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Author Topic: Solar Split System Inverter Air Conditioners  (Read 6940 times)

veggie

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Re: Solar Split System Inverter Air Conditioners
« Reply #15 on: July 31, 2019, 05:15:43 PM »
First you said:
The during day plug the AC unit into a grid outlet .... THEN connect the solar to the house through a cheap grid tie inverter and let the solar offset the power used by the grid powered AC.

And then:

I don't want to backfeed the grid.


By matching a GTI to supply equal to the demand from a mini-AC unit (say a 1600 watt GTI at 60% load and a 900 watt single room AC unit)  the GTI would not be backfeeding the grid. Anything produced would be gobbled up by the AC unit. So to clarify what I meant... backfeeding my house yes, backfeeding the grid no.
The GTI would run 8 hrs per day and so would the mini AC unit. Switch them both on during a sunny morning and turn them both off late afternoon. On startup the grid would feed any inrush current for the AC unit.
Meters here do not spin backwards unfortunately.
Im not saying this is a great idea, I'm just exploring ways to utilize some spare 220W panels.
 
« Last Edit: July 31, 2019, 05:23:25 PM by veggie »
- 6/1 GM90 Listeroid - Delco 33si Alternator
- Changfa R175 - Lease/Neville Alternator
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- Changfa S195 (Waiting for a project)

BruceM

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Re: Solar Split System Inverter Air Conditioners
« Reply #16 on: August 01, 2019, 03:14:24 AM »
Apparently that same bee gets around.  I'm  building a 1 hp, 230V air compressor to run off my inverter when I've got excess power.  It will keep my 500 gallon, 140psi receiver tank filled up. That and pumping water are the two "whenever I've got enough juice" loads.  Couldn't use a cheap homeowner compressor as they aren't designed to run continuously for 5 or 6 hours, nor 230V. 

I'm cooling the air with a transmission oil cooler, then separating the water with an auto drain.  My line from there down the hill is dry and I want to keep it that way. Cooling was essential since the buried supply line is 1 inch PVC.  I wouldn't want to test it with 300F air direct from a compressor.

I'm using a 3-way motorized ball valve for the connection to the air supply line, so the motor will start with no an open line for a few seconds.  Motorized ball valves don't leak, air check valves all do.

Not economically viable, but satisfying nonetheless.




BruceM

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Re: Solar Split System Inverter Air Conditioners
« Reply #17 on: August 01, 2019, 04:44:37 AM »
You might check your voltage at the panels to see how much you could improve things via wire size upgrade from inverter to panel.

I use the 500 gallon tank to run air tools and air motors for my shop.  A Gast 4AM will suck that tank down below 90psi in less than 10 minutes, so it's not oversized, it's undersized.

My Lister compressor can't keep up with a Gast 4AM, which I use on my table saw and radial arm saw.  The air consumption is a bit more than a high power orbital sander.  If steel pressure  tanks were cheaper I'd have 2000 gallons of storage!


BruceM

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Re: Solar Split System Inverter Air Conditioners
« Reply #18 on: August 01, 2019, 06:05:41 AM »
I forgot to mention, my power management microcontroller has state (float, bulk or equalize), net charge and load info, but what I need to add is solar potential.  I found that a tiny 6V solar panel oriented similarly to my two arrays, with a power resistor for a load gives me a voltage proportional to sun angle/intensity.  I can use that to calculate estimated available power. 



BruceM

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Re: Solar Split System Inverter Air Conditioners
« Reply #19 on: August 01, 2019, 03:08:40 PM »
Thanks for the good suggestion. Yes, the actual voltage drop across my low side (as much as -90V) PV regulator might be a fair stand in for solar potential, though I'll have to think about that a bit.  The commanded current to the linear PV regulator is already a 0-5V signal on my controller board and might also be an OK surrogate for (inverse) solar potential though I think there are some conditions where it's not.  I've got nothing but pain, fog and confusion in my head due to regular wildfire smoke lately.  I try to keep busy but there's a lot of mistakes.






 

veggie

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Re: Solar Split System Inverter Air Conditioners
« Reply #20 on: August 01, 2019, 08:15:02 PM »

A bit off topic, but since we are discussing the storage of excess energy what do you guys think about this ?

https://www.youtube.com/watch?v=U7a_LMM2_fE

Garavitricity
- 6/1 GM90 Listeroid - Delco 33si Alternator
- Changfa R175 - Lease/Neville Alternator
- JiangDong R165 Air cooled - 2 kw
- Changfa S195 (Waiting for a project)

BruceM

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Re: Solar Split System Inverter Air Conditioners
« Reply #21 on: August 01, 2019, 11:08:10 PM »
I've seen the same scheme pitched using a tall crane surrounded by weights. Makes batteries look appealing, but it certainly seems that it would be low risk and reliable if inefficient.

Hydro storage is apparently fairly advanced, with 75% efficiency.
https://www.youtube.com/watch?v=McByJeX2evM
« Last Edit: August 01, 2019, 11:10:57 PM by BruceM »

BruceM

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Re: Solar Split System Inverter Air Conditioners
« Reply #22 on: August 02, 2019, 12:09:11 AM »
Compressed air sucks as a power storage medium- my compressor is 5HP input, but it can't keep up with a 1/2 HP (Gast 3AM) air motor's demands.  In fact, it can't keep up with my Gast 1AM based string trimmer either, and that's about 1/4 HP.  Some of that is the inefficiency of rotary vane motors, but it is not a viable energy storage medium.

The pumped water system listed is almost 40 years old, is still in operation and has 75% efficiency.  I'll take some of those, please.  You need terrain with some serious vertical, and preferably an existing lake...






mikenash

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Re: Solar Split System Inverter Air Conditioners
« Reply #23 on: August 02, 2019, 09:02:34 AM »
I like it

Simple is good

It looks scaleable too

I can imagine folks building one using the regenerative braking bits off an old Prius or suchlike

mikenash

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Re: Solar Split System Inverter Air Conditioners
« Reply #24 on: August 02, 2019, 06:09:35 PM »
Dunno

Here in NZ in the late 20's we began to identify a need for a substantial National Electricity Grid and the Ministry of Works engineers started thinking about it

Some of them started scouting rivers/elevations/locations/terrain.  A couple went off to Mother England to look at dynamos and associated hardware

20 years and a lot of cock-ups later we had the Waitaki Dam in the South Island generating electricity.  It has been a faithful servant for sixty years.  So that's the first two lessons:

(one) Yes you can.  And (two) good infrastructure will serve for a long time

(And, of course, once we had built Waitaki, the later Benmore and Aviemore and subsequent hydro plants were a snip - more or less)

On the other side of the world, in the US of A, folks were pumping oil out of the ground.  But not with big, gigantic bloody things, but those mulitiudinous small rocker-arm reciprocating set-ups that have been working well since forever.  That tells us that there's nothing wrong with "lots of small" either and maybe that weight-on-a-string-attached -to-a-dynamo thing could work in a backyard tower-sized  setup?  Who knows?

There's a bloke down here with a micro hydro that only puts out a couple of hundred watts.  But, because it does it 24/7, it keeps his batteries topped up to the point where his solar gets a holiday a lot of the time

Also, of course, I suspect folks will have to learn to do more with less in the future.  How many big-screen TVs does the average household need, anyway?

veggie

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Re: Solar Split System Inverter Air Conditioners
« Reply #25 on: September 24, 2019, 07:07:50 PM »
UPDATE:

This system is now available where I live.
Quite interesting.
They also have a hybrid model that connects to panels as well as the grid.
Uses grid power when Solar is low.
https://www.youtube.com/watch?v=0719scj4uEE
- 6/1 GM90 Listeroid - Delco 33si Alternator
- Changfa R175 - Lease/Neville Alternator
- JiangDong R165 Air cooled - 2 kw
- Changfa S195 (Waiting for a project)