Hi,
Unfortunately I have been diagnosed with terminal liver cancer and probably don’t have very long to live at all.
Not long ago, my wife and I moved house which has an 8000W Deye hybrid inverter, 6000W in panels and 9,6 KWH in two batteries.
I myself only have very basic knowledge about solar systems and I haven’t really had the energy to see how our system works.
My wife has no knowledge whatsoever and we would really like to be able to leave the solar running with as little interference as possible, i.e. have a system that just takes care of itself.
We have too many panels for our needs, so would like to run the house during the day using the sun, while also charging the batteries to be used when the sun has gone down. I have tested here that some nights we get by without using the grid, but the batteries are at 20 or 30% in the morning, so I don’t know if it’s a good idea to discharge them so much during the night.
We also don’t want to send energy back to the grid and don’t have cheaper energy rates at night.
I was hoping someone could help me to use the right settings so our house can run autonomously without my wife having to do anything. I have looked for someone in my area to help but no one seems to know much about Deye inverters.
I’m pretty scared of having to leave her and running into problems or to be left in the dark.
Any suggestions would be really appreciated, so thanks in advance.

7 hours ago, Julian K said:

We have too many panels for our needs,

I think you mean you have more than you need most days. I have enough most days, but on overcast days I struggle. I'm thinking that when I have the dosh, I'm either going to put up more panels, or replace the existing north facing panels with something that has a bit more oomph. 

7 hours ago, Julian K said:

so would like to run the house during the day using the sun, while also charging the batteries to be used when the sun has gone down. I have tested here that some nights we get by without using the grid, but the batteries are at 20 or 30% in the morning, so I don’t know if it’s a good idea to discharge them so much during the night.

OK... So how much energy on average do you consume in a day? Before I got solar this house was using 13 to 14 kWh a day (I knew this because I was on prepaid and so had to feed the meter, which made me aware of what I was buying).

I have as much battery as you less panels, smaller inverter. But I usually have 50% (ish) at 7:00 and that's after the heat pump has run to heat the geyser.

We are just two, as I read it so are you. So you can get through the night on that battery and actually do. But I have more in hand in case of morning load shedding. 

The aim you state is the right one. Maximise your use of solar. We run all our appliances during the day, heat water during the day. So we reduce the work the batteries have to do at night. 

Some possible advantages we have are full gas cooking, and a heat pump to heat our geyser. The pump is more efficient than a regular element. All our lighting is LED. 

Check how much electricity you use in a day, and then try to get an idea of time of day you use it. Data from the Deye will help here. 

Think about how much night time use you can shift to the day. 

7 hours ago, Julian K said:

We also don’t want to send energy back to the grid and don’t have cheaper energy rates at night.

You don't say where you live. I'm assuming South Africa, which is why I mentioned load shedding. If you live somewhere with a reliable supply it can still be worth your while to reduce battery usage at night. You'll have more in hand on overcast mornings. And your battery isn't working as hard which may extend it's life. 

I live in Johannesburg. I can't see a way I could as much as break even by reselling, so I'm not interested. If they change the tariffs I'll think about it. 

You have all the right ideas, and good on you for wanting to sort this out for your wife. 

Edited February 8, 20251 yr by Bobster.

Thank you for your kind and quick reply Bobster. I actually live in Brazil and joined this forum a few years ago when I had a Growatt inverter. I realized that Brazil and South Africa seem to use similar brands in solar equipment, compared to the US, we’re both on the southern hemisphere and I personally found the people very friendly and helpful here. Solar isn’t very popular here yet unfortunately, so it’s also difficult to find knowledgeable people.

I think the energy we consume a day is very similar to yours, around 15 kWh a day, usually a couple of kWh more a day in the summer when we have the air conditioning running. If the battery is full at sundown we can usually run the air conditioner until early in the morning when the battery reaches around 20%.My ideal scenario would be to use solar as much as possible during the day running the house, while charging the battery, and go into the evening with a full battery. Maybe with a quick extra charge from the grid early evenings? Start the next day again on solar and re charging the battery using the panels. If necessary with a quick top up from the grid if really necessary.

We really don’t want to inject any energy surplus into the grid as it’s hardly profitable, and there’s a lengthy and expensive bureaucratic path to follow before it’s even allowed. We just want to make sure we don’t send anything back to the grid, as we have a lot of power outages and we don’t want to electrocute anyone working on the power lines.

Have you any idea if the scenario I described would be possible to do automatically? Without switching any switches etc? On the old Growatt we used to have we always seemed to be switching between grid and battery depending on the weather. To be honest, I don’t even know if the Deye inverter has this option to easily switch between the two. I really hope it can do both: be programmed to something similar to what I want, but also have an option to ‘quick choose’ between sun, battery or grid. I still need to try and find that out.

Anyway, thank you again for your last message and I hope you have a good weekend.

11 hours ago, Julian K said:

We really don’t want to inject any energy surplus into the grid as it’s hardly profitable, and there’s a lengthy and expensive bureaucratic path to follow before it’s even allowed. We just want to make sure we don’t send anything back to the grid, as we have a lot of power outages and we don’t want to electrocute anyone working on the power lines.

This you shouldn't need to worry about. I don't have a Deye, and I'm not an installer or an electrician, but most inverters we use here in South Africa (most that are used anywhere) have a feature that sounds odd but is actually necessary for the reasons you cite: When the grid goes down, they disconnect from the grid. They still are able to monitor the grid and the voltage on the grid, but that is all. The inverter will continue to generate voltage in the house, but, if property installed, the inverter will disconnect on the grid side.

 So I would be surprised if the Deye does not have this feature, but I don't know how to verify this in the settings.
 

12 hours ago, Julian K said:

My ideal scenario would be to use solar as much as possible during the day running the house, while charging the battery, and go into the evening with a full battery. Maybe with a quick extra charge from the grid early evenings? Start the next day again on solar and re charging the battery using the panels. If necessary with a quick top up from the grid if really necessary.

This is partly in your own hands, as I already outlined. 

Here's the data from my inverter yesterday - and Deye will have a similar tool.

Yellow line is load. Green line is SOC. Blue line is PV. Yesterday was a nice sunny day, and we used about 13.1 kWh. But you can see most of the usage was during the day or early morning. At 6:30 the heat pump (water heating( turns on. When that finished, the SOC was 44% with the sun starting to come up. Then 10 o'clock you can see the pool pump turn on, followed shortly after by the dishwasher (which heats water, so makes a significant difference to the load). 

Dishwasher finishes just after 11. Pool turns off at 15:00 - now look at our load. Very low. The spikes you see are most likely the electric kettle.

And this repeats this morning. Heat pump turns on at 6:30. By the time it is finished SOC is 51% and PV is just starting to get useful.

This isn't good luck or anything, this is the way we've planned it.

So check the data from your system and see what is going on at nights in terms of load. The more load, the quicker your battery discharges.

OK... You have AC, but how old? Modern AC units have an inverter drive. This is not just marketing jargon, it makes a real difference.

18 months ago we got rid of our old freezer and installed a new one. The new one has 70 l more capacity. It is also a modern unit (the old one was about 15 years old) with inverter drive, more efficient motor, different gas that is more easily compressed... I took measurement of the old and the new for an 8 hour period.

Old: Drew 0.577 kWh over 8 hours. Momentary low was 11.1 W. Momentary high was 1365 W (well up on the actual rating, and this is the motor starting up)
New: Drew 0.192 kWh over 8 hours. Momentary low was 2W. Momentary high was 107.8 W.

The big difference here is the amount drawn over 8 hours - 1/3 of what the old one drew (for a more capacious unit). The old one would have taken nearly  6% of the battery in 8 hours, the new one just under 2%.

Anyway, the graph I posted came from my Goodwe inverter. The Deye will give you something similar, and you can use this to see when your loads are high and hopefully identify what they are.

This, of course, is an example of having to spend money up front to save in the long run.

13 hours ago, Julian K said:

My ideal scenario would be to use solar as much as possible during the day running the house, while charging the battery, and go into the evening with a full battery. Maybe with a quick extra charge from the grid early evenings? Start the next day again on solar and re charging the battery using the panels. If necessary with a quick top up from the grid if really necessary.

Again, I can do these quick top ups on my Goodwe, you will surely be able to do the same with the Deye - but I can't tell you how. You will have to program the inverter. But I'm very sure you have the capability. Of course, doing this increases your electricity bill.

You say that outages are common where you live. Well this is the problem with this strategy. When my system was first installed we were having load shedding here in South Africa. Daily outages, at (usually) predictable times. Now I learned early on that we could get through the night on the battery, and I very quickly learned that if the battery was charged at 4pm, then I could go for hours as long as we controlled ourselves a little (the big loads, as previously demonstrated, are on timers or we have disciplined ourselves to use them during the day).

OK... so what if the weather is not so good? So I set the system to charge from grid, if necessary, from 3pm to 4pm. Simple. But I had to keep an eye on load shedding schedules because if there was going to be shedding at 2pm until 4pm (which was possible) then I couldn't top up.  If this happened on a sunny day then all was well, but there was a set of circumstances that could thwart my strategy.

 

13 hours ago, Julian K said:

On the old Growatt we used to have we always seemed to be switching between grid and battery depending on the weather. To be honest, I don’t even know if the Deye inverter has this option to easily switch between the two

The Deye is what is called a hybrid inverter. It has multiple sources of power - sun, battery, grid. A Deye expert will need to verify what I am about to say, but I believe it can accept input from a generator as well. Anyway, think of those three resources: It will be constantly balancing those according to it's own internal rules and the settings you put in place. This is not exceptional - lots of brands do that, so, again, I'm sure the Deye has that capability.

Usually what drives the change back to grid is the battery SOC, or demand exceeding what the inverter can deliver from PV and battery.

EG my system is set so that if there is grid, the battery cannot discharge below 40% SOC. If it reaches that level the system will seamlessly switch to grid. But this is exceptional. Most days there is PV and the battery doesn't discharge that far.

If there is no grid (or it disconnected because of poor grid quality) it will run the battery down to 10% SOC. Most lithium batteries will not allow themselves to be run completely down because that is when they do sustain some damage. My battery will shut down at 10% remaining anyway, and the inverter is designed to never run down past 10% remaining.

So you should check the data sheets and manuals for the Deye and for your batteries. If you don't have them, they are probably available on line.

Edited February 9, 20251 yr by Bobster.

12 hours ago, Bobster. said:

This is partly in your own hands, as I already outlined. 

Here's the data from my inverter yesterday - and Deye will have a similar tool.

Yellow line is load. Green line is SOC. Blue line is PV. Yesterday was a nice sunny day, and we used about 13.1 kWh. But you can see most of the usage was during the day or early morning. At 6:30 the heat pump (water heating( turns on. When that finished, the SOC was 44% with the sun starting to come up. Then 10 o'clock you can see the pool pump turn on, followed shortly after by the dishwasher (which heats water, so makes a significant difference to the load). 

Dishwasher finishes just after 11. Pool turns off at 15:00 - now look at our load. Very low. The spikes you see are most likely the electric kettle.

And this repeats this morning. Heat pump turns on at 6:30. By the time it is finished SOC is 51% and PV is just starting to get useful.

This isn't good luck or anything, this is the way we've planned it.

So check the data from your system and see what is going on at nights in terms of load. The more load, the quicker your battery discharges.

OK... You have AC, but how old? Modern AC units have an inverter drive. This is not just marketing jargon, it makes a real difference.

18 months ago we got rid of our old freezer and installed a new one. The new one has 70 l more capacity. It is also a modern unit (the old one was about 15 years old) with inverter drive, more efficient motor, different gas that is more easily compressed... I took measurement of the old and the new for an 8 hour period.

Old: Drew 0.577 kWh over 8 hours. Momentary low was 11.1 W. Momentary high was 1365 W (well up on the actual rating, and this is the motor starting up)
New: Drew 0.192 kWh over 8 hours. Momentary low was 2W. Momentary high was 107.8 W.

The big difference here is the amount drawn over 8 hours - 1/3 of what the old one drew (for a more capacious unit). The old one would have taken nearly  6% of the battery in 8 hours, the new one just under 2%.

Anyway, the graph I posted came from my Goodwe inverter. The Deye will give you something similar, and you can use this to see when your loads are high and hopefully identify what they are.

This, of course, is an example of having to spend money up front to save in the long run.

Thank you for your help. Seems like a good idea trying to plan using the heavier loads at different times while still benefiting the sun. That’s definitely something we’ll be planning to do.

As for the air conditioning units, luckily they have already been upgraded to the inverter type, and the consumption is really only about 20% to 25% of what the previous units used. Just need to update the freezer to an inverter type now. I hope to have that done soon.

12 hours ago, Bobster. said:

Again, I can do these quick top ups on my Goodwe, you will surely be able to do the same with the Deye - but I can't tell you how. You will have to program the inverter. But I'm very sure you have the capability. Of course, doing this increases your electricity bill.

You say that outages are common where you live. Well this is the problem with this strategy. When my system was first installed we were having load shedding here in South Africa. Daily outages, at (usually) predictable times. Now I learned early on that we could get through the night on the battery, and I very quickly learned that if the battery was charged at 4pm, then I could go for hours as long as we controlled ourselves a little (the big loads, as previously demonstrated, are on timers or we have disciplined ourselves to use them during the day).

OK... so what if the weather is not so good? So I set the system to charge from grid, if necessary, from 3pm to 4pm. Simple. But I had to keep an eye on load shedding schedules because if there was going to be shedding at 2pm until 4pm (which was possible) then I couldn't top up.  If this happened on a sunny day then all was well, but there was a set of circumstances that could thwart my strategy.

 

The Deye is what is called a hybrid inverter. It has multiple sources of power - sun, battery, grid. A Deye expert will need to verify what I am about to say, but I believe it can accept input from a generator as well. Anyway, think of those three resources: It will be constantly balancing those according to it's own internal rules and the settings you put in place. This is not exceptional - lots of brands do that, so, again, I'm sure the Deye has that capability.

Usually what drives the change back to grid is the battery SOC, or demand exceeding what the inverter can deliver from PV and battery.

EG my system is set so that if there is grid, the battery cannot discharge below 40% SOC. If it reaches that level the system will seamlessly switch to grid. But this is exceptional. Most days there is PV and the battery doesn't discharge that far.

If there is no grid (or it disconnected because of poor grid quality) it will run the battery down to 10% SOC. Most lithium batteries will not allow themselves to be run completely down because that is when they do sustain some damage. My battery will shut down at 10% remaining anyway, and the inverter is designed to never run down past 10% remaining.

So you should check the data sheets and manuals for the Deye and for your batteries. If you don't have them, they are probably available on line.

Thanks again for all this information and sharing your experiences. I think I’m really getting the idea of what I need to do now. Probably won’t get it right straight away, but hopefully several days or a couple of weeks of tinkering should do the trick, to get a set up similar to what you have done. Sounds pretty much ideal.

Our outages aren’t too bad. Probably about 10 times a year, but it’s nice to be able to keep the house running and comfortable when they do occur .

Our battery rarely goes beneath 40% if we don’t use any air conditioning, but definitely gets nearer 10% by morning when we do. Probably about 150 nights a year.

16 hours ago, Julian K said:

Thank you for your help. Seems like a good idea trying to plan using the heavier loads at different times while still benefiting the sun. That’s definitely something we’ll be planning to do.

Your need to do that is less than mine. You have an 8kW inverter. I have 4.6. You can carry much more simultaneous load than I can. 

You said you have more panels than you need. So maybe you can add some battery if the current 9.6 kWh is charging in good time. If everything else stays the same, now you have to worry less about night time loads running the battery too far down.