diy solar

diy solar

4 405w panels vs 12 100w panels...

Extension cord of suitable gauge is good up to 1800 watts. If inverter has multiple AC outlets, better two use two cords; the typical plug/socket is meant for up to 15A but circuits up to 20A so two loads on one duplex outlet. (I don't know your inverter's output)

Some ME connectors are rated for more current. If you want 8 awg try to find wires and "Y" of that size. Most MC connectors rated 30A (less if smaller than 10 awg), but a few are rated for more. You're supposed to size the wire for 1.56x Isc x number of parallel PV panels or strings. You can also convert from MC to another type of wire, usually in a box followed by conduit.

If you have fuse per PV string, probably no need for additional fuse on combined wire. But a breaker or switch of suitable rating is good as disconnect.

Your location may not have yet adopted code requiring RSD. If it does, I think it applies if wires from ground mount panels enter the house, except if all in conduit it does not.

With your panels configured 3s4p, I think a mechanical PV disconnect switch I saw somewhere around here could meet the need. RSD is supposed to isolate panels so voltage between any two wires is < 80V, also some wattage limit. Just a 4PST switch the the disconnect I saw might do that for you. At least if those are 100W panels so only 300W per string. That would be cheaper and simpler than an electronic RSD box per panel.

Even with RSD, you could string 3, 100W panels in series into its connectors. I saw one 4-panel RSD with ratings such that it should support a dozen of my 12V 120 panels. In my case I would have 4x 3s combined into 12s so that works. Not sure your 4x 3s could combine to 3s4p with one quad RSD; you might need four individual RSD.
 
Holy paragraph! :)

She is Ground Mounting the panels off grid up in the mountains.
GXMnow said:
If your system is never inspected, no one will know if you have rapid shut down or not, but if something goes wrong, you may not only injure a fireman on your roof, you could lose your insurance coverage. This is the sticky part. If you ask your local officials about the law, they will know you are doing something, and will expect you to pull permits etc. I could not risk it here, I had to pay a professional to install my solar panels up on the roof because the building codes here are crazy. The guy I used has done over 100 sites in this area, and he still had to go back and refile one of the document again. The permitting and all did add nearly $2,000 to the cost of my system, but the fine if someone complained about my panels and they found no permit for it, would have been way more. And if something shorted out and started a fire, my insurance would be voided. I would always recommend you get the building permit and follow the local codes. If it is a "portable" system, and the panels are separate from your building, then you can usually just DIY it and probably not have an issue. In my area, the rapid shut down it only required if the panels are on, or within 10 feet of a living quarters. Not sure it that would count on an attached or detached garage, but I do know a few have done solar panels on a car port without it. The problem is that you can't turn off the sun. Yank out all the wires, and the panels are still making power. If a fireman has to go on your array, they could be exposed to live wires. The idea of rapid shut down is that the lines will be powered down at or very near the panels, and clearly marked where they might still be live. I am in the north end of Los Angeles County, 30 miles north of Hollywood, and it is required here.

With 12 panels, in 3S 4P you need 4 of the 10 amp fuses. You maximum current should never exceed the ISC 5.7 amps x 4 or 22.8 amps, so #10 awg wire is safe from a capacity standpoint, but depending on the length of the run, you may want to step up to a #8 to reduce loss in the cables. Most MC4 connectors though, can't really take a wire that large. It is always good to use parts that can handle more power than you need. The 40 amp rated connectors should last a good long time when running under 2 amps. With most cheaper electronic components, we tend to run them around 50% of rating. 100 amps on a 200 amp BMS, things like that. With wire and connectors, you can run them closer, but it never hurts to have less resistance and heat buildup with higher rated parts.

A 1000 watt inverter is still able to make a decent amount of power. Running that in an extension cord is not a permanent solution. Again, if this a "portable system" you might get away with it, but this is a safety concern. Your description sounds like that cord is outdoors. I get nervous having an extension cord running out for Christmas lights for a month. I always have it plugged into a ground fault protector, and it has tripped a few times, just from morning dew on the cables. Extension cords are considered a temporary use item. You can certainly use that for testing and running things for a bit, but if it is going to be used for weeks, you should run some permanent wiring. How long is the run outside? I have not had to run any outdoor feeds here, but I seem to remember the code called for a feeder line to be buried 18 inches deep. One of my friends ran a feed out to a hot tub in his back yard. You can get some 3 x #10 UF cable at most hardware stores like a Home Depot etc. Here is an Amazon listing for 50 feet. This is overkill for your current system, but if you ever expand, you won't need to dig a new trench.

10/3 UF-B x 50' Underground Feeder Cable - - Amazon.com

10/3 UF-B x 50' Underground Feeder Cable - - Amazon.com
www.amazon.com
This will handle up to 30 amps of 120/240 split phase power.
Click to expand...
 
Hedges said:
Extension cord of suitable gauge is good up to 1800 watts. If inverter has multiple AC outlets, better two use two cords; the typical plug/socket is meant for up to 15A but circuits up to 20A so two loads on one duplex outlet. (I don't know your inverter's output)

Some ME connectors are rated for more current. If you want 8 awg try to find wires and "Y" of that size. Most MC connectors rated 30A (less if smaller than 10 awg), but a few are rated for more. You're supposed to size the wire for 1.56x Isc x number of parallel PV panels or strings. You can also convert from MC to another type of wire, usually in a box followed by conduit.

If you have fuse per PV string, probably no need for additional fuse on combined wire. But a breaker or switch of suitable rating is good as disconnect.

Your location may not have yet adopted code requiring RSD. If it does, I think it applies if wires from ground mount panels enter the house, except if all in conduit it does not.

With your panels configured 3s4p, I think a mechanical PV disconnect switch I saw somewhere around here could meet the need. RSD is supposed to isolate panels so voltage between any two wires is < 80V, also some wattage limit. Just a 4PST switch the the disconnect I saw might do that for you. At least if those are 100W panels so only 300W per string. That would be cheaper and simpler than an electronic RSD box per panel.

Even with RSD, you could string 3, 100W panels in series into its connectors. I saw one 4-panel RSD with ratings such that it should support a dozen of my 12V 120 panels. In my case I would have 4x 3s combined into 12s so that works. Not sure your 4x 3s could combine to 3s4p with one quad RSD; you might need four individual RSD.
Click to expand...
Does this drawing make sense?
20210305_125219.jpg
The panels are 3ft by 2ft-3in. The deck is south facing. 5ft wide by 4.5ft high usable sun space uninterfered with by eaves. Ive drawn a right triangle with 5ft and 4.5ft. Multiply those then divide by two for 11.25ft hypotenuse on which the panels can be configured. Stacking three lengthwise will be plenty of room for the angle totaling only 6ft 9in high I can drop down the angle to 30 degrees. Is that the angle i should use? Also, the wire lengths are 2.6ft so i will have 3 ys connecting the positives, 3 ys connecting the negatives. Then I will have two triple ys to connect those. I will have some 10awg red and black wire available should i need that for the fit along with mc4 connectors to make the connection. I will make my own lengths as needed to reach the triple y.. These panels will be bolted to a metal frame. 2 metal lengths for every vertical row of panels so two pieces of metal will need to carry three panels equivelent to approx 45lbs.. The metal will then be attached to the deck and to the side of the house. Additional 2 by 4 lumber can be added to these areas for reinforcement. Once the wires are joined at the triple y, they have become 2 cables. I think it will be 8awg at that point and a hole can be drilled in the wall to enter the house where it will run to the charge controller mounted on the wall. 8 awg will leave the charge controller to go to the batteries which will be lined up on a shelf right there.
20210305_154125.jpg
Batteries will be connected 2s2p by 6awg cables per maufacturer, or 2/0awg per this forum. Then the battery bank is connected to the inverter by the same gauge awg wire used at the batteries. Then the inverter has ac outlet for plugging in to. Does this plan sound accurate and correct so far?

the equipment is:
(12) 100w 12v panels
40amp renogy rover 12/24v charge controller
(4) 12v 100ah LiFeBO4 batteries
2000w samlex 24v inverter

i know i did not address fuses or busbar yet. Im very unfamiluar with these. My husband is doing the install. He has done solar installs professionally and i asked him about these things. He has only been electrician assistant with just on the job training, nothing formal. So he said we can do those things uf the plan calls for it. He doesnt know enough to tell me what we need. He said he just looks it up on the job. But he said they do the breaker box an he said they do the bus bar. But I have to write out the plan for him to follow and ensure all the equipment and materials are there. Its not his current job or else Im sure we could find the answers there. So the fuses will be inline from the panel to controller. It will be a 12amp fuse in a 15amp capacity case. Or maybe a 15amp is ok? Says max fuse 12amp on panels. I will need 4 of those placed on the positive wire just before first y connection. Or will it be before it joins the triple y? Just realized no triple y. Just 6 ys will do the job. Please verify the sketch. Each fuse location is marked with a gold spot and will be 15amp. Then a 50amp fuse just before the charge controller. Will that also be inline? Or should it be a breaker box? And if it is inline i will have to use 10awg instead of 8awg since the mc4 connectors dont fit 8awg. Then would a bus bar come before the batteries or after them? Is a fuse needed before the batteries? If so, what size? For a breaker box would that come after the batteries? Is that in replacement of a busbar and/or certain fuses? Should I do a breaker box or all inline fuses with busbar? What specs should i look for in a busbar? 4 posts, 3/8,...??? Do i need high quality here or could a cheaper one get me by just fine at least for now or will it cause burn outs or shorts or wreak havoc becayse its cheaply made? Will a breaker box take the place of fuses AND busbar? What size wiring is needed for a breaker box?

any advice or clarifications you can give is greatly appreciated! I hope this plan looks close to being complete.

also, the panel array spans 12 feet wide altogether. But its in 4 vertical rows. These rows could be spread out since its south facing with east on one end and west at the other. The deck spans 44 feet. Im hinking of spreading each vertical row out so that weight is not so concentrated. But im thinking 22 feet is the max spread so only half the available span. With 2 vertical rows angled toward east and two angled toward west. Gutters are not installed right now so rain or snow buildup on roof could accumulate. Snow is not a huge concern. Most it stays is two weeks id say. But should i be concerned about damage to the panels because theyll be licated under he eave where rain runs off?

going to load 2 of the pics on a separate post because its not letting me on this one
 
How much simpler is:
4 400 watt panels vs
12 100 watt?

Wired 2S2P with no fuses needed.

Tbleppy said:
Does this drawing make sense?
View attachment 39720
The panels are 3ft by 2ft-3in. The deck is south facing. 5ft wide by 4.5ft high usable sun space uninterfered with by eaves. Ive drawn a right triangle with 5ft and 4.5ft. Multiply those then divide by two for 11.25ft hypotenuse on which the panels can be configured. Stacking three lengthwise will be plenty of room for the angle totaling only 6ft 9in high I can drop down the angle to 30 degrees. Is that the angle i should use? Also, the wire lengths are 2.6ft so i will have 3 ys connecting the positives, 3 ys connecting the negatives. Then I will have two triple ys to connect those. I will have some 10awg red and black wire available should i need that for the fit along with mc4 connectors to make the connection. I will make my own lengths as needed to reach the triple y.. These panels will be bolted to a metal frame. 2 metal lengths for every vertical row of panels so two pieces of metal will need to carry three panels equivelent to approx 45lbs.. The metal will then be attached to the deck and to the side of the house. Additional 2 by 4 lumber can be added to these areas for reinforcement. Once the wires are joined at the triple y, they have become 2 cables. I think it will be 8awg at that point and a hole can be drilled in the wall to enter the house where it will run to the charge controller mounted on the wall. 8 awg will leave the charge controller to go to the batteries which will be lined up on a shelf right there.
View attachment 39737
Batteries will be connected 2s2p by 6awg cables per maufacturer, or 2/0awg per this forum. Then the battery bank is connected to the inverter by the same gauge awg wire used at the batteries. Then the inverter has ac outlet for plugging in to. Does this plan sound accurate and correct so far?

the equipment is:
(12) 100w 12v panels
40amp renogy rover 12/24v charge controller
(4) 12v 100ah LiFeBO4 batteries
2000w samlex 24v inverter

i know i did not address fuses or busbar yet. Im very unfamiluar with these. My husband is doing the install. He has done solar installs professionally and i asked him about these things. He has only been electrician assistant with just on the job training, nothing formal. So he said we can do those things uf the plan calls for it. He doesnt know enough to tell me what we need. He said he just looks it up on the job. But he said they do the breaker box an he said they do the bus bar. But I have to write out the plan for him to follow and ensure all the equipment and materials are there. Its not his current job or else Im sure we could find the answers there. So the fuses will be inline from the panel to controller. It will be a 12amp fuse in a 15amp capacity case. Or maybe a 15amp is ok? Says max fuse 12amp on panels. I will need 4 of those placed on the positive wire just before first y connection. Or will it be before it joins the triple y? Just realized no triple y. Just 6 ys will do the job. Please verify the sketch. Each fuse location is marked with a gold spot and will be 15amp. Then a 50amp fuse just before the charge controller. Will that also be inline? Or should it be a breaker box? And if it is inline i will have to use 10awg instead of 8awg since the mc4 connectors dont fit 8awg. Then would a bus bar come before the batteries or after them? Is a fuse needed before the batteries? If so, what size? For a breaker box would that come after the batteries? Is that in replacement of a busbar and/or certain fuses? Should I do a breaker box or all inline fuses with busbar? What specs should i look for in a busbar? 4 posts, 3/8,...??? Do i need high quality here or could a cheaper one get me by just fine at least for now or will it cause burn outs or shorts or wreak havoc becayse its cheaply made? Will a breaker box take the place of fuses AND busbar? What size wiring is needed for a breaker box?

any advice or clarifications you can give is greatly appreciated! I hope this plan looks close to being complete.

also, the panel array spans 12 feet wide altogether. But its in 4 vertical rows. These rows could be spread out since its south facing with east on one end and west at the other. The deck spans 44 feet. Im hinking of spreading each vertical row out so that weight is not so concentrated. But im thinking 22 feet is the max spread so only half the available span. With 2 vertical rows angled toward east and two angled toward west. Gutters are not installed right now so rain or snow buildup on roof could accumulate. Snow is not a huge concern. Most it stays is two weeks id say. But should i be concerned about damage to the panels because theyll be licated under he eave where rain runs off?

going to load 2 of the pics on a separate post because its not letting me on this one
Click to expand...
 
Hedges said:
Extension cord of suitable gauge is good up to 1800 watts. If inverter has multiple AC outlets, better two use two cords; the typical plug/socket is meant for up to 15A but circuits up to 20A so two loads on one duplex outlet. (I don't know your inverter's output)

Some ME connectors are rated for more current. If you want 8 awg try to find wires and "Y" of that size. Most MC connectors rated 30A (less if smaller than 10 awg), but a few are rated for more. You're supposed to size the wire for 1.56x Isc x number of parallel PV panels or strings. You can also convert from MC to another type of wire, usually in a box followed by conduit.

If you have fuse per PV string, probably no need for additional fuse on combined wire. But a breaker or switch of suitable rating is good as disconnect.

Your location may not have yet adopted code requiring RSD. If it does, I think it applies if wires from ground mount panels enter the house, except if all in conduit it does not.

With your panels configured 3s4p, I think a mechanical PV disconnect switch I saw somewhere around here could meet the need. RSD is supposed to isolate panels so voltage between any two wires is < 80V, also some wattage limit. Just a 4PST switch the the disconnect I saw might do that for you. At least if those are 100W panels so only 300W per string. That would be cheaper and simpler than an electronic RSD box per panel.

Even with RSD, you could string 3, 100W panels in series into its connectors. I saw one 4-panel RSD with ratings such that it should support a dozen of my 12V 120 panels. In my case I would have 4x 3s combined into 12s so that works. Not sure your 4x 3s could combine to 3s4p with one quad RSD; you might need four individual RSD.
Click to expand...

IMG_20210305_235951.jpgIMG_20210305_235932.jpg
 
Forbisher said:
How much simpler is:
4 400 watt panels vs
12 100 watt?

Wired 2S2P with no fuses needed.
Click to expand...
I agree. 4 400 watt panels is better. By far! My original post says I was planning to return the 100w panels. I had placed an order for 4 405 watt panels. Everything was going fine until a1solarstore.com would not process my order. They said CS failed. Called them and they didnt know a reason. Called my bank...got disconnected. I already have solar panels. 100watt ones. I was nervous about the freight shipment. I dont know how that works but Im on a hill and my driveway is steep. And I thought bird in the hand beats two in the bush. So I posed this question to see--is what I have possible to do? Or is it really a bad choice to proceed? I got a lot of answers on how to do it. Granted, its a lot of work to understand for myself. I am new to learning these things plus I have to move quickly. Im really grateful for this forum. I can read and read and the internet is full of resources. Theres also the discernment which comes along with all of it because on any given subject I can and do find information directly contradictory to another. Plus reading wont answer your questions. Getting these answers from helpful people who have been so nice and knowledgable and welcoming is a relief to me. So thank you for all your troubles to help me.

My return window has closed on the panels. I will have to proceed with what Ive got. Im almost there though. Just need wires, fuses, bus bar or breaker box or maybe just a heavy duty extension cord.

I am curious why 2s2p with 400w panels would not need fuses. ?
 
Tbleppy said:
I am curious why 2s2p with 400w panels would not need fuses. ?
Click to expand...

A single panel or series string of panels can't deliver enough current to overheat its wires. The wires are sized to carry about 2x Isc.
If someone built an array 1s10p, 10 panels in parallel, then if one wire shorted (or diodes in panel failed shorted), the other 9 panels would dump 9x Isc into it, burning something up.

With 2s2p, if one panel shorts the other one panel (or series string of panels) dumps 1x Isc into it. That current is low enough to not be a problem.

3 or more panels in parallel, then we fuse each one.
 
GXMnow said:
do add, but you should do the math on the VOC maximum voltage. Your panels' VOC rating is 22.64 volts each, so the string of 3 in series adds up to 67.92 volts. And it could climb over 80 or so if it gets very cold in your location. It is always good to allow at least 20% margin in case of a cold snap, like Texas is having. Even if it does not normally get cold, it could happen, and it just takes one cold morning to fry a charge controller.
Click to expand...
IMG_20210307_045655.jpg

max solar input power 24v @ 1040watts. I could be up to 80volts and am running 1200watts. This charge controller is too small? Its 40amp.
 
1040 / 24 = 43 amps, so they are allowing some over paneling. Many decent MPPT controllers will allow a bit more than that. Most of them will just hit their maximum output current and not fully load the solar panels, but if the MPPT algorithm is not smart enough, it might pull too much current and damage components, so when they do list a max input power, you do need to obey that. The bad part is it will rarely ever hit maximum power. Even if it is a once in 10 years event when the air is cold and the sun is perfectly square on the panels, it could hit maximum output. I see my 300 watt panels clip out my 240 watt Enphase inverters for up to 2 hours on cool sunny days. Enphase actually wants them over paneled to get the maximum watts per cost out of them. They will take double rated with no harm. The output just limits to 240 watts. I have 16 of them. Any charge controller that you can adjust the output current should also be able to properly limit output even with a larger solar panel. Just like when the battery is reaching fully charged, the current has to fall a lot. But you need to be absolutely sure that the VOC (Open Circuit Volts) can never exceed the charge controller or inverter rating. As the control needs to reduce current, the voltage will rise, all the way to VOC, and maybe a bit higher in cold weather. I did just a little searching, but I have not found any quick links to people running over paneling on a Renogy Rover series CC.
 
Hedges said:
You should also get MC fuse holders, and fuses of the value shown on panel label.

If you use "Y" cables, then no need for combiner box, just run MC cables back to charge controller.

Alternate to "Y" cables is a box with metal bar to connect several cables (like neutral or ground bar in breaker panel). Typically also has fuse holders or breakers for positive
Click to expand...
i found a 4pack of odyssey 15a inline fuse holders with fuses. My panel says 12a. Will 15a work?

what are mc cables?

should i use a din rail with circuit breakers for my 50a fuse, 150a t fuse?
 
This shows MC4 fuse holders and cables. Typical connector on modern PV panels. older models were MC3.

Solar Accessories | SanTan Solar

store.santansolar.com store.santansolar.com

You should get 12A if that's what panels say.

DIN rail is one kind. Others are panel mount.
 
Hedges said:
You should get 12A if that's what panels say
Click to expand...
I dont know where to find the 12amp inline fuse. 10awg cable. Mc4 connections. Is this suitable?
www.solarpanelstore.com

MidNite Solar Din Mount Breaker MNEPV 1-63A (Choose Ampere Rating) - MNEPV(X)

These breakers are available in 1A - 63A (Choose ampere rating above) 150VDC DIN rail mount breaker. MidNite's breakers are rated to break the full rated load at the rated voltage repeatedly, with NO DAMAGE. Always use a properly sized breaker for disconnecting.
www.solarpanelstore.com www.solarpanelstore.com
or do you know a good source to find this amperage fuse? I find the little glass tubes, i think theyre called midgets, but i need a case to install them in it looks like.

i am stuck on the 12amp fuse. Also, they will only go on the red wire and not on the black, right?
 
Here's one, Midnight Solar.
10 pack of 12A, $42

Product - MidNite Solar

MidNite Solar Product Page.
www.midnitesolar.com

Should be available individually somewhere.
 
With
Hedges said:
This shows MC4 fuse holders and cables. Typical connector on modern PV panels. older models were MC3.

Solar Accessories | SanTan Solar

store.santansolar.com store.santansolar.com

You should get 12A if that's what panels say.

DIN rail is one kind. Others are panel mount.
Click to expand...
with a din rail would it need an enclosure if its located inside? Could I buy 1 din rail, attach 1 50A din rail mountable fuse and 1 150A classT fuse to it and thats fine?

I spoke with the battery company. They said I can use a thicker gauge wire than the 6awg as long as i understand my limitations which is 100A discharge rate with 280A burst. So I have selected the 2/0 awg wire to connect the batteries to eachother and then to the inverter. My inverter directions say place a 120A fuse 7inches away from the positive battery post. I will need a class T fuse and the fuse holder. Should I do 150A or 120A? Will this be an inline fuse or can you explain how this is attached? Like I said its thick 2/0 wire. Thanks!
 
Tbleppy said:
With

with a din rail would it need an enclosure if its located inside? Could I buy 1 din rail, attach 1 50A din rail mountable fuse and 1 150A classT fuse to it and thats fine?

I spoke with the battery company. They said I can use a thicker gauge wire than the 6awg as long as i understand my limitations which is 100A discharge rate with 280A burst. So I have selected the 2/0 awg wire to connect the batteries to eachother and then to the inverter. My inverter directions say place a 120A fuse 7inches away from the positive battery post. I will need a class T fuse and the fuse holder. Should I do 150A or 120A? Will this be an inline fuse or can you explain how this is attached? Like I said its thick 2/0 wire. Thanks!
Click to expand...

The DIN rail components have electrical conductors fairly accessible, not recessed enough to be out of reach of the test finger labs use. A box with screwdriver operated latches would be best. Some lesser quality/rating fuses blast their surroundings, another reason a cover is good.

Fuses primarily protect wire from overheating and starting a fire. 2/0 is good for over 200A. A 280A surge of a few seconds wouldn't blow a fuse unless it is fast-blow. Seems like 125A is minimum fuse size considering 100A max continuous current. But that is the battery and BMS capability. Is inverter drawing max continuous of 100A or something less (e.g. 95A)? If so, 120A as they say would be good. Or 125A is what I see available.

Class T fuses have bolt holes. There are holders available for them, usually panel mount (screw holes). Some have covers. The ones I got from Blue Sea which are pinch-to-remove are difficult. Maybe I should file a ramp on the catch. Another holder they carry has latches, should be easier to use.

Class T Fuse Block with Insulating Cover - 110 to 200A - Blue Sea Systems

Allows use of Class T fuses for high speed circuit protection of electronic equipment and inverters.
www.bluesea.com www.bluesea.com
 
Hedges said:
inverter drawing max continuous of 100A or something less (e.g. 95A)? If so, 120A as they say would be good. Or 125A is what I see available
Click to expand...
dc input voltage range 21.4-33V DC. Rated DC input current 120A.
 
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