had been fitted a 5kW inverter, whereas I have actually only been fitted a 3.6kW inverter (the 3.6kW being the power the inverter can supply to grid/load)

Other curious things, the inverter is running in "LmtByEPM" mode, which means its output is limited I believe to the maximum allowed under the G98 rules, that is 3.68kW. But why bother when the inverter can only supply 3.6kW? Also when I signed the survey, I selected the I do NOT want to limit my export to 3.68kW option.

So all of this malarkey around using the full 5.5kW may be for nothing.

Lets hope this is all a mistake on their part otherwise I will be posting about mis-selling and rip off installers.

 

[thefilmmaker]

Hi Kent,
I do also understand your point - you're absolutely right. For those that still dont get it.

Let's say you have a 10kw solar array and a 6kw invertor and a 10kw battery..

When the sun is sub-optimal (time-of-day/time-of-year/weather) such that the array is producing 6kw or less then happy days -> all the energy goes to the invertor, which distributes it between the battery, home and grid.

When the sun is however in all it's glory, such as in the middle of the day in the summer such that your solar array is producing 10kw of power for that window of time - then the invertor still takes 6kw of energy (because thats the max a 6kw invertor can do) and still sends that 6kw off to the battery, home or grid - but there is a remaining 4kw being produced in that window of time that is being thrown away. It's being thrown away because the invertor cannot take it.

Now.. if you can charge the battery from 0-100% with that clipped energy, then the entirety of the rest of your production goes to your home or the grid (for money back). But, if you charge the battery with 'un-clipped' excess energy from the morning that you could have instead sold; then the battery is now charged, meaning you have nowhere to divert the remaining 4kw of clipped energy that you know is coming later in the day - and so that is thrown away.

It is better to charge the battery with clipped energy first (midday) and then top it up if necessary after - as that charges the battery and maximises the amount you sell to the grid.

However you do need a setup that allows the battery to take the clipped energy.
Kent -> Did you achieve this in the end as it's exactly what I'm trying to specify at the moment?

Thanks
Rob

 

[thefilmmaker]

Update. I called the company who installed my setup yesterday. The customer service chap said that I had been fitted a 5kW inverter, whereas I have actually only been fitted a 3.6kW inverter (the 3.6kW being the power the inverter can supply to grid/load)

Other curious things, the inverter is running in "LmtByEPM" mode, which means its output is limited I believe to the maximum allowed under the G98 rules, that is 3.68kW. But why bother when the inverter can only supply 3.6kW? Also when I signed the survey, I selected the I do NOT want to limit my export to 3.68kW option.

So all of this malarkey around using the full 5.5kW may be for nothing.

Lets hope this is all a mistake on their part otherwise I will be posting about mis-selling and rip off installers.

don't forget that the invertor size is not just about grid export, it's also about how much power your home draws at any one time etc.
eg. in the evening you have an oven, induction hob and everything on the go - if you only had a 3.6kw invertor then you will find yourself pulling from the grid as well to supplement your shortterm energy need. But if you have a 5kw invertor then you can take 5kw from the battery (depending on the invertor, some have a seperate rating for that) even if your invertor is still limited to 3.6kw for export.

 

[radurus]

Hi Kent,
I do also understand your point - you're absolutely right. For those that still dont get it.

Let's say you have a 10kw solar array and a 6kw invertor and a 10kw battery..

When the sun is sub-optimal (time-of-day/time-of-year/weather) such that the array is producing 6kw or less then happy days -> all the energy goes to the invertor, which distributes it between the battery, home and grid.

When the sun is however in all it's glory, such as in the middle of the day in the summer such that your solar array is producing 10kw of power for that window of time - then the invertor still takes 6kw of energy (because thats the max a 6kw invertor can do) and still sends that 6kw off to the battery, home or grid - but there is a remaining 4kw being produced in that window of time that is being thrown away. It's being thrown away because the invertor cannot take it.

Now.. if you can charge the battery from 0-100% with that clipped energy, then the entirety of the rest of your production goes to your home or the grid (for money back). But, if you charge the battery with 'un-clipped' excess energy from the morning that you could have instead sold; then the battery is now charged, meaning you have nowhere to divert the remaining 4kw of clipped energy that you know is coming later in the day - and so that is thrown away.

It is better to charge the battery with clipped energy first (midday) and then top it up if necessary after - as that charges the battery and maximises the amount you sell to the grid.

However you do need a setup that allows the battery to take the clipped energy.
Kent -> Did you achieve this in the end as it's exactly what I'm trying to specify at the moment?

Thanks
Rob

Peobably this is valid in most cases.
In my case, the spf5000es can take 6kw from sun but deliver only 5...5.5kw to the house.

I mean the output instant power to the load + battery charging power > 5 kw

The MPPT can do 22A and ~400V VMP.
That means in theory 8.8kw from sun if the POWER is not limited by SW.

For the Solis only a real test can tell if it is really limited to 6kw of solar power.