Help me understand: Delegating devices to remain online when the grid goes down

[clokwise]

I'm getting quotations for a 10Kwh + battery on/off grid system. I don't have any prior knowledge of solar installations, so it's all new to me.

 

One of the questions the contractors are asking is to decide now which devices in the house I wish to stay online when there is a power cut at the grid. Not so much asking, but insisting, that I do this.

 

It was my prior assumption that, since I have will a battery backup, when the grid goes down the entire home will simply switch over to battery, at which point our smart home automation or myself can turn off any unneeded devices drawing excess power.

 

Apart from perhaps the A/C or fridge, nothing in my home actually requires a lot of current. I fail to understand the necessity of literally rewiring my brand new home to put unrelated and randomly scattered devices onto a new circuit. Further, it seems that if I did do this and my needs change later (likely will), we will have to rewire again.

 

The contractor is saying that if the grid goes down that there will suddenly be too much power drawing from the inverter/battery. But will that happen - actually? We rarely use more than one A/C at a time, and a handful of lights and fans surely can't demand that much power? And worst case - wouldn't the breaker at the battery shut it off if it's overloaded? I can deal with that, unless it can't handle much current at all - in which case I'm now questioning why I should install a battery backup at all if I can't even use it like I want?

 

My home was wired by a professional electrician familiar with solar installations - they have even already built the conduits and wired them up ready to go. He did such a terrific job - the circuit breaker box is practically a work of art.

 

So, why can't I just leave my home as-is and simply install a battery and inverter ?

 

Is this really a thing? Help me understand why I need to rewire my home.

 

[Bandersnatch]

Some solar installations treat the battery as a giant UPS that backups certain circuits in the house. The battery is always kept in reserve for these power-out situations.

 

This seems a bit of a waste in my opinion unless power outages are a nearly daily occurrence.

 

If you think power cuts in your area will only be a couple of hours it would be better to use solar, then battery, then grid power.

[JBChiangRai]

Some switch the entire house over to inverter (mine does that), it switches over instantaneously to inverter if there is a power cut.

[atpeace]

3 hours ago, clokwise said:

I'm getting quotations for a 10Kwh + battery on/off grid system. I don't have any prior knowledge of solar installations, so it's all new to me.

 

One of the questions the contractors are asking is to decide now which devices in the house I wish to stay online when there is a power cut at the grid. Not so much asking, but insisting, that I do this.

 

It was my prior assumption that, since I have will a battery backup, when the grid goes down the entire home will simply switch over to battery, at which point our smart home automation or myself can turn off any unneeded devices drawing excess power.

 

Apart from perhaps the A/C or fridge, nothing in my home actually requires a lot of current. I fail to understand the necessity of literally rewiring my brand new home to put unrelated and randomly scattered devices onto a new circuit. Further, it seems that if I did do this and my needs change later (likely will), we will have to rewire again.

 

The contractor is saying that if the grid goes down that there will suddenly be too much power drawing from the inverter/battery. But will that happen - actually? We rarely use more than one A/C at a time, and a handful of lights and fans surely can't demand that much power? And worst case - wouldn't the breaker at the battery shut it off if it's overloaded? I can deal with that, unless it can't handle much current at all - in which case I'm now questioning why I should install a battery backup at all if I can't even use it like I want?

 

My home was wired by a professional electrician familiar with solar installations - they have even already built the conduits and wired them up ready to go. He did such a terrific job - the circuit breaker box is practically a work of art.

 

So, why can't I just leave my home as-is and simply install a battery and inverter ?

 

Is this really a thing? Help me understand why I need to rewire my home.

 

I have 6.5 Kw Inverter and a 15Kwh battery.  I can shut down PEA at the breaker box and my system has no issues.  This is while running two ACs and electronics.  Most inverters also have a 5-10 second period where they can handle 30-40% more than what they are rated.  

 

How many volts is your battery and how many amps can it handle.  I have a 48 volt battery and 100 amp output.  To get the max watts output you multiple the amps by the volts ( e.g. 48x100= 4800 watts).

 

Have them separate your water heaters(2k-4k watts per heater) and you should be fine.  Maybe he is including these into his calculation.  Can you take cold showers while the electricity is off? I actually didn't separate them and have had no issues.  Haven't had both hot water heaters and both ACs on at the same time while off the grid but you get the point.

 

They should be able to do this in a couple hours.  I used a guy that does farm pump solar setups and he had no problem.   

 

What is he charging?

 

 

[clokwise]

11 hours ago, atpeace said:

How many volts is your battery and how many amps can it handle.  I have a 48 volt battery and 100 amp output.  To get the max watts output you multiple the amps by the volts ( e.g. 48x100= 4800 watts).

What is he charging?

 

This is one quotation:

 

Deye Hybrid Inverter 10kW. 3Phase
Freesun Lithium Battery 48V. 280Ah

20x Longi Tier1 Solar Panels 580W

+ assorted accessories and installation

= THB 377,000

 

We tend to get power cuts every couple weeks which is why we're looking at hybrid off-grid with battery. My wife is fine with cold showers, me, not so much, but no big deal.

 

Good to see replies here saying it is possible to just switch the entire house over to solar or battery. We have had a couple extended power cuts that weren't back up until early morning.  Is it possible to keep a house running on battery for an entire night?

 

[gamb00ler]

My solar installer added a second consumer unit.  The circuits that will get power during grid failure were moved from the main unit to this unit.  There is an ATS (Automatic Transfer Switch) that will route power from the batteries to this backup CU when the grid fails.  I think the ATS also disconnects our solar installation from the grid.

 

We have a 3 phase installation with a 10kW inverter.  That means during grid failure the load limit is 10kW spread over the three phases.  All the high load devices (oven, clothes dryer, shower heaters and A/C) are not included in the backup CU to ensure that we aren't exceeding the load limit of 10kW during grid outage.

[atpeace]

10 minutes ago, clokwise said:

 

This is one quotation:

 

Deye Hybrid Inverter 10kW. 3Phase
Freesun Lithium Battery 48V. 280Ah

20x Longi Tier1 Solar Panels 580W

+ assorted accessories and installation

= THB 377,000

 

We tend to get power cuts every couple weeks which is why we're looking at hybrid off-grid with battery. My wife is fine with cold showers, me, not so much, but no big deal.

 

Good to see replies here saying it is possible to just switch the entire house over to solar or battery. We have had a couple extended power cuts that weren't back up until early morning.  Is it possible to keep a house running on battery for an entire night?

 

That is expensive! I have a thread on my install last month which is similar to yours.  I bought the components and found someone to install.  Where do you live?

 

I just woke up one morning after debating for months and jumped in a car and drove to  solar panel shops.  Three shops and chose the shop I liked the most.  Purchased the panels with the agreement they would install asap.  They charged 2 baht per kw for wiring and putting on the roof.  The wires and the framing were extra.  Think about 7k.

 

The panels were on the roof in a day and everything was ready to go by end of second day.  Total cost for my system was 130k.  I have more power than I know what to do with and am going to buy an EV.

 

As for the battery being able to run all night.  Yes, I use 50% of the capacity and I also have a 48v/280 ah battery.  I'm still on the grid but haven't drawn any power from it in a month.

 

Here the thread on my install.

It is not as complicated as it seemed going into the project.  It is simply putting the panels on the roof then plugging them into the inverter, and lastly connecting the inverter to the grid.  IMO, you need a cost breakdown because  because something doesn't add up. Panels are so inexpensive and that inverter is super expensive for your needs. 

 

You mentioned you just need a backup and you are getting a premium install for a large house.  Knowing what I know now, I could put together a dependable backup system that could handle 5,000 watts for around 95k and it could be expanded in the future.

[gamb00ler]

16 hours ago, clokwise said:

at which point our smart home automation or myself can turn off any unneeded devices drawing excess power.

I am currently learning how to implement some home automation.  Do you already have a system installed?  Can you share what you are using?

 

We were experiencing many very short grid failures and the ATS switchover time was too long such that the computers and network gear would reboot and sometimes all connections would not be properly restored.  I since bought two small UPS with fast switchover to stop those problems.

 

[BritManToo]

1 hour ago, clokwise said:

This is one quotation:

 

Deye Hybrid Inverter 10kW. 3Phase
Freesun Lithium Battery 48V. 280Ah

20x Longi Tier1 Solar Panels 580W

+ assorted accessories and installation

= THB 377,000

 

Deye 3 phase inverter = 90,000bht

48v 280ah battery = 50,000bht

Longi 580W =3200bht x20 = 64,000bht

 

So thats 20kbht for parts, installation another 20kbht seems a bit expensive.

 

 

[Bandersnatch]

45 minutes ago, gamb00ler said:

I am currently learning how to implement some home automation.  Do you already have a system installed?  Can you share what you are using?

 

 

Maybe this deserves it’s own discussion as I am been toying with smart home kit for a while.

 

I will start one and link it here.

 

 

[atpeace]

1 hour ago, Bandersnatch said:

 

Maybe this deserves it’s own discussion as I am been toying with smart home kit for a while.

 

I will start one and link it here.

 

 

That is a nice looking interface.  I get all the above data using Sonoff smart devices and Anern's inverter app but I have to open different apps and not as clean. 

 

Do you use Google nest devices?   That was the game changer for me.  Just created simple commands and the wife can now easily turn on/off lights, play music, etc. and the kids that come around enjoy the "Hey Google" experience.

[Bandersnatch]

18 minutes ago, atpeace said:

That is a nice looking interface.  I get all the above data using Sonoff smart devices and Anern's inverter app but I have to open different apps and not as clean. 

 

Do you use Google nest devices?   That was the game changer for me.  Just created simple commands and the wife can now easily turn on/off lights, play music, etc. and the kids that come around enjoy the "Hey Google" experience.

Can you ask the Q on the smart home discussion I just created so we don’t hijack this one.

[UWEB]

On 9/14/2024 at 4:53 PM, clokwise said:

I'm getting quotations for a 10Kwh + battery on/off grid system. I don't have any prior knowledge of solar installations, so it's all new to me.

 

One of the questions the contractors are asking is to decide now which devices in the house I wish to stay online when there is a power cut at the grid. Not so much asking, but insisting, that I do this.

 

It was my prior assumption that, since I have will a battery backup, when the grid goes down the entire home will simply switch over to battery, at which point our smart home automation or myself can turn off any unneeded devices drawing excess power.

 

Apart from perhaps the A/C or fridge, nothing in my home actually requires a lot of current. I fail to understand the necessity of literally rewiring my brand new home to put unrelated and randomly scattered devices onto a new circuit. Further, it seems that if I did do this and my needs change later (likely will), we will have to rewire again.

 

The contractor is saying that if the grid goes down that there will suddenly be too much power drawing from the inverter/battery. But will that happen - actually? We rarely use more than one A/C at a time, and a handful of lights and fans surely can't demand that much power? And worst case - wouldn't the breaker at the battery shut it off if it's overloaded? I can deal with that, unless it can't handle much current at all - in which case I'm now questioning why I should install a battery backup at all if I can't even use it like I want?

 

My home was wired by a professional electrician familiar with solar installations - they have even already built the conduits and wired them up ready to go. He did such a terrific job - the circuit breaker box is practically a work of art.

 

So, why can't I just leave my home as-is and simply install a battery and inverter ?

 

Is this really a thing? Help me understand why I need to rewire my home.

 

Your Installer is talking about a so called Back Up Box. In case of a Grid Shut down everything connected to this Box will keep on running, while non connected ones will shut down. When I have recently have got an upgrade including Batteries I decided to exclude my Pool Pump (2 HP) and my Irrigation System as they are the biggest Consumer I have and would drain the Batteries within some hours.

If you don't have such consumers just tell your Installer everything should be connected and running while the Grid is offline.

[KhunLA]

Unless the sun is not out, very overcast/raining, 10kW inverter w/14kWh battery (if reading right) should keep the house going with no problem.   Depending how long you need it for, ease up in the AC use.

 

If that overcast and or raining, consider you won't really be needing the ACs.

 

We have 8kW inverter w/20kWh of battery, and we use about 8kWh overnight (14 hours), that's only using one 13BTU AC in the bedroom, 2 frigs (sm/med), 65" TV as monitor to my laptop, and wife is on her laptop.

 

Our usage can range from <15-50kWh a day (24 hr period) depending on sun, how little or abusive with ACs, & charging the EVs.

 

<15kWh a day (24 hrs) on our very conservative use days.   We've been basically off grid for 2 years now.  Most produced/consumed ~50kWh.

[clokwise]

8 hours ago, atpeace said:

It is not as complicated as it seemed going into the project.  It is simply putting the panels on the roof then plugging them into the inverter, and lastly connecting the inverter to the grid.  IMO, you need a cost breakdown because  because something doesn't add up. Panels are so inexpensive and that inverter is super expensive for your needs. 

 

You mentioned you just need a backup and you are getting a premium install for a large house.  Knowing what I know now, I could put together a dependable backup system that could handle 5,000 watts for around 95k and it could be expanded in the future.

 

Thanks very much for the advice and encouragement. Yeah, I'm also looking into buying these parts myself but paying a professional to install. Still taking my time with getting quotations from many places. While a battery backup is a major reason for going solar, we also want to send less baht to PEA every month.

 

[clokwise]

34 minutes ago, KhunLA said:

Our usage can range from <15-50kWh a day (24 hr period) depending on sun, how little or abusive with ACs, & charging the EVs.

 

Have you encountered any limitations when charging EVs?

[clokwise]

1 hour ago, UWEB said:

Your Installer is talking about a so called Back Up Box. In case of a Grid Shut down everything connected to this Box will keep on running, while non connected ones will shut down. When I have recently have got an upgrade including Batteries I decided to exclude my Pool Pump (2 HP) and my Irrigation System as they are the biggest Consumer I have and would drain the Batteries within some hours.

If you don't have such consumers just tell your Installer everything should be connected and running while the Grid is offline.

 

Good point. I think we could exclude the pool pump, washing machine, oven, EV charger, and possibly water heaters from the backup box. But I feel it would be reasonable to use the inverter/battery system for everything else, including AC since we generally only have one medium sized AC on in the house at any time, and no other devices use much electricity.

[clokwise]

8 hours ago, BritManToo said:

 

Deye 3 phase inverter = 90,000bht

48v 280ah battery = 50,000bht

Longi 580W =3200bht x20 = 64,000bht

 

So thats 20kbht for parts, installation another 20kbht seems a bit expensive.

 

Agreed. We're also getting quotes for installation only. We'll likely go that way.

[clokwise]

8 hours ago, gamb00ler said:

I am currently learning how to implement some home automation.  Do you already have a system installed?  Can you share what you are using?

 

We were experiencing many very short grid failures and the ATS switchover time was too long such that the computers and network gear would reboot and sometimes all connections would not be properly restored.  I since bought two small UPS with fast switchover to stop those problems.

 

 

I posted a response here.

[KhunLA]

37 minutes ago, clokwise said:

 

Have you encountered any limitations when charging EVs?

EVs get charge with solar ... BUT ... 2.3kWh is the largest drain.  That's using the MG granny/emergency charging cord.   The MG wall charger is 7.4kWh, so that is connected to the grid, and actually the only thing on the grid, that is used.  That is rarely used, as simply not needed.   Solar has plenty of excess produced that the house doesn't use.

 

EVs are MG ZS, DECO SUSU (MC), and a DIY ebike.

[KhunLA]

@clokwise Our whole house is on solar, water heaters & water pump.  Both of those used sporadically, as the water comes out of the ground via PWA pretty warm by itself.   Rarely full power, and they're only 3500w water heaters.

 

And the water pump used more during rainy season, as we store rain water, 8 tanks, and need to use when full during the day.  Topped up after rainy season, and unless PWA having water issues (drought), we really don't need to use.  We did this year, but for only couple weeks, if that, as pressure was low just before rainy season.

 

We do a lot of home cooking, baking, and two ACs; 13KBTU, on almost 24/7, and 24kBTU on 8hrs a day when hot.   We're at Prachuap municipality area, so warm all year.

 

Only time we need to be conservative, is like now, solid week of overcast & rain.   But solar still produces enough to run the house & recharge batteries from overnight use.

 

Chiang Mai, and half the year, you may not even use the ACs.   Just a few air purifiers, and they don't use much.

 

Unless have large family, a bunch of ACs, you should be able to be just about be off grid with 10kW inverter.   Really don't see the point of a back up box if using solar as priority 1, then battery as 2, grid as last resort.

 

If using grid and power goes out, and your battery just happens to be lower than you want, just don't turn stuff on.  Frigs & fans would be our bare necessities, and don't use much at all.

 

We're connected to the grid, at 26 baht a month, but rarely use.  Just over 2 years with solar & digital meter, and the meter is at 969 units/kWh.  We've used that many kWh in one month of solar.   

 

Most of that 75% was used by the EV (car), after O&A (Our & About) away from house, as I like returning near 20%.  PEA is 4 baht/kWh vs 7.5 baht/kWh at CS (Charging Stations).   So if using the car the next day, need to use grid to charge up.

[mateusz1945]

10 hours ago, BritManToo said:

 

48v 280ah battery = 50,000bht

 

example? i think you talking DIY. OP might not want headache of dealing with that 
ready batteries that communicate with deye are something like 70K for this kind of capacity

[BritManToo]

10 minutes ago, mateusz1945 said:

example? i think you talking DIY. OP might not want headache of dealing with that 
ready batteries that communicate with deye are something like 70K for this kind of capacity

https://s.lazada.co.th/s.qSIIq

51k, 55k if you want a nicer white box. 

 

Not sure why you'd want comms between box and inverter.

There's no practical reason for that.

Not sure why you'd want an expensive Deye inverter either.

I paid 12k for my mrpower 5k5w inverter and it works perfectly.

 

All the bells and whistles are ignored after you've been running it a month.

[mateusz1945]

33 minutes ago, BritManToo said:

 

Not sure why you'd want comms between box and inverter.

There's no practical reason for that.

Not sure why you'd want an expensive Deye inverter either.

I paid 12k for my mrpower 5k5w inverter and it works perfectly.

 

All the bells and whistles are ignored after you've been running it a month.

agree that for faster return on investment  everything you mention can be done and working fine.
for me Devil is in details.  Deye likely to last longer and has more flexibility connecting generator/microinverter/ smart load  ( ups mode has no delays)
also is modular . Can expand system and connect additional inverters .Battery comms can be cloud backed and remotely accessed, including errors. 
so piece of mind , futureproofing system , and of course play with bells n whistles too.  Couldn't help it

[mateusz1945]

actually looks like batteries coming down and you can buy  300ah for something like 50k after all 
adds like that poops on my facebook

[Pink7]

13 hours ago, clokwise said:

 

This is one quotation:

 

Deye Hybrid Inverter 10kW. 3Phase
Freesun Lithium Battery 48V. 280Ah

20x Longi Tier1 Solar Panels 580W

+ assorted accessories and installation

= THB 377,000

 

We tend to get power cuts every couple weeks which is why we're looking at hybrid off-grid with battery. My wife is fine with cold showers, me, not so much, but no big deal.

 

Good to see replies here saying it is possible to just switch the entire house over to solar or battery. We have had a couple extended power cuts that weren't back up until early morning.  Is it possible to keep a house running on battery for an entire night?

 

I did a setup a year ago around this size. My electric bill used to be 3xxx/month and now im 99% offgrid. I have a ATS that i switch over to the grid if needed or it switch it self the few times i do not have enough power from solar or battery. In a year it happened maybe 3-4 times.

 

I dont know the details on your power needs but i would consider double the batteries but i see your looking into a on/offgrid setup. Mine setup costed more or less 300K. 2 x 5k Growatt inverters and 28 x 320w panels and 280x32 batteries.  I did the setup and hired some manpower for for mounting on roof etc with plans and instructions from me.

 

Pink

[gamb00ler]

4 hours ago, clokwise said:

While a battery backup is a major reason for going solar, we also want to send less baht to PEA every month.

Having a battery gives you another option to save money.

 

You could switch to the Time of Use (TOU) rate which saves about 40% from 10PM - 9AM weekdays and all day Sat.+Sun+National holidays.  But, you want to make sure you don't use much power the remaining hours because it is substantially higher.  If the weather doesn't look good for solar generation during the upcoming day, you can charge your battery from the grid before 9AM to eliminate/reduce consumption during the expensive daytime hours.

[BritManToo]

8 hours ago, mateusz1945 said:

agree that for faster return on investment  everything you mention can be done and working fine.
for me Devil is in details.  Deye likely to last longer and has more flexibility connecting generator/microinverter/ smart load  ( ups mode has no delays)
also is modular . Can expand system and connect additional inverters .Battery comms can be cloud backed and remotely accessed, including errors. 
so piece of mind , futureproofing system , and of course play with bells n whistles too.  Couldn't help it

What delay would you imagine there is and why would it affect anything?

They all switch seamlessly between power sources.

 

You can't connect additional inverters after the first 6-12 months as the inverter models change every year, and never work with previous models.

 

Future proofing is an imaginary concept, there is no such thing. Even the solar panels have completely changed in the past 5 years.

 

 

[BritManToo]

7 hours ago, gamb00ler said:

Having a battery gives you another option to save money.

 

You could switch to the Time of Use (TOU) rate which saves about 40% from 10PM - 9AM weekdays and all day Sat.+Sun+National holidays.  But, you want to make sure you don't use much power the remaining hours because it is substantially higher.  If the weather doesn't look good for solar generation during the upcoming day, you can charge your battery from the grid before 9AM to eliminate/reduce consumption during the expensive daytime hours.

It's nearly 400bht a month for a TOU meter, that's more than my existing monthly PEA bill (around 300bht).

Battery charges from the solar cells, sure, in extended periods of bad weather the battery grabs some from the grid, and with all the rain my system may have needed 5 units this month ........ 20bht (ish).

[UWEB]

11 hours ago, mateusz1945 said:

example? i think you talking DIY. OP might not want headache of dealing with that 
ready batteries that communicate with deye are something like 70K for this kind of capacity

Where you have got this prices from?