Re: [Emc-users] Going off-grid [Was: Thinking about going off-line eventually.

[Chris Albertson]

I bet you actually have more electronics, a computer, a router, a remote
control for the TV (yes it will not run directly off the AAA battery there
is a power control system in it) maybe an electric shaver they show up
inside all kinds of devices like the battery chargers for your DeWalt power
drill and then another one inside the drill itself

Yes, I figured 30.  I guessed about 20 light bulbs and I assumed you had a
computer if you are reading this some phone chargers   Then I assume you
must have a CNC milling machine or lathe if you are reading this EMC list
The typical CNC machine will have multiple switch mode power supplies and
if the spindle motor is DC a supply for that too.   30 is a low estimate.


Going off grid means adding even more.   For example solar panels will need
inverters if they are to supply AC power or DC:DC concerts if used to
charge batteries.   These inverters can be per panels or one large unit.
Same applies to wind power.  Likely each turbine has its own electronics.
No modern electronics will use big iron transformers.  collecting power
adds more of these switching supplies and powerful ones at that.


I might be an exception but I bet not by much.
Where I sit right now I have three computers, 4 phone charges, three AA
size battery chargers a router and Ethernet switch and some powered studio
monitors and five light bulbs.  I think that is 22 switch mode power
supplies in just one small size office.   The devices are EVERYWHERE and
for good reason they save money both in use and in manufacturing.

On Thu, Apr 26, 2018 at 7:25 PM, Erik Christiansen 
wrote:

> On 25.04.18 09:28, Chris Albertson wrote:
> > My guess is that there are already close to  30 active switch mode power
> > supplies in your house.
>
> Chris, both your posts are pure assumption and baseless supposition,
> taking little or no heed of the information I presented. The only SMPS
> in the off-grid farmhouse are in the one TV and a bunch of 240v LED
> lamps. The only other piece of electronics in the house is a battery
> powered 7-transistor radio from well back in last century.
>
> > Are they killing you TV, Radio and WiFi?
>#
>
> Please read the post over which you're firing your preconceptions. It
> read: "But cheap switchmode power supplies tend to radiate RF, and wipe
> out radio reception in my remote rural location."
>
> So your question was answered before being posed, but allow me to repeat:
> I can only listen to the radio during the day, as (at least some of) the
> LED lamps interfere overpoweringly with the radio.
>
> Thus my design is based on real-world experience, and architected to
> mitigate existing problems. It is not based on mere supposition.
>
> Erik
>
> 
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Re: [Emc-users] Going off-grid [Was: Thinking about going off-line eventually.

[Erik Christiansen]

On 25.04.18 10:20, Jon Elson wrote:
> On 04/25/2018 04:48 AM, Erik Christiansen wrote:
> > As mentioned upthread, a linear regulator wastes power. But cheap
> > switchmode power supplies tend to radiate RF, and wipe out radio
> > reception in my remote rural location.

> It is possible to place switchmode supplies in shielded enclosures to reduce
> radiated EMI as much as you want to.

Yup, that's granted, and I considered it and decent filtering at input
and output, but significant numbers of distributed "linear current
sinks, and one central very well screened & filtered SMPS" make for a
simpler design, and is risk free. (I have chased EMI reduction at a
testhouse, trying to get a plastic-cased Japanese telecommunications
product through certification, and it was a hell of a hassle. I'm not
looking for a similar experience while building one house and renovating
a second, with a 500 km return trip in between.)

> The power savings can be enormous.  If your DC bus voltage is VERY
> stable, then you can use linear regulation with minimal loss.

Indeed. As previously stated: "For that reason, rather than make the
aforementioned LED lamp dimmers switchmode, they will be linear current
sinks, and one central very well screened & filtered SMPS will drop the
48v battery bank to 21 or 22v."

> But, if the lights have to work when the battery is being charged
> through being discharged, you can't be that efficient.

That's what the one central very well screened & filtered SMPS is for.
I can buy that, add EMI filtering if needed, put it in one extra enclosure
if needed, and entirely avoid those issues in the multiple distributed
linear current sinks. (Skipping any potential need for ugly metal enclosures.)

Designing is fun, redesigning less so. This needs to just work, so I can
move on.

Erik

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Re: [Emc-users] Going off-grid [Was: Thinking about going off-line eventually.

[Erik Christiansen]

On 25.04.18 09:28, Chris Albertson wrote:
> My guess is that there are already close to  30 active switch mode power
> supplies in your house.

Chris, both your posts are pure assumption and baseless supposition,
taking little or no heed of the information I presented. The only SMPS
in the off-grid farmhouse are in the one TV and a bunch of 240v LED
lamps. The only other piece of electronics in the house is a battery
powered 7-transistor radio from well back in last century.

> Are they killing you TV, Radio and WiFi?
   #

Please read the post over which you're firing your preconceptions. It
read: "But cheap switchmode power supplies tend to radiate RF, and wipe
out radio reception in my remote rural location."

So your question was answered before being posed, but allow me to repeat:
I can only listen to the radio during the day, as (at least some of) the
LED lamps interfere overpoweringly with the radio.

Thus my design is based on real-world experience, and architected to
mitigate existing problems. It is not based on mere supposition.

Erik

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Re: [Emc-users] Going off-grid [Was: Thinking about going off-line eventually.

[Chris Albertson]

New design Switch mode supplies do not even need shielding.  Try
dis-assembling a cell phone charger and see for yourself.   In the old
days, shielding and filtering was used but today they design the parts so
they don't radiate.  The primary method is to control the raise time of the
signals so there is less RF energy in the signal.  Next they might go with
spread spectrum rather then constant frequency so the radiated power per Hz
is very much reduced and finally the PCB can be designed so the traces
carrying the signal are very poor antennas.  Doing all of this requires
specialist engineers and a lot of up front design effort and computer
simulation but it saves a ton of manufacturing cost by not needing a metal
shield or filters.

My guess is that there are already close to  30 active switch mode power
supplies in your house.  Are they killing you TV, Radio and WiFi?

When I first studied SMPS I was a student in the 1970's and the ones we
designed  and built as a student projects were horrible.  The technology
has matured a lot, like I said to the point ware now they don't even need
shielding.

On Wed, Apr 25, 2018 at 8:20 AM, Jon Elson  wrote:

> On 04/25/2018 04:48 AM, Erik Christiansen wrote:
>
>> As mentioned upthread, a linear regulator wastes power. But cheap
>> switchmode power supplies tend to radiate RF, and wipe out radio reception
>> in my remote rural location.
>>
> It is possible to place switchmode supplies in shielded enclosures to
> reduce radiated EMI as much as you want to.  The power savings can be
> enormous.  If your DC bus voltage is VERY stable, then you can use linear
> regulation with minimal loss.  But, if the lights have to work when the
> battery is being charged through being discharged, you can't be that
> efficient.
>
> Jon
>
> 
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Re: [Emc-users] Going off-grid [Was: Thinking about going off-line eventually.

[Jon Elson]

On 04/25/2018 04:48 AM, Erik Christiansen wrote:
As mentioned upthread, a linear regulator wastes power. 
But cheap switchmode power supplies tend to radiate RF, 
and wipe out radio reception in my remote rural location.
It is possible to place switchmode supplies in shielded 
enclosures to reduce radiated EMI as much as you want to.  
The power savings can be enormous.  If your DC bus voltage 
is VERY stable, then you can use linear regulation with 
minimal loss.  But, if the lights have to work when the 
battery is being charged through being discharged, you can't 
be that efficient.


Jon

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Re: [Emc-users] Going off-grid [Was: Thinking about going off-line eventually.

[Chris Albertson]

That old wives tale about switching power supplies is obsolete by at least
25 years.   If you buy a radio or TV set look inside.  There is certainly a
switcher right inside the radio or TV and it is not harming reception.

Yes if yu tried to design you own switch mode supply and did not understand
modern design techniques it would likely radiate noise.

If yu do build a power supply remember you do NOT want a VOLTAGE regulator
you want a CONSTANT CURRENT power supply for LEDs  Let the voltage go where
it wants

I suggest that you MEASURE RF radiation from the power supply before you
assume it is bad

On Wed, Apr 25, 2018 at 2:48 AM, Erik Christiansen 
wrote:

> Late reply - just back from a week off-net.
>
> On 17.04.18 11:49, Lester Caine wrote:
> > But thinking about the 'off grid' situation, a 12V battery with a low
> > dropout regulator could provide lights efficiently. While bigger
> > appliances need 'mains', quite a number around here are also 12V
> > powered, so 'building from scratch' could a DC supply direct off a
> > storage system be an alternate way forward?
>
> As mentioned upthread, a linear regulator wastes power. But cheap
> switchmode power supplies tend to radiate RF, and wipe out radio
> reception in my remote rural location. For that reason, rather than make
> the aforementioned LED lamp dimmers switchmode, they will be linear
> current sinks, and one central very well screened & filtered SMPS will
> drop the 48v battery bank to 21 or 22v. The big 10W LEDs I bought on
> fleabay for 83c each are like searchlights on 1A @ 10v. Two of them in
> series (a pair of matched luminaires) = 20v + 1 or 2v for the linear
> current sink, setting 1A max for LED survival. As even 20/22 is 91%
> efficiency, I'll go with that for the complete absence of RFI from the
> distributed units.
>
> So long as the circuit breakers or fuses protect the wiring, rather than
> the other way round, safety oughtn't be an issue. Nor will arcing, as
> MOSFETs will do all the current control.
>
> Erik
>
> 
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Re: [Emc-users] Going off-grid [Was: Thinking about going off-line eventually.

[Erik Christiansen]

Late reply - just back from a week off-net.

On 17.04.18 11:49, Lester Caine wrote:
> But thinking about the 'off grid' situation, a 12V battery with a low
> dropout regulator could provide lights efficiently. While bigger
> appliances need 'mains', quite a number around here are also 12V
> powered, so 'building from scratch' could a DC supply direct off a
> storage system be an alternate way forward?

As mentioned upthread, a linear regulator wastes power. But cheap
switchmode power supplies tend to radiate RF, and wipe out radio
reception in my remote rural location. For that reason, rather than make
the aforementioned LED lamp dimmers switchmode, they will be linear
current sinks, and one central very well screened & filtered SMPS will
drop the 48v battery bank to 21 or 22v. The big 10W LEDs I bought on
fleabay for 83c each are like searchlights on 1A @ 10v. Two of them in
series (a pair of matched luminaires) = 20v + 1 or 2v for the linear
current sink, setting 1A max for LED survival. As even 20/22 is 91%
efficiency, I'll go with that for the complete absence of RFI from the
distributed units.

So long as the circuit breakers or fuses protect the wiring, rather than
the other way round, safety oughtn't be an issue. Nor will arcing, as
MOSFETs will do all the current control.

Erik

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Re: [Emc-users] Going off-grid [Was: Thinking about going off-line eventually.

[Dale Ertley via Emc-users]

 Kent, Ohio
BOSs are built in to mil spec plastic shipable cases.
Search yahoo for HDT Global BOS. 
orwww.hdtglobal.com/product/balance-of-systems-unit-bos

On Wednesday, April 18, 2018, 10:21:04 PM EDT, Kirk Wallace 
 wrote:  
 
 On 04/18/2018 04:36 PM, Dale Ertley via Emc-users wrote:
>  This might be a nice way to go off grid. I have 2 HDT Balance of System 
>(BOS) units with 5 solar panels. Engineer told me I could tie 2 together to 
>get 220 v ac out. Outback GTFX2524, FLEXmax 60, and alot more in them. I will 
>let them go for my cost. Got at gov auction. No batteries.
> Balance of Systems Unit (BOS)

... snip

Thoughts that come to mind:

Outback products are top drawer

This seems to be a 24 Volt battetry system, my cheapish solar charger 
has set battery parameters: flooded LA, Gel LA,  but also a user 
selection that can be set for whatever such as LiFePO4 or any other 
chemistry if the user knows what they want. I would assume the Outback 
has a similar feature but I haven't found it yet. I am collecting 
LiFePO4 Headway 38120 cells when good deals come along. AlarmHookUp 
seems to be a good source of batteries, but not totally risk free.
> https://www.topratedseller.com/ebay/alarmhookup

(I'm eying these for a TIG welder
> https://www.ebay.com/itm/183036786061)

Shipping would be a very significant cost. What general origin location 
would these BOSes ship from? I'm in Kalifornia, Usa.


-- 
Kirk Wallace
http://www.wallacecompany.com/machine_shop/
http://www.wallacecompany.com/E45/

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Re: [Emc-users] Going off-grid [Was: Thinking about going off-line eventually.

[Kirk Wallace]

On 04/18/2018 04:36 PM, Dale Ertley via Emc-users wrote:

  This might be a nice way to go off grid. I have 2 HDT Balance of System (BOS) 
units with 5 solar panels. Engineer told me I could tie 2 together to get 220 v 
ac out. Outback GTFX2524, FLEXmax 60, and alot more in them. I will let them go 
for my cost. Got at gov auction. No batteries.
Balance of Systems Unit (BOS)


... snip

Thoughts that come to mind:

Outback products are top drawer

This seems to be a 24 Volt battetry system, my cheapish solar charger 
has set battery parameters: flooded LA, Gel LA,  but also a user 
selection that can be set for whatever such as LiFePO4 or any other 
chemistry if the user knows what they want. I would assume the Outback 
has a similar feature but I haven't found it yet. I am collecting 
LiFePO4 Headway 38120 cells when good deals come along. AlarmHookUp 
seems to be a good source of batteries, but not totally risk free.

https://www.topratedseller.com/ebay/alarmhookup


(I'm eying these for a TIG welder

https://www.ebay.com/itm/183036786061)


Shipping would be a very significant cost. What general origin location 
would these BOSes ship from? I'm in Kalifornia, Usa.



--
Kirk Wallace
http://www.wallacecompany.com/machine_shop/
http://www.wallacecompany.com/E45/

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Re: [Emc-users] Going off-grid [Was: Thinking about going off-line eventually.

[Dale Ertley via Emc-users]

 This might be a nice way to go off grid. I have 2 HDT Balance of System (BOS) 
units with 5 solar panels. Engineer told me I could tie 2 together to get 220 v 
ac out. Outback GTFX2524, FLEXmax 60, and alot more in them. I will let them go 
for my cost. Got at gov auction. No batteries. 
Balance of Systems Unit (BOS)

On Tuesday, April 17, 2018, 10:35:17 PM EDT, Jon Elson 
 wrote:  
 
 On 04/17/2018 03:56 PM, Dave Cole wrote:
>
>
> If you Google absorption chiller you will see that Ammonia 
> is again being considered for solar -refrigeration 
> systems.  I really don't understand why, but there is a 
> lot of chatter on that topic.
>
Direct thermal refrigeration may make sense.  Sun heats a 
water loop, drives off the ammonia, and then it is 
reabsorbed to cool the cold side.  You could do the same 
with lithium bromide, although that is a salt that could end 
up clogging things.
> Ammonia can be a hazard, but its used all of the time by 
> farmers for fertilizer around me.  I've been exposed to 
> ammonia gas and it is not fun.
When confined to a building, it can cause MASSIVE 
explosions.  The fire marshalls just LOVE ammonia systems!

Jon

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Re: [Emc-users] Going off-grid [Was: Thinking about going off-line eventually.

[Jon Elson]

On 04/17/2018 03:56 PM, Dave Cole wrote:



If you Google absorption chiller you will see that Ammonia 
is again being considered for solar -refrigeration 
systems.   I really don't understand why, but there is a 
lot of chatter on that topic.


Direct thermal refrigeration may make sense.  Sun heats a 
water loop, drives off the ammonia, and then it is 
reabsorbed to cool the cold side.  You could do the same 
with lithium bromide, although that is a salt that could end 
up clogging things.
Ammonia can be a hazard, but its used all of the time by 
farmers for fertilizer around me.   I've been exposed to 
ammonia gas and it is not fun.
When confined to a building, it can cause MASSIVE 
explosions.  The fire marshalls just LOVE ammonia systems!


Jon

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Re: [Emc-users] Going off-grid [Was: Thinking about going off-line eventually.

[Todd Zuercher]

I used to fill those anhydrous ammonia tanks for farmers.  Ah, the memories of 
donning the goggles and thick rubber gloves and holding my breath while trying 
to stay up wind.  Leaks were uncommon, but... things happen.

Todd Zuercher
P. Graham Dunn Inc.
630 Henry Street 
Dalton, Ohio 44618
Phone:  (330)828-2105ext. 2031

-Original Message-
From: Dave Cole [mailto:linuxcncro...@gmail.com] 
Sent: Tuesday, April 17, 2018 4:57 PM
To: emc-users@lists.sourceforge.net
Subject: Re: [Emc-users] Going off-grid [Was: Thinking about going off-line 
eventually.

I got out of the plant engineering end of things in the early 80's.

If you Google absorption chiller you will see that Ammonia is again being 
considered for solar -refrigeration systems.   I really don't understand why, 
but there is a lot of chatter on that topic.

Ammonia can be a hazard, but its used all of the time by farmers for fertilizer 
around me.   I've been exposed to ammonia gas and it is not fun.  This was back 
in the blue print days.  As a entry job, I ran off thousands of blue prints.   
Sometimes the machine would malfunction and drive me out of the "blue print 
room" which was force ventilated to the outside air because of the ammonia 
hazard.

Dave

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Re: [Emc-users] Going off-grid [Was: Thinking about going off-line eventually.

[Dave Cole]

On 4/16/2018 9:43 PM, Jon Elson wrote:

On 04/16/2018 10:43 AM, Dave Cole wrote:


If you want to get fancy, you can chill water with heat using an 
ammonia absorption system (chiller).   That's what hospitals and many 
large commerical buildings use for air conditioning.    But they get 
complex and you need to deal with ammonia.   Really nasty stuff. 
IMO, not worth the complexity.



Nobody is using ammonia absorption chillers anymore (at least in the 
US).  It is very inefficient.
There was this co-generation fallacy in the 1960's through the 1980's, 
maybe.  The idea is, if you have to make steam for process heat, then 
it is free to extract energy to run turbine alternators to make 
electricity from the high-pressure steam, and then send the 
low-pressure exhaust from the turbines to the process (hot water, 
steam heat, whatever).  And, if you have to provide electricity from 
the turbines, then the process steam is free. Well, the fallacy is 
that neither of these is actually free!


So, everybody finally understood the error in thinking, and cut WAY 
back on the size of their boilers.


So, almost anyplace where a steam-powered chiller once stood, there is 
now an electric turbine chiller with a variable-speed drive and 
variable vane control, and it uses WAY less energy than the old steam 
chillers.


Oh, and the ammonia absorption systems were mostly phased out in the 
1950's for lithium bromide absorption chillers.  Less hazardous and 
more efficient.


Jon



I got out of the plant engineering end of things in the early 80's.

If you Google absorption chiller you will see that Ammonia is again 
being considered for solar -refrigeration systems.   I really don't 
understand why, but there is a lot of chatter on that topic.


Ammonia can be a hazard, but its used all of the time by farmers for 
fertilizer around me.   I've been exposed to ammonia gas and it is not 
fun.  This was back in the blue print days.  As a entry job, I ran off 
thousands of blue prints.   Sometimes the machine would malfunction and 
drive me out of the "blue print room" which was force ventilated to the 
outside air because of the ammonia hazard.


Dave

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Re: [Emc-users] Going off-grid [Was: Thinking about going off-line eventually.

[Gene Heskett]

On Tuesday 17 April 2018 12:49:19 Przemek Klosowski wrote:

> On Tue, Apr 17, 2018 at 9:00 AM, Gene Heskett  
wrote:
> > i don't see why not, Lester. 12 or 24 volts would go a long ways
> > toward keeping the NEC out of your hair. Insurance folks are
> > stickier about such stuff, so I'd ask them if they had any special
> > wireing rules for low voltage led lighting. The only thing that
> > comes to my pre-coffee mind is the heavier wire the 12 volt stuff
> > would need, whereas 24 could run on a gauge smaller, and 48 on
> > really small wire.  I would fuse it, using fuses of 150 to 200% of
> > the leds draw though. Provided that was also under the wires
> > textbook ampere capacity.
> >
> > I don't know if the NEC has addressed that yet. but I'd sure do some
> > checking before I built a $100k house with all led lighting. My copy
> > is now 20 years old, and that chapter wasn't even a twinkle in
> > anybodies eyes then.
>
> Be careful with DC: the DC circuit arcing is much worse than AC.

That is somewhat subjective. A DC circuit always has to interrupt the 
full load amps, where as the AC circuit will arc a bit as the switch is 
opening, but will not re-establish that arc after the first zero 
crossing extinguishes it.

This is of course assuming a resistive load. But adding the inductance of  
a transformer or a motor to the load circuit, and the AC still functions 
pretty well, but the DC has to contend with the arc for a much longer 
and more damaging time, until the switch contacts have separated far 
enough to extinguish the arc, since the inductance wants to maintain the 
current flow until the arcing has finally used up the energy stored in 
the inductance.  One trick often used in DC contactor coil controls is 
to have 2 SCR's, anode coupled by a major fraction of a microfarad, but 
only one controls the coil. Both SCR's are triggered by the same signal. 
The one thats on, see's the huge negative pulse coupled from the one 
thats off turning on, which reverses the voltage on the one that is on 
long enough for it to turn off. Next pulse reverses the state of the 2 
SCR's, turning the relay coil back on. The SCR's are typically able to 
withstand 600 or more volts, and the inductance's energy is quickly 
absorbed by the on SCR. The energy that would cause the arc just rings 
back and forth, with some of the reversed current getting shoved back 
thru the coil, with a slight improvement of the off time if everything 
is tuned right.

> That's why DC specs for switches and relays are significantly derated
> compared to AC. The LED lighting fortunately mitigates that somehow by
> using much less current, but if you wire the whole system and push
> tens of amps, it would be a mistake to just wing it because "NEC
> doesn't cover low voltage".
>
Agreed, 200%.

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--
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-Ed Howdershelt (Author)
Genes Web page 

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Re: [Emc-users] Going off-grid [Was: Thinking about going off-line eventually.

[John Kasunich]

On Tue, Apr 17, 2018, at 12:53 PM, Chris Albertson wrote:
> What I meant was "no fixture" not "better fixture"  For example if you
> design the room for LED lighting you can design in something like a
> crown molding.  Then you can runs a LED strip all the aw atone the top
> of every wall.
> 
> In a large my cousin tore out all is hanging florescent fixtures and
> then directly attached LED strips to the painted ceiling he spaced the
> rows of LEDs every 24 inches.  It looks bad if yu do this in a living
> room but i the garage is is bright as daylight.  The strips are
> self-adhesive and very easy to use

Until the chinese LED strips develop a short somewhere, and the low-voltage but 
fairly high current power supply overheats the strip.  Would not want the strip 
mounted directly to wooden joists in the garage.  There is a reason that even 
the el-cheapo 4' shop lights are made of metal.

-- 
  John Kasunich
  jmkasun...@fastmail.fm

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Re: [Emc-users] Going off-grid [Was: Thinking about going off-line eventually.

[Chris Albertson]

 Yes that is true, there is a threshold for what is considered "low
voltage" an when this went into NEC they were thinking about door
bell, telephones and alarm system and heat thermostats.

But you can use high voltage as long as you follow the code.   When
solar panels are installed they almost always use conduit for the DC
wire.


> Yes, quite a bit, for starters it must be class 2 compliant. And they
> draw a line at 30 volts. With separate 12 and 24 volt categories.
>
> This is probably the best starter reading:
>
> 
>
> The language used is much closer to easily understood than the typical
> NEC edicts.
>
> --
> Cheers, Gene Heskett
> --
> "There are four boxes to be used in defense of liberty:
>  soap, ballot, jury, and ammo. Please use in that order."
> -Ed Howdershelt (Author)
> Genes Web page 
>
> --
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> engaging tech sites, Slashdot.org! http://sdm.link/slashdot
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Re: [Emc-users] Going off-grid [Was: Thinking about going off-line eventually.

[Chris Albertson]

What I meant was "no fixture" not "better fixture"  For example if you
design the room for LED lighting you can design in something like a
crown molding.  Then you can runs a LED strip all the aw atone the top
of every wall.

In a large my cousin tore out all is hanging florescent fixtures and
then directly attached LED strips to the painted ceiling he spaced the
rows of LEDs every 24 inches.  It looks bad if yu do this in a living
room but i the garage is is bright as daylight.  The strips are
self-adhesive and very easy to use

On Tue, Apr 17, 2018 at 4:18 AM, Erik Christiansen
 wrote:
> On 17.04.18 03:14, Chris Albertson wrote:
>> If you are thinking about LED lighting, don't try and replace incandescent
>> bulbs.  That works and is what people do but if you are building from
>> scratch yu design the LEDS into the architecture.The most obvious
>> example is to place them under the wall cabinets in a kitchen.   Just glue
>> a strip of them on."Everyone" does this with new kitchens.  The idea
>> can be extended to living rooms and bedroom and other places.   Use some
>> kind of trim molding to shield the LEDs from direct view but let the light
>> bounce off the ceiling.   Convetional designs use one of a few fixtures but
>> with LEDS you want hundreds often distributed over a wide space but hidden
>> by a baffle.
>
> You've sold me. My father always favoured that, but never managed to
> implement it. I'll keep the wall lamps I've designed, for ambience, but
> omit ceiling lights in favour of higher wall-mounted angled uplights for
> light off the ceiling. Oh ... may be able to design the uplights
> into the top of the one wall lamp design ... where's that bit of paper?
>
> Erik
>
> --
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Re: [Emc-users] Going off-grid [Was: Thinking about going off-line eventually.

[Przemek Klosowski]

On Tue, Apr 17, 2018 at 9:00 AM, Gene Heskett  wrote:
>
> i don't see why not, Lester. 12 or 24 volts would go a long ways toward
> keeping the NEC out of your hair. Insurance folks are stickier about
> such stuff, so I'd ask them if they had any special wireing rules for
> low voltage led lighting. The only thing that comes to my pre-coffee
> mind is the heavier wire the 12 volt stuff would need, whereas 24 could
> run on a gauge smaller, and 48 on really small wire.  I would fuse it,
> using fuses of 150 to 200% of the leds draw though. Provided that was
> also under the wires textbook ampere capacity.
>
> I don't know if the NEC has addressed that yet. but I'd sure do some
> checking before I built a $100k house with all led lighting. My copy is
> now 20 years old, and that chapter wasn't even a twinkle in anybodies
> eyes then.
>
Be careful with DC: the DC circuit arcing is much worse than AC.
That's why DC specs for switches and relays are significantly derated
compared to AC. The LED lighting fortunately mitigates that somehow by
using much less current, but if you wire the whole system and push
tens of amps, it would be a mistake to just wing it because "NEC
doesn't cover low voltage".

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Re: [Emc-users] Going off-grid [Was: Thinking about going off-line eventually.

[Chris Albertson]

If efficiency  is the goal then don't use 12VDC.   Go up to 36 or 48
volts at lest.   The best systems are like those use in the solar
industry at 400+ volts DC.   Power loss in the wire is "I squared R"
so there should be an incentive to reduce I.  Doubling the voltage
reduces loss by 4X doubling it twice to 48V cuts the loss by16x.
The LEDS do NOT run off 12 volts.  Your power supply might accept 12V
but the output is "constant current"

Do NOT use a "low dropout" regulator.. They voltage regulation by
converting excess voltage to heat and wasting it.  You want a switch
mode supply.  Those can be very efficient.  If you have a little box
that takes 12V and powers LEDs it is almost certainly a switching mode
power supply.

In the worst case where you have one 12V battery and you want to power
one LED and you use a simple low dropout regulated about 90% of the
power is wasted while on the other hand a switcher type regulator can
waste less then 5% if setup right.

12 volts DC is a very poor distribution system.  The cost of the wire
is so much and almost noting runs on 12V.  It has to be converted
using some kind of power supply

A power supply to takes AC and converts to constant current for LED
uses no more or less input power then a 12V power supply.  Where you
get the gain from DC is that you loose the need for the DC-> inverter,
you simply distribute the DC.

On Tue, Apr 17, 2018 at 3:49 AM, Lester Caine  wrote:
> On 17/04/18 11:14, Chris Albertson wrote:
>>
>> If you are thinking about LED lighting, don't try and replace incandescent
>> bulbs.  That works and is what people do but if you are building from
>> scratch yu design the LEDS into the architecture.
>
>
> I've replaced almost all the existing light bulbs with LED ones. The best
> change was in the workshop where the fluorescent tubes are now LED versions.
> Instant start and no flickering! But while fitting them I began to wonder if
> now is the time the lighting circuits in the house simply move to 12V DC?
> The kitchen has a number of 12V transformers powering the lights. The LED
> bulbs are taking a 20th of the power the original bulbs used so one power
> pack could power the whole lot with power left over! But thinking about the
> 'off grid' situation, a 12V battery with a low dropout regulator could
> provide lights efficiently. While bigger appliances need 'mains', quite a
> number around here are also 12V powered, so 'building from scratch' could a
> DC supply direct off a storage system be an alternate way forward?
>
> --
> Lester Caine - G8HFL
> -
> Contact - http://lsces.co.uk/wiki/?page=contact
> L.S.Caine Electronic Services - http://lsces.co.uk
> EnquirySolve - http://enquirysolve.com/
> Model Engineers Digital Workshop - http://medw.co.uk
> Rainbow Digital Media - http://rainbowdigitalmedia.co.uk
>
>
> --
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Re: [Emc-users] Going off-grid [Was: Thinking about going off-line eventually.

[Gene Heskett]

On Tuesday 17 April 2018 06:49:34 Lester Caine wrote:

> On 17/04/18 11:14, Chris Albertson wrote:
> > If you are thinking about LED lighting, don't try and replace
> > incandescent bulbs.  That works and is what people do but if you are
> > building from scratch yu design the LEDS into the architecture.
>
> I've replaced almost all the existing light bulbs with LED ones. The
> best change was in the workshop where the fluorescent tubes are now
> LED versions. Instant start and no flickering! But while fitting them
> I began to wonder if now is the time the lighting circuits in the
> house simply move to 12V DC? The kitchen has a number of 12V
> transformers powering the lights. The LED bulbs are taking a 20th of
> the power the original bulbs used so one power pack could power the
> whole lot with power left over! But thinking about the 'off grid'
> situation, a 12V battery with a low dropout regulator could provide
> lights efficiently. While bigger appliances need 'mains', quite a
> number around here are also 12V powered, so 'building from scratch'
> could a DC supply direct off a storage system be an alternate way
> forward?

i don't see why not, Lester. 12 or 24 volts would go a long ways toward 
keeping the NEC out of your hair. Insurance folks are stickier about 
such stuff, so I'd ask them if they had any special wireing rules for 
low voltage led lighting. The only thing that comes to my pre-coffee 
mind is the heavier wire the 12 volt stuff would need, whereas 24 could 
run on a gauge smaller, and 48 on really small wire.  I would fuse it, 
using fuses of 150 to 200% of the leds draw though. Provided that was 
also under the wires textbook ampere capacity.

I don't know if the NEC has addressed that yet. but I'd sure do some 
checking before I built a $100k house with all led lighting. My copy is 
now 20 years old, and that chapter wasn't even a twinkle in anybodies 
eyes then.

I wonder if a google search might turn up something?

Yes, quite a bit, for starters it must be class 2 compliant. And they 
draw a line at 30 volts. With separate 12 and 24 volt categories.

This is probably the best starter reading:



The language used is much closer to easily understood than the typical 
NEC edicts.

-- 
Cheers, Gene Heskett
--
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 

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Re: [Emc-users] Going off-grid [Was: Thinking about going off-line eventually.

[Erik Christiansen]

On 17.04.18 03:14, Chris Albertson wrote:
> If you are thinking about LED lighting, don't try and replace incandescent
> bulbs.  That works and is what people do but if you are building from
> scratch yu design the LEDS into the architecture.The most obvious
> example is to place them under the wall cabinets in a kitchen.   Just glue
> a strip of them on."Everyone" does this with new kitchens.  The idea
> can be extended to living rooms and bedroom and other places.   Use some
> kind of trim molding to shield the LEDs from direct view but let the light
> bounce off the ceiling.   Convetional designs use one of a few fixtures but
> with LEDS you want hundreds often distributed over a wide space but hidden
> by a baffle.

You've sold me. My father always favoured that, but never managed to
implement it. I'll keep the wall lamps I've designed, for ambience, but
omit ceiling lights in favour of higher wall-mounted angled uplights for
light off the ceiling. Oh ... may be able to design the uplights
into the top of the one wall lamp design ... where's that bit of paper?

Erik

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Re: [Emc-users] Going off-grid [Was: Thinking about going off-line eventually.

[Lester Caine]

On 17/04/18 11:14, Chris Albertson wrote:

If you are thinking about LED lighting, don't try and replace incandescent
bulbs.  That works and is what people do but if you are building from
scratch yu design the LEDS into the architecture.


I've replaced almost all the existing light bulbs with LED ones. The 
best change was in the workshop where the fluorescent tubes are now LED 
versions. Instant start and no flickering! But while fitting them I 
began to wonder if now is the time the lighting circuits in the house 
simply move to 12V DC? The kitchen has a number of 12V transformers 
powering the lights. The LED bulbs are taking a 20th of the power the 
original bulbs used so one power pack could power the whole lot with 
power left over! But thinking about the 'off grid' situation, a 12V 
battery with a low dropout regulator could provide lights efficiently. 
While bigger appliances need 'mains', quite a number around here are 
also 12V powered, so 'building from scratch' could a DC supply direct 
off a storage system be an alternate way forward?


--
Lester Caine - G8HFL
-
Contact - http://lsces.co.uk/wiki/?page=contact
L.S.Caine Electronic Services - http://lsces.co.uk
EnquirySolve - http://enquirysolve.com/
Model Engineers Digital Workshop - http://medw.co.uk
Rainbow Digital Media - http://rainbowdigitalmedia.co.uk

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Re: [Emc-users] Going off-grid [Was: Thinking about going off-line eventually.

[Chris Albertson]

If you are thinking about LED lighting, don't try and replace incandescent
bulbs.  That works and is what people do but if you are building from
scratch yu design the LEDS into the architecture.The most obvious
example is to place them under the wall cabinets in a kitchen.   Just glue
a strip of them on."Everyone" does this with new kitchens.  The idea
can be extended to living rooms and bedroom and other places.   Use some
kind of trim molding to shield the LEDs from direct view but let the light
bounce off the ceiling.   Convetional designs use one of a few fixtures but
with LEDS you want hundreds often distributed over a wide space but hidden
by a baffle.

On Tue, Apr 17, 2018 at 12:24 AM, Erik Christiansen  wrote:

> On 16.04.18 09:53, Chris Albertson wrote:
> > >
> > > I'm also looking at a camping fridge with phase-change material inside
> > > the insulation. That only needs power for a couple of hours in the
> > > morning, and again in the afternoon, so does not load the batteries if
> > > there's sun.
> > >
> >
> > Not a "camping" fridge but a marine refrigerator.  These are installed in
> > sailboats and are really common.  First you buy vacuum panels,  There are
> > made of stainless steel and you assemble the panels into a container
> shape.
>
> Many thanks Chris. "DC marine refrigerator" provides interesting hits.
> I'm partial to the ready-made ones, as it'll be much more fun building
> LED lighting than reimplementing refrigeration. (Not much call for
> glossy woodwork in a fridge, either. I have some centuries old Redgum or
> Redbox¹, from small logs that were in a fire at least a century ago.
> They are charred on the outside, but the heat darkened the inner wood to
> a deep burgundy. Even in the round, it hasn't cracked. Some of it's sawn
> up, but some small (8") rounds not yet. They'll make good lamp parts.
> Some bits of Manuka burl are sketched in for wingtips on one design.
> (With 1/3 of a microwave oven platter as diffuser, if I can cut 'em into
> 120° sectors.) Just need time, and either clear out the workshop here,
> or build the one there.)
>
> Erik
>
> ¹ Eucalyptus
>
> 
> --
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Re: [Emc-users] Going off-grid [Was: Thinking about going off-line eventually.

[Erik Christiansen]

> Thanks Erik. Some of the above I've not heard about till now, like the 
> salt water battery. And its sounding like costs are coming down, just 
> not fast enough to do me a lot of good.

The brand is Aquion, and there's a blurb here:
https://www.youtube.com/watch?v=1EhnmWo2CZ8

I kept the URL, but decided against the batteries on the basis of
economics, not just limited charge rate.

There's also an "UltraBattery", which is LA with supercaps in front. The
supercaps take the frequent charge/discharge, and the LA provides the
depth, AIUI. They are supposed to last twice as long as LA, but were
also twice the price when I last looked.

Out of chemical batteries, I think it's between ZnBr and LiFePO4 at the
moment.

Erik

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Re: [Emc-users] Going off-grid [Was: Thinking about going off-line eventually.

[Erik Christiansen]

On 16.04.18 09:53, Chris Albertson wrote:
> >
> > I'm also looking at a camping fridge with phase-change material inside
> > the insulation. That only needs power for a couple of hours in the
> > morning, and again in the afternoon, so does not load the batteries if
> > there's sun.
> >
> 
> Not a "camping" fridge but a marine refrigerator.  These are installed in
> sailboats and are really common.  First you buy vacuum panels,  There are
> made of stainless steel and you assemble the panels into a container shape.

Many thanks Chris. "DC marine refrigerator" provides interesting hits.
I'm partial to the ready-made ones, as it'll be much more fun building
LED lighting than reimplementing refrigeration. (Not much call for
glossy woodwork in a fridge, either. I have some centuries old Redgum or
Redbox¹, from small logs that were in a fire at least a century ago.
They are charred on the outside, but the heat darkened the inner wood to
a deep burgundy. Even in the round, it hasn't cracked. Some of it's sawn
up, but some small (8") rounds not yet. They'll make good lamp parts.
Some bits of Manuka burl are sketched in for wingtips on one design.
(With 1/3 of a microwave oven platter as diffuser, if I can cut 'em into
120° sectors.) Just need time, and either clear out the workshop here,
or build the one there.)

Erik

¹ Eucalyptus

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Re: [Emc-users] Going off-grid [Was: Thinking about going off-line eventually.

[Jon Elson]

On 04/16/2018 10:43 AM, Dave Cole wrote:


If you want to get fancy, you can chill water with heat 
using an ammonia absorption system (chiller).   That's 
what hospitals and many large commerical buildings use for 
air conditioning.But they get complex and you need to 
deal with ammonia.   Really nasty stuff. IMO, not 
worth the complexity.



Nobody is using ammonia absorption chillers anymore (at 
least in the US).  It is very inefficient.
There was this co-generation fallacy in the 1960's through 
the 1980's, maybe.  The idea is, if you have to make steam 
for process heat, then it is free to extract energy to run 
turbine alternators to make electricity from the 
high-pressure steam, and then send the low-pressure exhaust 
from the turbines to the process (hot water, steam heat, 
whatever).  And, if you have to provide electricity from the 
turbines, then the process steam is free.  Well, the fallacy 
is that neither of these is actually free!


So, everybody finally understood the error in thinking, and 
cut WAY back on the size of their boilers.


So, almost anyplace where a steam-powered chiller once 
stood, there is now an electric turbine chiller with a 
variable-speed drive and variable vane control, and it uses 
WAY less energy than the old steam chillers.


Oh, and the ammonia absorption systems were mostly phased 
out in the 1950's for lithium bromide absorption chillers.  
Less hazardous and more efficient.


Jon

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Re: [Emc-users] Going off-grid [Was: Thinking about going off-line eventually.

[Jon Elson]

On Monday 16 April 2018 06:29:12 Erik Christiansen wrote:


In my new build, lighting will all be LED, run from DC. 
The inverter
won't need to be running for that. The plan is to make 
some of the

light fittings.
Yes, I think you can do much better making your own LED 
setups than buying commercial.
I have been using 102 Lm/W Cree LEDs from Digi-Key.  Not 
super cheap, but at the time they were the best efficiency.  
Probably you can get even better today.  I'm still on-grid, 
and was VERY happy with a massive reduction in electricity 
consumption with these. I've finally replaced all 3 
fluorescent tube fixtures in our kitchen, which get a LOT of 
use.  Went from 103 W (read by a real Wattmeter) down to 21 
W, and about the same light output.


See
http://pico-systems.com/Lighting.html

for more description and a pic.

Jon

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Re: [Emc-users] Going off-grid [Was: Thinking about going off-line eventually.

[Chris Albertson]

>
> I'm also looking at a camping fridge with phase-change material inside
> the insulation. That only needs power for a couple of hours in the
> morning, and again in the afternoon, so does not load the batteries if
> there's sun.
>

Not a "camping" fridge but a marine refrigerator.  These are installed in
sailboats and are really common.  First you buy vacuum panels,  There are
made of stainless steel and you assemble the panels into a container shape.
  There are many shops who can do this for you.  The refrigerant is used to
freeze a block of  some kind of liquid.  The liquid has very high heat of
solidification, even higher then water and on the boat they might use
engine power or shore power to run th mechanical refrigerator pump to
freeze the coolant.   You can go a week with no power and the food stays
cold or even frozen.

Most are set up to run either off the engine with a belt driver
electrically from an AC motor if shore power is available.  They use a
mechanical control to select the drive motor.  It is not hard to find very
nice units that last a lifetime even in a saltwater environment.

Marine hardware stores are good paces to shop for DC power equipment.  For
example need nice looking LED fixtures or a breaker panel for DC circuit
breakers the is not make from cheap plastic?  The parts are all plated and
finish so as to stand up to a salt water environment for 20+ years

The equipment made for sailboats is ideal for people needing to conserve
power.   A person crossing an ocean on a small boat has with them perhaps
30 hours diesel fuel for the 21 day trip and they want to have lights,
radio, food and so on.   You can do it running a 20HP engine about 5% duty
cycle., for a few hours every few days. On a small boat wind and solar
can work but the amount you get is tiny because yo lack space for a large
system

If you are on land then you can install a huge grid-tie system.   I know of
one person whoalsay has a negative electric bill.  Hs large house is
covered in solar panels, even on the sides of the rood that face the
"wrong" way.


>
>
-- 

Chris Albertson
Redondo Beach, California
--
Check out the vibrant tech community on one of the world's most
engaging tech sites, Slashdot.org! http://sdm.link/slashdot
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Re: [Emc-users] Going off-grid [Was: Thinking about going off-line eventually.

[Dave Cole]

I've had a open loop ground water heat pump in my house for 22 years.   
I'm ripping it out soon since they just ran natural gas down the road.  
I travel for work, and I need  a system that works very reliably.   
Ground water heat pumps can be high maintenance.

PM me if you want to discuss.

I will be installing some PV panels in the next year as I have a large 
section of roof that is almost perfectly positioned.   It will be a grid 
tie system.
The power company will buy back power at the same rate as I buy it for 
the next 10 years or so.   So that is pretty much a no-brainer.   If 
the power company is volunteering to be my battery bank, I'm good with 
that!


I'm also in a good location for wind.   They have put up a very large 
wind farm just southeast of me about 10 miles.   But I have't gone down 
that road yet.  If I do the grid tie for the solar it makes sense to tie 
in windpower as well.


If you have a source of waste oil around you, that could be a good heat 
source.   Its not hard to find for $1/gallon or less if you want to buy 
it.    Most gas stations pay to have waste oil removed, so if you offer 
to remove it for free..  you will frequently get an ok.. just do it.   
The tank is behind the building.. etc.   Used 55 gallon steel drums are 
not hard to find for storage.    One gallon has about 120K btu of heat 
content. Waste oil is a lot easier to move and handle than wood!  You 
just need the right pump.


If you want to get fancy, you can chill water with heat using an ammonia 
absorption system (chiller).   That's what hospitals and many large 
commerical buildings use for air conditioning.    But they get complex 
and you need to deal with ammonia.   Really nasty stuff. IMO, not 
worth the complexity.



On 4/16/2018 7:45 AM, Gene Heskett wrote:

On Monday 16 April 2018 06:29:12 Erik Christiansen wrote:


On 15.04.18 19:40, Gene Heskett wrote:

Greetings all;

I see Banggood has a 500 watt wind thingy for under $200 that net
folks are calling professional grade stuff. I am looking to put up
an anerometer to record the wind speeds, one of those 3 cups designs
that isn't direction sensitive, and one of these card computers to
log what it sees so as to get an idea who many of these 500 watt
things I'd need to keep a bank of truck batteries topped up while
running the house, including the AC.

Has anyone else walked this trail, or do I have to start with a
machete?

Gene, my off-grid build has so far only passed planning approval, and
I've just embarked on building approval. It is based on wood-stove
heating plus 7¹ kW of PV panels on a 30° roof, not quite matching my
38° south latitude. Battery requirements are reduced by trying to use
the aircon(s) only/mostly when it's hot & sunny, and using a heat pump
for non-winter water heating, as that uses only a quarter of the power
of direct water heating, taking the other 3/4 of the energy from the
air. The secret is to run dishwasher, washing machine, lathe, milling
machine, anything you can in the middle of the day, powered directly
from the PV array, not the battery.
In winter, water heating is by an in-flue SS double-skinned tubular
unit. (Hot water system vented, so it's not a pressure vessel.) Fuel
supplied by 2 sq. km. of forest on the property.

I think grandpa's hot water was pressurized, it was a copper coil in the
firebox of grandma's wood fired Monarch cookstove. The water was pumped
up to a water tanks of 5k gallons on a 25 foot tower so the gravity fed
pressure wasn't very high.  Fed by several hundred acres of riverbottom
forest. Ice from the coon river was covered with sawdust from his
sawmill that made all the building materials needed although the ice
house itself was hollow tile. Several tons of river ice was cut and
hauled up to the ice house in Jan/Feb, and he had ice for the icebox all
summer and into a foot of snow on the ground in late fall.


Batteries: Even deep-cycle LA are not worth the biscuit. LiFePO4 are
better than plain Li-Ion for fixed installation, being _much_ less
flammable, and more robust. The zinc-bromide flow battery from Redflow
is more robust still. Not only can it be left for years on a shelf
either charged or 100% dead flat, but it needs to to be run dead flat
every few weeks to keep it young. It is a SS box on top of a 190 L
tank full of water & chemicals, so it'll tend to put a fire out if
that melts the tank. A vent tube to outdoors is advised, as in
extremis there could be a smell of bromine, possibly.

It was originally sold as the ZBM2 for about $7k for a 10 kWh unit
with inbuilt long-life BLDC pumps and controller. Now it comes in a
consumer-friendly lockable outdoors enclosure and what-not for around
$12k installed. I've been umming and aahing about a second one for
long dark winter weeks, but I live alone, and it's cheaper by several
country miles to just arc up the petrol generator the year that
happens.

Or fire up the 20kw nat gas fed standby out back of my garage/shop.

Re: [Emc-users] Going off-grid [Was: Thinking about going off-line eventually.

[Gene Heskett]

On Monday 16 April 2018 06:29:12 Erik Christiansen wrote:

> On 15.04.18 19:40, Gene Heskett wrote:
> > Greetings all;
> >
> > I see Banggood has a 500 watt wind thingy for under $200 that net
> > folks are calling professional grade stuff. I am looking to put up
> > an anerometer to record the wind speeds, one of those 3 cups designs
> > that isn't direction sensitive, and one of these card computers to
> > log what it sees so as to get an idea who many of these 500 watt
> > things I'd need to keep a bank of truck batteries topped up while
> > running the house, including the AC.
> >
> > Has anyone else walked this trail, or do I have to start with a
> > machete?
>
> Gene, my off-grid build has so far only passed planning approval, and
> I've just embarked on building approval. It is based on wood-stove
> heating plus 7¹ kW of PV panels on a 30° roof, not quite matching my
> 38° south latitude. Battery requirements are reduced by trying to use
> the aircon(s) only/mostly when it's hot & sunny, and using a heat pump
> for non-winter water heating, as that uses only a quarter of the power
> of direct water heating, taking the other 3/4 of the energy from the
> air. The secret is to run dishwasher, washing machine, lathe, milling
> machine, anything you can in the middle of the day, powered directly
> from the PV array, not the battery.

> In winter, water heating is by an in-flue SS double-skinned tubular
> unit. (Hot water system vented, so it's not a pressure vessel.) Fuel
> supplied by 2 sq. km. of forest on the property.

I think grandpa's hot water was pressurized, it was a copper coil in the 
firebox of grandma's wood fired Monarch cookstove. The water was pumped 
up to a water tanks of 5k gallons on a 25 foot tower so the gravity fed 
pressure wasn't very high.  Fed by several hundred acres of riverbottom 
forest. Ice from the coon river was covered with sawdust from his 
sawmill that made all the building materials needed although the ice 
house itself was hollow tile. Several tons of river ice was cut and 
hauled up to the ice house in Jan/Feb, and he had ice for the icebox all 
summer and into a foot of snow on the ground in late fall.

> Batteries: Even deep-cycle LA are not worth the biscuit. LiFePO4 are
> better than plain Li-Ion for fixed installation, being _much_ less
> flammable, and more robust. The zinc-bromide flow battery from Redflow
> is more robust still. Not only can it be left for years on a shelf
> either charged or 100% dead flat, but it needs to to be run dead flat
> every few weeks to keep it young. It is a SS box on top of a 190 L
> tank full of water & chemicals, so it'll tend to put a fire out if
> that melts the tank. A vent tube to outdoors is advised, as in
> extremis there could be a smell of bromine, possibly.
>
> It was originally sold as the ZBM2 for about $7k for a 10 kWh unit
> with inbuilt long-life BLDC pumps and controller. Now it comes in a
> consumer-friendly lockable outdoors enclosure and what-not for around
> $12k installed. I've been umming and aahing about a second one for
> long dark winter weeks, but I live alone, and it's cheaper by several
> country miles to just arc up the petrol generator the year that
> happens.

Or fire up the 20kw nat gas fed standby out back of my garage/shop.

> Its one weakness is that you can only charge it at 42A (~ 2.5 kW),
> which isn't very compatible with a DC-couples system, i.e.
> PV Array -> MPPT charger -> Battery -> Battery inverter -> 220v
> To fully utilise the array output, we need to swallow up to 7 kW. The
> Redflow is better suited to an AC-coupled system:
>
> PV Array -> Solar/Battery inverter -> 220v -> AC charger -> Battery
>  \___/
>
> Then you can use much of the 7 kW directly, storing only what's not
> used.

Which makes way more sense.

> There are though two units (with small losses) between array and 
> battery. But most systems on the market are built this way.
>
> There are some saltwater batteries on the market, but they are
> enormous, heavy, and have an even lower permissible charge rate, on my
> reading of the datasheet.

They could also be used as a heat sink, for night heating I'd assume.

> OK, supercapacitors are coming, and they will annihilate the chemical
> batteries, but the first ones are not as good as the ones still in the
> labs, so I'll be reevaluating when I have a roof up, towards the end
> of the year.
>
> Wind? The consumer generators provide piffling amounts of power, are
> disproportionately expensive compared to solar, and die in the arse as
> there isn't enough wind enough of the time. That fusion reactor in the
> sky still delivers a useful bit even in light overcast, and who needs
> to run the washing machine when the weather's no good for hanging the
> washing out?
>
> In my new build, lighting will all be LED, run from DC. The inverter
> won't need to be running for that. The plan is to make some of the
> light 

[Emc-users] Going off-grid [Was: Thinking about going off-line eventually.

[Erik Christiansen]

On 15.04.18 19:40, Gene Heskett wrote:
> Greetings all;
> 
> I see Banggood has a 500 watt wind thingy for under $200 that net folks 
> are calling professional grade stuff. I am looking to put up an 
> anerometer to record the wind speeds, one of those 3 cups designs that 
> isn't direction sensitive, and one of these card computers to log what 
> it sees so as to get an idea who many of these 500 watt things I'd need 
> to keep a bank of truck batteries topped up while running the house, 
> including the AC.
> 
> Has anyone else walked this trail, or do I have to start with a machete?

Gene, my off-grid build has so far only passed planning approval, and
I've just embarked on building approval. It is based on wood-stove
heating plus 7¹ kW of PV panels on a 30° roof, not quite matching my 38°
south latitude. Battery requirements are reduced by trying to use the
aircon(s) only/mostly when it's hot & sunny, and using a heat pump for
non-winter water heating, as that uses only a quarter of the power of
direct water heating, taking the other 3/4 of the energy from the air.
The secret is to run dishwasher, washing machine, lathe, milling machine,
anything you can in the middle of the day, powered directly from the PV
array, not the battery.

In winter, water heating is by an in-flue SS double-skinned tubular unit.
(Hot water system vented, so it's not a pressure vessel.) Fuel supplied
by 2 sq. km. of forest on the property.

Batteries: Even deep-cycle LA are not worth the biscuit. LiFePO4 are
better than plain Li-Ion for fixed installation, being _much_ less
flammable, and more robust. The zinc-bromide flow battery from Redflow
is more robust still. Not only can it be left for years on a shelf
either charged or 100% dead flat, but it needs to to be run dead flat
every few weeks to keep it young. It is a SS box on top of a 190 L tank
full of water & chemicals, so it'll tend to put a fire out if that melts
the tank. A vent tube to outdoors is advised, as in extremis there could
be a smell of bromine, possibly.

It was originally sold as the ZBM2 for about $7k for a 10 kWh unit with
inbuilt long-life BLDC pumps and controller. Now it comes in a
consumer-friendly lockable outdoors enclosure and what-not for around
$12k installed. I've been umming and aahing about a second one for long
dark winter weeks, but I live alone, and it's cheaper by several country
miles to just arc up the petrol generator the year that happens.

Its one weakness is that you can only charge it at 42A (~ 2.5 kW), which
isn't very compatible with a DC-couples system, i.e.
PV Array -> MPPT charger -> Battery -> Battery inverter -> 220v
To fully utilise the array output, we need to swallow up to 7 kW. The
Redflow is better suited to an AC-coupled system:

PV Array -> Solar/Battery inverter -> 220v -> AC charger -> Battery
 \___/

Then you can use much of the 7 kW directly, storing only what's not
used. There are though two units (with small losses) between array and
battery. But most systems on the market are built this way.

There are some saltwater batteries on the market, but they are enormous,
heavy, and have an even lower permissible charge rate, on my reading of
the datasheet.

OK, supercapacitors are coming, and they will annihilate the chemical
batteries, but the first ones are not as good as the ones still in the
labs, so I'll be reevaluating when I have a roof up, towards the end of
the year.

Wind? The consumer generators provide piffling amounts of power, are
disproportionately expensive compared to solar, and die in the arse as
there isn't enough wind enough of the time. That fusion reactor in the
sky still delivers a useful bit even in light overcast, and who needs to
run the washing machine when the weather's no good for hanging the
washing out?

In my new build, lighting will all be LED, run from DC. The inverter
won't need to be running for that. The plan is to make some of the light
fittings. I need something to build in the two workshops which make up
1/3 of the build. (Also have to find time to finish the design of a
networkable LED dimmer (3 channel), and send off for some boards to be
made. The firmware needs a fair bit of work too. The light switches are
to be neat clicky pushbuttons. The last build, 30 years ago, was as
owner-builder. This time I'm paying a builder, so I _hope_ to find time
for the fiddly bits, despite having to prepare the old build for sale.)

I'm also looking at a camping fridge with phase-change material inside
the insulation. That only needs power for a couple of hours in the
morning, and again in the afternoon, so does not load the batteries if
there's sun.

Cooking is microwave and induction hotplate - not a complete cooktop.
I get out of bed late enough so that will rarely draw on the batteries.

Double glazing reduces heat loss and gain, and might help if you have to
run the aircon after sunset. An MPPT charger or solar inverter which