150 amp sub panel

[AV ELECTRIC]

My son is having a 8kw solar system installed . . He has a manufactured home with a 100 amp sub panel that the solar installers want to use to put there 40 amp breaker in . I thought the panel is to small for this size system but they said they have some sort of controller to prevent overload but I would think this would limit what the solar system would be allowed to produce making this size system not worth paying for . There is one power wall that they said helps .

My thought if possible is upgrading that 100 amp sub panel to 150 amp . There is a 200 amp pedestal where the 100 amp sub is fed from . I think it's a Siemens pedestal and was installed in 2007 ( sorry not much info ) . Now they don't make a 150 breaker for that situation unless maybe a quad which would not work as only 2 spaces are available . The other 2 are used for the well pump house sub panel .

Now is there alternative ? Maybe adding some lugs and do a direct feed to the 150 amp main breaker sub panel . I presume the wire would need to be sized for 200 amp if that could be done . No experience with solar except for putting in breakers for a new system . It seems hokie to put a 8kw system into a 100 amp panel

 

[tortuga]

Presumably the 100A feeder starts at a breaker and ends at a 100A main.
If so simply install a dedicated disconnect for the solar, forget putting a breaker in the panel.
You can intercept the 100A feeder and install a feeder tap box or if there is room just put taps ahead of the main.
See 705.12(A)(2) [2023 NEC]

 

[AV ELECTRIC]

Presumably the 100A feeder starts at a breaker and ends at a 100A main.
If so simply install a dedicated disconnect for the solar, forget putting a breaker in the panel.
You can intercept the 100A feeder and install a feeder tap box or if there is room just put taps ahead of the main.
See 705.12(A)(2) [2023 NEC]

There is a 12 by 12 j box under the modular that the 100 amp feeder goes into . 2 inch PVC from pedestal goes into box . Than a pipe goes out and into the 100 amp sub panel . I don't think it's a problem to run the solar number 8s into that j box with the feeders and head back to the pedestal to install the solar breaker which I believe is a 2ole 40 amp.

 

[jaggedben]

My son is having a 8kw solar system installed . . He has a manufactured home with a 100 amp sub panel that the solar installers want to use to put there 40 amp breaker in . I thought the panel is to small for this size system but they said they have some sort of controller to prevent overload but I would think this would limit what the solar system would be allowed to produce making this size system not worth paying for . There is one power wall that they said helps

This is at least somewhat plausible, since an 8kW solar system won't produce anywhere near 8kW most of the time. But hard to say without a lot more info and an analysis beyond the usual scope of this forum.

My thought if possible is upgrading that 100 amp sub panel to 150 amp . There is a 200 amp pedestal where the 100 amp sub is fed from . I think it's a Siemens pedestal and was installed in 2007 ( sorry not much info ) . Now they don't make a 150 breaker for that situation unless maybe a quad which would not work as only 2 spaces are available . The other 2 are used for the well pump house sub panel .

A 125A panel fed by the same breaker and feeder would (probably) suffice. Or, if the existing load doesn't really need 100A, possibly downsize the existing 100A breaker to 80A (but not allowed if serving a whole dwelling? And load calc required.)

... It seems hokie to put a 8kw system into a 100 amp panel

Not to me. A 100A rating on a panel tells you next to nothing about how much energy passes through it.

 

[AV ELECTRIC]

My son decided to allow to go into the 100 amp sub panel and use a Siemens quad for the solar . Going to a 125 amp sub panel will probably be done at a later date as the existing is full . The company Guarantees the production the system can produce .

Thanks for the responses . They were helpful .

 

[Jpflex]

. It seems hokie to put a 8kw system into a 100 amp panel

if your system is a standard 120/240 volt single phase system then your ampere will only be 8,000 VA / 240 V = 33.33 or 34 amperes but not 100 amperes but other than that if we’re speaking dwelling then 100 amperes is small for todays standards

 

[jaggedben]

if your system is a standard 120/240 volt single phase system then your ampere will only be 8,000 VA / 240 V = 33.33 or 34 amperes but not 100 amperes but other than that if we’re speaking dwelling then 100 amperes is small for todays standards

We don't know if 8kW is the DC rating of the panels or the AC output rating of the inverter. Most likely the inverter has a 32A output so it can be put on a 40A breaker. Solar inverter outputs are considered continuous so circuit conductors and overcurrent devices need to be sized for 125% of output (unless using the rarely used exception).