Installing solar panels

[Isetech]

Panel connectors, MC4, H4 and T4

Can you connect an MC 4 to an H4 ? Yes you can.

Can you connect an MC4 and a T4 connector ? Apparently it is not a good idea.

You can open the connector with 2 screwdrivers, however there is a multi function tool which can be used to open the connection.

[Isetech]

Doing some research I noticed some of these connectors are tinned copper, So out with the sharp knife and a magnet.

After a good scratch, I got to the copper. the connector did not stick to the magnet, so that is a good sign.

Did a search for one of the brands I purchased - leader

Found the spec sheet to attach to the commissioning sheet:

https://www.leadergroup-cn.com/product/pv-plugs-solar-panel-connectors-types

The certificate for the model purchased:

Rated to TUV 1000 and UL 600 VDC VDC. The question you need to ask, is it suitable for a panel rated at 1.5 KV?

Rated to 20 - 30 amps, that would work as the panels I am installing are fused at 15 amps.

Or do you have to use the connector rated for 1.5KV

https://www.leadergroup-cn.com/product/pv-cable-solar-panel-wire-connectors-1500v-tuv-ul

I keep getting told that I need to go do a solar course to learn all this stuff, do they cover all this kind of info in the courses?

If they do and offer the lithium battery guide with all the regs for safe installation I need to find out which course and go and do it.

If the panel indicates 1.5 kv, do you have ti use 1.5 KV connectors and are all the inspectors signing off COC's have these details included in the commissioning sheet, especially if you are not the person buying and installing the equipment.

[Isetech]

Which standard applies to us in SA now that we no longer need to follow the SANS anymore.

TUV IEC 62852 1000 VDC (class II )

or UL 6703 - 1500 VDC

[Justloadit]

When installing panels, ensure that the user is able to at some time or other be able to access the panels for cleaning. Making a roof full of panels, does not give any access to clean the center installed panels. Also do not clean panels using cold watere between say 10H00 and 16H00 hours, as the panels get really hot when working at full power,and can reach 70°C. Using cold water could crack the glass.

Dirty panels can cause up to a 30% loss of energy due to dust, and when panels are placed in series, a single large bird dropping, can cause a loss in that complete array. Remember that when panels are placed in series, the current has to travel through each cell in the PV panel, one cell not exposed to light will reduce the current flow in the string.

There are MC4 terminals and there are MC4 terminals. The choice is yours to make!
Another point with respect to the MC4 connectors, look for the machined ones, these have a better connection, and they are manufactured for the different sizes of PV cable, 4/6/10mm especially when you are using the hex crimper. You will note that the machined pins or female side, will have a tiny hole drilled on the side near the centre end. Took me a while to figure out the reason for this, but because of the tight fit, air would get trapped inside the tube, and be compressed, causing the pin to pop out of the female one, like a piston. The drilled hole allows this air to escape, and not placing stress on the 2 parts.

The rolled MC4 terminals are cheap, and can expand with heat or with multiple insertions, and may not contract when they cool allowing for a poor contact from male to female, so the next time that DC current flows, arcing could commence and cause a fire.
I have used my thermal camera on terminals, and was shocked to see the amount of heat generated on poor quality terminals, in some cases I measured over 100° C with in the terminal mated area. Now place this terminal in the hot African sun at midday, and you are inviting a disaster.

MMMM what can I say about combiners.....
What you may find is that many combiners simply have parallel terminations inside the combiner. Sounds good, have a number of panels in series, and a number of them in parallel, and you have a nice big system. The reason that PV panels have a 1000V rating, is that you can place many panels in series, and every time a panel is added, the total string voltage increases. Placing 20 say 50V panels in series, gives you a 1000V at 12Amps. Hence the rating of the PV cable and Panels of 1000V.

Now back to the combiner box and strings in parallel. Now recall I mentioned about the bird droppings on one panel, so now 2 strings are placed in parallel, they become unbalanced, because the one string works harder than the other and heats up, so the total series voltage is no longer the same, so the one string feeds into the other, and wham you have a problem, panels could over heat and self destruct, fire...... Now add more arrays, and currents become a major issue.
So combiners should have isolated strings, this can be done with diodes, but another problem, lets say at midday we have 12A flowing in the string, a silcon diode will have approximately 0.8V drop across the junction. Power is Volts Times Amps. That equates to 9.6Watts of heat across the diode. Does not sound like much, but place a number of diodes in a small enclosure, IP65, no way to get cooling and again wham bang another problem. Has anyone measured the temperature of the fuse holder in operation? Using the thermal camera shows approximately 60°C radiating from the suitably rated fuse. Now place this in an enclosure in the midday African sun, and you will see distorted fuse holders. Not saying that the DC breakers are any better withy the heat generated inside, but you need to overate them because the heat build up inside will cause the mechanism to trip, and you lose a string, and will require manual resetting.

So a well designed combiner box will cost lots of Rands, to deal with all these issues. One way they try and get away with the diode issue, is to place a DIN rail fuse holder with a rated fuse for the string for each string. Sounds good, until you disconnect the fuse under load, and suddenly you have a nice arc and a damaged fuse holder. Okay so a well designed combiner box, which has "Schotky" diodes suitably rated for the string, because they have a lower volt drop, therefor a lower heat across the junction, and DC circuit breakers, and now you have an expensive piece of equipment. You are trying to compete with Mr Cheap Installer.

[Isetech]

Dodgy solar installers, they are like electrical contractors, a dime a dozen. Thank goodness I have been around long enough that I dont have to advertise and deal with cheap quotes.

All my work is word of mouth, I live by my company motto "doing it right first time every time". I completed a project a couple of weeks ago, the customer posted a picture of his installation. I got 8 new projects just from the picture and the recommendation from the customer. I just dont have the manpower to tackle all of them.

Anyway back to the solar stuff...

The problem with entering into a new field, it is going to take a while to figure out which products work and which are cheap junk.

It seems that the brand of MC4/H4 connectors to use is going to be Amphenol or Staubli and evo 2.

Its just a connector. We all know what happens when the weakest link in a system fails.

[Isetech]

Not forgetting you need to decide the orientation of the panels, some say the best is to face north. Unfortunately this is not always possible.

You need to consider shading from obstacles and other issues which will hinder the placement.

This where it starts getting a little complicated, do you use a free online package or do you get an engineer to design the layout.

At some stage we are going to be forced to register the system with the local municipality. In some cases you will need an engineer to sign off the installation.

You will still need the electrical contractors COC and all the other stuff , so my thoughts are to get the engineer to design the solar and work with them from the start.

The big question is going to be, at what point do you need an engineer to get involved, a small 5 KVA unit with a hand full of panels on the roof or only when you start installing 12 KVA units.

I dont know how long it is still going to take for the shyte storm to settle and the electrical industry and the solar industry to come up with a set of guidelines and regulations they can agree on.

It is also going to be interesting to see how they tackle the registration of more than 200 000 installations already installed.

I had to smile the other day when I heard someone mention that they had installed their system on the roof which is not facing the road, in case the council saw they has panels Yip this is Africa you can only smile.

[Isetech]

The PV installation including the DC , Panels , inverters etc is all part of the Electrical installation and needs to be covered by your COC -
To issue the COC you need to be in general control and test the installation
See attached article

Looking at the picture on the article, I just smile, the oke standing on the panels with boots on. the instruction manual clearly stats that you should "NOT" stand on the panels . You shouldnt even carry them on your shoulder or on your head. The solar industry are looking at the pic saying look at these idiots, this is why electricians should stick to what they do best and leave the solar industry to the qualified solar installers

It makes me think of the guidelines for installing lithium batteries, then you look at all the pics on social media and clearly nobody gives a rats a$$ about guidelines and regulations

[GCE]

If the panel indicates 1.5 kv, do you have ti use 1.5 KV connectors and are all the inspectors signing off COC's have these details included in the commissioning sheet, especially if you are not the person buying and installing the equipment.

It means that you could use that panel in a 1,5Kv string - If the panels are VOC48v - then you could string +/- 30 panels giving you a VOC of 1440 - You would need to take temp etc into account so best to give at least 10% under for VOC to climb
Your MPPT will determine the string voltage that you want to use

If you are only going to put 5 panels in a string then the VOC will be +/-240v and so rate the connectors accordingly

[Isetech]

Solar cable...it seems to be another challenge.

I bought a couple of meters of this cable to check. The first thing I noticed about the cable, it doesnt seem to be double insulated, this is very important, especially if you plan to install on a surface.

I read one article indicating that you can bury the cable, but on the next page it indicates that it cannot be submersed in water. If you bury a cable in conduit underground, chances are the cable will be submerged in water, no matter how well you seal the couplings. We even blow the pipes clear before we pull in the wiring, but every cable I have ever pulled out that is buried is full of mud.

[Thys LOW Elektries]

Lets start talking about the installation of solar panels and what you should consider. This is all new to me, so feel free to add anything I might have missed or correct me. This is going to be a dummies guy to solar installations.

Before you tackle the installation you have to consider the following:

1/ The direction the roof is facing.

2/ The type of roof.

3/ The gap/space between the roof and the panel, for air movement and cooling.

4/ The space around and between the panels, for example if you mount the panels to close to the gutter the water will clear the gutter.

5/ If the roof can actually support the weight of all the panels.

6/ Maintenance on the roof prior to the panel installation, for example if there is no plastic under the tile, this might be a good time to install and you could check the battens at the same time and replace as needed.

Depending on the existing roof you have to look for signs of damage to the roof and roof structure also for signs of water damage or leakage. The last thing you want is be blame or sue for something that is not yoyr fault

[Isetech]

As we build the DC combiner boxes , I noticed that the bottom of the fuse is used to connect the wires from the panels and the output of the isolator is used to connect the wiring to the inverter DC input.

I am thinking if the power is entering the combiner box from the panel, surely you would want to connect the panel wires to the top of the Dc isolator (because the one I am using actually has line at the top and load at the bottom) out the bottom to the surge arrester and the top of the fuse holder, then out the bottom to the inverter. That way you isolate the power source. IF not you have power on the the surge arrester.

Some might say you can pull the fuse, to isolate the panel, but if you look at the fuse holder you will notice the fuse is in the bottom part.

The power flows from the panels to the inverter not the other way.

[Isetech]

I managed to find a crimper with the correct die today, and just like that all the connectors are crimped and ready for site.

We have decided which panels we are going to use. Taken the max VOC and max current of the inverter, did a quick search on the WWW and found ones which suit the application.

The panels will not be north facing because of all the trees, so we might add a few panels on the opposite roof at a later stage. the remote reporting will provide more accurate data for future upgrades, be it for more batteries or more panels or both.

I am sure there are many free solar design programs to calculate the data required, but for this project it is too small to worry about all that stuff.

Now to decided on the roof hooks rails etc.

A few considerations:

The type of roof tile.

Galvanised or Stainless steel .

Adjustable or a fixed hook.

Secure to the batten or the rafter.

The clearance between the roof tile and panel.

The spacing between the tile hooks.

The gaps between the top and bottom rail.

The type of rail:

Galvanised (P2000) or aluminum.

Top or side rail to secure to the hook and the panel clamps.

Renusol Varisole+.

Valsa rail.

Photon rail.

There are others but these are being considered.

[Isetech]

Then it time to fit the panels, link the cabling and wire down to the DC combiner box.

Considering the max current is only 15 amps with a fuse, (Voltage between 250 and 450 VDC, a 4 mm solar cable should be fine (current rating 44amps) . Do I buy a roll of red and black or just a black and some red hear shrink ? I think just a black coil and heat shrink for now.

The next consideration will be the wireway from the room down to the DC combiner. I did consider the DC isolator on the wall outside, but have decided against it.

The solar wire is double insulated, so no need to enclose the wire in conduit, some say bosal conduit (then you have to consider the metal and earthing etc) should be used, other just cable tie it to the cable tray, for the domestic project I think a 25 mm PVC conduit will be just fine. The pvc conduit will make it look neater.

[Isetech]

This is where it gets interesting again, earthing bonding of the panels and rails.

Considering the max current is only 15 amps, however the earth wire from the roof down to the dedicated earth terminal for all the earthing and bonding should be at least 10 mm.

This is a tricky one, do we run a 16 mm, 10 mm or 6 mm? Some say a 16 mm is required, but I dont agree.

Then we need to link an earth wire from the dedicated earth terminal down to an earth spike.

Then its time to link all the equipment (bonding). I noticed the supplier supplied the inverter 8KVA with a short piece of what looks like a 4 or 6 mm earth wire.

[Justloadit]

The earthing of the PV panel frame and mounting rack has nothing to do with the electrical earth in the DB board.
What you have now done, is added a great metal grid to the top of the roof, which will now attract lightning. The actual silicon pf the PV panel is well insulated from earth by the glass that it is mounted in.
The purpose of earthing the frame is to divert the lightning should it strike the roof to ground.
Now lightning likes to travel the shortest path to earth, so I believe when panel frames are earthed, and I like to use this one 'good practice' to use the maximum copper diameter you can afford, and find the shortest path to earth, and directly bolted to a good quality (maybe copper too expensive) earth spike as deep as you can afford/push into the earth.

Then use surge arresters on the DC side, with the earth point of the surge arresters the the DB earth point, this will protect the electrical equipment that is wired in the DB board of any stray voltage that may be transferred to the PV silicon through the capacitive effect if there is a lightning strike.