diy solar

diy solar

(Another) Newbie DIY'er looking for advice.

Watchamawho

New Member
Joined
Mar 30, 2022
Messages
8
Hi all.

Sorry in advance, I can imagine beginners ask the same questions over and over, so apologies if my post frustrates. I'm pretty much learning as I go.

I thought i'd post as I hope to learn alot from the community, and apply it to my specific solar setup.

Speaking of...

So, I aquired two 150w panels for reasonably cheap, alongside two great condition, 12v, 100ah Leisure Batteries (Wired in Parallel) for a combined pool of 200ah (100ah usable). I'd love to make my own personal solar setup in the brick shed in my garden, so I decided to buy a 30a PWM controller, and now i'm researching into how to correctly (And safely) hook it all together.

Here's what I've concluded so far:

1. Am i right in thinking the solar panels need to be in Parallel? Will it also need to be fused? (If so, what sort of fuses?)

2. From solar panels to the controller, it's approximately a 4.5meter/15 feet max along the roof and down the exterior wall of the shed (Exposed to the elements). From what i've calculated I need at least 8AWG wiring for this, would that be right?

3. Do i need a particular standard of wiring as it'll be exposed outside? What is the best way to make this weather/damage resistant?

I've attached a Image of the specs of the solar panel (Both are identical) and a link to the PWM Controller I have (Below). If anyone could just verify that my maths are correct I'd hugely appreciate it.



Again, many thanks for your help!
 

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8.7a each in parallel gives you 17.4a, and the PWM controller is going to limit you to about 14v so you might get 240-ish watts out of those panels. Fortunately no fuses needed there.

Those leisure batteries are only good for 50% DoD so your batteries in parallel are good for 12v @ 100Ah of usable power.

8AWG seems pretty thick for less than 20a over 15ft. Plus, most MC4 connectors are only able to take 10AWG wire.

Any wire that's rated for outdoor use will be fine as long as the connections themselves are water tight.

If you put in an inverter you'll want a fuse right at the battery to feed it, everything else is pretty low end and shouldn't need fuses. Having said that you can always add fuses if it makes you feel more comfortable.
 
1. Am i right in thinking the solar panels need to be in Parallel? Will it also need to be fused? (If so, what sort of fuses?)
They don't need to be fuse but you will REALLY want to have a switch to turn off the array. So most people use a circuit breaker which has the functionality of both. 25A would be a good breaker size (20A max be too close and cause nuisance trips but if you have one handy as its a common size, it would be worth trying).

Look for MC4 Y connectors to easily combine your 2 panels in parallel. Search Amazon to see what it looks like. They are pretty common and cheap (about $15).

10Awg (standard solar wires) should be fine. I don't think 8Awg will fit into the little connectors on that SCC.

That should be a nice little setup.
 
8.7a each in parallel gives you 17.4a, and the PWM controller is going to limit you to about 14v so you might get 240-ish watts out of those panels. Fortunately no fuses needed there.

Those leisure batteries are only good for 50% DoD so your batteries in parallel are good for 12v @ 100Ah of usable power.

8AWG seems pretty thick for less than 20a over 15ft. Plus, most MC4 connectors are only able to take 10AWG wire.

Any wire that's rated for outdoor use will be fine as long as the connections themselves are water tight.

If you put in an inverter you'll want a fuse right at the battery to feed it, everything else is pretty low end and shouldn't need fuses. Having said that you can always add fuses if it makes you feel more comfortable.

Great, cheers for the input - I was concerned about routing the 8AWG cable as it'll be fairly thick, saves drilling a large hole in my shed wall.

Looking online, I keep coming across 4.5mm2 cable (Which i think is closer to 11AWG guage) would this be ok?

Here's a link:


They don't need to be fuse but you will REALLY want to have a switch to turn off the array. So most people use a circuit breaker which has the functionality of both. 25A would be a good breaker size (20A max be too close and cause nuisance trips but if you have one handy as its a common size, it would be worth trying).

Look for MC4 Y connectors to easily combine your 2 panels in parallel. Search Amazon to see what it looks like. They are pretty common and cheap (about $15).

10Awg (standard solar wires) should be fine. I don't think 8Awg will fit into the little connectors on that SCC.

That should be a nice little setup.

with the switch/breaker, would it be more suitable to have it closest to the solar panels or closest to the Controller?

Would something like this suffice?:


Thank you both very much for your replies. Much appreciate it.
 
with the switch/breaker, would it be more suitable to have it closest to the solar panels or closest to the Controller?

Would something like this suffice?:
That's the kind of breaker that i had in mind though i cannot speak of the quality of that one. I use a Bussman that looks the same - apparently there are a lot of cheap chinese knockoffs that get warm in use and trip lower than rated amps.

A fuse/breaker normally protects the wire that follows it. But from solar, where a fuse in fairly optional on small setups, having the switch in a handy location (and out of the weather) is most important to me.
 
Sorry to revive the thread, but I've another question.

I've got a 1000w inverter and batteries on a wooden trolley rack which I'm able to cart around the shed and/or interior property based upon power needs.

However, this has posed issues with grounding the inverter, which obviously isn't fixed to a rigid pole in the earth.

Would it be ok to connect the inverter ground post (located on metal casing) to the battery negative?

I keep getting conflicting advise on this, how the ground is for ac current and connecting it to 12v DC Negative would be bad.

If anyone here can clarify I'd appreciate it.

I should also mention that the inverter has internal fuses and its also on a 100a breaker
 
Welcome to the party Watchamawho.

Now you've opened a can of worms. Grounding can go anywhichway. This may help or confuse.

Enjoy the show. ;)
 
Ok, so here's where things are gunna really get interesting:

I sorted the grounding issue, i think, by buying a RCD plug which will at least offer some protection from electric shock.

Anyways; i connected this new solar setup to a load intended to use occasionally - two lithium battery ebike chargers. Low amperage, pull about 250w max each. To the 1500w, PURE sine wave inverter i have (had) for this build. It was nothing special - quite a cheap buy....

Anywhoo, upon connecting the two chargers, the inverter started to buzz heavily, and promptly burst into smoke and flames.

after i got my composure, I decided i'll just return the inverter and buy a better brand one, and be done with it.

I tested the chargers on typical mains house electric for a few hours afterwards, all worked fine. When i got the new inverter and hooked it all up, it started to display the same issue within about a minute or so of connecting it to the chargers; a hum and buzz, that grew with increasing intensity. I quickly turned it all off.

I then thought i'd use ANOTHER two lower power chargers (About 100w or so max from each) and within a minute, they too trigger the same response!

The new inverter is a 1000w BELTTT, pure sine wave inverter found here:



What on earth is going on? From what i've been told or read, what i might be experiencing is either destructive harmonics, or a combination of poor power factor of the chargers stressing out the inverters i connect these to, leading to smoke and fire.

I should clarify that, if i use only ONE charger (to charge one battery) it works absolutely fine. Doesn't matter what charger or to what battery either. Two at once though, i get scary issues! - and again, both run perfectly fine off of the grid on the same house socket.

I plugged in a socket monitor into the inverter to see what was going on, and when both chargers are in, the voltage drops DRAMATICALLY (to almost half of 240v - 149 ish) before i lose the confidence to push it further. Power factor of each charger is around 0.5.

If i connect this new inverter to say, a 900w space heater, it runs it with no issues whatsover. No odd voltage drops, nothing. It seems the inverters just HATE running two of my lithium Ebike chargers lol.

Im no expert with this, but this is some crazy weird stuff going on that maybe someone here could offer some clarity to?
 
Last edited:
Sorry to revive the thread, but I've another question.
Its your thread! You can even grant yourself 3 more wishes in your own thread.

Anywhoo, upon connecting the two chargers, the inverter started to buzz heavily, and promptly burst into smoke and flames.
Did you connect the chargers to the battery or SCC load output?
The load output is VERY limited on what it can power. Batteries are made to power loads, SCCs not so much.
 
Ok, so here's where things are gunna really get interesting:

I sorted the grounding issue, i think, by buying a RCD plug which will at least offer some protection from electric shock.

Anyways; i connected this new solar setup to a load intended to use occasionally - two lithium battery ebike chargers. Low amperage, pull about 250w max each. To the 1500w, PURE sine wave inverter i have (had) for this build. It was nothing special - quite a cheap buy....

Anywhoo, upon connecting the two chargers, the inverter started to buzz heavily, and promptly burst into smoke and flames.

after i got my composure, I decided i'll just return the inverter and buy a better brand one, and be done with it.

I tested the chargers on typical mains house electric for a few hours afterwards, all worked fine. When i got the new inverter and hooked it all up, it started to display the same issue within about a minute or so of connecting it to the chargers; a hum and buzz, that grew with increasing intensity. I quickly turned it all off.

I then thought i'd use ANOTHER two lower power chargers (About 100w or so max from each) and within a minute, they too trigger the same response!

The new inverter is a 1000w BELTTT, pure sine wave inverter found here:



What on earth is going on? From what i've been told or read, what i might be experiencing is either destructive harmonics, or a combination of poor power factor of the chargers stressing out the inverters i connect these to, leading to smoke and fire.

I should clarify that, if i use only ONE charger (to charge one battery) it works absolutely fine. Doesn't matter what charger or to what battery either. Two at once though, i get scary issues! - and again, both run perfectly fine off of the grid on the same house socket.

I plugged in a socket monitor into the inverter to see what was going on, and when both chargers are in, the voltage drops DRAMATICALLY (to almost half of 240v - 149 ish) before i lose the confidence to push it further. Power factor of each charger is around 0.5.

Im no expert with this, but this is some crazy weird stuff going on that maybe someone here could offer some clarity to?
This post looks like a great THREAD STARTER in UP IN SMOKE.

I would run those two chargers on the same outlet and feel the circuit breaker BEFORE & AFTER running the chargers a while.

If the breaker doesn't show signs of warming, you may not have that grounding issue resolved. I have no idea how, but maybe.
Or maybe just a loose connection somewhere.
 
Its your thread! You can even grant yourself 3 more wishes in your own thread.


Did you connect the chargers to the battery or SCC load output?
The load output is VERY limited on what it can power. Batteries are made to power loads, SCCs not so much.
the lithium ebike chargers are mains AC powered, so they were connected directly to the inverter.

As the pair only pulled 500w max (250w each) i assumed that would be plenty safe to use on the inverter. I understand inductive/resistive loads are also a thing, but i figured this would surely be fine. (Obviously not, but no idea why!)

This post looks like a great THREAD STARTER in UP IN SMOKE.

I would run those two chargers on the same outlet and feel the circuit breaker BEFORE & AFTER running the chargers a while.

If the breaker doesn't show signs of warming, you may not have that grounding issue resolved. I have no idea how, but maybe.
Or maybe just a loose connection somewhere.

The RCD plug also does get warm to the touch, and when i test it via it's buttons, it works as intended.
 
I searched this thread, but still do not know what an RCD plug is.
 
I searched this thread, but still do not know what an RCD plug is.

 
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