48v solar build questions

[Oldtimmer69]

1 MPPT controller, 80A charging, 5000W max array.

24, 285W PV panels, 8.03 Imp. 6840 W STC.

I would set up 12 strings, each 2 panels in series. Orient 4 strings toward winter Noon sun, 4 strings summer 10:00 AM, 4 strings summer 4:00 PM sun.
If the 6840W of panels were in two arrays aimed 90 degrees different (6 hours apart), they would produce peak 0.707 of their total watts or 4836W STC. (Ignoring difference in how much light enters panel vs. reflecting due to incident angle.) That is well under spec.
Using 2 or 3 different orientation would spread power production out over the day and over seasons.

Each of the 12 strings to its own fuse or breaker in a combiner box as SolarQueen said. From panel label, 15A is a good value.
Those 12 strings in parallel would produce 96A Imp if oriented the same, 68A if two arrays 90 degrees apart. Current can be higher than Imp or Isc; I've measured it. That calls for at least 4 AWG, probably 2 AWG would be good. Easiest to put combiner box next to inverter with conduit in between to carry the thick wire, and use MC cables coming out of combiner box to connect panels. I use conduit with 12 awg to where my arrays are.

The panel will be mounted on the roof not alot I can do about direction. My house does face 182°south and I have no shading.

Thanks for all the input!! After all this discussion I've quickly realized I didn't do all my home work. I called and discussed the samething we have here and did all the math again same numbers and I was assured in series of 3 on the best winter day every it would never produce over 1000 somethings per square inch. ( sorry I forgot what he called it). .

Because my inverter is new and never used I'm Goin to ship it back to them and buy the 12k. They will give me a credit towards the ne one And I won't have to worry.. Now I'll be limited to my batteries capacity until I purchase the other two batteries.

I'd like a combiner box. I'm less than a 100' from the pannls to the inverter breaker box room. I figure 8 sets 3 panels in series. What are good combiner boxes?

 

[Hedges]

One of these boxes would connect 6 PV strings and provide a breaker for one leg of each. You'd need two for 12 strings or 8 strings. (and perhaps a splice for the two wires, like a split bolt.)

Product - MidNite Solar

MidNite Solar Product Page.

www.midnitesolar.com

Here's one with room for 10 fuses or 12 breakers (not included). Configured as two sets of 5 or 6, so you still need to join two wires.

Product - MidNite Solar

MidNite Solar Product Page.

www.midnitesolar.com

8 strings of 3 - I'd still worry about being up to if not over max input voltage spec. Even if the inverter is rated for 150V, there is the possibility actual breakdown voltage varies between units. I've designed things I thought were 10V below specs of the IC but they failed. After reducing voltage by 1/3 there were no more problems.

Of course we also do our own for less, I put DIN rails and touch-safe fuse-holders in a waterproof box.

One sloped roof face with that orientation is good. If it has enough excess area, some panels could be tilted West and some tilted East; they need to be space far enough apart not to cast a shadow on each other most of the day. Spreading power production out over the day reduces cycling of battery and leaves more charge in battery as night comes.

Certainly a bigger inverter/charger is a good thing. Instead of barely making use of all the PV panels with the 6 kW, you might have the ability to add more later if desired.

Do you have a fuse for the battery? I used class T. Not cheap, but rated to interrupt high currents from DC source.

 

[Oldtimmer69]

I think I can get them all on there even if I did spread them out and try to tweak them east and west. I have two plumbing vents to work around that's really it.

I'll need two of the combiner boxes. I was going to put a disconnect on the solar and tie to my breaker box. I'll run everything off solar and nothing from the grid. Not sure what NEC says about that. But I'll have everything in the breaker room together. I have a regular ribbed metal roof I need to find fasters for. The ones solar queen posted are for commercial roofing pannls. I saw some that look like they have bigrubber washers on them.. And they used unistrut to put the pannls on.

I attached a link with the specs on that inverter.

 

[Bearpaw]

WOW ?! What a great exchange of thoughts, ideas, and experience! Thank you all for your time and effort invested into helping others get where they need to be! I have been dealing with similar issues as Oldtimer69 in designing my own off grid replacement system for the current and outdated one. I have done a ton of reading, watching, and other research before joining here recently. This exchange has confirmed the results of my research and tauget me a couple more things as well. I feel a lot better prepared to begin my equipment acquisition process. You guys (and gals-let’s not forget the Solar Royal) are amazing! Glad I joined. Hopefully I can contribute and pay it forward sometime in the future.

 

[Hedges]

I think I can get them all on there even if I did spread them out and try to tweak them east and west. I have two plumbing vents to work around that's really it.

I'll need two of the combiner boxes. I was going to put a disconnect on the solar and tie to my breaker box. I'll run everything off solar and nothing from the grid. Not sure what NEC says about that. But I'll have everything in the breaker room together. I have a regular ribbed metal roof I need to find fasters for. The ones solar queen posted are for commercial roofing pannls. I saw some that look like they have bigrubber washers on them.. And they used unistrut to put the pannls on.

I attached a link with the specs on that inverter.

So you have grid available?
You said you wanted to build an off-grid system, but at first you showed a couple grid-tie inverters.
Grid-tie with net metering is the simplest and cheapest. PV gets converted to AC and shoved back into the grid, recorded as a credit on your bill.
You draw power from the grid (and/or PV if sun is shining at the same time.) No batteries, little concern about making the right size system. It just reduces how much power you buy from the grid.

Primary issue with grid tie and net metering is that the utilities get the rules changed, trying not to let you have one-for-one credit for the kWh you produce.

With an off-grid system, you usually have to produce 100% of your power. If < 100%, battery gets run down and system shuts off. Or you have to stop using as much power. If sized for > 100%, battery is fully charged every day but then PV is idle, producing less power than it could.

With a battery backup grid-tie system, you would ideally use 100% of your PV power and if more was needed get that from the grid. Mine does that with net metering; battery stays full all the time (which lead-acid such as I have likes), and during power failure it becomes an off-grid system. I have lots of PV and small battery so at night the battery discharges 50% to 70%, but during the day battery is kept fully charged and not all PV is used. (I have both gas and electric heat, also A/C, so avoid excessive electric loads while grid down.)

For a battery backup system that isn't grid-tie net metering, you would like to use 100% of PV, keep batteries optimally charged (probably less than 100% for lithium) and draw additional power as needed from the grid. You may or may not want to run on batteries at night because cycling batteries wears them out, and they cost more than grid power.

I'm not sure, but I think GroWatt can charge batteries from PV, or charge from grid. I think it can pass through AC from grid, or operate as an inverter and create AC from batteries. But can it make use of all available PV and draw just enough from grid to provide the power you need? Or, can it only drain batteries to make AC and then charge back up from grid (cycling batteries)?

It looks like GroWatt offers a "zero export" (or export limit) function you might want. By adding their "single phase meter" CT (current transformer) at grid connection, it can monitor what power comes from or goes to the grid, and reduce inverter output so it doesn't backfeed the grid.

Growatt

Decide if you really want battery backup, in which case you need a large enough battery. If not, then maybe a very minimal battery.
For battery backup, protected loads have to be on the output of the inverter. If not battery backup, then (at least some models) should work like a grid-tie inverter, backfeeding the grid and other loads in the house. But with the zero export configuration and a CT at the grid connection, only enough power for the house would be produced, none would ever flow back into the grid.

An off-grid system would usually have a battery big enough for 3 days without sun. You'll have 6 kW of PV, 33 kWh/day, 100 kWh suggested battery capacity (2000 Ah @ 48V) which is quite expensive (around $25,000). If you can instead rely on the grid you might have 100 Ah @ 48V (around $1250 worth of batteries.)

 

[Oldtimmer69]

So you have grid available?
You said you wanted to build an off-grid system, but at first you showed a couple grid-tie inverters.
Grid-tie with net metering is the simplest and cheapest. PV gets converted to AC and shoved back into the grid, recorded as a credit on your bill.
You draw power from the grid (and/or PV if sun is shining at the same time.) No batteries, little concern about making the right size system. It just reduces how much power you buy from the grid.

Primary issue with grid tie and net metering is that the utilities get the rules changed, trying not to let you have one-for-one credit for the kWh you produce.

With an off-grid system, you usually have to produce 100% of your power. If < 100%, battery gets run down and system shuts off. Or you have to stop using as much power. If sized for > 100%, battery is fully charged every day but then PV is idle, producing less power than it could.

With a battery backup grid-tie system, you would ideally use 100% of your PV power and if more was needed get that from the grid. Mine does that with net metering; battery stays full all the time (which lead-acid such as I have likes), and during power failure it becomes an off-grid system. I have lots of PV and small battery so at night the battery discharges 50% to 70%, but during the day battery is kept fully charged and not all PV is used. (I have both gas and electric heat, also A/C, so avoid excessive electric loads while grid down.)

For a battery backup system that isn't grid-tie net metering, you would like to use 100% of PV, keep batteries optimally charged (probably less than 100% for lithium) and draw additional power as needed from the grid. You may or may not want to run on batteries at night because cycling batteries wears them out, and they cost more than grid power.

I'm not sure, but I think GroWatt can charge batteries from PV, or charge from grid. I think it can pass through AC from grid, or operate as an inverter and create AC from batteries. But can it make use of all available PV and draw just enough from grid to provide the power you need? Or, can it only drain batteries to make AC and then charge back up from grid (cycling batteries)?

It looks like GroWatt offers a "zero export" (or export limit) function you might want. By adding their "single phase meter" CT (current transformer) at grid connection, it can monitor what power comes from or goes to the grid, and reduce inverter output so it doesn't backfeed the grid.

Growatt

Decide if you really want battery backup, in which case you need a large enough battery. If not, then maybe a very minimal battery.
For battery backup, protected loads have to be on the output of the inverter. If not battery backup, then (at least some models) should work like a grid-tie inverter, backfeeding the grid and other loads in the house. But with the zero export configuration and a CT at the grid connection, only enough power for the house would be produced, none would ever flow back into the grid.

An off-grid system would usually have a battery big enough for 3 days without sun. You'll have 6 kW of PV, 33 kWh/day, 100 kWh suggested battery capacity (2000 Ah @ 48V) which is quite expensive (around $25,000). If you can instead rely on the grid you might have 100 Ah @ 48V (around $1250 worth of batteries.)

Yea when I first started looking I didn't realize there was off grid / grid tied systems that's why I posted those inverters, then I saw I was looking at the wrong ones.


I have grid available wear I am now, I want off of the system. Also, what happens when the grid is down? All those power people with grid tied systems and no back up are in trouble and some don't even realize it...
We're also going to move just not sure how quick that's going to happen. Hopefully here soon.. Property is at a record high right now and we have the ability to make some money and move farther out. So that is going to happen. I bought this system for the property and had no intention on hooking the solar up here but I'd rather do it and use it and sell it with the home.. It will increase the value even more to the people escaping the madness for rural peace, off grid living, solar power, rain collection system and self-sufficiency. This system right now will be someone else system but will give me some experience putting it in and some all around knowledge about the system then I'll build another one when we move. ?? Soon.

When I have all 4 batteries that's 14k 5.12kwh each and should be enough to make it through the night the way the house is built and set up it's very efficient. The array should keep my batteries topped off and allow me to use power freely during the day. Then normal stuff at night ac being the biggest draw in the summer. We only need the Air conditioner a few months out of the year and we burn wood in the winter. The new cabin will be smaller and very efficient also. I'll put in a power saver mini split to help combat summer hear and usage. We should be good. We'll make changes as needed.

 

[Oldtimmer69]

WOW ?! What a great exchange of thoughts, ideas, and experience! Thank you all for your time and effort invested into helping others get where they need to be! I have been dealing with similar issues as Oldtimer69 in designing my own off grid replacement system for the current and outdated one. I have done a ton of reading, watching, and other research before joining here recently. This exchange has confirmed the results of my research and tauget me a couple more things as well. I feel a lot better prepared to begin my equipment acquisition process. You guys (and gals-let’s not forget the Solar Royal) are amazing! Glad I joined. Hopefully I can contribute and pay it forward sometime in the future.

I agree or of good information in here. Definitely learning alot and I'm glad it's helpful for you too!

 

[Hedges]

Yea when I first started looking I didn't realize there was off grid / grid tied systems that's why I posted those inverters, then I saw I was looking at the wrong ones.


I have grid available wear I am now, I want off of the system. Also, what happens when the grid is down? All those power people with grid tied systems and no back up are in trouble and some don't even realize it...
We're also going to move just not sure how quick that's going to happen. Hopefully here soon.. Property is at a record high right now and we have the ability to make some money and move farther out. So that is going to happen. I bought this system for the property and had no intention on hooking the solar up here but I'd rather do it and use it and sell it with the home.. It will increase the value even more to the people escaping the madness for rural peace, off grid living, solar power, rain collection system and self-sufficiency. This system right now will be someone else system but will give me some experience putting it in and some all around knowledge about the system then I'll build another one when we move. ?? Soon.

When I have all 4 batteries that's 14k 5.12kwh each and should be enough to make it through the night the way the house is built and set up it's very efficient. The array should keep my batteries topped off and allow me to use power freely during the day. Then normal stuff at night ac being the biggest draw in the summer. We only need the Air conditioner a few months out of the year and we burn wood in the winter. The new cabin will be smaller and very efficient also. I'll put in a power saver mini split to help combat summer hear and usage. We should be good. We'll make changes as needed.

People advertising solar will claim it increases property values. It may or may not, might even reduce what a property sells for. If panels are away from the street they're out of sight, but facing the street they can be unsightly. For a buyer barely able to afford payments or make 20% down, having to buy the PV system upfront makes it less affordable. Do you really think selling price of your property will be increased by at least the cost of the components you purchase and install?

Off-grid systems are cost effective compared to having the utility string 1000' or a mile of wire. But batteries are so expensive that very few have a cost per kWh (by the time they are worn out) less than simply buying kWh from the grid. And, you have to pay for them upfront, which costs more considering the time value of money. My utility rates are $0.15 to $0.45/kWh depending on time of day. The grid-tie PV system I put in 15 years ago, after rebates and amortized over 15 years, cost $0.20/kWh. Today I can buy PV panels and grid tie inverters to generate power for $0.05/kWh amortized over 10 years (without rebates.) My batteries cost $0.60/kWh. Some batteries cost less, but I selected a simple, undersized bank for a grid-backup system to last 10 years with only occasional power failures. Because PV costs a fraction of what batteries do, I throw away unused PV kW while the sun shines (during grid failures) and draw as little as possible from batteries at night. For instance, during these hot spells when PG&E has shut down, I run A/C during the day.

My Sunny Island & SunXtender battery backup setup costs more than my Sunny Boy and SunPower grid-tie setup. They play together with Sunny Boy being grid tie until there is a power failure, then Sunny Island takes over and regulates Sunny Boy production of AC to match my power usage. The battery backup system is a luxury I put in because I had money to spare. Otherwise, a small UPS possibly with PV to keep phone/internet/PC operating would have been sufficient.

 

[Oldtimmer69]

People advertising solar will claim it increases property values. It may or may not, might even reduce what a property sells for. If panels are away from the street they're out of sight, but facing the street they can be unsightly. For a buyer barely able to afford payments or make 20% down, having to buy the PV system upfront makes it less affordable. Do you really think selling price of your property will be increased by at least the cost of the components you purchase and install?

Off-grid systems are cost effective compared to having the utility string 1000' or a mile of wire. But batteries are so expensive that very few have a cost per kWh (by the time they are worn out) less than simply buying kWh from the grid. And, you have to pay for them upfront, which costs more considering the time value of money. My utility rates are $0.15 to $0.45/kWh depending on time of day. The grid-tie PV system I put in 15 years ago, after rebates and amortized over 15 years, cost $0.20/kWh. Today I can buy PV panels and grid tie inverters to generate power for $0.05/kWh amortized over 10 years (without rebates.) My batteries cost $0.60/kWh. Some batteries cost less, but I selected a simple, undersized bank for a grid-backup system to last 10 years with only occasional power failures. Because PV costs a fraction of what batteries do, I throw away unused PV kW while the sun shines (during grid failures) and draw as little as possible from batteries at night. For instance, during these hot spells when PG&E has shut down, I run A/C during the day.

My Sunny Island & SunXtender battery backup setup costs more than my Sunny Boy and SunPower grid-tie setup. They play together with Sunny Boy being grid tie until there is a power failure, then Sunny Island takes over and regulates Sunny Boy production of AC to match my power usage. The battery backup system is a luxury I put in because I had money to spare. Otherwise, a small UPS possibly with PV to keep phone/internet/PC operating would have been sufficient.

 

[SolarQueen]

I'll need two of the combiner boxes. I was going to put a disconnect on the solar and tie to my breaker box. I'll run everything off solar and nothing from the grid. Not sure what NEC says about that. But I'll have everything in the breaker room together. I have a regular ribbed metal roof I need to find fasters for. The ones solar queen posted are for commercial roofing pannls. I saw some that look like they have bigrubber washers on them.. And they used unistrut to put the pannls on.

S-5! has a solution for every type of metal roof. They have several for ribbed roofs. If you are planning on putting rails on the feet, this is the product they recommend, https://s-5.com/products/clamps-brackets/solarfoot/

What model inverter are you thinking about trading for? Just want to make sure a bigger inverter solves your problem by also having a larger charger.

With all of the conflicting information you've been getting, how have you decided to wire the panels, and how many? If all of the panels are going on one section of roof, you should be able to use 1 combiner box up there. How many parallel strings are you going to do so we can tell you the right model?

In TN you are on 2017 NEC version. That does require module level shutdown, which does complicate the installation. Are you planning on getting the system permitted and inspected? Have you talked to the electrical inspector? If you are planning on selling the house with the solar system installed, you need to be extra careful to follow code, or you will fail the home inspection when trying to sell. Read the 2 part blog about rapid shutdown here, https://www.altestore.com/blog/2020...s-on-buildings-part-1-inverters/#.X0_QcFVKiUk

 

[Oldtimmer69]

I'm in a different part of the world. And 400' off the road.. Lol I would agree with you about pannls on the front of your home. Mine will be on the back and not really seen. Property like mine are being sold site unseen.. Its really unbelievable!

We know MAJOR CHANGES are coming and with that it will bring hardship and pain.. I need to be prepared.

S-5! has a solution for every type of metal roof. They have several for ribbed roofs. If you are planning on putting rails on the feet, this is the product they recommend, https://s-5.com/products/clamps-brackets/solarfoot/

What model inverter are you thinking about trading for? Just want to make sure a bigger inverter solves your problem by also having a larger charger.

With all of the conflicting information you've been getting, how have you decided to wire the panels, and how many? If all of the panels are going on one section of roof, you should be able to use 1 combiner box up there. How many parallel strings are you going to do so we can tell you the right model?

In TN you are on 2017 NEC version. That does require module level shutdown, which does complicate the installation. Are you planning on getting the system permitted and inspected? Have you talked to the electrical inspector? If you are planning on selling the house with the solar system installed, you need to be extra careful to follow code, or you will fail the home inspection when trying to sell. Read the 2 part blog about rapid shutdown here, https://www.altestore.com/blog/2020...s-on-buildings-part-1-inverters/#.X0_QcFVKiUk

This is the inverter. 8 strings of 3 is the plan. I'll look at the rapid shutdown. And I'll read what you sent. Yes I was going to leave the system, I haven't talked to a inspector, I wasn't going to pull a permit but looks like I may. I'll do all the work just need to know what the NEC says

 

[JoeHam]

Also, what happens when the grid is down? All those power people with grid tied systems and no back up are in trouble

That is exactly how I feel about it.

In addition the power company gets to make all the rules that you must abide by. Some of that is good (safety considerations) but I cannot tolerate the bad.

Buying your power at a discount while selling it back to you at a premium! No thanks.

Also, what happens when they unilaterally change the rules?

Enough said, now back to our regularly scheduled programming.

 

[Oldtimmer69]

That is exactly how I feel about it.

In addition the power company gets to make all the rules that you must abide by. Some of that is good (safety considerations) but I cannot tolerate the bad.

Buying your power at a discount while selling it back to you at a premium! No thanks.

Also, what happens when they unilaterally change the rules?

Enough said, now back to our regularly scheduled programming.

I agree brother.. We went down the truth rabbit hole years ago.. Its only going to get worse.. We see the nonsense already bubbling up from everywhere.. Thank goodness I live where I do..

 

[SolarQueen]

If you decide not to do rapid shutdown, and just need a combiner box, the Midnite Solar MNPV12 will fit up to 12 strings. You need to also get 8 15A DIN rail breakers, one for each string.

 

[Hedges]

This is the inverter. 8 strings of 3 is the plan. I'll look at the rapid shutdown. And I'll read what you sent. Yes I was going to leave the system, I haven't talked to a inspector, I wasn't going to pull a permit but looks like I may. I'll do all the work just need to know what the NEC says

Your new inverter has two PV inputs, so no longer any need to join wires from the two busses in the combiner box[es]. I still think you should do 12 strings of 2, just for extra margin from Voc limits. That doesn't really cost anything more except 4 more breakers and a couple more MC cables.

The newer codes require module-level disconnects (rapid shutdown) and arc-fault detection when panels are on the roof. Those would not be required if using ground mounts, and the money saved not buying an extra box per panel probably covers the extra structure.

In my area there is also a requirement of walkway 3' wide on to sides and below ridge, for fireman. Here that may be interpreted to count width of eaves toward the 3', but in some locations "solid support" is taken to mean the 3' is inside the building walls, so if eaves are 2' wide there is 5' lost. In my area, permits for rooftop are cheaper and expedited - get it online, and inspector only looks at plans when he arrives to see the finished work. Ground mount permits are more involved, but I got around that with multiple arrays having 120 square foot footprint (non-permit size structure.)

You might consider building it so you can pack everything up and take to your new place. My structures are 2" pipe verticals and horizontals, with diagonal bracing. Rails are attached with angle aluminum and U-bolts. Typically pipes are set in concrete, but I bolted some to existing concrete and drove others a few feet into the ground. I used these for my first array, but but did roll-your-own after that:

UNIRAC LARGE ARRAY (ULA) - Unirac

HOME » GROUND MOUNT » UNIRAC LARGE ARRAY (ULA) FLEXIBILITY FOR ANY SIZE PROJECT UNIRAC LARGE ARRAY (ULA) supports a wider range of site and climatic challenges than any other PV structure on the market. ULA aluminum components merge with SOLARMOUNT rails and installer-supplied steel pipe to form...

unirac.com

 

[Oldtimmer69]

Your new inverter has two PV inputs, so no longer any need to join wires from the two busses in the combiner box[es]. I still think you should do 12 strings of 2, just for extra margin from Voc limits. That doesn't really cost anything more except 4 more breakers and a couple more MC cables.

The newer codes require module-level disconnects (rapid shutdown) and arc-fault detection when panels are on the roof. Those would not be required if using ground mounts, and the money saved not buying an extra box per panel probably covers the extra structure.

In my area there is also a requirement of walkway 3' wide on to sides and below ridge, for fireman. Here that may be interpreted to count width of eaves toward the 3', but in some locations "solid support" is taken to mean the 3' is inside the building walls, so if eaves are 2' wide there is 5' lost. In my area, permits for rooftop are cheaper and expedited - get it online, and inspector only looks at plans when he arrives to see the finished work. Ground mount permits are more involved, but I got around that with multiple arrays having 120 square foot footprint (non-permit size structure.)

You might consider building it so you can pack everything up and take to your new place. My structures are 2" pipe verticals and horizontals, with diagonal bracing. Rails are attached with angle aluminum and U-bolts. Typically pipes are set in concrete, but I bolted some to existing concrete and drove others a few feet into the ground. I used these for my first array, but but did roll-your-own after that:

UNIRAC LARGE ARRAY (ULA) - Unirac

HOME » GROUND MOUNT » UNIRAC LARGE ARRAY (ULA) FLEXIBILITY FOR ANY SIZE PROJECT UNIRAC LARGE ARRAY (ULA) supports a wider range of site and climatic challenges than any other PV structure on the market. ULA aluminum components merge with SOLARMOUNT rails and installer-supplied steel pipe to form...

unirac.com

When I buy the combiner box do I buy short Mc cables and cut them in half to tie into the box, That's about the cheapest way right? I just may do the ground mount. I wonder if I can split my pannls into 3 sections and skew them like you were saying earlier- east, south, west to get the most sun., I get some shade in the morning on the ground from the apple tree but should get full sun about 915/930am all the way until 730pm.

 

[Hedges]

When I buy the combiner box do I buy short Mc cables and cut them in half to tie into the box, That's about the cheapest way right? I just may do the ground mount. I wonder if I can split my pannls into 3 sections and skew them like you were saying earlier- east, south, west to get the most sun., I get some shade in the morning on the ground from the apple tree but should get full sun about 915/930am all the way until 730pm.

You can also split summer vs. winter tilt. Just have all in a given string oriented the same.

Yes, short or possibly long MC cables if that's better for the home run from the last panel. I have several ground mount arrays, so I buried 3/4" rigid conduit from combiner box to each array and have a waterproof outlet box at the end, with short MC pigtails coming coming out gland fittings. Cutting cables was easier than doing good crimps. I tried to minimize how many longer MC cables it took to connect the array. I originally used wire nuts to connect 12 AWG wire to the cut MC cables, but have used set-screw type nuts more recently.

The MC connectors will keep polarity correct, after you wire the pigtails correctly the first time. I color code the wires with tape or heatshrink so I can tell which array and which string goes to which fuse in the combiner. You only need to distinguish the two sets, but it is convenient to identify down to which fuse/breaker. Check that Voc is similar for all before closing breakers; that will confirm same number of panels in each string.

All strings to a given inverter MPPT input need to have same number of panels in series, but each string having different orientation works well. If there is shade on one panel out of a string of 2 or 3, likely that entire string won't contribute power. So better to wire panels so two panels in one string get shade rather than one panel in each of two strings.

Here's one way to connect a ground wire to panels. This allows a panel to be removed without interrupting ground to other panels:

GBL4 DBT Solar Module Grounding Lug Kit

GBL4 DBT Solar Module Grounding Lug Kit

www.solar-electric.com

That mentions an alternate type WEEB:

Using the WEEB solution for grounding in solar applications?

A brief introduction to the WEEB grounding and bonding products.

www.cedgreentech.com

 

[JoeHam]

WEEB is available on Amazon as are these:

Amazon.com

 

[Oldtimmer69]

Inverter showed up today. I'm working on getting some 4" steel pipe to build the post for the racks for scrap cost so waiting, but thinking four groups of 6 pannls, one post per group and let them swivel and tilt. And I can manually adjust them 3, 4 times a year. Racks will be 20' away frome the house but still around 100' from the beaker room. Hoping to have 4 batteries by October. Not sure that's going to be enough without changing some things. Hot water heater pulls alot. And I'm not sure I can grow vegetables inside anymore on solar alone.. We used 44 kwh yesterday.. 20 during the day and 24.at night. We'll take showers differently tonight.. And see what the big spike was.. I'm thinking hot water heater, stove, drier, coffee pot. But still didn't think I'd be over daytime kwhs at night..

 

[Oldtimmer69]

Inverter showed up today. I'm working on getting some 4" steel pipe to build the post for the racks for scrap cost so waiting, but thinking four groups of 6 pannls, one post per group and let them swivel and tilt. And I can manually adjust them 3, 4 times a year. Racks will be 20' away frome the house but still around 100' from the beaker room. Hoping to have 4 batteries by October. Not sure that's going to be enough without changing some things. Hot water heater pulls alot. And I'm not sure I can grow vegetables inside anymore on solar alone.. We used 44 kwh yesterday.. 20 during the day and 24.at night. We'll take showers differently tonight.. And see what the big spike was.. I'm thinking hot water heater, stove, drier, coffee pot. But still didn't think I'd be over daytime kwhs at night..