System Design Feedback

[Bobgar]

Hi Everyone!

I'm looking to get some feedback on a system in planning to buy later this week. Signature solar has a sale going on and i want to take advantage of it. This would be a grid tied system using micro inverters. The system would be roof mounted. The system would be sitting on a 4-12 roof in Maine. The ground snow load is 80psf. When this building was built the trusses where engineered to support a future solar installation. the parts I'm looking at right now are,

probably 32 of these panels

13.3kW Pallet - NE Solar 370W Mono Solar Panel (Black) | NESW 370MH-M6 | Full Pallet (36) - 13.3kW Total

Signature Solar provides solar panels, off-grid solar systems, grid-tie, and hybrid systems. Quality solar inverters, bifacial solar panels, complete solar kits, solar batteries. Featuring brands such as EG4 Electronics with their solar battery, LifePower4 and EG4 LLifePower4 and EG4 LL

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probably 16 of these micro inverters and trunk cable

APTOS MAC-800 Dual Unit | 2:1 Trunk Version Microinverter

Signature Solar provides solar panels, off-grid solar systems, grid-tie, and hybrid systems. Quality solar inverters, bifacial solar panels, complete solar kits, solar batteries. Featuring brands such as EG4 Electronics with their solar battery, LifePower4 and EG4 LLifePower4 and EG4 LL

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Aptos AC Trunk Cable 2.2M | 2.2M 12G AC TRUNK CABLE

Signature Solar provides solar panels, off-grid solar systems, grid-tie, and hybrid systems. Quality solar inverters, bifacial solar panels, complete solar kits, solar batteries. Featuring brands such as EG4 Electronics with their solar battery, LifePower4 and EG4 LLifePower4 and EG4 LL

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probably 70 of these mounting brackets

SnapNrack | TopSpeed™ | Solar Panel Roof Mount KIT (1 Mount (A) and 1 Clamp (B)

Signature Solar provides solar panels, off-grid solar systems, grid-tie, and hybrid systems. Quality solar inverters, bifacial solar panels, complete solar kits, solar batteries. Featuring brands such as EG4 Electronics with their solar battery, LifePower4 and EG4 LLifePower4 and EG4 LL

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Additional racking material to include

SnapNrack | TopSpeed™ | Universal Link

Signature Solar provides solar panels, off-grid solar systems, grid-tie, and hybrid systems. Quality solar inverters, bifacial solar panels, complete solar kits, solar batteries. Featuring brands such as EG4 Electronics with their solar battery, LifePower4 and EG4 LLifePower4 and EG4 LL

signaturesolar.com

SnapNrack | TopSpeed™ | RL Universal Skirt | 70 inch

Signature Solar provides solar panels, off-grid solar systems, grid-tie, and hybrid systems. Quality solar inverters, bifacial solar panels, complete solar kits, solar batteries. Featuring brands such as EG4 Electronics with their solar battery, LifePower4 and EG4 LLifePower4 and EG4 LL

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I know I'm also going to need some conduit, an AC disconnect, Some THHN Wire going back to the breaker box, and some kind of breaker, though not sure exactly what size or if it needs to be a special kind of breaker. I think the wire gauge needs to be 8 and I think the breaker needs to be a 60 amp breaker. I think the AC disconnect needs to be a 60 amp switch.

Any advice or obvious flaws? Any parts I'm missing?

 

[SignatureSolarJess]

Hi! You can refer to this Aptos microinverter kits component list to reference all of the components needed. It seems you may be missing a couple. I hope this helps!

Complete Grid-Tie Solar Panel Kit - 8kW Aptos Microinverter Kit - Aptos MAC-800

Signature Solar provides solar panels, off-grid solar systems, grid-tie, and hybrid systems. Quality solar inverters, bifacial solar panels, complete solar kits, solar batteries. Featuring brands such as EG4 Electronics with their solar battery, LifePower4 and EG4 LLifePower4 and EG4 LL

signaturesolar.com

This kit doesn't include the solar panels you selected so you would have to piece out the kit.

 

[1201]

why micro inverters?

 

[Bobgar]

why micro inverters?

Mostly for ease of installation. Partly to avoid the single point of failure of a string inverter. Partly because I like the Idea of near individual panel level measurements. I also wanted to make sure partial shading didn't reduce the output of the whole array. So if I was gonna have to attach optimizers to the array anyway, why not cut the middle man?

This way I don't have to worry about sticking the array in any sort of series or parallel configuration and worry about blowing up the string inverter. Just make sure the panels are suited to the micro inverters and your good to go. No messing about with DC circuitry or specialized DC breakers.

I hope that answers your question.

 

[1201]

Mostly for ease of installation. Partly to avoid the single point of failure of a string inverter. Partly because I like the Idea of near individual panel level measurements. I also wanted to make sure partial shading didn't reduce the output of the whole array. So if I was gonna have to attach optimizers to the array anyway, why not cut the middle man?

This way I don't have to worry about sticking the array in any sort of series or parallel configuration and worry about blowing up the string inverter. Just make sure the panels are suited to the micro inverters and your good to go. No messing about with DC circuitry or specialized DC breakers.

I hope that answers your question.

Some good points, like panel level monitoring but you go from one point of failure to 16 points, and on the roof at that. If one fails and you have to get on the roof and maybe remove a panel to replace it it could get expensive.

I'll take things that can fail at ground level over things that can fail at roof level.
There is also the fact of the equipment being exposed to extreme temperatures, vs being able to have the equipment in conditioned space at ground level

 

[Bobgar]

Does one failed Micro-inverter stop production of the entire array? And that's fair, if your not comfortable on a roof then keeping as many components at ground level as possible would be quite important. Thanks for responding!

 

[1201]

Does one failed Micro-inverter stop production of the entire array? And that's fair, if your not comfortable on a roof then keeping as many components at ground level as possible would be quite important. Thanks for responding!

It doesn't. For the same price you can get about 3 grid tie inverters so you could buy a spare and still be money ahead, if you're worried about the inverter failing

 

[Solar Guppy]

I've done both micro and string, getting up on the roof to find the correct micro that failed and then in the middle of an array isn't fun and will happen many times compare to having to replace a single string inverter at ground level. With todays panel price, I no longer even care what the harvest is ( I have full custom monitoring but it just pretty much the same thing every day ), its more than I can use and the panels are the cheapest part of the system.