Some pointers for newbie would be helpful.

[tj07161990]

hello all,

Please forgive my ignorance as I learn more everyday.
I am at the early stages and thinking of design ideas for potential whole home solar. My goal is to install panels on roof of my storage building. It’s a 12x20 building. I believe I can fit 12 panels on this roof and it faces directly south. I’m hoping I can squeeze another row and get 16 panels but need to do some measurements..
But I’m a bit worried about the distance. This building is located 220ft from my main electric panel. With this goal of powering my entire home one day, I was thinking I needed a wire than can handle 200amps since I have a 200amp service currently. I wanted to go with a sol ark interested and looking into it a bit more I see the Sol Ark 15k output 67.5amp max. Is a 15k overkill for 12 panels? What about 16? So it seems I only need a cable than can handle this which would be a bit easier to get my hands on. The plan would be to have battery storage, and a Sol-Ark inverter in my exterior building and feed my home.

I want the benefits of reduced energy costs and the peace of mind if we lost power. I’m not sure if it’s best for me to try to grid tie my setup or if it’s better to setup an off grid system than I can switch to for a few hours or more per day? Would it be possible to a grid tie system with sol ark so far away from main panel?

thank you in advance.

 

[BentleyJ]

220 ft will require up-sizing the wire to compensate for voltage drop but that distance is manageable. The wire cost is going to be a little high for something like 250MCM but there are alternatives like parallel runs of smaller ga wire or using Aluminum.

 

[Ampster]

Is there any benefit to comparing the cost of an additional panel to compensate for the voltage loss versus the cost of upgrading the wire?

 

[wdwtx2.0]

I have 2 ea. 6000 watt inverters.
They each are powered by a 16 panel array (8S2P).
When I upsize to the Sol-Ark 15K, I will be using 3 arrays for it.
One 16 panel array per MPPT, 48 total.
Also it would be much much cheaper to run DC solar voltage to your house, and have the inverter on your house.
6, or 8AWG is much cheaper than 200 amp rated wire.

 

[EZPZ]

First get an idea of how much you are consuming in your home. Panel dimensions vary so for how many you can get on the shed roof will also be a limiting factor so have a look into that so you can then get a good idea of how much power you would be able to make on said shed. It might not be nearly enough to run your whole home. But it will give you an idea to mull around with while thinking about it all. Do you have another location for more panels if needed to run your whole house? I would worry about this before worrying about an inverter and wire size. My solar panels are over 450ft away from my inverter.

 

[Ampster]

One 16 panel array per MPPT, 48 total.

With the SolArk 15k, are you able to put each of those 16 panels in series?

 

[tj07161990]

First get an idea of how much you are consuming in your home. Panel dimensions vary so for how many you can get on the shed roof will also be a limiting factor so have a look into that so you can then get a good idea of how much power you would be able to make on said shed. It might not be nearly enough to run your whole home. But it will give you an idea to mull around with while thinking about it all. Do you have another location for more panels if needed to run your whole house? I would worry about this before worrying about an inverter and wire size. My solar panels are over 450ft away from my inverter.

That’s good advice. Currently I only have the shed but have a wide open backyard with nothing in it. Do I could potentially install more. I’m not sure certain how many I would need. My current usage is approx 40Kwh per day. 1250 per month average. How many panels should I be aiming for??

 

[tj07161990]

That’s good advice. Currently I only have the shed but have a wide open backyard with nothing in it. Do I could potentially install more. I’m not sure certain how many I would need. My current usage is approx 40Kwh per day. 1250 per month average. How many panels should I be aiming for??

 

[tj07161990]

Is there any benefit to comparing the cost of an additional panel to compensate for the voltage loss versus the cost of upgrading the wire?

220 ft will require up-sizing the wire to compensate for voltage drop but that distance is manageable. The wire cost is going to be a little high for something like 250MCM but there are alternatives like parallel runs of smaller ga wire or using Aluminum.

I would love copper but i believe I can cut costs for the cable by 1/3 by using a 250ft spool of AL SEC. I think I seen a spool for $1k

 

[EZPZ]

The wattage per panel vary along with the size of the panel - bigger size panel generally can produce more wattage and also weigh more - no fun dragging huge 60lb panels up onto a roof - it’s common now for the 400w per panel and upwards. Measure the shed roof. Check a couple of website panels and see sizes and wattage and pricing. That will give you a good idea of how many panels could go up on the shed and what the potential wattage they could produce. What is the angle of the shed roof as that has an impact on solar production. As an example my panel sizes are 68 in x 44.7 in x 1.18 in and are rated at 400w. But measure measure measure. A Canadian 390w is 67.8 x 44.6 x 1.38 in. So maybe something along those sizes will give you an idea. As reference I have 42 400w panels and on a sunny day can generate 100kwh right now.

Check https://pvwatts.nrel.gov/ as that will also give you a good idea of how much solar your can generate at your specific location.

Then it ends up how much money you want to spend and what exactly you want to accomplish.

 

[tj07161990]

I have 2 ea. 6000 watt inverters.
They each are powered by a 16 panel array (8S2P).
When I upsize to the Sol-Ark 15K, I will be using 3 arrays for it.
One 16 panel array per MPPT, 48 total.
Also it would be much much cheaper to run DC solar voltage to your house, and have the inverter on your house.
6, or 8AWG is much cheaper than 200 amp rated wire.

I was under the impression dc = bad due to voltage drop. Or is this not the case if you have a high enough voltage

 

[Ampster]

I was under the impression dc = bad due to voltage drop. Or is this not the case if you have a high enough voltage

With solar voltage it does not matter as much because sometimes you can just add another panel for less money than increasing the wire size. Yes low voltage DC does suffer more from voltage drop.

 

[tj07161990]

The wattage per panel vary along with the size of the panel - bigger size panel generally can produce more wattage and also weigh more - no fun dragging huge 60lb panels up onto a roof - it’s common now for the 400w per panel and upwards. Measure the shed roof. Check a couple of website panels and see sizes and wattage and pricing. That will give you a good idea of how many panels could go up on the shed and what the potential wattage they could produce. What is the angle of the shed roof as that has an impact on solar production. As an example my panel sizes are 68 in x 44.7 in x 1.18 in and are rated at 400w. But measure measure measure. A Canadian 390w is 67.8 x 44.6 x 1.38 in. So maybe something along those sizes will give you an idea. As reference I have 42 400w panels and on a sunny day can generate 100kwh right now.

Check https://pvwatts.nrel.gov/ as that will also give you a good idea of how much solar your can generate at your specific location.

Then it ends up how much money you want to spend and what exactly you want to accomplish.

Thank you. I will take some measurements and see how many I can fit. I was looking at Canadian solar 390 watt panels but nothing is set in stone as I try to design. 42 panels??! You have a farm! My end goal is to enough to power my home without relying on utility company. So rounding up 50kwh day. (Half of yours!)

 

[tj07161990]

Thank you. I will take some measurements and see how many I can fit. I was looking at Canadian solar 390 watt panels but nothing is set in stone as I try to design. 42 panels??! You have a farm! My end goal is to enough to power my home without relying on utility company. So rounding up 50kwh day. (Half of yours!)

The pitch of my roof is 8/12 so approximately 33 degree roof. Would there be any benefit to adding panels on the north side of roof?

 

[wdwtx2.0]

I was under the impression dc = bad due to voltage drop. Or is this not the case if you have a high enough voltage

As Ampster said, with high voltage DC it doesn't make much difference.
However, 16 panels for a 15K is underpowered by a lot.
If that's all of the panels you would ever have, I would go with a less expensive inverter.
Panels on the north side are not worth it.
Is there any way you could have a ground array(s)?

 

[wdwtx2.0]

With the SolArk 15k, are you able to put each of those 16 panels in series?

No.
Mine are 8S2P.
I have 2 ea. EG4 6000EXs.
I will use the same array setup when I get the Sol-Ark, except I will build a third array.

 

[Hedges]

No problem having PV array 220' away, if it is high voltage. Like 600V max input allowed by inverter, nominally 500Voc +/- from the array.
There is also 1000V equipment, although > 600V may or may not be allowed for your installation. One guy here did that with Fronius inverters and ground mount.

What is slope of North facing roof? Is it due North, or at an angle?
Obviously it will generate more in Summer, very little in Winter. Does that match your consumption?
You can also tilt those panels off the roof slope, possibly flat, possibly South. But if more than just one row, have to consider how much time/seasons they cast a shadow on each other.

Is net metering available? That makes a difference in cost-effectiveness, and how big a battery is needed.

 

[tj07161990]

No problem having PV array 220' away, if it is high voltage. Like 600V max input allowed by inverter, nominally 500Voc +/- from the array.
There is also 1000V equipment, although > 600V may or may not be allowed for your installation. One guy here did that with Fronius inverters and ground mount.

What is slope of North facing roof? Is it due North, or at an angle?
Obviously it will generate more in Summer, very little in Winter. Does that match your consumption?
You can also tilt those panels off the roof slope, possibly flat, possibly South. But if more than just one row, have to consider how much time/seasons they cast a shadow on each other.

Is net metering available? That makes a difference in cost-effectiveness, and how big a battery is needed.

Slope of roof is 8/12 so 33.7 degree roof. Roof is facing Exactly south/ north A frame. Net metering is not available with my utility provider. That’s a good idea to install panels in series and raise voltage. I’m assuming most panels are 12 volts?

As Ampster said, with high voltage DC it doesn't make much difference.
However, 16 panels for a 15K is underpowered by a lot.
If that's all of the panels you would ever have, I would go with a less expensive inverter.
Panels on the north side are not worth it.
Is there any way you could have a ground array(s)?

Thank you for the reply. Ground arrays are a possibility. Do you know of any good mounts for 20+ panels?

 

[EZPZ]

Slope of roof is 8/12 so 33.7 degree roof. Roof is facing Exactly south/ north A frame. Net metering is not available with my utility provider. That’s a good idea to install panels in series and raise voltage. I’m assuming most panels are 12 volts?

Thank you for the reply. Ground arrays are a possibility. Do you know of any good mounts for 20+ panels?

No - most panels are not 12v. Mine are 37.07voc. The Canadian ones are 36.4voc.
I built my own ground mount….

 

[Ampster]

I’m assuming most panels are 12 volts?

If you are referring to the Original Poster, he did mention he was thinking about 390 Watt panels. Most 250-400 Watt panels have a VOC of 30 volts or more.