The Electric Revolution

[Dabop]

I do not know what you are doing. I wasn't even aware of how a home solar system was controlled before reading this thread. But I did learn something from it. Now I want one more.

I am only aware that a bit of research is required when modifying battery bank systems. Or an expert in my case.

Maybe whatever you did is OK if no problems?

Either way stop feeling attacked by everything. It's unbecoming.

Designing and installing (and commissioning) a solar system is not something that should be done without knowing ALL of the details of how they work (in Australia for example, I had to do a four year apprenticeship as an electrical fitter as a minimum, before doing a six month TAFE college course to do 'the solar stuff' and I regularly have to update my knowledge of whats available and how it works as technology advances...
'SOME' believe a thirty second google is the equivalent- which is why there are so many poorly performing systems out there- or even ones that have caused major damage...

In Australia, only approved hybrid inverters can do gridtie, using approved battery packs, and only installed by approved installers (of which I happen to be one...)
In fact, here if you 'fiddle' with any part of your hybrid system- and they catch you- that is cause for a involuntary disconnection notice to be issued until the system is checked and passed by a qualified person.....

Seems the UK has some catching up to do if they are still letting unqualified people touch any part of the system....

Offgrid is less regulated here, but even then- there are guidelines that should be followed, and offgrid systems are even more 'critical' in one sense- in that you dont have the luxury of a fallback to the grid if you stuff up your system- from design , installation and running....any mistake will be costly....
(the internet (including AI 'answers') should be taken with a grain of salt- many DIY offgriders are decades behind in their thinking, and following outdated advice can be both costly, and lead to an extremely poorly operating system....

 

[8enotto]

Designing and installing (and commissioning) a solar system is not something that should be done without knowing ALL of the details of how they work (in Australia for example, I had to do a four year apprenticeship as an electrical fitter as a minimum, before doing a six month TAFE college course to do 'the solar stuff' and I regularly have to update my knowledge of whats available and how it works as technology advances...
'SOME' believe a thirty second google is the equivalent- which is why there are so many poorly performing systems out there- or even ones that have caused major damage...

In Australia, only approved hybrid inverters can do gridtie, using approved battery packs, and only installed by approved installers (of which I happen to be one...)
In fact, here if you 'fiddle' with any part of your hybrid system- and they catch you- that is cause for a involuntary disconnection notice to be issued until the system is checked and passed by a qualified person.....

Seems the UK has some catching up to do if they are still letting unqualified people touch any part of the system....

Offgrid is less regulated here, but even then- there are guidelines that should be followed, and offgrid systems are even more 'critical' in one sense- in that you dont have the luxury of a fallback to the grid if you stuff up your system- from design , installation and running....any mistake will be costly....
(the internet (including AI 'answers') should be taken with a grain of salt- many DIY offgriders are decades behind in their thinking, and following outdated advice can be both costly, and lead to an extremely poorly operating system....

We would go for a professionally installed system. My electrician skills are quite basic.

But I would want a system using common parts and batteries for future maintenance.

 

[Dabop]

We would go for a professionally installed system. My electrician skills are quite basic.

But I would want a system using common parts and batteries for future maintenance.

You have the issue that your system is a US style one (120v/240v 60hz) and would likely need to be UL approved- which severely restricts whats available to you, compared to us in 'TROTW' where 230v 50hz is the norm...
Add in the US xenophobia regarding the Chinese and that again takes away much of the most common (and price effective) systems...

BYD for example is one of the largest sellers in Australia (and worldwide) for both EVs and home power battery systems- yet is basically unknown in north America...

eg

Sigenergy is another that sells worldwide, and is very popular (in both Australia, the UK and Europe) yet likely unheard of your way....

Sungrow is one of the cheaper ones, but still popular here

And the Ecoflow I showed before (thats in the UK, all the others are local to me here)

Once thing you should notice is that all of them are 'modular' systems- these are even making major inroads into the offgrid scene (being hybrids, they can be used as gridties (where approved of course) or offgrid- and as they are the most common install these days in Australia (passing gridtie only installs ie no battery) they can have extra battery capacity fitted readily (just 'add another drawer to the stack') and having economy of scale, means that they are actually cheaper than an equivalent 'homebrew' DIY offgrid system in many cases...

The days of the 'homebrew offgrid system' are passing quickly here in Australia indeed- at least half of the 'new build' offgrids local to me are BYD or Sigenergy hybrids.....

 

[8enotto]

Our home runs on a 15 amp main breaker even on peak use. For 110 to 120 VAC single phase that's not a lot. It would have to be a US type system but not the biggest one out there.

More market research is required, then an installer that could be local.
There are those battery banks and inverters out there for camping use that can take solar cells. They run things with more draw than my home. So a rooftop system certainly exists.
I want my son to be able to keep the system up for decades at minimal costs. Maybe change a battery every few years or so at the most.

 

[Dabop]

Our home runs on a 15 amp main breaker even on peak use. For 110 to 120 VAC single phase that's not a lot. It would have to be a US type system but not the biggest one out there.

More market research is required, then an installer that could be local.
There are those battery banks and inverters out there for camping use that can take solar cells. They run things with more draw than my home. So a rooftop system certainly exists.
I want my son to be able to keep the system up for decades at minimal costs. Maybe change a battery every few years or so at the most.

Quite frankly- you could do it with a Ecoflow, Jackery or similar 'powerbank' which is probably what you are thinking of... they start at little 500w versions and work their way up to ones that can output 5kw or more and run welders and stuff like that....

Thats a mob you might be worth looking at, I have been following their channel for several years- and they are in the US so aimed more at US style offgridding (including complete 'how to' videos on everything from a small single bedroom 'dome house' system for their teenage daughter

Their 'goatshed solar install'

And their main solar array that runs 'everything'

Personally not a huge fan of those powerbanks- good for a beginner/novice- but you pay (and how) for that plug n play ability- they cost a LOT for what you get..... in both power and storage....

At least TinyShinyHome is pretty upfront about what works and what doesn't lol

and being in the US, the equipment he is using is readily available there...

Tiny Shiny Home

Jonathan & Ashley Longnecker and their 4 kids are building naturally and sustainably off-grid in Cochise County, Arizona providing wholesome entertainment and useful educational resources for those interested in getting back to nature, spending more time with their family, and learning to be...

www.youtube.com

 

[acbytesla]

Actually- LFP (and LYP) can actually be used as a 'straight drop in' replacement for L/A...
It's done regularly in 4wds for their 'house battery' for running the fridge etc....
No need for any changes whatsoever to the charging system...
There are literally tens of thousands (if not more) of these exact batteries in use Australia wide lol (in fact the system I was working on today has 6 of that exact same brand, but the 300Ah version)

From ny understanding this is tricky. Starting lead acid batteries have very different electrical characteristics than Lithium batteries of various chemical compositions. The resistance on the LIFEPO4 batteries is too low for the alternator and the surge fries the diodes on the alternator and can also damage the BMS on the LIFEPO4 battery.

To address this my on my RV with its dual battery system I used to employ a mechanical switch to isolate the 300ah 12 volt Lifepo4 house battery. bank from the starting system. I added a DC to DC charger between so the alternator can also charge the house batteries while driving.

The RV roof has 2ea 300 watt solar panels connected to 60 amp MPPT charge controller.

 

[acbytesla]

Quite frankly- you could do it with a Ecoflow, Jackery or similar 'powerbank' which is probably what you are thinking of... they start at little 500w versions and work their way up to ones that can output 5kw or more and run welders and stuff like that....
View attachment 65001
Thats a mob you might be worth looking at, I have been following their channel for several years- and they are in the US so aimed more at US style offgridding (including complete 'how to' videos on everything from a small single bedroom 'dome house' system for their teenage daughter
View attachment 65005
Their 'goatshed solar install'
View attachment 65003
And their main solar array that runs 'everything'
View attachment 65004
Personally not a huge fan of those powerbanks- good for a beginner/novice- but you pay (and how) for that plug n play ability-
they cost a LOT for what you get..... in both power and storage....

Exactly. They're convenient and simple. But they are expensive for what you get. But I see a lot of campers buying them.

 

[Dabop]

From ny understanding this is tricky. Starting lead acid batteries have very different electrical characteristics than Lithium batteries of various chemical compositions. The resistance on the LIFEPO4 batteries is too low for the alternator and the surge fries the diodes on the alternator and can also damage the BMS on the LIFEPO4 battery.

To address this my on my RV with its dual battery system I used to employ a mechanical switch to isolate the 300ah 12 volt Lifepo4 house battery. bank from the starting system. I added a DC to DC charger between so the alternator can also charge the house batteries while driving.

The RV roof has 2ea 300 watt solar panels connected to 60 amp MPPT charge controller.

Starting L/A aren't what these batteries are being used as replacements- they replace deepcycle L/A and you don't need a mechanical switch for the dual battery system (with its likelihood of forgetting and flattening the start battery)- a standard dual battery isolator is normally used ....

(indeed, pop the bonnet on the lux and you will find one of these charging its LYP battery pack that runs the fridge and inverter)


LFP/LYP aren't the major issue with alternator overheating problems- its just that ANY large battery pack on a stock alternator is going to have the same issues- they simply aren't designed to run at full output for hours on end- fit upgraded cooling fans on any alternator used for large battery banks- be they LFP or L/A.....
(lol- the system I was working on yesterday has SIX 300Ah Kings LFP batteries in it (24v- so a 2S3P battery bank)- 12v outside the US is pretty much 'cars and 4wds' if its a truck or motorhome (RV) its 24v....)

 

[acbytesla]

Starting L/A aren't what these batteries are being used as replacements- they replace deepcycle L/A and you don't need a mechanical switch for the dual battery system (with its likelihood of forgetting and flattening the start battery)- a standard dual battery isolator is normally used ....

(indeed, pop the bonnet on the lux and you will find one of these charging its LYP battery pack that runs the fridge and inverter)
View attachment 65008
View attachment 65009
LFP/LYP aren't the major issue with alternator overheating problems- its just that ANY large battery pack on a stock alternator is going to have the same issues- they simply aren't designed to run at full output for hours on end- fit upgraded cooling fans on any alternator used for large battery banks- be they LFP or L/A.....
(lol- the system I was working on yesterday has SIX 300Ah Kings LFP batteries in it (24v- so a 2S3P battery bank)- 12v outside the US is pretty much 'cars and 4wds' if its a truck or motorhome (RV) its 24v....)

A lot of trucks (like pretty much all Semis) and big bussess/RV in the US use 24 volt starting systems.

I'm building what we call a skoolie. It has two 12 volt lead acid starting batteries.

I'm planning on installing 400 watt panels on the roof. Two or four of the panels will be designed to slide out on heavy duty locking drawer slides from under the top panel. So I'll have 1600 watts, maybe 2400 watts to run a heat pump AC, induction stove, microwave and refrigerator. I would prefer a 48 volt house system. But 12 volt probably makes more sense.

 

[Dabop]

A lot of trucks (like pretty much all Semis) and big bussess/RV in the US use 24 volt starting systems.

I'm building what we call a skoolie. It has two 12 volt lead acid starting batteries.

I'm planning on installing 400 watt panels on the roof. Two or four of the panels will be designed to slide out on heavy duty locking drawer slides from under the top panel. So I'll have 1600 watts, maybe 2400 watts to run a heat pump AC, induction stove, microwave and refrigerator. I would prefer a 48 volt house system. But 12 volt probably makes more sense.

The entire electrical system is 24v, not just the starting system (outside the US that is)
Lights, radio, everything...


As 99% of motorhomes are native 24v (being based on truck chassis here) then it makes sense to have basically as much as possible running on that 24v directly (saving inverter losses) which is why you readily find 24v microwaves, induction cookers and the like...

The 48v fad really doesnt make much sense- it has its advantages yes- a charge controller can handle 4 times the wattage array on 48v as on 12v- but even the biggest RV cant carry tens of kw of panels- so thats no advantage...in a mobile situation...
It means your battery bank cant directly run any low voltage appliances directly (12v for a 12v system, 24v for a 24v system) so you need to run voltage converters pretty much continually- making added losses....- eating up your (usually quite limited) storage capacity....
Sure your copper losses are less at 48v- but that really only starts to become apparent at the tens of KW level- again- not something you find in most mobile situations....
And you lose the ability to use the vehicles alternator as an extra 'emergency generator' directly....

So lots of downsides, and basically no upside imho....

 

[8enotto]

Quite frankly- you could do it with a Ecoflow, Jackery or similar 'powerbank' which is probably what you are thinking of... they start at little 500w versions and work their way up to ones that can output 5kw or more and run welders and stuff like that....
View attachment 65001
Thats a mob you might be worth looking at, I have been following their channel for several years- and they are in the US so aimed more at US style offgridding (including complete 'how to' videos on everything from a small single bedroom 'dome house' system for their teenage daughter
View attachment 65005
Their 'goatshed solar install'
View attachment 65003
And their main solar array that runs 'everything'
View attachment 65004
Personally not a huge fan of those powerbanks- good for a beginner/novice- but you pay (and how) for that plug n play ability- they cost a LOT for what you get..... in both power and storage....

At least TinyShinyHome is pretty upfront about what works and what doesn't lol
View attachment 65006
and being in the US, the equipment he is using is readily available there...

Tiny Shiny Home

Jonathan & Ashley Longnecker and their 4 kids are building naturally and sustainably off-grid in Cochise County, Arizona providing wholesome entertainment and useful educational resources for those interested in getting back to nature, spending more time with their family, and learning to be...

www.youtube.com

Those are great for temporary use at a remote-ish site.

I am thinking current usage plus 50% more for future unknown draw, then ability to add on storage/panels should someday we want to charge a car.

I don't want my son to have to replace it all or have to hunt down proprietary batteries for a special system. Not all types would be easy to get here.

Obviously numbers need to be crunched to know the capacity we install.

 

[Dabop]

Those are great for temporary use at a remote-ish site.

I am thinking current usage plus 50% more for future unknown draw, then ability to add on storage/panels should someday we want to charge a car.

I don't want my son to have to replace it all or have to hunt down proprietary batteries for a special system. Not all types would be easy to get here.

Obviously numbers need to be crunched to know the capacity we install.

I know some that have been using them quite happily for smaller offgrid setups- they just arent particularly 'wallet friendly' so to speak....
As with ANY system setup, hybrid or offgrid, the very first step is an energy audit- without knowing what your needs are- you cant correctly size anything....

An energy audit will list the wattage of the devices you have (both start and run wattages- fridges for example can be 3-5 times the listed 'running wattage' to actually start- meaning a much larger inverter is needed than a newbie may think is required....)
eg


Time of day matters- during the day, they run off panel power, but nighttime usage means battery storage is needed (how much- that depends on the loads and length of time they run at night)- then you need to be able to run your daytime loads AND recharge your nighttime battery usage- that means more panels than just the daytime loads require....

Then you need the best and WORST solar generation figures for your location- this sets the size array you need for example where I am in northern Australia- best conditions (spring and autumn) are about 0.53kWh per day per '100w of panel rating'- summer is less due to heat (yes PV panels dont work well when they get hot lol- despite what some people think...), winter is less due to lower sun angle and increased airpath losses....

If I was back in the UK, then the exact same '100w' panel would only be making about 0.28kWh per day at its best (in summer)- basically about half the total daily generated power than I would get here- from the exact same 100w panel!!!!!

Designing a properly functioning system is a lot more than just 'slapping some panels on a battery'.....

 

[8enotto]

I know some that have been using them quite happily for smaller offgrid setups- they just arent particularly 'wallet friendly' so to speak....
As with ANY system setup, hybrid or offgrid, the very first step is an energy audit- without knowing what your needs are- you cant correctly size anything....

An energy audit will list the wattage of the devices you have (both start and run wattages- fridges for example can be 3-5 times the listed 'running wattage' to actually start- meaning a much larger inverter is needed than a newbie may think is required....)
eg
View attachment 65014

Time of day matters- during the day, they run off panel power, but nighttime usage means battery storage is needed (how much- that depends on the loads and length of time they run at night)- then you need to be able to run your daytime loads AND recharge your nighttime battery usage- that means more panels than just the daytime loads require....

Then you need the best and WORST solar generation figures for your location- this sets the size array you need for example where I am in northern Australia- best conditions (spring and autumn) are about 0.53kWh per day per '100w of panel rating'- summer is less due to heat (yes PV panels dont work well when they get hot lol- despite what some people think...), winter is less due to lower sun angle and increased airpath losses....

If I was back in the UK, then the exact same '100w' panel would only be making about 0.28kWh per day at its best (in summer)- basically about half the total daily generated power than I would get here- from the exact same 100w panel!!!!!

Designing a properly functioning system is a lot more than just 'slapping some panels on a battery'.....

Yup. Precisely why I want a professional installer to get the best panels for the tropics on an adequate system, with room for growth.
This is a two story home, not a 16' Airstream.

 

[acbytesla]

The entire electrical system is 24v, not just the starting system (outside the US that is)
Lights, radio, everything...
View attachment 65010
View attachment 65011
As 99% of motorhomes are native 24v (being based on truck chassis here) then it makes sense to have basically as much as possible running on that 24v directly (saving inverter losses) which is why you readily find 24v microwaves, induction cookers and the like...
View attachment 65013View attachment 65012
The 48v fad really doesnt make much sense- it has its advantages yes- a charge controller can handle 4 times the wattage array on 48v as on 12v- but even the biggest RV cant carry tens of kw of panels- so thats no advantage...in a mobile situation...
It means your battery bank cant directly run any low voltage appliances directly (12v for a 12v system, 24v for a 24v system) so you need to run voltage converters pretty much continually- making added losses....- eating up your (usually quite limited) storage capacity....
Sure your copper losses are less at 48v- but that really only starts to become apparent at the tens of KW level- again- not something you find in most mobile situations....
And you lose the ability to use the vehicles alternator as an extra 'emergency generator' directly....

So lots of downsides, and basically no upside imho....

Not just the charge controller is cheaper. So is the inverter and charger. It makes longer runs to devices much cheaper and simpler to install as well. Think about it for a minute. You can move the same amount of power on a cable 1/4 the size with 48 volt instead of 12 volt system. Price the cost of 00 guage 20 foot copper cables as opposed to 8 guage or smaller. My off grid home is 48 volt. It works great.

12 volt makes less and less sense if you ask me. I also wanted to go with a 48 volt server rack batteries on my skoolie as I own multiple spare server racks at home and it makes the cabling cheaper and simpler. If I look up 24 volt server rack batteries on Amazon, there is none to be found. Lots of 48 volt batteries. Everything about 48 volt is cheaper.

 

[acbytesla]

And DC converters are pretty cheap.

 

[Rolfe]

I'm noticing my battery looking after itself this evening. I set it to discharge as usual, and noticed the rate of discharge slowing quite a lot as it got near the limit of its discharge. It's a cold evening. It was doing that all last winter too, then stopped doing it as the temperatures rose. It's at it again now. It also offers me a winter battery conditioning setting, which tells the inverter to charge/discharge the battery for ten minutes if it gets down to 2C. This is optional because as they warn the customer this might result in drawing peak rate electricity. I always have it enabled of course, but I've only seen it do it about once, in the early morning, when of course the battery is full anyway and it discharged, netting me a small profit. I can't see any situation where it would decide to charge during peak-rate times, because of the cold.

It also, in winter, sometimes stops discharging completely before it's got to the discharge limit set, presumably because it doesn't like that limit in the cold. This can cause a small amount of peak-rate usage, but I learned last year to allow for that possibility and set the discharge a bit later to compensate. It is set up to look after itself.

 

[acbytesla]

I'm noticing my battery looking after itself this evening. I set it to discharge as usual, and noticed the rate of discharge slowing quite a lot as it got near the limit of its discharge. It's a cold evening. It was doing that all last winter too, then stopped doing it as the temperatures rose. It's at it again now. It also offers me a winter battery conditioning setting, which tells the inverter to charge/discharge the battery for ten minutes if it gets down to 2C. This is optional because as they warn the customer this might result in drawing peak rate electricity. I always have it enabled of course, but I've only seen it do it about once, in the early morning, when of course the battery is full anyway and it discharged, netting me a small profit. I can't see any situation where it would decide to charge during peak-rate times, because of the cold.

It also, in winter, sometimes stops discharging completely before it's got to the discharge limit set, presumably because it doesn't like that limit in the cold. This can cause a small amount of peak-rate usage, but I learned last year to allow for that possibility and set the discharge a bit later to compensate. It is set up to look after itself.

You can get electric pads to keep your batteries warm enough to charge and discharge. Still, you're using electricity to keep the batteries functioning.

 

[Dabop]

Not just the charge controller is cheaper. So is the inverter and charger. It makes longer runs to devices much cheaper and simpler to install as well. Think about it for a minute. You can move the same amount of power on a cable 1/4 the size with 48 volt instead of 12 volt system. Price the cost of 00 guage 20 foot copper cables as opposed to 8 guage or smaller. My off grid home is 48 volt. It works great.

12 volt makes less and less sense if you ask me. I also wanted to go with a 48 volt server rack batteries on my skoolie as I own multiple spare server racks at home and it makes the cabling cheaper and simpler. If I look up 24 volt server rack batteries on Amazon, there is none to be found. Lots of 48 volt batteries. Everything about 48 volt is cheaper.

Actually watt for watt, there is practically no difference between the three voltages in inverters ,charge controllers 48v wins, only because the same amperage charge controller will run more at 48v ie a 60A charge controller runs 750-800w at 12v, 1500-1700w at 24v and 3kw at 48v)

Copper costs are not really an issue either- as although thicker cables are needed at 12v- thy are readily available- even come with the right sized terminals on them- called starter motor cables and are readily available at any auto parts store lol- even my 8kw 12v inverter only needed a pair of them on each supply rail (luckily they thought of that hey- and its fitted with two negative terminals and two positive one lol) and in a mobile plant- well its not like you are running the inverter 100m away from the battery bank is it- in fact they are usually right next to each other,,,
'
My own system for my home is 48v- I got it dirt cheap as 'new old stock' because 48v really isnt used in homes anymore- and really hasnt been here for half a decade or more- 96v systems are better than 48v although even these are being sidelined by HV hybrid systems these days for offgrid...
This is an obsolete 48v system (mine in fact)

This is its replacement from the same company 96v...

Although you are more likely to find one of these being installed instead these days even in offgrid situations....


And yes- I did mean a 8kw 12v inverter- thats it on the left (and what it is supposed to look like minus over a decade of use)- it was running my caravan 24/7 since 2020 until earlier this year... prior to that was used fulltime in my work ute to run powertools and the like (including up to my welder...)

 

[Dabop]

You can get electric pads to keep your batteries warm enough to charge and discharge. Still, you're using electricity to keep the batteries functioning.

Or (heres a novel idea) buy the batteries appropriate to your climate????

Astounding right????

L/A or LFP are basically from slightly below zero to about 40C- outside of that range , neither is a good choice...

Luckily theres LYP- which can happily be used from minus 45C to 85C without needing heating or cooling lol

Which is why (as my summers can be well over 40C for weeks on end) I use LYP cells instead of LFP....

If you are in extreme cold conditions- well you can faf about fiddling with heater pads and all that nonsense, or -you know- just buy the appropriate cells in the first place....

 

[Dabop]

If I look up 24 volt server rack batteries on Amazon, there is none to be found.

Amazon??? PMSL....
24v rack mount batteries are a dime a dozen....
Hell you can get them from EG4 who sell in practically every country in the world...

Or EGBatts (different company) who have multiple sales in the US...

I know I wouldnt touch Signature Solar in the US with a ten foot bargepole (hell no- apart from their ripoff policies they are a yank company, so thats a deal breaker for me in the current climate...) but they stock them as well...

If you can't find them, you haven't been looking very hard lol