Growatt SPF5000 ES questions

[MikeMynis]

Hello, I have 9 panels (each 450 Watts) connected to a Growatt SPF5000 ES. Also 2 lead acid battery banks
2 x 4 batteries 48Volt connected with Victron battery balancers.

The problem is that during a gray day (no sun) the panels only deliver around 800 watts.
This 800 watts goes to the batteries first.

The house uses 3 kW, and this 3kW comes from the grid.

What I want is that the solar energy FIRST goes to the house and then use the grid for the rest.
That means 800 watts to the house and taking 2.2kW from the grid.

So charging the batteries must be last priority.

How can I do this?

I checked everything in the documentation but find it very confusing.

Any Growatt experts here who can please help me out here?

Thanks,
Mike

 

[siker442]

Not an expert, but
https://autosolar.es/pdf/manual-spf-3500-5000.pdf
Page 15, program 1, "SUB priority"

?

 

[MikeMynis]

Thanks for your answer.
I played around with that setting, but it doesn't do what I need. This setting manages the output source priority. It does nothing with the charge priority.

When I look at program 14 (Charge source priority) I have 3 options.

1. Solar First. Solar will charge the battery as first priority. Utility will charge the battery only when solar energy is not available.
2. Solar & Utility. Solar energy and utility will both charge the battery.
3. Only Solar. Solar energy will be the only charger source, no matter if utility is available or not.
   

What I need is that solar for charging the batteries is last priority.
Solar must first go to the house and if there is solar energy left, THEN charge the batteries with it.

So in program 1, I have SBU priority. First solar goes to the house. If solar is down, battery will provide power to the house. And when the batteries are at 50%, then the grid powers the house. That's a good order.

I know it's very confusing... That's why I'm struggling with this, as a beginner...

 

[MikeMynis]

Any ideas?

 

[kirkdis]

In your initial post you described SUB mode.

charge priority is set individually in P14 as you stated. The SPF´s are off grid inverters. Those inverters don´t know when there is unused energy available from pv. They only provide as much energy they can serve to the house or the battery.
Once the battery falls below P12 or P21 the inverter will override the charge priority for the battery to prevent damage to it due to low SoC. This functionality is not described in the manual but at least at firmware 067/068 this is the case. Hope that helps to tinker out a solution for your setup.

 

[Haxx]

The inverter is always going to prioritize putting juice back in the batteries, just because almost any battery type is damaged if left to drain to nothing.

Is grid power cheaper at night? Perhaps letting the batteries top up at night via Utility Charging Time (program 49?) would be an option?

 

[MikeMynis]

Thanks. Grid power is slightly cheaper at night, but still insanely expensive. That's why I disabled grid charging completely. The thing is that with grid charging enabled, my monthly grid bills are HIGHER, than when I disable grid charging.
So solar is the only energy source to charge the batteries. But it's still a shame that the batteries get first priority when charging from solar and then the rest (for the house) is taken from the grid.

After all, it's starting to look like that disconnecting the batteries completely, will drop my monthly grid bills even more.
So at this point, it looks like using batteries is only making the monthly grid bills higher, instead of lower.

PS: when charging the batteries, it takes many, many hours. They stay at 75%. No idea why. And then at some point it switches to using battery power, for about 3 minutes. Then battery drops to 25% (in the display). ONly with ~800 Watts usage on average.

Then it switches back to charging the batteries. And so on.

So after all I think that these lead acid batteries are a complete disaster. (2 x 4 x 12V, 260AH, combined in to two 48V banks.)
Theoretically I should have 24.9 kWh available. When using 50% it should at least deliver 12.4 kWh. But with this system, I'm not even getting 1kWh. So something must be wrong here, but I don't know what.

 

[Haxx]

Maybe the charge/absorb/float voltages need to be adjusted?

If i was in your shoes, i would try and sort the battery issue so they can get charged to full (for long term storage). Then, turn off the breaker to the batteries and just charge them every couple months so they are ready in emergency.

Then, as you said, the solar would be free to assist the grid in powering your load.

 

[BartHenry]

Solar and utility cannot work at the same time, there is no load shedding feature

 

[Haxx]

In that case, charge batteries on solar only, adjust bat2ac and ac2bat so that whenever they have enough juice, they take over while they can?

Still would need to sort out what is wrong with the battery charging.

 

[MikeMynis]

Solar and utility cannot work at the same time, there is no load shedding feature

Solar and utility cannot work at the same time, there is no load shedding feature

I think they can deliver at the same time, because when I disconnect the batteries, and the load (house) takes, for example, 4 kW, and solar delivers only 2.5kW, then I see that 1.5kW is taken from the grid. Is that what you mean?

 

[MikeMynis]

Maybe the charge/absorb/float voltages need to be adjusted?

If i was in your shoes, i would try and sort the battery issue so they can get charged to full (for long term storage). Then, turn off the breaker to the batteries and just charge them every couple months so they are ready in emergency.

Then, as you said, the solar would be free to assist the grid in powering your load.

I will indeed first start to play around with the charge/absorb/float voltages... But it's not so easy to track these changes. It takes time. Does the Growatt shine wifi give me daily usage stats? Like how much went into the batteries, how much was taken from the batteries, how much solar was used and how much grid was used? If I have those stats on a daily basis, testing would be much faster.(instead of waiting for the monthly grid bill)

 

[Haxx]

I will indeed first start to play around with the charge/absorb/float voltages... But it's not so easy to track these changes. It takes time. Does the Growatt shine wifi give me daily usage stats? Like how much went into the batteries, how much was taken from the batteries, how much solar was used and how much grid was used? If I have those stats on a daily basis, testing would be much faster.(instead of waiting for the monthly grid bill)

I think it should? I've yet to set up the wifi on my Growatts (i'm off grid, so i only care how much solar was pulled in, which is tracked on the unit's display) so I don't know what the Shine info tracks yet.

Regarding the batteries; the house I moved to recently had a (small) solar setup with some flooded lead acid batteries and i had never dealt with setting up batteries before, so i looked on the manufacturer website for that model. It gave me all the voltages for charging as well as things like their suggested low voltage cutoffs, etc.

 

[schmism]

Does the Growatt shine wifi give me daily usage stats?

Yes? I dont know how accurate it is but yes. (from my spf 3000 lvm) which does not grid sell back.

 

[schmism]

At the end of the day its a zero sum game. If you put 800w*5hrs = 4000w into the battery, and that charged them up enough to trigger the inverter to switch off grid, then you'll get your 4kw back out before it switches back to the grid. (losses understood) you still got to use your 4kw, even if you didn't sell it back to the grid as soon as it came in.

And yes charging from the grid is always more expensive option. So yes, configure to never charge from the grid. (unless your trying to time shift, aka charge at a time of day of cheep power and avoid using the grid at times of expensive power)

however it sounds like your battery is well undersized for the size of the solar you have so extensive time spent off grid seems unlikely

 

[MikeMynis]

Okay, thanks guys. I will order, install and setup the wifi dongle to get me more insights. And @schmism , its 8 x 12v, 260Ah batteries. 2 banks in parallel. Each bank is 4 batteries to make 48v. I have 9 panels, each 455 Watts. So on a good day, solar delivers up to 4kW. So my feeling is IF there is a size mismatch, then the batteries are oversized. But I'm not sure.

 

[timselectric]

Solar and utility cannot work at the same time, there is no load shedding feature

They can in SUB mode. Which the 5000ES has.

 

[timselectric]

I never got the dongle to work. After a couple of months I gave up and got Solar Assistant. Very happy with that decision.
If I understand what functionality you are looking for. SUB mode should be what you want.
When I started I didn't have enough battery capacity to get through the night. So I would use SUB mode during the day and save the battery for emergency backup.
In SUB mode the solar powered whatever loads it could. And the grid covered whatever was left. Battery charging only happened when solar covered all loads and had extra production. The extra was used to charge the batteries. Charging was set to solar only.

 

[MikeMynis]

AFAIK, SUB of SBU mode determine the order or energy sources to the loads. I prefer SBU mode, because Solar first, then Battery (to prevent taking power from the grid, even when batteries are full), and then, when batteries are at 50% and sun is away, switch to Utility (grid).

But when the sun is up, I need to change the CHARGING order. Utility never charges the batteries. So that's good. Only Solar charges the batteries.

Solar energy should first go to the house and then, if there's energy left, charge the batteries.

But now, the Growatt FIRST charges the batteries. As a result, there is not enough energy left for the house. So then it starts taking from the grid too to feed the house. So the house gets a bit of solar + a big chunk of grid power.

So basically what I want is SBU mode and that solar energy must first feed the house. And what's left should be used to charge the batteries.
It's only the charging order that needs to be reversed.

Today I got my wifi dongle. Will try to set it up

Thanks for all your support guys, really appreciate it.

 

[timselectric]

The dongle doesn't give you access to any more features. All features are available from the LCD panel.
I think that your program settings are not right for what you want it to do. Both SUB and SBU put solar production to the loads first. And anything extra goes into the battery. The difference between the two is where the power comes from if the solar doesn't cover the loads.
In SUB, it covered by the grid.
In SBU, it's covered by the battery. Until the battery reaches setting #12 value. Then it switches to bypass mode. And all loads are covered by the grid.
Solar can charge the batteries in any mode. Grid can charge the batteries only in bypass or SUB mode. If allowed by setting #14.