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Author Topic: Blasphemy..... Solar power.  (Read 95220 times)

glort

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Re: Blasphemy..... Solar power.
« Reply #435 on: January 23, 2018, 01:01:25 PM »

Thanks Bruce, you're a champion mate.  I have put the specifics in the other post.
So while I'm taxing your help, the other thing I want to do is a hot water diverter. I know they are around and complex and exy but there is a simple way for  me.

All I want/ need to do is sense my line voltage and use that to trip a switch. I was thinking this should be simple for an arduino and an SSR.
When the inverters backfeed the line voltage goes up, often too high in my case.  If I have one of those voltage sensor units ( which I have a few already) and could monitor the phase voltage and switch on the water heater when the voltage got to say 255V, that would indicate I was making good power for the heater. I figure I'd need some hysteresis in setting the cutoff to say 250V with a check every say 15 Sec to allow for a cloud or whatever.

Using the line voltage would obviously be a lot better than a timer as it would sense wether there was solar generated power or not.  I'd have to play with setting obviously and also look at my generation over time once all the panels are in play. I'm thinking i Should be able to over supply my needs most of the time but if not, using the off peak at 11C kwh is a lot cheaper than using the regular power at 30c.

Something like this would also be good for the other thing with the AC. Senses a voltage, trips a relay. Kind of reverse application but same set-up with different numbers would work fine. 

BruceM

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Re: Blasphemy..... Solar power.
« Reply #436 on: January 23, 2018, 03:44:59 PM »
High AC voltage sensing with hysteresis is what you're asking for.  I would do this by doing a somewhat filtered peak voltage circuit (transformer, bridge diode, resistors, capacitors) and analog comparator with trim pot for set point and trim pot for hysterisis.  The fiddly bit is getting the peak voltage sense to ignore spikes and other line transients and have good immunity from inverter generated EMI.  This is an electronics build project for an intermediate skilled technician.   

An arduino could be used instead for the AC voltage sensing (peak would suffice or RMS if you wanted to get fancy) and is handy in that hysterisis and time delays can be programmed. 

I'll have a look around online to see if someone is making and selling some bits of this which would make your task easier.  Either analog or arduino would be fine, it's just a matter of cost and difficulty for you to build.


 

BruceM

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Re: Blasphemy..... Solar power.
« Reply #437 on: January 23, 2018, 04:27:23 PM »
Had a look and your best bet is to use a voltage monitoring relay. Macromatic makes some nice ones, but you may be able to find a china clone for a lot less $.  The macromatic units are self powered, which helps simplify the setup.

These relays have a set over/undervoltage which trips the relay, with an adjustable time delay as well.  Since the water heater is a sizeable load you would want to use the monitoring relay output to operate a second relay to switch on the water heater. 

https://www.macromatic.com/products-main/voltage-monitor-relays

This would eliminate the need for any fiddling with arduino or analog circuits, both are significant time and patience eaters, and give you something that anyone could maintain.

Give a holler if you need help on a specific unit you might find available to you there in Australia.


glort

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Re: Blasphemy..... Solar power.
« Reply #438 on: January 24, 2018, 12:36:36 PM »

Thanks again Bruce!
I had a look and found a knock off of the unit you linked.  Got to love the chinese cheap manufacturing.

Would this be what I need?

https://www.aliexpress.com/item/SVR1000-AD220-LCD-display-single-phase-AC-DC-110-240V-Overvand-Under-voltage-Monitoring-Relays-china/32835033539.html?spm=2114.search0104.3.57.4fb49eaejR424f&ws_ab_test=searchweb0_0,searchweb201602_3_10065_10344_10068_10130_10342_10547_10343_10340_10548_10341_10084_10617_10616_10083_10618_10615_10307_10131_5920011_10132_10133_10313_10059_10534_100031_10103_441_10624_442_10623_10622_10621_10620_10142,searchweb201603_25,ppcSwitch_5&algo_expid=e2ed3426-5109-4035-862e-bed7ea024e64-8&algo_pvid=e2ed3426-5109-4035-862e-bed7ea024e64&priceBeautifyAB=1


It has a C/O contact which I assume can be set so when i hit the desired voltage it  turns on the supply in this case to the hot water system.
I'll get a few of these if it is what it does because I can see other things these would be good for.
It sure would be one very easy way to switch Hot water systems with solar generation if it will as I hope turn on a load when the voltage set on it is met.

I would have this on the phase with the solar power so when it hits the desired level ( 255V) it turns on.  I would program it to turn off around 245 which would indicate low solar generation but I'd have to test obviously when the thing was in circuit. As the heater is 3800W and I don't want to run another dedicated supply, I'd go through a PWM controller to knock it back to around 8A. ( PWM might be the answer to my High/ low supply with the AC as well, just thought of that!  :-[ )  i'd run that into a contactor and to the heater Element.

As I would want to retain the off-peak for cloudy days, the contactor should stop any back feed to the other phase which the solar is on correct?

I can see one other things these may work for although would require a DC contactor.
When I get cloud edge effect on my solar panels the voltage goes nuts and keeps tripping out the inverter.  When I'm home and see it I switch off one array.  These could be set up the same way.  When the voltage goes high, one string is turned off. When it is low, another string could be switched in.
Now to find a High voltage DC contactor......

Thanks again for your help, it really is very much appreciated!

BruceM

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Re: Blasphemy..... Solar power.
« Reply #439 on: January 24, 2018, 04:23:59 PM »
Yes, that voltage monitoring relay looks like it should suffice.

I think it will be a challenge to find a current limiting device for your water heater.

Here in the US you can get water heater elements of various wattages.  Replacing the lower element with something suitable might be an easier solution-  plus adding a separate thermostat for it. 

Normally, the lower element (only) goes on at a higher temperature, and the upper comes on at a somewhat lower temperature to provide faster recovery of the water at the top of the tank.  A single thermostat has the bimetal switches to do this and turn on one or the other element.  So the lower element could be disconnected from the upper thermostat and used separately, or with a contactor could be diverted for your use only when needed.  You'd have to add a thermostat for the lower element to avoid boiling the tank.

Heavier wiring from inverter to the meter might an easier solution if voltage at the meter isn't going too high but it is going high measured at the inverter.

glort

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Re: Blasphemy..... Solar power.
« Reply #440 on: January 26, 2018, 05:24:46 PM »

Ordered a couple of the Digital Voltage controlled relays.
I'm hoping they work as I think because if they do they will be a very cheap, easy and effective soloution to the task.

I did ask about them on another electronic savvy forum and got offered a whole lot more complicated and expensive soloutions. No one said they wouldn't work or there would be a problem so I think that's a win and a vote the right way in itself.

The HWS I have is big and single element only.  I heard somewhere we are only allowed single element now but haven't looked into it.
I don't want to put a smaller element in the thing because If I do it will take longer than the off peak period to bring the thing up to temp if it's run out of water.

The approach I have in mind is Voltage sensing Relay will trigger relay/ contactor which will go to water heater element at 2000W through a PWM controller rated at 6KW. ( element is 3.8. ) I'll likely make the setup something I can plug into the wall socket hence the modest power regulation.
I could actually go to 3600W  out of our  sockets but I think that may drag the line voltage down  far enough to confuse the relay as to if the solar is generating or not.

I'll try to remember to open the Suspect Junction box from the shed to the house this weekend and have a look see.  Might run a connection while I'm there for another inverter I want to put nearby for the array to go on the house.  See what's there anyway.

I'm going to have to think about my arrays and phases now.  I have 7Kw running atm with another 7Kw to put on the roof. Ideally each one should have it's own phase but that will require a wiring upgrade from the shed and probably another circuit for the 7KW I want to put on the house.

Still keeping an eye out for cheap panels. I have been getting a few people down substantially in price.  Most were asking way too much in the first place but I have got them down to worthwhile levels.  If I can find stuff at a good price, I'll grab it whilever I still have some worthwhile roof space left.
Should get 5KW on the north side of the house and I reckon there is space easily for maybe another 10 KW on the west.

Now I'll have to start keeping an eye out for inverters.
Got a locally made one with one lot of panels I got which is weird.  Pretty sure it has a big transformer built in but has a max input of 200V meaning I could only do stings of 4 panels ea which will be a pain to wire up given the thing will do 2.5 Kw.  It does seem to have a capeability to run off batteries as well which may be a plus in future but I'm  not sure if it can be set for standalone or grid tie only.

http://www.latronics.com.au/sites/default/files/dl/separate/manual_pv_edge_circuit_breaker.pdf

BruceM

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Re: Blasphemy..... Solar power.
« Reply #441 on: January 26, 2018, 10:11:02 PM »
Glort- The PV Edge unit doesn't do battery, that's a separate inverter product according to their diagram. 

I don't know of a piece of power regulating electronics suitable for limiting current to your water heater; it may exist, I'm just not aware of it. A variable speed motor drive might do it so perhaps that's the sort of thing you are referring to when you say PWM.

A 2000 watt, 230V variac might be a simple reiliable solution. The latter would let you dial in whatever voltage you need to get the desired current draw.  It would also be possible to use a variac, modified with more than one lead soldered in place to the windings instead of the adjustable graphite wiper, to have two or more voltages to switch between via relay, to get you more than one fixed current.  You can determine the location(s) to solder via the adjustable wiper...just use a clamp on amp meter and dial it to where you get the desired current.  Sand and solder tin the marked winding spot and then solder on your wire(s).  A variac is a very handy form of toroidal transformer and is often at 95% efficiency.







glort

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Re: Blasphemy..... Solar power.
« Reply #442 on: January 27, 2018, 01:34:02 AM »
Bruce,

I just want to thank you for your suggestion of the voltage monitor. 
I'm really excited and confident this will work just as I want and is such an easy and low cost solution.  I have been looking at these electronic hot water diverters and they are all freaking expensive for what they are or difficult to build for someone of my lacking electronic skills.  The voltage monitor seems a great way of doing this and is so cheap, easy to implement and I can't see why would not be just as effective.

I did see one Diversion unit that logs into weather forecasts to predict when to kick in the how water if there has been a period of low solar generation.  Very clever and sophisticated but the price of the thing would meanI would have to have a Nil hot water bill for over 5 years ( which it could not do anyway) in order to get my money back.

The Voltage monitor system will repay itself with ancillary's in less than one quarter, Will take maybe a couple of hours fun ( instead of frustrating ) setup
and so far i'm at a loss to see how it will be any less effective than any more elaborate and complicated devise.

I have put this on another electrnics / home grown power forum where people frequently do this sort of thing and No one has come up with any significant objection to the Idea yet and the comments that have been made, at least for my purposes, are not significant and easily overcome if they apply at all.

I'll probably in time claim this was my brilliant idea through bad memory moreso than ego, but we'll be under no doubt as to whom the real genius is!

This is the PWM controller I bought.

https://www.ebay.com.au/itm/4KW-SCR-Super-Power-Electronic-Digital-Regulator-Dimmer-Speed-Thermostat-T1K/362119874183?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

Thought it was 6kw but only 4. Only intend driving the element to around 2000 anyway so should be fine.
I have a couple of these on different things. One is controlling the big dirty water pump that feeds my aeroponic system so it literally does not blow the plants away.  The other one I used a good few months controlling an electric urn when running it off a solar/ battery system I was playing with.
They are the analouge ones but look the same design and I have had no trouble with them at all. I have a panel meter sitting here too which uses an inductive pickup I'll use for setting the power output and monitoring voltage etc.

 Have to find a case of some sort now to built it all into.


BruceM

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Re: Blasphemy..... Solar power.
« Reply #443 on: January 27, 2018, 03:53:05 AM »
Good find, Glort.  That dimmer unit is very high capacity!  If it doesn't confuse the grid tie converters with waveform distortions and EMI it should be a very simple and low cost solution. Good chance it will do the job nicely. Bravo!






 

ajaffa1

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Re: Blasphemy..... Solar power.
« Reply #444 on: January 27, 2018, 09:12:16 PM »
Here in Australia, we only get six cents per Kilowatt hour from the utility companies. We also have to pay $150 a quarter for the man to come and read the meter.  Grrrr.

Bob

glort

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Re: Blasphemy..... Solar power.
« Reply #445 on: January 27, 2018, 10:59:45 PM »
Here in Australia, we only get six cents per Kilowatt hour from the utility companies. We also have to pay $150 a quarter for the man to come and read the meter.  Grrrr.

Bob

There are some companies paying 15c kwh FIT  but they slug you the other end for the power you buy so as to keep their margins at the disgusting level.
The $150 is not for the man to read the meter, you pay that even if you have a smartarse meter they read every 10 seconds and spy on you with.
No, the Supply charge is to maintain the grid. Ya know, those gold plated power poles and pure silver wire aint cheap!
Not like there is any profit in buying the power you generate at 6c KWH and selling it to the next door neighbour for .30C kwh.  Nope,  need to make some profit you know!   ::)

I was at my last place over 20 years and not once did they touch any pole I could see or the wires.
Of course at one stage, they did did the ( main) road up completely 3 times in 18 months.
Once to redo and up grade it, once ( afterwards) to put in new water pipes and once to run an underground cable 3 suburbs between sub stations.

WTF these utilities couldn't submit their plans and co-ordinate so they only had to dig the roads up once, I can only guess would be too efficient and not spend enough of their budgets. It was a joke. Road not touched in 20 years then the whole thing dug up 3 times in 18 months.

Was OK in the end.  When they did it in winter, Mrs and I took them out some Coffee and Biscuits.  Next thing we know our cracked Driveway is being jack hammered up  and a new one was laid. Did an excellent job of it too. They reckoned someone had ordered extra concrete and they had to get rid of it somehow. 
Made the sleepless nights, again, a lot more bearable.  ;D

I'm a bit dissapointed in my solar efforts.
Did a quick meter read late yesterday and figured my bill is about $400 atm.  2 weeks till the quarter is finished.
That includes the " Supply" charges which I can't do anything about if I want to stay on grid.  Main Bill is that 3rd leg for the electronically metered phase which I need to work on to offset . Only supplys  part of the 3 phase AC and the hot water.

Think I have found the soloution to the hot water charges thanks to Bruce and waiting for parts to arrive to implement that and have to work on that 3rd leg of the AC offset.
We have been running the AC a HEAP during the hot weather  and the fact one leg is basically at about  $3 and the other is at $30 atm is testament to the  amount we have saved with my solar activities. The $30 phase is due to the array I had feeding that going down while I was away and not being able to catch up. Like the other phase I just have enough atm to break even on average.  I have a bunch of panels atm waiting to go up but I might do a temp setup and feed the output to that phase to bring it down.

Next bill should be far cheaper. As well as doubling my solar capacity, we will be over the worst of summer and I expect the AC will be needed a heap less. Unusually, it was really muggy and uncomfortable last night and I got up at 3 am to put the air on which made all the difference and allowed everyone to get back to sleep comfortably.  If the hot water diverter works as hoped and envisaged, that will save at least another $50 there and the AC offset will save maybe $200.

LowGear

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Re: Blasphemy..... Solar power.
« Reply #446 on: January 28, 2018, 06:09:44 PM »
Quote
Here in Australia, we only get six cents per Kilowatt hour from the utility companies. We also have to pay $150 a quarter for the man to come and read the meter.  Grrrr.

I feel your pain.  And to think I was complaining about 15 cents a KW buy back here in Hawaii.  Gosh, they're only making 100% per day instantaneously on my investment as they charge > 30 cents retail - that's me when I'm not selling to them.  "Gee Whiz Aunt Minnie how can they make a living with only 35,600% return per year?"  The $150 a quarter would really frost my sack too.  How much do they charge you when you buy electricity from them? 
NPR Tipper/Dump Truck
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BruceM

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Re: Blasphemy..... Solar power.
« Reply #447 on: January 28, 2018, 06:43:07 PM »
A brief power co. rant follows:

The whole scheme of "public utilities" run by corporations and "regulated" by corporation commissions was developed by private utilities while throwing money at legislators to get it passed.  This and propaganda to paint all government power programs as socialism and communism was very successful here in the US.  This despite highly successful programs such as the TVA which provided power at half the rate of the private power co.s.  In the US, state corporatation commissioners are handpicked and have campaigns overtly funded by power companies, which is why this approach was initially pitched by the power co.s (mostly those owned through various holding companies by JP Morgan).  It is very, very cheap to buy a politician (for a large corporation) and this solves the problem quite nicely as the populace is easily manipulated to vote against their own best interest by repetition of sound bites and images on TV. (Better than 90% of elections go to whoever bought the most advertising.) The corporation commissioner jobs are often stepping stones to higher political positions so they are a very good investment (for peanuts) for power companies.

I'm glad I am no longer am under the thumb of a power company.  I encourage others to do likewise.

Here's an interesting article about what Germany has been doing in converting power back to local control and localized generation.  The global boon in lower PV prices is largely due to Germany's  aggressive RE program.  They have managed it quite impressively. 

https://www.ft.com/content/2f3b0b1e-4dee-11e3-8fa5-00144feabdc0






« Last Edit: January 28, 2018, 06:53:06 PM by BruceM »

ajaffa1

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Re: Blasphemy..... Solar power.
« Reply #448 on: January 28, 2018, 09:21:01 PM »
Quote
Here in Australia, we only get six cents per Kilowatt hour from the utility companies. We also have to pay $150 a quarter for the man to come and read the meter.  Grrrr.

I feel your pain.  And to think I was complaining about 15 cents a KW buy back here in Hawaii.  Gosh, they're only making 100% per day instantaneously on my investment as they charge > 30 cents retail - that's me when I'm not selling to them.  "Gee Whiz Aunt Minnie how can they make a living with only 35,600% return per year?"  The $150 a quarter would really frost my sack too.  How much do they charge you when you buy electricity from them? 
With Government taxes it works out around 26 cents a Kwh. so they are making more than 400% on the solar power I export.
What really gets me is that they can`t even maintain supply, yesterday in Victoria they had a hot day so a lot of people turned on the AC and overloaded the supply. 50,000 homes and businesses without power. The government and shareholders must be very proud. I guess disconnecting everyone is one way to meet the emissions reduction targets.

glort

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Re: Blasphemy..... Solar power.
« Reply #449 on: January 29, 2018, 12:08:36 AM »

Don't get me started on the power thing..... Ooops, too late!

Here I pay .30c for "normal" power and 11 c Kwh for off peak.
My father in the country pays closer to .40C and 17c. 
 If you read some of the now 1000+ power "Plans"  ( WTF you need a " Plan" for, how about the normal straightforward pricing?) you can pay up to .56c Kwh if you are on one of their Time of use scams....errr, I mean " Plans"

Friend of mine with a solar setup from way back just got a new supplier and get .15C FIT but power is TOU and again priced to kill.  He gets to use his own power through the day, when no one is home but then when everyone gets home, he's charged like a bull.

Here is OZ the green movement has had a huge role in driving power prices through the roof. We have literally been blowing up power stations so far and intently in the name of saving the environment  that there is a Huge shortfall now in generation ability. We keep hearing about renewable s being the cheapest power yet prices keep going north at an alarming rate.  There is far too much Hype and spin doctoring to appease the social religion of the times to reveal the damage this is doing on so many levels including security of supply, the affect on jobs and industry and many other aspects where the detriments outweight the effect.

Our own cheif Scientist and greenwashed advocate has said that if Australia reduces it's green house emissions to Zero, it will have NO effect on the worlds climate or air quality. Still we go along busting a gut to be seen to be doing the trendy thing when the whole time we are pissing into the wind.... which may or may not be driving a turbine given how many of the wind farms produce no worthwhile power or are damaged through incorrect siteing.

Reading industry rather than media predictions, power is set to go up some astronomical amount yet.
At the same time, the power companies keep posting record profits showing power charges are not out of necessity but rather unbridled and unregulated greed. I don't dispute a company has a right to make profit but when it is essentialy a monopoly and a basic human need in the civilised world, I think it need to be put in a different class. Of course as Bruce alludes to, the regulation and watchdogs of the industry are all bought and paid for the world over no doubt so they will always go in favour of the hand that feeds them and feeds them Caviar and truffles no less.

The whole basis of this thread is to use solar generation to back feed the spiny meters.
 Just this morning I was given positive legal clarification this is not Illegal here. It is likely to be against my agreement with my supplier, ( but there is nothing mentioned in the agreement they sent me when I connected here 5 months back) and there is nothing illegal about what I'm doing.
I CANNOT be charged with theft or anything else basicaly because I am not stealing.  The power company could try to sue me for loss of profit but they do not even have very strong grounds for disconnecting me and if they did THEY would be putting themselves at very great risk through failing to provide essential services and under health and Hgene regulations.
Despite what many in the internet world believe, HERE they cannot just disconnect you ( Power, water or gas) without good reason.  They cannot disconnect water here if you don't pay the bill, only restrict it if the premises is occupied.

In any case, my advise is the chances of them taking ANY sort of action against me is about the chances of winning lotto.  Not worth their time, sure as hell not worth the significant risk of negative publicity an the amounts would be too small to be bothered with anyway.  What they would probably do is make me sign an agreement to cease and desist and install smart arse meters..... Which will happen in the foreseeable future anyway.
At that point I'll have to see which way I jump with regards to my power supply.

 I didn't care about the legalities of what I'm doing anyway TBH,  It's a case of screw them or be screwed and I chose the first.
Others that want to get all moralistic, are scared to stand up for themselves and never want to do anything wrong can make their own choices that suit them and I'll make mine. As I have.

We also get hit for a " Supply" charge as mentioned here. Mine is over $1 a day. Closer to about $1.20 all up.  This is supposed to pay for the infrastructure and cost of maintaining the network.
When I read about Feed in tariffs (6-15C kwh) I read that they pay lower because there is the cost of maintaining the grid etc they have to pay. I already paid that in the supply charge so this is clearly Double dipping.  Pretty sure that sending power down a line does not wear it out, the post holding it, transformers etc.  Of course the fact that the power I'm back feeding goes no further than next door or across the road also pretty much puts pay to that BS excuse.

The destruction of so many coal fired stations has left the country in a very delicate situation with power and they now have the ability to simply turn off sections of the grid  when they want. No guessing the more elite areas where the pollies and CEO's live are not going to have to worry but the battlers are the ones going to have to do without.

I was reading an article on " The big battery" that Champion Blowhard  Musk and his here today, gone this time next year company Tesla built in south Australia.  Heralded as the saviour of the State ( "Power 30,000 homes" ) in a state of over 200K homes  ::)  )  the battery and the operator are in fact using their capacity to drive power prices up to the limit in the wholesale market and then cashing in on them.  Not a matter of saving the state from blackouts and keeping the lights on, They are profiteering from something they conned the state gubbermint into footing the bill to build while they run and manipulate the wholesale power price to profit from.

Yeah, tell me all about this cheap, clean renewable Bullshit again?   ::)