Help needed building a grid-tie system based on SunPower 435 panels

Ripples

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Sep 12, 2021
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Retired engineer but newbie with solar. Would appreciated any help/advice from those with more knowledge/experience.

Am considering buying a pallet of used SunPower 435w panels and am researching the components needed to build a residential grid-tie system to offset costs. Prefer to avoid batteries altogether. I'd like to keep it simple but happy to pay for reliability.

We typically use 1200 kwh per month. So thinking a system somewhere between 5kw and 7.5kw would work.

I'm in the Virgin Islands, so single phase 60hz. Good roof area facing south and have space for 1 row of 10 panels and another of 6 panels. Am thinking maybe 3 stings of 5 panels, but may have to go for 3 strings of 4 panels because of inverter input voltage limit.

Like the look of the SolarEdge Inverters ideally with optimizers, but I can't locate a single phase optimizer that can handle the 435w panel VOC of 85.6v.

Does anyone have any experience with these 128 cell commercial grade panels? (Panel specs attached)

Thanks
Peter
 

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Roqm

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Messages
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Retired engineer but newbie with solar. Would appreciated any help/advice from those with more knowledge/experience.

Am considering buying a pallet of used SunPower 435w panels and am researching the components needed to build a residential grid-tie system to offset costs. Prefer to avoid batteries altogether. I'd like to keep it simple but happy to pay for reliability.

We typically use 1200 kwh per month. So thinking a system somewhere between 5kw and 7.5kw would work.

I'm in the Virgin Islands, so single phase 60hz. Good roof area facing south and have space for 1 row of 10 panels and another of 6 panels. Am thinking maybe 3 stings of 5 panels, but may have to go for 3 strings of 4 panels because of inverter input voltage limit.

Like the look of the SolarEdge Inverters ideally with optimizers, but I can't locate a single phase optimizer that can handle the 435w panel VOC of 85.6v.

Does anyone have any experience with these 128 cell commercial grade panels? (Panel specs attached)

Thanks
Peter
These are capable and are the new revisions.
 

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  • TS4-A-O-Optimization-Add-on-TÜV.pdf
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svetz

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Welcome to the forums!

We typically use 1200 kwh per month. So thinking a system somewhere between 5kw and 7.5kw would work.
1200 kWh/m / 30 d/m = 40 kWh/d output needed.
From the insolation calculator, assuming flat roof and panels flat for high winds, then the minimum insolation is 4.76 in December.
Assuming 40 kWh/d needed in December, then 40 / 4.76 / .86 conversion efficiency is a minimum of a 10 kW array if off-grid.

Since you're on grid, every little bit helps and you probably use most of your power in summer. With a good net-metering agreement you can use the excess credits from winter to pay for the summer usage. You can get a lot more detailed information with SAM.

I'm in the Virgin Islands, so single phase 60hz.
Normally I see single-phase and 110V and think they're confused because the US the standard is 240V/120V split-phase. Countries that run single-phase usually have higher voltages (e.g., 220 to 240V).

But, according to this, you really are 110V. The UK is typically single-phase, but 230V; and BVI is also listed as 110V. So, no clue about that or if you need special gear to be grid-tied. For example, the SolarEdge datasheets I looked at didn't have a 110V output (they were split-phase with 240V).

Like the look of the SolarEdge Inverters ideally with optimizers, but I can't locate a single phase optimizer
SolarEdge optimizers are DC, no phase worries there.

Like the look of the SolarEdge ... can't locate ... optimizer that can handle the 435w panel VOC of 85.6v.
Looks like the P485 can. 125V max and up to 485Watts.

Does anyone have any experience with these 128 cell commercial grade panels? (Panel specs attached)

This might help if you go a traditional MPPT approach:
 
Last edited:

theshaww

New Member
Joined
Nov 8, 2021
Messages
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Welcome to the forums!


1200 kWh/m / 30 d/m = 40 kWh/d output needed.
From the insolation calculator, assuming flat roof and panels flat for high winds, then the minimum insolation is 4.76 in December.
Assuming 40 kWh/d needed in December, then 40 / 4.76 / .86 conversion efficiency is a minimum of a 10 kW array if off-grid.

Since you're on grid, every little bit helps and you probably use most of your power in summer. With a good net-metering agreement you can use the excess credits from winter to pay for the summer usage. You can get a lot more detailed information with SAM.


Normally I see single-phase and 110V and think they're confused because the US the standard is 240V/120V split-phase. Countries that run single-phase usually have higher voltages (e.g., 220 to 240V).

But, according to this, you really are 110V. The UK is typically single-phase, but 230V; and BVI is also listed as 110V. So, no clue about that or if you need special gear to be grid-tied. For example, the SolarEdge datasheets I looked at didn't have a 110V output (they were split-phase with 240V).


SolarEdge optimizers are DC, no phase worries there.


Looks like the P485 can. 125V max and up to 485Watts.



This might help if you go a traditional MPPT approach:
Thanks for the help!!!!
 
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