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Thank you for the great forum, Safe Driving over the weekend. Sincerely Jason


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Elbow last won the day on August 7 2019

Elbow had the most liked content!

About Elbow

  • Birthday October 19

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  • Location
    Cape Town
  • Interests
    Solar, Digital control, IOT, Software, smark home

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  1. So Pres Ramaphosa just announced that municipalities can buy power privately. So who is the contact person at CoCT - want to offer to put up another 6 or 7 kW to sell to them...?
  2. After power came on here just after 10pm my inverter re-tied, then voltage browned out down to 193 volts and the inverter isolated again. I suppose when power comes back every geyser in the neighbourhood comes on and there is a ton of load. Still, frustrating since my batteries are quite low and there is a chance I might lose my essentials supply.
  3. Hi, I made a NodeRed flow that attempts to predict available solar power. It does it using a node calls "Solar Power Forecast Plus" that takes your position, panel alignment etc and predicts the power that should be available. I then took a www-request node to request weather info from darksky.net, and attempted to factor in the cloud cover to try to come up with a prediction. The resulting info I send into MQTT to EmonCMS so I can chart it and so on. My flow looks like so: An export of the flow is also attached if anyone wants to play. The MQTT message generated looks like so - EmonCMS can import it nicely: You can see that right not the ideal available power is 3019W. Darksky says there is 98% cloud cover, so my estimation gave 1243W achievable. The formula is a guess, I used: actual = ideal * (1 - 0.6*cloudCover); I'm finding that Darksky overstates the amout of cloud - so my estimates are too pessimistic. Still - here's how it came out compared to actual yield this morning: You can see Darksky saying 98% cloud. Nevertheless my actual yield was close to the "ideal" figure. The actual weather reported at Cape Town Airport is FACT 060900Z 16011KT 130V190 9999 FEW030 21/11 Q1015 NOSIG - ie few clouds at 3000ft. Looking out the window there seems to be high clouds but its a bright day. Did anyone try to do something like this before? solar-prediction.flows.json
  4. I've learned not to keep my hobby projects as hobby projects. I remember my MythTV system 20 years ago. Everyone would tell me I should make systems and sell them. I was smart enough even then to know that what satisfied me would not satisfy a "it needs to just work" customer. I hardly noticed the quirks. I've also done VOIP for nearly as long and in that space it took some time to get the wrinkles out and to be able to deliver service that just works. We are there now, but its always harder than you think to get tech to the "just works" stage.
  5. Been raining since early in Cape Town (yes, I know...). Sun appeared from behind the clouds for a bit and I see I'm getting way above my panels rating:
  6. Elbow

    Inverter USB

    I worked from this: https://github.com/MindFreeze/hassio-axpert @Coulomb sent doc links - I'm sure he knows them better than the manufacturer.
  7. Just to keep things interesting for Cape Town solar geeks. My permission to commission my system contains this sentence: Groan. I have an existing Landis+Gyr prepaid meter. Now these meters can be configured to cut the power if they detect reverse energy (its considered as a tamper attempt). Mine though has that set off. So it bills me for reverse energy if I overshoot - and of course when the iron is being used or the oven then I do see some overshoot when the iron or oven thermostat turns off. So its a concern for me that they want to swap the meter - since I may end up with trip problems if a heavy load goes off in the house and it takes my inverter too long to back off the power and enough reverse energy flows to trip the reverse energy detection.
  8. Hi @Ironman, You will find various photos etc if you look back through my posts. I've been a pain on Powerforum I'm sure but the ou manne and others have been fantastic with advice and referring me to good guys to help me - most of whom are on this forum. My system has a "Renesola Replus" hybrid inverter. These were being cleared out a few years ago at a great price. Its a Voltronic Infinisolar OEM. It is on the CoCT magic list of approved devices though it does not meet the latest standard so I needed to get my approval complete before the end of 2019. Its rated 3kVA but that really only becomes a limitation when the power is out. When the power is present the inverter really connects the grid and essentials together and then the DC/AC inverter feeds both. Practically that means that even on the essentials side you can exceed 3kVA. (Obviously if the grid disappears in that state the inverter will trip so its to be avoided). I have 9 Canadian Solar 350W panels - I could probably have used 10 but my inverter maximum voltage is 500v and I didn't want to take a chance. So 9 means 3150kW. COCT rules would have allowed me 3500. In practice I think 10 of these would have been fine. I have 2 2.4kWh Pylontech US2000B batteries. I used 80A fuses in both + and - and also fitted a Victron battery monitor. I probably didn't need a battery monitor since the batteries are smart but its handy at a glance to see the charge state etc. My inverter has a "grid" connection and an "essentials" connection. The essentials goes to a sub-board and all my lights, my computer dedicated circuit and some plugs around the house are connected to that. On the grid side are the high load stuff. I elected not to feed in to the grid. So to get that right I fitted a Carlo Gavazzi ET112 meter and a modbus card in the inverter. The inverter reads the nett power flow from the meter and uses that to try to balance what it feeds in so that it doesn't feed back into the grid. After buying the ET112 I discovered it was not compatible with my inverter's modbus card - I'm stubborn and a programmer so I wrote a program that runs on a Raspberry Pi and converts the format so that the inverter is happy. Paperwork wise in Cape Town: It starts with a form and a basic diagram of what you intend to do. You then get a permission to install letter (I did have to hassle them to get it). You then do the install, and you may "test". Once done you will need to have a COC for the electrical work, and there are requirements to be able to isolate, to mark main switches, and etc. In that process I had to improve my ground for the house. We also established that my supply from the council is out of spec - heavy load in the house and the voltage at the point of connection sags to something like 195V. Council came and stuck a meter on the supply and didn't do anything to load it down and shrugged and said its OK and that was the end of that. You also need a Professional Engineer to sign off that the required automatic isolation works properly - the requirement that the inverter disconnects from the grid if the grid goes off. He also checks grounding, isolation points, labelling and etc. @Rautenk did that testing for me - with careful testing which is a bit tricky in the case of a hybrid. Then you need to do a "single line diagram" which is a sort of circuit diagram of the house electrics. Karel gave me an example and pointed me at something called profiCAD and I did the diagram. Took some time but was quite fun. Lastly, you sign a new supply contract and send all this stuff off the the council who I suppose study it carefully (?) and issue the permission to commission the system. And you are all official. Whether that's a good thing remains to be seen! I did discover that my inverter doesn't ground neutral when disconnected from the grid and supplying from solar or batteries. So in that case neutral floats at 115 volts or so relative to ground. We've had lots of disussions here about that, especially because my inverter uses a switching inverter and not a transformer creating a question about whether its OK to connect the output neutral to ground. But mine, at least, seems perfectly happy. Apparently the inverter is approved, but I didn't think that was safe so I fitted a contactor that links neutral and ground if the grid drops out. In June I got 315kWh from the panels - so about R800 worth at the higher Cape Town rate. 425kWh in October - R1100 maybe? In the summer I don't have enough daytime usage to use up the available energy, and I don't have enough batteries to save it all for overnight - so sometime I'll buy another Pylontech. On a sunny day with lots of demand in the house I saw as much as 22.6kWh from the panels (October 25th). I guess I spend R65k and of course many hours. It was a fun project so I'll pay myself R0. So on that basis I guess it pays itself off after 6 years.
  9. So who wants to play Eskom "business rescue practitioner" and put forward what _you_ would do to change the decline in the state of Eskom? A business rescue practitioner has wide powers and is exempt from many of the governance limits that apply in the ordinary course of business. Here's an article: https://www.findanattorney.co.za/content_duties-business-rescue-practitioner A person in this role has got enormous power to do what it takes. Can we take as read that you will use these powers fully: The Business Rescue Practitioner (“The Practitioner”): (a) has full management control of the Company in substitution for its Board and pre-existing management; (b) may delegate any power or function of the Practitioner to a person who was part of the Board or pre-existing management of the Company; (c) may remove from office any person who forms part of the pre-existing management of the Company; or (d) may appoint a person as part of the management of the Company, whether to fill a vacancy or not. (there are requirements however as to who may be appointed by the Practitioner). And: The Practitioner finds voidable transactions or reckless trading If the Practitioner finds evidence which indicate that, before the Business Rescue proceedings began, that the Company entered into voidable transactions, or finds that the Company or any director of the company failed to perform any material obligation relating to the Company, then the Practitioner must take any necessary steps to rectify the matter and may direct the management of the Company to take appropriate steps to fix the problem. If the Practitioner during his/her investigation finds that any of the directors traded recklessly or committed fraud, or contravened any other law relating to the Company, then the Practitioner must forward the evidence to an appropriate authority for further investigation and possible prosecution. Apart from this, the Practitioner must also direct the management to take any necessary steps to rectify the matter, including recovering any assets of the Company that may have been misappropriated. But what do you say is the way forward for Eskom? I guess as an business rescue practitioner for Eskom your job is to make Eskom successful again. So market liberalisation is probably not what you are wanting. However - generation is the problem, and not having enough electricity to sell limits the business. So generation side market liberalisation is probably in the interests of Eskom. But who would invest for generation when the only customer is a single SOE. So to get people to make that investment to build generation will mean that they have to be able to sell directly (or, practically, through various "energy companies"). In such a liberalised market Eskom will stll be the major buyer for many years - In principle the UK has 34 "energy companies" (companies you can buy electricity and gas from). There are 6 big players. You can switch "suppliers", though you still get the same electricity and gas down the same wires and pipes. Behind these energy companies are, I assume, various commercial contracts for distribution and generation. I am sure those contracts vary according to the varying circumstances of the businesses contracting. For the user the result is lots of interesting options - "green" suppliers, clever time of day tariffs and etc etc. But for the old big players - eg British Gas - their Eskom of gas - well they have 15 million customers in the UK so they are not doing so badly. Having 20 electricity companies competing, who have contracted with generation companies on commercial terms, and who are contracting distribution through Eskom distribution partnered with municipalities - now we have a way forward. Business efficiency will be essential. Into such a market you could even imaging people like us - home generators - form a business together and sell our electricity into this market together.
  10. Well it took me a long time to get through all the process on my side - draw the diagrams and get the signoff etc - CoCT was reasonably prompt with their side. I wonder really if they are able to properly review all the information provided - but I did my best with @Rautenk to build a safe and compliant system.
  11. Yay. All official! Thank you to @Rautenk, @Mike, @Carl, @Jaco de Jongh, and tons of advice from the ou manne of the forum and lots of others besides. What an interesting project - I learned a lot in the process and so far not a single shock! On a day when we face Stage 6 shedding I feel like very clever to have this system in the house! Thanks, @Elbow / Steve
  12. Elbow

    Stage 6??

    We had 0h00 till 2h00 and 16h00 till 18h00. I can tell when we are being shed since my inverter regulates the voltage much closer than the council does...
  13. ESP, News24 et al are reporting Stage 6 from 18:00. No idea what that means for shedding schedules - ESP only shows up to stage 4 and the Cape Town municipality web site is crashed. But it does mean to dump 6GW of load according to Eskom. So since Stage 4 means (for Cape Town) 7.5 hours off out of 24, I presume stage 6 means 11.25 hours off out of 24. So - how to set the inverter to survive it? I suppose we need to permit charging from the grid, only use batteries when there is no grid power - objective to get the batteries charged as quick as possible and only use them when needed. What a pain.
  14. Hi, Last night I was woken up at midnight with my inverter beeping. Went to look, muted the alarm and all seemed OK. But this morning I see my servers rebooted at that time so its clear that the inverter dropped my essentials loads (and then restored them immediately). My server, NAS and two Pis all restarted. Now normally this works fine - when the grid goes off the inverter seamlessly switches to the solar and/or batteries. My inverter is programmed in Grid tie with backup mode. I have set the battery discharge threshold with grid is present much higher than the threshold when the grid is not present. I also limit how much power is taken from the batteries when grid is present. But it seems like these two discharge thresholds don't work properly? My batteries normally discharge down to that "grid present" threshold in the evening and the inverter then switches to powering the essentials from the grid. I think that what happened was: Batteries were at or just below the "grid present" threshold Grid dropped. Inverter logic is flawed and it dropped the loads because the batteries were below the "grid present" threshold. And set off the alarm. Then it noticed the grid gone and switched in the lower threshold since there was no grid and turned the loads back on but now from the batteries. So it looks like this: (The "Grid watts" between 00:00 and 02:00 is misleading since my ET112 has no power do can't be queries to get the data - that's why there it doesn't show 0 - no readings) Zooming in: The power loss was probably shorter that the 10 minutes here - when the inverter dropped and restored the power the EmonPI and other gear had to reboot so measurements were lost. Did anyone using the Infinisolar or other OEM stuff similar to this have this happen? Any ideas as to how to sort it out? My NAS especially doesn't enjoy losing power - it will now spend the next 11 hours resynchroning its RAID, so I'd like to avoid this! Thanks!


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