Jump to content

Low budget complex system for very unstable utility power network in Guinea


davidduarte
 Share

Recommended Posts

Hello to all,

Although it's my first post, I did a lot of research on this forum and others, so I would like to thank you very much for all the experiences and knowledge shared!

I'm living some months in Guinea each year in a rural area with very poor utility network power and some power outages. Besides the need to improve my solar system, I need to install an automatic Phase to Line transfer system.

At the moment I need to have an AVR on almost every appliance and to manually change the input from Phase to Line when the tension goes down and Line to Phase when the tension goes up. Usually this happens only in the morning or at night, but sometimes it can happen during the day or during the night.
Even if my 3W led lamps (chinese, the european last 1 week only) can acept 80VAC~275VAC, wen the tension goes to 300VAC~400VAC I loose them.

I've designed what I think it would be the best low-cost system that will handle everything that I need, but as a newbie in solar, I'll appreciate your comments/advice/warnings.

I hope that this can also help others that are in a situation like mine.


Best regards,
David

guinea_solar_setup.pdf

Link to comment
Share on other sites

  • 4 weeks later...
1 hour ago, davidduarte said:

At least one reply please? 🙏😅

Nice design that’s some serious protection you have to install, however you have a “typo” you need to swop polarity L1 and N on the incoming side of your drawing. Other thing to check is the Novatec contact it could take a bit of a beating when switching at full load as geysers eat contacts for breakfast 😂👌

Link to comment
Share on other sites

Hello Gerrie,

 

Thank you very much for your feedback.

 

What do you mean by swapping polarity on L1 N. I need to have L1 + N or L1 + L2, not L2 + N.

Regarding the Novatec, it seems it can handle 16A. They have the RN118 that can only handle 10A. I guess this one will handle the 500W  Geyser don't you think? When talking with them, the main issue they mentioned was the pump. That's another reason why it has an AVR with delay, to protect the RN119 from arc so we don't have any breakfast as you said 😅

 

Please let me know if even when 16A you think it's risky for a 500W Geyser.

Edited by davidduarte
Link to comment
Share on other sites

6 minutes ago, davidduarte said:

What do you mean by swapping polarity on L1 N. I need to have L1 + N or L1 + L2, not L2 + N.

Sorry my mistake I thought you need L1 + N or L2 + N. 

What confused me is when following the blue line (N) it goes through the switch contact on the Novatec relay and normally us South Africans never switch a neutral but only a live, I know the Italian’s also switch neutrals which confuses guys like me 😅

38 minutes ago, davidduarte said:

I guess this one will handle the 500W  Gueyser don't you think?

I see now it’s only a 500W geyser but what will happen when there is no Sunshine and all your loads (geyser + fridge + washing machine) switch over on the Novatec, It might still burn the contacts prematurely. Or is it not possible for everything to be on at once?

Link to comment
Share on other sites

1 minute ago, Gerrie said:

What confused me is when following the blue line (N) it goes through the switch contact on the Novatec relay and normally us South Africans never switch a neutral but only a live, I know the Italian’s also switch neutrals which confuses guys like me 😅

I'm Portuguese/Spanish born in France but I love pizza 😅. I would also prefer to switch the live, but I don't have any other way to get the voltage/switch I need. I prefer to close the normally open contact when the voltage is stronger and to just go back to the normally closed contact when the voltage is lower. I guess it will reduce arc probability?

 

5 minutes ago, Gerrie said:

Or is it not possible for everything to be on at once?

You are right. They will never be all connected at the same time.

However I was thinking to have the fridge connected at the same time with one of the other appliances (less the geyser and the pump).

But now that you've pointed that out, I'm afraid that after connecting another appliance, or with an appliance running and the fridge start, the relay will switch as voltage will go down. I'll have to check how it handles this.

This "detail" was always my main concern and you've got it right away.

I was thinking to go with a contactor, but impossible as I'll not have constant voltage to the coil. Variable coil voltage contactors cost a lot $$$.

I'll need to test and see and maybe give "someone" a breakfast 😭?

 

 

Link to comment
Share on other sites

10 hours ago, davidduarte said:

I'm Portuguese/Spanish born in France but I love pizza

Espetada’s, Pregos and pizza is some of my essential foods 😂.

 

11 hours ago, davidduarte said:

I prefer to close the normally open contact when the voltage is stronger and to just go back to the normally closed contact when the voltage is lower.

It makes sense when the voltage is much out of range for a coil it will probably start to heat up and lead to failure. 

Have you considered to put all your loads through the inverter as essential loads? And not use any over or under voltage relays and even do away with the AVR’s. I’m sure the inverter have it’s own protection built in as it should be able to handle voltage inputs 120V to 280V. It might require up scaling batteries and PV panels for maximum loads but might be another solution to deal with the bad utility power.

Link to comment
Share on other sites

20 minutes ago, Gerrie said:

Have you considered to put all your loads through the inverter as essential loads?

That would be the easier setup and for sure more reliable, but for some reasons that are not technical, I can't do it.

I'll have to try with this setup, and if needed, do some changes.

An option would be to have a more powerful AVR after the relay, this will assure that all the load connect is done be the AVR. But I'll have to buy it. Instead, the small AVR are already at home for a long time.

I'll just loose the almost zero transfer time for lights, but I agree to sacrifice some seconds, to avoid breakfasts for "people" who do not deserve it 😂

I'll post the results.

Link to comment
Share on other sites

There may be an unexpected consequence for you, depending on how your inverter is programmed. My inverter (Goodwe) is set to South African standard 230V AC. That means it expects 230v-ish volts at 50 hz on the grid side. It allows for some fluctuations, but where I live the grid voltage was, for a while, fluctuating outside of the range the inverter would accept. Always down, and sometimes down to the 180s. I think the Goodwe disconnects at 210 and reconnects at 220, so sometimes I would technically have grid available, but the system would draw the batteries down very low because although I could stick my hand in the box where the municipal feed comes in and get a shock, the Goodwe was having nothing to do with the grid. This meant everything it supplied got a nice 230V with a beautiful 50hz sine wave, but it got that from the batteries. I understand there is an upper limit too, but this was only a theoretical problem in my case.

Forgive me if you've figured all this out, but, again, depending on brand of hardware and the settings, your system may disconnect from grid if voltage fluctuates too much either way and just use PV and batteries - and drop the non-essential loads completely.

Link to comment
Share on other sites

18 minutes ago, Bobster said:

Forgive me if you've figured all this out

That's a very good point! 👌🏽

I didn't choose Goodwe and other more high quality brands for that reason. That's the same for my lights and appliances. They can all work with higher and lower voltages. If I use European brands as an example, they will get burn or will not work at all.

It seems that Easun Isolar SMV 24000W AIO can take 90V-280V. Manual provided by Tully from Easun attached if anyone need it.

The thing I can't control is the frequency. I don't have any idea about the frequency range I have there. But there are people on the same network using this Chinese AIO (I promoted them to a solar reseller) and they are working pretty well.

I will know it after the installation 😊.

ISolar SPV SMV 2400W User Manual.pdf

Edited by davidduarte
Link to comment
Share on other sites

Following the idea to have a bigger AVR, to avoid all the complex setup to switch from phase to line tension, I've found this AVR option https://m.alibaba.com/product/1600117097545/product.html?spm=a2706.7835515.0.0.515d49cf8oufrx&__detailProductImg=//s.alicdn.com/@sc04/kf/H1b924f34f8bf44499d1ad8c554ea448fw.png_220x220.png.

They can have 45V-280V range with 7 relays and 15.000VA. Even if power factor is reduced, I guess this would handle well 2400W. It is not expensive, but maybe impossible to find there. Anyone with experience with this model, or other brands with the same specs?

The servo motor options, usually have a smaller voltage range, so not an option, unfortunately.

Already asking to some resellers there.

Link to comment
Share on other sites

58 minutes ago, davidduarte said:

I didn't choose Goodwe and other more high quality brands for that reason. That's the same for my lights and appliances. They can all work with higher and lower voltages. If I use European brands as an example, they will get burn or will not work at all.

I can set the Goodwe to 50Hz default, which means it accepts pretty much any grid voltage as long as it's at 50Hz, but then if grid goes to 180, the inverter serves up 180, and I presume that if the grid goes to 300V then that's what the inverter will serve up.

Link to comment
Share on other sites

2 hours ago, Bobster said:

I can set the Goodwe to 50Hz default, which means it accepts pretty much any grid voltage as long as it's at 50Hz, but then if grid goes to 180, the inverter serves up 180, and I presume that if the grid goes to 300V then that's what the inverter will serve up.

I see. I didn't know that as they don't mention AC input voltage range for XS models, as other brands do.

Most of AIO will just do that, a bypass when the voltage is in range. Some however seem to have an AVR included, but more weight on both sides kg and $$$. 😅

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...