Which solar cables to use
Modern panels produce ~43V at ~10A in their maximum power point. The diameter of the cable attached to the panel is 4mm².
If you have to extend DC cables in an ES-Micro system 4mm² will always be enough.
If you link panels in series (ES-Hybrid systems) you need to calculate the necessary diameter for the long DC cables which you must provide to connect the string array to your inverter. Thin cables produce more loss but are cheaper than thicker cables. Assuming that you have two strings with a maximum of 16 panels each a diameter of 4mm² will be ok if you have less than 30m of distance between the inverter and the panels. You can check this, if you enter 688V and 10A and 2*30=60m into the calculator linked below.
https://www.solar-wind.co.uk/info/dc-cable-wire-sizing-tool-low-voltage-drop-calculator
You should choose red color for the positive wires and black for the negative ones. A single cable will always have two different types of MC4-connectors (male [-] and female [+]) at its ends. This means that a red (positive) cable will have a female connector [+] and a male connector [-]. You plug its male side into the positive end (female plug) of your panel string and then its other end (the female plug) become the plus side of the string – which you must connect to the inverter.
You will buy the necessary length of cables and some connectors. You need a special tool for crimping the cables. Look at the video. Do NOT try to crimp wires without the special crimper tool. You will produce bad connections which probably will produce problems later when operating at full load.
How to connect DC cables
Connecting cables to panels is the last step after the panels have been properly mounted. Sometimes it is possible to make all connections after all panels have been mounted. But usually you mount a panel and then connect it to its predecessor in the string (or to its micro inverter in the case of an ES-Micro system). You should have a painted sketch which clearly shows how panels are arranged physically and electrically. Keep this plan even after your system is working. It may be useful if something fails some day.
Connecting panels to micro inverters can be done at any moment without special care. The rest of this chapter deals with string arrays used in ES-Hybrid systems.
Careful attention is needed for ES-Hybrid systems. Connecting panels to a string means, that at the two ends of the growing string you will instantly have the sum of the idle voltages of the connected panels (if there is sunlight).
Check the path which will lead from the panels to the inverter. This could be an unused channel of a chimney if panels are mounted on a roof.
First you cut cables roughly to the necessary length. You end up with two black and two red cables of similar length. They may differ a little bit because the ends on the roof will later go to different positions (first and last panel of each string).
Now mark a red and a black cable with a blue tape at both ends and mark the other pair of cables in the same way with a yellow tape. Place your color marks at least 20 cm away from the ends of the cables.
Then you tie the four cables together with some adhesive tape at one end; place the adhesive tape directly at the end and another ring of tape one meter away. Now you have a stable bundle of four wires, two red and two black ones. From the roof you lower this bundle down into the chimney until it will arrive at the basement floor (or wherever your inverter and battery are placed).
You pull the bundle out until it is close enough to the inverter to be connected comfortably (not being too mean with cable length ..) Now you untie the bundle and connect two MC4 plugs with a male pin to the black cables and two sockets with a female pin to the red cables. Make sure that your color markings (blue and yellow tape) are not removed during the crimping process.
Now put a plastic bag around the two black plugs and another one around the two red MC4 sockets – making sure that no one will touch them while you are on the roof.
Go back to the roof and bring the other ends of your cable pairs into position. Fix the cables as needed, for example with cable ties. Shorten the cables if you want, but make sure you can easily connect them to the correct cable end of their associated panel.
Then crimp MC4 connectors to the cable ends. This time you use male plugs for the red cables and female sockets for the black cables.
Then start to mount and connect panels beginning with the first panel of the first string, linking all panels which face into the same direction according to your plan. Do not connect more than 16 panels to a string. Finally mount the last panel and connect the red wire (the one with the same color mark as your initial black wire) going to the inverter.
Repeat the same procedure with the second group of panels.
The final step should be done when there is no sun, i.e. early morning or late evening. You remove the plastic bags and connect the cable pairs to the corresponding inverter inlets. The color code helps you to find the correct connection points. It does not matter whether “blue” will be associated to #1 or to #2.
Which AC cables to use
https://www.elandcables.com/cable-calculator
Traditional panel placement for flat surfaces [FLAT-S]
The classic way is to orient panel surfaces heading south [FLAT-S]. You will have a strong energy peak around noon and a relatively small production in the morning and evening. If you choose a relatively high angle of attack you need large spaces between the panels.
There are some aids for calculating the necessary spacing deoending on the angle of attack, see this table.
Alternative way of panel placement for flat surfaces [FLAT-EW]
An alternative way is like this, panel surfaces headig east/west [FLAT_EW]. You will have a more evenly distributed energy production which in many cases matches your daily consumption profile better. Wind forces are smaller and the whole construction can be more light weight. Spave requirement is also smaller so that more panels fit into the same area. The overall energy produced will be slightly less with [FLAT-EW], however. So, if you have a really large battery and a strong concrete floor [FLAT-S] may be a little better. But generally speaking, we have a preference for [FLAT-EW].
In both cases you must be careful not to violate the roof covering, which will usually be a layer of bituminous roofing felt (tar board). You should place an additional layer of this material under the points where the metal pieces of the stands touch the roof. No screws must be used. Just put some paving blocks at the places which are designed for them.
A combination is possible [FLAT-EW-S]
Although you will not find this constellation frequently, at least in theory it unites the best of two worlds. You would place 80% of your panels EAST/WEST and at the northern side of your area you add one row of panels heading SOUTH with a really steep angle (70 degrees or so). You must fix these panels firmly. Ideally they would be fixed to a white wall and have solar cells on both sides. These panels will give high yield in winter when the sun is very low on the horizon.
Considering weight
The total weight including pavement stones, aluminium rods and panels will be between 12 and 33kg / m² – which is a significant difference. Old panels usually are heavier, and [FLAT-EW] can live with much less ballast weight. Regions wit7h heavy winds need more ballast. Ask an enigneer to check the statics of your building before you decide.
Details on East/ West mounting
It is important to keep some distance between the lower edges of the panels and the roof and also between the top edges of two adjacent edges. This will allow for some air circulation. Hot panels produce less energy than cooler ones.
As you can see the construction shown above has six solid rubber-like pieces which provide places for 12 stones. 2 persons can mount two panels in 10 minutes.
The product shown above is just an example which contains many cleverly designed details. Go and look for similar mounting solutions at your place.
This one is fairly cheap and lead to our estimation of ~40€ / panel.
String Separation and inverter limits
ES-Micro can handle panels with different orientation perfectly. With ES-Hybrid you need to connect all panels facing East to one string and the other ones to the second string. Our ES-Hybrid inverter needs at least 120V in a string for startup. This means that you should have a minimum of 5 or 6 panels in each string. On the other hand you cannot have more than 16 (modern) panels in a string because their idle voltage may go up to 60V and the sum of their idle voltages would become dangerously high (1000V is the tolerable maximum for the inverter).
If you want to have 32 panels facing the same direction you would have to split them into two groups of 16.
The combined placement [FLAT-ESW] would in fact require three strings. Our ES-Hybrid inverters (as many others in the market) have only two maximum power pount trackers, i.e. two strings. Maybe this is a reason why we see this placement pattern so rarely.