diy solar

diy solar

Wiring Panels in Series-Parallel | Is this diagram correct?

The one protection they don't have is over-voltage.
Except Midnight Solar, with "Hyper VOC" feature.
Make sure that with Voc and temperature coefficient of Voc from PV panel data sheet, record coldest temperature of your location, adjust from nominal 25 degree condition where Voc is spec'd, it will never exceed max input rating of equipment.

Some systems do have protection mechanisms built in, in which case they have a hard and fast rule on max short circuit current. Because that's their backup plan.

Just don't exceed those specs. Exceeding wattage recommendation is commonly done, however.

The equipment will log highest voltage, just so manufacturer knows to deny warranty claim.
 
The one protection they don't have is over-voltage.
Except Midnight Solar, with "Hyper VOC" feature.
Make sure that with Voc and temperature coefficient of Voc from PV panel data sheet, record coldest temperature of your location, adjust from nominal 25 degree condition where Voc is spec'd, it will never exceed max input rating of equipment.

Some systems do have protection mechanisms built in, in which case they have a hard and fast rule on max short circuit current. Because that's their backup plan.

Just don't exceed those specs. Exceeding wattage recommendation is commonly done, however.

The equipment will log highest voltage, just so manufacturer knows to deny warranty claim.
Ok the all time low is 1979 and it was 11 Fahrenheit. Now what?
 
The one protection they don't have is over-voltage.
Except Midnight Solar, with "Hyper VOC" feature.
Make sure that with Voc and temperature coefficient of Voc from PV panel data sheet, record coldest temperature of your location, adjust from nominal 25 degree condition where Voc is spec'd, it will never exceed max input rating of equipment.

Some systems do have protection mechanisms built in, in which case they have a hard and fast rule on max short circuit current. Because that's their backup plan.

Just don't exceed those specs. Exceeding wattage recommendation is commonly done, however.

The equipment will log highest voltage, just so manufacturer knows to deny warranty claim.
And what about an over current breaker right before the SCC unit? Do they make 450v dc breakers? I’ve tried a basic search and I’m not seeing them. Lots of 250v and 500v
 
11F = -11.7C

37V x (25 + 11.7) x .003 tcoef = 4.1V change (41.1Voc)

450V / (41.1V / panel) = 10.95 panels in series
My god man, your a magical calculator!

So my last reply is Moot I shouldn’t need any over voltage protection. Especially with global warming I think we are along ways from 1979s 11f. I do however need a good quality dc disconnect. I’m still shopping around. Thanks again magical calculator man!
 
400VAC.
Not DC rated.
It would just burn.
In the questions section it stated DC. ugh this is why I hate Amazon. Upon deeper digging yes this is not DC but they don’t make it very easy to determine. I’m only finding 500v DC 20amp breakers so Maybe I’m just better off with a isolation switch and not breaker… the SCC has over current but would have better peace of mind with my own OCPD before it. Maybe that’s just unnecessary overkill…. Where could I find this in DC from a reputable manufacturer? Or should I just give up on that and go to bed haha. If the SCC over current fails they would replace it. But would not be a fun day….
 
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Picture shows 400V~

Midnight Solar has good DC breakers. Many are "polarized", which I have some issues with.
Schneider has some.

What I've got now is touch-safe fuse holders and separate switch.
One switch I've used is Square-D "heavy duty" 600V AC/DC. Not cheap, but sometimes on eBay.
 
It's like asking a question here, except they don't have a reputation to keep ;)

"Question:
Is this ac or dc?
Answer:
dc
By larry on July 14, 2020
50hrz is not DC.
THIS IS NOT DC rated
By Trae Greenlee on March 28, 2021
I’m using this in a dc application.
By Amazon Customer on July 13, 2020
This is rated for 400 Volts, with over current protection of 50 amps.
By Anthony D. on July 15, 2020"

(We make mistakes too)
 
Yeah the reviews on that thing were so far off haha. Amazon can get crazy sometimes.

Is it common place to have some protection device before the all in one unit as a redundancy? I’ll check out Midnight Solar for breakers. If I’m gonna buy and install a DC disconnect switch it might as well serve another function and be an over current breaker. That’s my thinking.
 
PV panels have a max fuse rating. That is the current they can safely get backfed if a short develops in the string.
With two strings in parallel, backfed current wouldn't exceed what one string produces.
If you have 3 or more PV strings in parallel, then they need over-current protection.

If your higher voltage inverter lets you arrange as 2 strings in parallel, all you need is a switch (or breaker), one for the combined wires.
Properly sized (at least 1.56 x Isc x 2, if 2 strings in parallel), it will never trip. That's the minimum ampacity of the wire as well.

If on a house, big boxes work. For mobile, need something smaller.
Some of my GT PV inverters have switch built in, some include fuse holders.

I have a concern that several polarized breakers for parallel strings don't provide the protection they're supposed to (which direction current flow, forwards or backfed?) But a single 2-pole breaker to disconnect the array should be fine.
 
PV panels have a max fuse rating. That is the current they can safely get backfed if a short develops in the string.
With two strings in parallel, backfed current wouldn't exceed what one string produces.
If you have 3 or more PV strings in parallel, then they need over-current protection.

If your higher voltage inverter lets you arrange as 2 strings in parallel, all you need is a switch (or breaker), one for the combined wires.
Properly sized (at least 1.56 x Isc x 2, if 2 strings in parallel), it will never trip. That's the minimum ampacity of the wire as well.

If on a house, big boxes work. For mobile, need something smaller.
Some of my GT PV inverters have switch built in, some include fuse holders.

I have a concern that several polarized breakers for parallel strings don't provide the protection they're supposed to (which direction current flow, forwards or backfed?) But a single 2-pole breaker to disconnect the array should be fine.
Hello, I hate to interrupt but, I’m about to order an inverter. Much advice needed!
I’m a newbie looking to power my barn.
Looking y to o power
-mini fridge
3-9watt bulbs
1-60 watt chicken water heater
2 15 watt fans in chicken coop
Not plan your. Powering everything in the beginning but, once I get more panels that’s my plan.

1-Exide 24mdc marine battery
1-100 watt Renogy solar kit
I NEED HELP finding the best modified sound wave inverter under $100.
Thanks for any advice
 
Hello, I hate to interrupt but, I’m about to order an inverter. Much advice needed!
I’m a newbie looking to power my barn.
Looking y to o power
-mini fridge
3-9watt bulbs
1-60 watt chicken water heater
2 15 watt fans in chicken coop
Not plan your. Powering everything in the beginning but, once I get more panels that’s my plan.

1-Exide 24mdc marine battery
1-100 watt Renogy solar kit
I NEED HELP finding the best modified sound wave inverter under $100.
Looks like you already have a thread asking this. But sure why not jump into a random thread that’s got a lot of replies lol
alright let’s see if we can’t help you out. Can’t exactly tell what your trying to say in this post, looks like maybe it’s a 24v battery so here’s a good small inverter that’s 24v
If I’m wrong and it’s 12v battery than Will Prowese the man the myth the legend, speaks well of this one for a small budget. Hope this helps.
 
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Looks like you already have a thread asking this. But sure why not jump into a random thread that’s got a lot of replies lol
alright let’s see if we can’t help you out. Can’t exactly tell what your trying to say in this post, looks like maybe it’s a 24v battery so here’s a good small inverter that’s 24v
If I’m wrong and it’s 12v battery than Will Prowese the man the myth the legend, speaks well of this one for a small budget. Hope this helps.
Thanks much for helping. Yes, asking for help everywhere because I have to order ASAP. I’m just getting started and just looking to power a mini fridge for now then, on to my chicken coop.
 
"I’m using this in a dc application.
By Amazon Customer on July 13, 2020"

I think people who use an AC breaker for PV string can usually get away with it because it doesn't see full voltage.

VOC is 37.6v
VMP is 30.3v

If you had 10 panels in series, SCC operates at Vmp of 303V.
If circuit breaker is opened, PV voltage rises to 376V.
There is only 73VDC across a breaker rated 400VAC, so good chance it is able to open.

If the breaker had been closed into a short circuit (e.g. wired backwards to SCC which hopefully has a diode to clamp reverse voltage), Isc flows. When you open breaker, it sees 376V across it, so is likely to sustain an arc.

The other situation where an AC breaker (or DC breaker with low AIC rating) is likely to have a problem is when connected to a battery and opening due to over-current from a short circuit. Battery dumps several thousand amps, and breaker has to interrupt that. This (and high voltage) are situations where polarity matter most for DC breakers that are polarized.

Breakers are primarily for fault conditions, to prevent a fire. So it is important they are rated for the application (and were tested with an overstress beyond their ratings.)
 
Ok than 10AWG it is!!! 10AWG is 31Cents cheaper per foot! Also cables will be underground, likely in conduit because we have pesky underground dudes here in the desert that like to go munch. Mmmm… 400Vdc roasted rat anyone? Yum!
Using a combiner box near your array will allow you to:
1) utilize circuit breakers to disconnect the array,
2) enter conduit which will help protect wires from the critters and shovels, I believe this is a "MUST DO"
3) switch from "Solar Cable" to regular ole building wire (that is approved for use in conduit)

Is temp really a big deal with these kind of fancy all in one units?
I think that question will be answered when you have decided on which unit(s) you will purchase.

Ok the all time low is 1979 and it was 11 Fahrenheit. Now what?
Glad you dropped that temp.


Maybe I’m just better off with a isolation switch and not breaker… the SCC has over current but would have better peace of mind with my own OCPD before it. Maybe that’s just unnecessary overkill….
The correct OCPD is never overkill. It's out there. Pretend it's an Easter Egg hunt.
You should be pleased when you figure out where that piece of the puzzle is.
 
Because I’ve already been planning on 2 large pole mounts 9 panels each.
Hmm, I wonder who will win, the microburst (quite common in AZ during the Monsoon season) or large panels on a pole mount.
AZ Microburst 2.JPGAZ Microburst.JPG
According to the National Weather Service:
"A microburst is a downdraft (sinking air) in a thunderstorm that is less than 2.5 miles in scale. Some microbursts can pose a threat to life and property, but all microbursts pose a significant threat to aviation. Although microbursts are not as widely recognized as tornadoes, they can cause comparable, and in some cases, worse damage than some tornadoes produce. In fact, wind speeds as high as 150 mph are possible in extreme microburst cases." ?
 
Thats a beefy solar rack. I’d bet my money on the solar rack holding up. And in our area particularly we have had some good storms but nothing that would seriously concern me as far of bending, lifting, or breaking the mounting system.
 
Well it’s 2am here and I got a notification that Will Prowse uploaded a new video about the exact unit we’ve been discussing, the LVX6048 and after watching that I’ve learned I really should be looking at the LV6548 instead. Only problem is that unit has a max PV input of 250v. So using MisterSandals math “37V x (25 + 11.7) x .003 tcoef = 4.1V change (41.1Voc)” I could just BARELY wire my array S6 P3.
41.1v x 6 = 246.6v this is cutting it close is it not? Or because the math takes temps into account it’s safe? Because my other option is wiring the opposite, meaning S3 P6. But that’s a lot of parallels, I’ll do which ever one gives the safest, most practical results. Thanks everyone!
 
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