Finally, solar panels

[Isetech]

Yip its that time. I have done my fair share of generator, UPS and inverter installations, but never a solar panel install. Due to the ridiculously high demand from customers requesting not only a load shedding solution, but they want a money saving solution.

Before you ask, was a load profile for the property carried out for at least a week, the simple answer no, the only time we will do a load profile is if the customer has an open ended budget. That way the load profile will determine the size of the standby system.

What we have learnt is that the budget determines the capacity of the standby unit. You can install a recorder for months, spend 2 days doing all the calculations to come up with a perfect system for the application, however that is where the fight begins . When you hand the estimate to the customer who had this vison of being off grid with a 5 kva unit, 5 kwh battery and 5 panels , which would last a week with clouds and rain. Well the reality is that unless you have money to buy a 50 kva diesel generator with a 500 litre tank, a 12 kva inverter, maybe 3 X 10 kwh batteries in parallel and a roof full of panels, you going to wake up and your coffee will be cold with a skin covering it.

[Isetech]

This is how we are tackling these projects-

First question- what is the budget, R20 ? or R900k ? Once we have a understanding of the how to invest in the project, then we ask the next question, quality of the product required.

Do you want cheap, medium or a good quality installation.

Onesto, hager or ABB.

Axpert/luxpower/kodak/MCE/RCT/MECCER etc , Deye/Sunsynk, or Victron.

Pylontech, BSL, freedom one or Tesla.

in no particular order to offend anyone You get the idea.

Once the equipment is selected, then its time to determine the load profile suitable for the equipment.

NO you cant run the stove, washing machine, tumble drier, dishwasher, 5 x 18000 BTU AC units and a a pol pump on a 5 kva unit with 1 battery and 3 solar panels, if your budget if your budget is only R150k, unless you add a PLC and lots of contactors and relays, anything is possible if you prepared to spend the money and make a many life changing adjustments to your daily routine. We do the impossible immediately, unfortunately miracles take a little longer

[Isetech]

The next step is the electrical installation and all the other stuff which requires power, with cables or wireless. This is also the point where we consider the type of wireways to be used etc. We have to consider what it will look like once completed and how it it will affect the aesthetics. In some cases the building is clean and minimalist, ie no clutter, then you come along and run cable and piping all over the place and throw ugly panels visible from the main entrance.

We identify every single part of the elctrical installation, create a single line diagram, sketches with the points and circuit identified and record it. We then create an XL spreadsheet and list everything in as much detail as possible. This part of the project includes the alarm system, the CCTV, the network cable layout, the gate and associated components, electric fence. If it switches on/off, it is noted and added to the list.

Once the spreadsheets and sketches are complete, then we sit down and identify and highlight what has to be connected to the essential and non essential circuits, taking the budget and equipment selected into account.

[Isetech]

We start by pre wiring the DB's in the workshop. IF you need a 12 way, make sure you install a 18 or 24 way because once you go down this rabbit hole, that DB will be populated so quickly, you will wish you doubled the size.

Focus on the neutral bars, earth bars and the how to get those bigger cables into the top of the breakers, surge arrestors etc. That is where those terminal type busbars come in handy, but the size of the DB will determine what you can fit in it.

[Isetech]

I have just completed an 8 kw unit (solar panels installed by others). This setup was a little tricky because the property main DB became the essential DB only.

The panel next to the inverter became the main DB (non essential) , the changeover panel and Aux supply and the input and output for the inverter.

When selecting the supply (input) cables, you need to consider all the requirements of the code and the max load including the pass through current. Some people cant understand why the input cable must be bigger than the output cable.

If you have a 5 kva inverter for example, the max output current is generally around 20-25 amps, however if you have a bi-directional hybrid unit, chances are that there is a higher pass through current and this current must be taken into consideration.

What I have found working with standby systems (DB'S) is that the labels are the most important part of the installation. It gets rather tricky and dangerous if the labels dont clearly identify circuits. The labels identifying circuit are all black on white and warning labels are yellow.

The indicators lights also help. We have standardised the indicator lights on all the installations. Red is grid, blue is UPS and green for anything else.

The neutral bars are installed to the left and right of the breakers, the mains on the left and the ELU circuit on the right.

[Isetech]

Feel free to add or correct anything I might be doing wrong, I am new to these solar installations and there is still a lot I need to learn.

Things like where we can install lithium batteries, there is a lot of jiba jaba on social media, but in reality I dont believe there are many, if any, who have clue what they are talking about. I see a lot of batteries installed below 1200 mm in garages without suitable barriers to protect them from being damaged by a motor vehicle. If you read the warnings, it clearly states that impact to the battery will cause an explosion, just imagine the consequences of an explosion next to a petrol or diesel motor vehicle.

Lets talk about lithium batteries and safe locations.

Certainly not below 1200 mm in a garage which has motor vehicles, unless there is suitable mechanical protection.

Something else to consider is thermal runaway, parking a vehicle close to the battery if the engine is still hot.

Garages dont normally have a ceiling, which could result it much higher than normal temperatures.

What else would make it dangerous to install a lithium battery in a garage, if it is used a workshop.

You do a bit of steel or wood working in the garage, moving the long pieces of wood or steel around or a piece of steel comes loose and flies across the garage.

Still think the garage is the safest location?

[Isetech]

Then we move onto what makes it dangerous to install a lithium battery inside the house?

Considering the batteries have a BMS and other types of protection built in, what are the chances that it is going to blow up inside the house?

What are the chances it is going to get anywhere near as hot as the battery mounted in the garage, there is a good chance there are aircons and fans inside the house, ceiling which will reduce the heat compared to the garage.

Ok so maybe installing it in a cupboard inside the house with little of no ventilation would be a really stupid thing to do. It doesn't mean you cant, if you take the recommended spacing around the inverter and battery into consideration, and air movement, maybe a fan or 2 to consider a reasonable air exchange.

Then we need to look at fire walls, doors and fire escapes.

[Isetech]

The project we are busy with will have a pile of 460 watt panels.

Time to secure the panels to the roof, install a wireway and take the earth and bonding of the panels into consideration.

The panels (460watt)will create around 2760 pW, not really, due to many factors, the voltage will be around 400 VDC and the current around 11 amps.

The volt drop because the voltage is over 400 should be minimal, a short run (about 15m)

The wireway will be a 25 mm PVC conduit from the roof down to the combiner box, just to keep it looking neat. I did consider a wire tray, but decided to rather install PVC conduit.

The wire size will be 4mm red and black and 10 mm earth wire. The solar wire has a much higher current carrying capacity than standard house wire, it is also double insulated and has UV protection and therefore can be installed directly onto cable tray.

While designing the panel installation, a few things need to be considered,

the spacing from the edge of the roof,

the distance from the gutters to prevent the water gushing over the drains,

the space between the roof tiles and the panels.

the direction the panels will be facing and the angle of the roof.

how many panels per string and how many panels in parallel, the VOC (very important) and the current must not exceed the MPPT rating.

the earthing and bonding for the rails and panels.

then something I have noticed most people seem to miss, how and where to isolate the panels/strings in case of an emergency. I believe there should be a weather proof isolator on the outside wall where the solar cables drop down from the roof and go into the building.

[Justloadit]

Don’t want to frighten you , but see the attached link which shows what can go wrong when it is not done right.
Ensure all connections are electrically and mechanically good.
The inline MC4 connectors are of good quality on the PV panels. Many companies sells the cheap crap, those ones are rolled metal, not even spring form brass, which causes a mechamical failure which in turn cause the electrical failure.
Get the ones which are machined from solid brass then plated to prevent oxidization.

http://www.acsolarwarehouse.com/news...solar-systems/

Just remember that there should be a minimum of 150mm from the roof to the back of the PV panel to allow for the hot air to create air flow.
PV panels when they work at full load in the middle of the day, the glass/panel can exceed 60 Degrees C.