My system diagram and here is my specifications, parts and schematic.
I am not an expert but from spending time on searching and learning and with some novice knowledge on electronics i came up with this schematic and components.
I would appreciate any guidance on parts that are not neccessary or parts that are not good or wrong or anything that can be of a handy cause i am in my first steps and my first build.
Solar Specs : Rated Power 220W (±5W)
Open Circuit Voltage 21.5V
Short Circuit Current 12.4A
Optimal Operating Voltage 18.4V
Optimal Operating Current 11.9A
For cables i just mention them as AWG since i havent got the time to find which ones to buy yet (any recomendations would be nice)
so from Solar to Mppt if i am correct i will need 12AWG
from Mppt to Battery if i am correct i will need 10AWG
from Battery to Inverter if i am correct i will need 6AWG
I will use also some other victron extras like Dongle and usb cable, battery monitor and sense but didnt think i need to mention them on the schematic (except the shunt now that i recheck it but i think its gonna be easy)
My main concern is about fuses and protection of the components like using fuses and mcb`s so i can isolate solar panels and battery whenever needed from the hole system for maintainance or updates.
Ignore the asteriscs (*) in the lines cause its from italian and bold letters that they dont get fixed by editing them
Thank you in advance for any help, correction, suggestion etc etc on my diagram (schematic)
I recommend to use a panel with higher voltages. PV voltage needs to be Vbat+5V in order to start the MPPT process. Your controller can handle up to 100V of PV, so rather get a panel with 40Voc
Cable cross section depends on max current and length, use the Victron toolkit app and/or take a look at the Wiring Unlimited guide from Victron
The inline fuse doesnt do much, it will never blow since the panel can only supply 12A. If you choose a higher voltage panel, then the current will be even lower. Inline fuses in general are handy if you want to combine three or more strings in parallel.
Same for the circuit breaker. If you want/need it as a disconnect then thats ok, but it will never trip on overload or shortcircuit.
Using both fuses and circuit breakers is weird to me, but ok. Maybe you planned to use switches only? Because circuit breakers also contain overload and short circuit protection.
I would be cautious with switching the negative path, if you plan on using communication cables. Their shield and GND signals might not be isolated from the negative, so opening the negative path could send DC power over a shield.
The panel is the only one i can`t change from the diagram cause i allready have it. All others are changable. My panels output is almost above the 17.8 Volts in optimal operation but yeah if you mean that it may not reach in some conditions that volt, i will have to check it out. I really dont know yet but its from the latest N-type bifacial solar cells, and i hope to be ok.
Cables sorry for not mentioning yes, they will be smaller than 1.8 meters so by checking the tables according to amps and meters as well as fuses too i think they are inside the conditions to outstand even a higher overcurrent till some fuse take action.
Thanks for the inline Fuse help, cause i got confused a bit on that and now i get it.
Yes, all the circuit breakers i use them only as an on/off switch for me in case i need to isolate panel or battery
I use both breakers and fuses cause circuit breakers doesnt seem to be so trustable in many cases so i use them as an on/off switch with a bit of higher amps for avoiding overheating and for the rescue i use the fuses at the maximum Amps
I really dont know. I ve seen others as well using Mcb switches but i dont know if it was 2p or just on the positive. Should i use 2 switches instead only on the positive for isolating battery instead of the 2 double pole MCB`s ?
My panel is portable so i need to remove it and reattach it, so if i use an MCB at panels point or not is the same thing i guess when removing it so i guess a 2pole switch there would be ok or should i search for something else for that also ?
This reminds me of how I started 4 years ago: found some cheap, almost new, 230Ah 12V lead-acid batteries and decided to try and run a raspberry pi 3 year-round on solar-power.
Also found a cheap 250W solar panel, a discounted 100/20 mppt and a 12V USB converter, hooked it all together with 4mm² (~11awg) and indeed run it for a year. Only thing I should have done different was adding a “battery terminal block fuse” to the +pole of the battery. Batteries can deliver a lot of current and fireworks if something goes wrong!
The mppt protects itself from shorts so I would not add too many connections between MPPT↔Solar and MPPT↔load: every connection increases resistance and thus energy loss. You should reconsider fusing/switching solar when you have >1kW of solar power though, on a larger MPPT.
Even with low-power panels, it is not recommended to disconnect anything under load. MCB, MC4-plugs, other switches/fuses: they will be slightly damaged and wear down faster every time you disconnect under load. If it is indeed a mobile setup: face the panel to the ground and just disconnect the MC4 plug.
After a year I got another cheap 250W panel and another 100/20 MPPT. Still no fuse on the battery , and added a 375VA 230V inverter (50A inline fuse), 10mm² (~7awg) deciding to run my 80W fridge on solar as well. This failed horribly since my fridge draws 1200W for a second when it starts up, tripping the inverter. Make sure you take the startup power into consideration when choosing your inverter.
Then I attached my PC and that worked when I was not gaming. Gaming, drawing more power because of the GPU, also tripped the inverter. After a few trips I noticed the inverter tripping when I powered on the PC. Even changing it back to the grid: my 16A 230V breaker tripped when powering on the PC.
Seems I destroyed my PC power-supply because of the trips: Do not try to use the inverter near max power for delicate hardware.
(After that 12/3000 multiplus on lead-acid with proper fusing and now 3x48/5000 multiplus on LiFePo.) This hobby will get out of hand And you’ll love it.
Yeap it helped!
Thank you for all the advices from your experience snowwie, for a 12v system all of these are too much but since i dont know i had to be sure about protections and i got it with your help and experience and with chrigu too.
Sure thing i wont turn off anything while having a load or charging it except extreme situation that it needs to shut down before it goes boom.
I have some considerations about gaming laptops sparkling when getting on ac plug but they dont usually say anything about startup power, just mentioning the input and the output on their main charger and sure they must draw 3 times their output when connecting on a plug to do such sparkle and yeah GPU is something to keep in mind, thanks
I had the love for solars and such systems since i was a kid when i was learning my first smart-kits and checking the solar water heater of that time produces so much power. I lost the hobby later, got it back again and yeah after many years solar systems, batteries and supercaps are at this level and will advance more.
Depends on how its mounted/angled towards the sun. If its mounted flat on a car roof, then it may never reach enough voltage, but you’ll find out. If you already have the panel then just try it out
The issue is limiting voltage loss. You “only” have 12V, so you dont want to loose them to cable resistance
I personally would use single pole breakers on the positive connection and leave the negative connected. The circuit is broken, so theres not going to be any current flow. But if you want to switch both positive and negative, then use two-pole breakers, so that both positive and negative switch together
MC4 connectors are not made to be reconnected often, the original Stäubli MC4 is only rated for 100 connection cycles. I use an XT90-S on my portable panel, its internal precharge resistor prevents sparks when plugging them in, also rated at 500VDC (but i only use them on low voltage), 40A continuous and 1000 connection cycles
I sometimes think i should make this hobby my job, but then it would not be as fun anymore
Thanks, yeap, i was searching to fix the 2p with 1pole breaker or switch on the positive line for the battery isolation and use one fuse on the positive pole instead of two.
Since i will use a switch for maintenance i prefer to go for 1p breaker instead of just an on/off switch.
MC4 connectors are on the panel so for the moment i dont want to change anything cause it is new. Later on if something goes off from time and usage i will think of your advice and thanks about it cause i didnt know that.
, and added a 375VA 230V inverter (50A inline fuse), 10mm² (~7awg) deciding to run my 80W fridge on solar as well. This failed horribly since my fridge draws 1200W for a second when it starts up, tripping the inverter. Make sure you take the startup power into consideration when choosing your inverter.
And you’ll love it.