Jump to content

My journey from Off-grid to Grid tied ... what not to do


Guest

Recommended Posts

My journey started in 2008 with UPS'es, me wondering back then about UPS / solar panels ... why not?
The not part being the cost of panels, like R30 per watt. MPPT's not available in SA yet and PWM's quite expensive.

By 2012 I had my first 2 x 200w panels and by 2013 3 x 310w panels added, all off grid. 

Off grid because CoCT has been talking about solar systems and connecting them to DB boards for a very very long time now. I became aware of that in 2008 - 2012, therefor me going off-grid then, basta me and regs. Then CoCT started charging the R150pm connection fee and insist we must register all solar installations. So I though ok, lets play, and promptly swapped from off-grid to grid tied. The savings are so much better with grid tied than off-grid, in cities.

I have been harping on the legally installed solar systems because connecting anything to a DB board has regulations (solar, generator, UPS) all contained in your local municipal / Eskom rules and regs. Nothing new. Proper Sparkies know exactly what to do with generators, large UPS'es ... for decades now. Nothing new. Solar, just a few more checks.

And it is all over SA, not just CoCT. CoCT just the first municipality to throw down the gauntlet, NERSA being the driving force behind it.

 

This is where I started, PERFECTLY safe, all the safeties in place yet a very cool (literally) install as I have lost a MPPT due to heat yonks ago, using a 100% legal Interlock built by a electrical engineer (the grey box) to switch from Solar to Eskom using the BMV's relay with a online double conversion APC UPS to handle the one second break. All perfectly legal off-grid, was just not registered, as it was not required.

System ran from 2012 to last quarter in 2018, going 24/7/365, before I sold everything bar the batts, going forward with a Multigrid with a 150/100 MPPT. 

Here is how you use burglar bars (on a inside window) to the next level. The draft in the window during the day was awesome see. :D
Note: Photo was taken to show a lot of wires ... as there are a lot of computer stuff connected direct. So it looks worse than it seems. ;-)

1224309856_ForChris.thumb.jpg.784f095db714fb1a55b5a4e36a0d54fb.jpg

 

Once I have the CoC in hand, as I had to move the new setup again late in Dec 2018(!), will show how it looks now, being grid tied and all that, legal with all the paperwork in place.

A fault came out that no-one foresaw, one that has been around since the house was built.

So my first piece of advice: Before you buy anything, no, before you even think of buying anything, have your DB board tested. 

There could be a dormant or underlying issue that no-one knew about, like I recently found a N/E bonding, done when the house was first built, which only came to light when the final tests where done as required by CoCT on the application. Costly spanner in the works I tell you.

 

FWIW. My application was send in months before, was lost, then found, for being already a solar user since 2012, there is a grace period.

New installs done by solar installers, cannot be switched on until CoCT gives approval. It can take up to 3 months. 

So test the board ASAP, send in the application, then buy, as it can cost a bit to fix / alter / move anything in and around a DB board.

Edited by Guest
Link to comment
Share on other sites

With my newly discovered NE bonding issue, I sent an email to CoCT late Dec to ask if they must fix, or I. Being on our property, it is my problem, which is fair as the original electrician took a massive shortcut.

The tests showed:
1) Earth Loop impedance (Z'E) 33 ohm.
2) PSC 0.771kA
 

This is what he did, the original electrician:

image.thumb.png.68808995fc6a097f55145d207f775eda.png

 

With them checking where their box is, I got this picture from them, showing me where they stop ... the picture showed the solar panels on the roof.

What I found very interesting was that this photo is way WAY newer than Google Maps. Like a few months old if I look at the pool we had back-filled last year.

image.png.8c1f5080ee8ef6309dbfc105daece283.png

 

 

Edited by Guest
Link to comment
Share on other sites

15 minutes ago, Chris Hobson said:

How is your BF sparkie going to rectify this?

They tested the existing earth spike right next to the DB but cannot use it as they are not going to chop up a concrete slab to verify that all measurements are as expected.

So they have to install a new earth spike at the point where the wires enter the house.

They flatly refuse to give me a CoC for the install till all is tested.

And the are "forcing" me to put all the DC side in a save box ... can you imagine THAT! Me, putting stuff in a box where I cannot tinker with it!? :D

 

No seriously, I see where they are going. Everything they do, they take photo's. No-one can change things after they left and claim they signed it off. I like that.

Link to comment
Share on other sites

3 minutes ago, Chris Hobson said:

 :o Alas - Belville fire dept are rendered redundant. :P

What ... nooooo, they use water, recycled water on top of that, and recycled water and DC is not a good match see ... and the germs!

Me, I have a red fire extinguisher. One made for electronics.

For it to work properly you need to point the fire extinguisher to the base of the fire, as per the pictures ... right?

So I had a great idea!!!

Why bother with a box, which cost a lot of money, if you need to unlock the burning door to get to the base of the fire in the first place? 

Be gone with the box, say I, it is unsafe in a fire condition. :rolleyes:

:P

Note: In case someone thinks I am serious ... don't. 

Link to comment
Share on other sites

On 2019/01/04 at 11:57 AM, The Terrible Triplett said:

With them checking where their box is, I got this picture from them, showing me where they stop ... the picture showed the solar panels on the roof.

What I found very interesting was that this photo is way WAY newer than Google Maps. Like a few months old if I look at the pool we had back-filled last year.

image.png.8c1f5080ee8ef6309dbfc105daece283.png

 

I came across the following link for photos of Cape Town from Feb 2018. They also have photos from 2017, so we may get another update in a month or two?

http://www.arcgis.com/home/webmap/viewer.html?url=https%3A%2F%2Fcitymaps.capetown.gov.za%2Fagsext1%2Frest%2Fservices%2FAerial_Photography_Cached%2FAP_2018_Feb%2FMapServer&source=sd 

Link to comment
Share on other sites

image.png.c33ddcb8c11bd758584236f0d70de46f.png

Inside - the box on the left:
1 x fuse on negative and 1 x fuse on positive
With a double pole NoArk breaker
And panels are earthed onto the earth-spike that conveniently sits below the installation.

To do:
1 - VE.Direct cable is a wee bit too long, its a 5m cable, was a good idea, not anymore
2 - Should maybe get the connectors neater ... but I am NOT letting go of the connectors ... can unplug it all in seconds.

 

And then the issue @Chris Hobson re the Fire Brigade ... the infamous box ... 

The trunking around the Multigrid contains all the wires the electrician connected to and from the main and secondary DB's.

image.thumb.png.f68eaa7f06c37b707f93b6bee8c2bde3.png

To Do
1 must be installed into 2 which must be mounted at 3.
BMV to get a shorter 90deg VE.Direct cable, so that I can close and mount the box.
6 must also be in truncking as it is the dedicated circuits going into the ceiling to select points all over the house.
8 needs trunking as it goes to the MPPT on the other side of the wall.

The rest:
4 is the dedicated circuits DB with the lights in there also. Doing it with THIS type of DB board, one can save a lot as you can now use standard extensions leads if you want. All the ACDC breakers it came with has been replaced.
Red 3 point plug stays, feeds all the computer stuff, as it shows clearly there is power on that board. Electricians suggestion.
5 is just a network switch in this part of the house - still to neaten its power cable.
7 is the LTRON PAYG meter, one that does not trip when there is some accidental feedback, it does charge for that though, but it is cents.

Once all is done and dusted, that corner will be behind doors, locked doors, with a large vent opening at the bottom and totally open at the top.

That is for every time my bud walks past the setup and just itches to press buttons. Promised him I will switch his entire DB and UPS off if he touches one button on MY setup. ;)

Edited by Guest
Link to comment
Share on other sites

  • 2 weeks later...

Right, I now have a proper TN-C-S (whatever that means). All I know, if there is any problem at the electricity box in the street, the house is now safe.

The new box outside, replacing that orange one, with not one but 2 earth spikes installed. 
The earth wire goes to the 2 earth spikes, all properly bonded as shown. 
DB board is at LAST testing within parameters ... just the DC side left to put in a safe box, then the engineer can come. 

image.png.7304c42fe66ce5bf729a24ee68c04c21.png

Readings was from here:

image.thumb.png.64b070cd725ca9ee36cd394bcab8231c.png

 

To here - after the 2nd spike went in.

image.png.34f500ba6d37302eb9178cd01b7d2db4.png

Edited by Guest
Link to comment
Share on other sites

59 minutes ago, The Terrible Triplett said:

TN-C-S (whatever that means).

Terra Neutral - Combined - Separate.

It means neutral and earth is bonded (the TN bit), the neutral and earth is COMBINED (ie from the transformer to your house there is only two wires, the black wire is both neutral and earth), and then from that point (where it is bonded and tied to the earth spike) there is a SEPARATE earth conductor.

It is different from TN-S where the earth conductor runs all the way to the transformer down the street, ie it is SEPERATE the whole way.

Link to comment
Share on other sites

6 hours ago, plonkster said:

Terra Neutral - Combined - Separate.

It means neutral and earth is bonded (the TN bit), the neutral and earth is COMBINED (ie from the transformer to your house there is only two wires, the black wire is both neutral and earth), and then from that point (where it is bonded and tied to the earth spike) there is a SEPARATE earth conductor.

It is different from TN-S where the earth conductor runs all the way to the transformer down the street, ie it is SEPERATE the whole way.

Typically there won't be a local earth spike at the consumer for a TN-C-S and the PEN (C) is separated at the point of control which is at the municipal / utility meter in most cases 

Screenshot_2019-01-16-04-16-43-668_com.google.android.apps.docs.png

Link to comment
Share on other sites

5 hours ago, Jaws said:

Typically there won't be a local earth spike at the consumer ...

The tests, if I understood correctly, testing from the municipal supply in the road to the box outside the house, was not up to standard.

The way I gather, if that municipal box in the street is run over by a car (yes it can it is that close) and the Multigrid feeds power to the house with that box dead, that their would be an potential issue if it is not TN-C-S.

The form asks:

image.thumb.png.a2e642baa9b000f0b824b87bd7ee10b1.png

 

And this is the part on the form, innocuous as can be (1 & 2) , that must be tested, that has costed me a pretty penny to fix. Without this grid tied installation, this problem would never have come out as it has been there since the house was built decades back.

The 0.22 ohm reading can be lower as the earth is dryer than dry where the 2 rods are in. Both sparkies (they area a team) are now satisfied and will give the CoC now for AC and DC side ... once the DC side is tucked away.

image.thumb.png.2eaee1036983824480ee3e6f92b401e5.png

 

Only part they are unsure of, busy reading up on that, is the open cables here.
Connectors are there for MY safety - and to remove stuff fast in case of an issue. :-) 

image.png.de680fd8e36d39dca9ce5039acef94fc.png

 

Edited by Guest
Link to comment
Share on other sites

6 minutes ago, The Terrible Triplett said:

open cables here

It needs strain relief or trunking, as far as I know. The trouble is that I can grab that cable going into the charger and yank hard on it, and if I manage to pull it out of the clamped connection I have two wires with a big battery bank on the other end, a large spark, and potentially a fire. Yeah it should probably blow a fuse, but as I understand it that is the gist of it. Either put on strain relief (usually using a cable gland, which implies a box of some kind) or tuck the cables away so it can't be pulled at.

I'm not at all sure how you're going to retain your quick disconnects.

Link to comment
Share on other sites

5 hours ago, Jaws said:

the PEN (C) is separated at the point of control which is at the municipal / utility meter in most cases

In TTT's case this was screwed up. So they fixed it by installing an earth spike on the premises, essentially making the system a proper TN-C-S setup.

Link to comment
Share on other sites

2 minutes ago, plonkster said:

I'm not at all sure how you're going to retain your quick disconnects.

Therein the challenge. Have the same on the battery bank, larger connectors, to pull it apart. When I disconnect, it must be disconnected, not "switched off".

Thanks for the rest, makes perfect sense. Never thought of anyone yanking them cables out of the MPPT - we must take care of the stupid roving between us all, me being the leader. ;)

I now have an inkling to form an idea of what I could do.

Link to comment
Share on other sites

6 hours ago, PJJ said:

If you really want to go all out with the safety stuff you could also add a MPPT Wirebox

Thanks PJJ, for that awesome titbit.

Has been ordered, will take 2-3 weeks to arrive, for about R480 or thereabout.

@plonkster thanks for your heads-up, once installed, I can keep my quick disconnects and the wires cannot easily be pulled out of the MPPT.

Link to comment
Share on other sites

50 minutes ago, The Terrible Triplett said:

Thanks PJJ, for that awesome titbit.

Indeed, I had forgotten about those nice little things. I think I'll get some of them too. Not sure what size I need, but I know I need two.

Link to comment
Share on other sites

2 hours ago, The Terrible Triplett said:

Come per MPPT model.

I bought one of these for my MPPT and they look good and provide good strain-relief!  The only issue I picked up is that my MPPT does not have threaded holes on the underside of the heatsink for fitting it. I am not 100% sure, but it looks like these holes may only be on the "SmartSolar" version of the MPPT and not the "BlueSolar" version. I tried getting an answer from Victron on this, but was not successful.

I eventually solved this by gluing the plate to the heatsink with a small amount of strong 2-part epoxy. I would be interested in whether your unit is also missing these holes.

288-clipboard02.thumb.jpg.067661a25ae65afc7bae65caa247e221.jpg

Edited by NigelL
Link to comment
Share on other sites

12 minutes ago, NigelL said:

I would be interested in whether your unit is also missing these holes.

Having a quick remove design ... the 150/100 TR does not have the holes either.

Thanks for that heads-up - 2 steps forward, 1 back. :-) 

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.

×
×
  • Create New...