New to solar, setting up my first lab!

[BreezyReputation]

Hi everyone!

I’m brand new to the Solar scene. I want to start learning the basics now, and eventually work up to a system that will be able to support at least a portion of my home, or a camper.

I’ve just purchased some pretty basic hardware to set up a little lab and get familiar with terms, operation, setup, wants, and needs.
I picked up a Renogy 100w panel that came bundled with the Wanderer 10A charge controller. I already have a 410W inverter, and I’m going to pick up a 12v 10Ah Li battery probably today.

I’ve spent the morning refreshing on electrical basics, and shopping for fuses and cables.

It seems like 10A fuses aren’t very common, which doesn’t surprise me; with such a small current, most probably don’t even bother with a system that small.

So far, this is what I've come to:

panel > controller
20V, 5A = 21awg @ 3ft, 19awg @ 6ft, 17awg @ 9
5A x 25% safety factor = 6.25A maximum current, round up to 10A inline fuse.

controller > battery
12v, 10a (120w) = 16awg @ 3ft, 13awg @ 6ft, 12 @ 9ft
Fuse should match the controllers rating, 10A

battery > inverter
410w, 50a, 12v = 8awg @ 3ft, 7awg @ 6ft, 5awg @ 9ft
410w / 12v / .85 x 1.25 = 50.24A
inverter rating / battery voltage / efficiency rating x 25% safety factor


I appreciate any feedback on what I've got planned. Also, any reference to cable sizes would be appreciated...there's a lot more to consider when it comes to choosing the right cable. I'm trying to do everything exactly to spec on this small scale, and then slowly scale up as I become more comfortable with the system.

Thanks!

 

[sunshine_eggo]

Sizing based purely on ampacity ignores voltage drop/wiring losses. It's often easiest to buy common wire sizes even if they're overkill.

As you've indicated, fuses should be 1.25X current. 10A fuse on 10A controller means the fuse will blow.

For panels, you use Voc/Isc for safety calcs and Vmp/Imp for performance/voltage drop.

Solar panels have a fuse rating on the label. That's the easy way to calc the fuse.

A single series string of panels or two series strings of panels in parallel do not need fuses or breakers. They are essentially self-fusing.

3 strings in parallel require a fuse/breaker on each string.

 

[73powerstroke]

Hi everyone!

I’m brand new to the Solar scene. I want to start learning the basics now, and eventually work up to a system that will be able to support at least a portion of my home, or a camper.

I’ve just purchased some pretty basic hardware to set up a little lab and get familiar with terms, operation, setup, wants, and needs.
I picked up a Renogy 100w panel that came bundled with the Wanderer 10A charge controller. I already have a 410W inverter, and I’m going to pick up a 12v 10Ah Li battery probably today.

I’ve spent the morning refreshing on electrical basics, and shopping for fuses and cables.

It seems like 10A fuses aren’t very common, which doesn’t surprise me; with such a small current, most probably don’t even bother with a system that small.

So far, this is what I've come to:

panel > controller
20V, 5A = 21awg @ 3ft, 19awg @ 6ft, 17awg @ 9
5A x 25% safety factor = 6.25A maximum current, round up to 10A inline fuse.

controller > battery
12v, 10a (120w) = 16awg @ 3ft, 13awg @ 6ft, 12 @ 9ft
Fuse should match the controllers rating, 10A

battery > inverter
410w, 50a, 12v = 8awg @ 3ft, 7awg @ 6ft, 5awg @ 9ft
410w / 12v / .85 x 1.25 = 50.24A
inverter rating / battery voltage / efficiency rating x 25% safety factor


I appreciate any feedback on what I've got planned. Also, any reference to cable sizes would be appreciated...there's a lot more to consider when it comes to choosing the right cable. I'm trying to do everything exactly to spec on this small scale, and then slowly scale up as I become more comfortable with the system.

Thanks!

I used to have a really nice chart that would give you the ampacity of a wire gauge at the different voltages so a lot of stuff is based off of the national electric code which assumes 120 V or 240 V are somewhere around there and it simply isn't the same at 14.4v (12v)
Here's a chart. If you go to 24v system later you can run smaller wires . Ohms law is good to learn. But basically when volts go up , current goes down. And more efficiency. And vice-versa. Here is a few charts I grabbed off net for you . Ask lots of questions. Don't be afraid to say you don't know or don't understand. Lots of good people on here who like to help. And welcome.

 

[BreezyReputation]

Thanks for the replies!

Based on that new info, I picked up a few more things.

I got 30 feet of 6 awg, some crimpers, and some terminals. Terminals ended up being the wrong size (gauge was correct, ring is too big...good for cable practice and maybe future projects).

I already had some shrink tube and solder, so I ordered a butane torch to make that all much easier.

The battery I ordered showed up, but I wasn't paying attention to the terminals, which were F2. I'm not able to find any 6 awg F2 connectors, so I'm shopping for another battery that will have more accessible terminals.

I have some fuses on the way as well; a 20A and 60A ANL fuse w/assembly, and a solar cable inline fuse rated at 10 amps.

 

[73powerstroke]

Thanks for the replies!

Based on that new info, I picked up a few more things.

I got 30 feet of 6 awg, some crimpers, and some terminals. Terminals ended up being the wrong size (gauge was correct, ring is too big...good for cable practice and maybe future projects).

I already had some shrink tube and solder, so I ordered a butane torch to make that all much easier.

The battery I ordered showed up, but I wasn't paying attention to the terminals, which were F2. I'm not able to find any 6 awg F2 connectors, so I'm shopping for another battery that will have more accessible terminals.

I have some fuses on the way as well; a 20A and 60A ANL fuse w/assembly, and a solar cable inline fuse rated at 10 amps.

Good deal. Yeah I accidentally got 2ga lugs for 1/2 stud and not 3/8 a few times.

 

[Bud Martin]

I used to have a really nice chart that would give you the ampacity of a wire gauge at the different voltages so a lot of stuff is based off of the national electric code which assumes 120 V or 240 V are somewhere around there and it simply isn't the same at 14.4v (12v)
Here's a chart. If you go to 24v system later you can run smaller wires . Ohms law is good to learn. But basically when volts go up , current goes down. And more efficiency. And vice-versa. Here is a few charts I grabbed off net for you . Ask lots of questions. Don't be afraid to say you don't know or don't understand. Lots of good people on here who like to help. And welcome.

The chart #1 of your picture can't be right.
I.E. 3' 10ga handle 200A? Link to that chart?

 

[73powerstroke]

The chart #1 of your picture can't be right.
I.E. 3' 10ga handle 200A? Link to that chart?

Yeah that's the same one we were discussing before. I linked it in the other thread. I clicked the image quickly thinking it was the reg one. I'll go back and delete it. It's certainly way off

 

[BreezyReputation]

So, I'm having some trouble finding a battery I'm comfortable with. I was trying to stick with something around $50 bucks because its just a lab, but it seems like even bumping my battery budget to $100, all the batteries have terminals that require connectors that are all too small to terminate a 6 gauge cable.

Do I need to
a) increase my battery budget? If so, any recommendations for the least expensive battery that will fit my circuit? I now have some copper 1/4" ring connectors for my 6g cable (these fit my inverter)
b) search harder for a better selection of connectors?
c) spend some effort right sizing my cables?
d) all of the above?

Thanks!

 

[Bud Martin]

So, I'm having some trouble finding a battery I'm comfortable with. I was trying to stick with something around $50 bucks because its just a lab, but it seems like even bumping my battery budget to $100, all the batteries have terminals that require connectors that are all too small to terminate a 6 gauge cable.

Do I need to
a) increase my battery budget? If so, any recommendations for the least expensive battery that will fit my circuit? I now have some copper 1/4" ring connectors for my 6g cable (these fit my inverter)
b) search harder for a better selection of connectors?
c) spend some effort right sizing my cables?
d) all of the above?

Thanks!

What kind of battery terminals do you see on the batteries you are looking at?
You cannot get the correct ring lugs for it?

 

[Risky Rob]

So, I'm having some trouble finding a battery I'm comfortable with. I was trying to stick with something around $50 bucks because its just a lab, but it seems like even bumping my battery budget to $100, all the batteries have terminals that require connectors that are all too small to terminate a 6 gauge cable.

Do I need to
a) increase my battery budget? If so, any recommendations for the least expensive battery that will fit my circuit? I now have some copper 1/4" ring connectors for my 6g cable (these fit my inverter)
b) search harder for a better selection of connectors?
c) spend some effort right sizing my cables?
d) all of the above?

Thanks!

Maybe a used car battery would be OK for testing? At Walmart you can get "marine terminals" that give you a 5/16" post and a wingnut.

 

[BreezyReputation]

What kind of battery terminals do you see on the batteries you are looking at?
You cannot get the correct ring lugs for it?

The one I'm looking at now is a 20ah with M5 terminals, which are .190" diameter post. The 1/4" rings I have will totally fit that, but they feel kinda big...I guess I'm just not sure if that's ok, or they should be 'right sized'.

I wasn't having any luck finding connectors with a ring smaller than 1/4", but still 6g.

Maybe a used car battery would be OK for testing? At Walmart you can get "marine terminals" that give you a 5/16" post and a wingnut.

I was trying to stick with LiFePO4 batteries, just to get familiar with their properties (charging, discharging, capacity, etc), but maybe the difference between battery types is negligible at this point. I will definitely look into this.

Are there any types of batteries that I should stay away from?

 

[Hedges]

What kind of service do you want to get from the batteries? In terms of charge rate, discharge rate, cycle life, operating temperature?

A 12V 10Ah lithium battery would still need BMS.
Lead acid is simple and dumb. You can get a used, not dead yet, one from a wrecking yard. Good place to start, just don't cycle too deeply. If it is 40Ah or 50Ah, you could use the 10Ah you were looking for.
AGM or gel preferred for a low-labor and safe system. Gel has its own unique charging parameters. AGM is common in automotive, although the car's charging system if made for FLA won't charge it properly.

Are there any types of batteries that I should stay away from?

That depends on how much you enjoy fireworks.