jaggedben
Senior Member
- Location
- Northern California
- Occupation
- Solar and Energy Storage Installer
Solar Battery and Generator
- Thread starter Another C10
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Another C10
Electrical Contractor 1987 - present
- Location
- Southern Cal
- Occupation
- Electrician NEC 2020
thanks for the input every one, maybe I should just let this one go.
analog8484
Senior Member
- Location
- CA
- Occupation
- Tech
The diagrams definitely look off.
Here is SE's recommendation for ATS/Genset setup with the BUI:
It should be straight forward to add the ATS between the existing backup panel and the meter main panel. If only partial backup by the generator is required then nothing else needs to done.
If whole house backup by the generator is required then the non-solar backup loads need to move to a new panel since it's a meter main panel. Then another ATS (tied to the same generator) needs to be added between the meter main panel and the new panel.
Here is SE's recommendation for ATS/Genset setup with the BUI:
It should be straight forward to add the ATS between the existing backup panel and the meter main panel. If only partial backup by the generator is required then nothing else needs to done.
If whole house backup by the generator is required then the non-solar backup loads need to move to a new panel since it's a meter main panel. Then another ATS (tied to the same generator) needs to be added between the meter main panel and the new panel.
jaggedben
Senior Member
- Location
- Northern California
- Occupation
- Solar and Energy Storage Installer
The problem is the photos don't show the Solaredge Backup Interface which can pass 200A through to the load. They show the older StorEdge inverter that can only pass 40A through (really only 25A, but in this case they did 40A).
So if the customer wants to add any more backup loads that may not really work.
analog8484
Senior Member
- Location
- CA
- Occupation
- Tech
Good point about the photos. I was just going by OP's diagrams that appear to show the BUI.
Looking at StorEdge, I think the solution is still similar:
ATS1 only needs to pass whatever the solar backup loads need (40A?). ATS2 would need to pass more (200A?).
Another C10
Electrical Contractor 1987 - present
- Location
- Southern Cal
- Occupation
- Electrician NEC 2020
I've made an adjustment, not sure if this is feasible but its definitely better than my original idea. this choice may actually work.
Another C10
Electrical Contractor 1987 - present
- Location
- Southern Cal
- Occupation
- Electrician NEC 2020
actually it only looks beneficial during an outage, During normal function I believe the solar would not contribute to the branch circuits with this design. unless engaged by the manual switch therefore eliminating the other 160A of utility potential.
jaggedben
Senior Member
- Location
- Northern California
- Occupation
- Solar and Energy Storage Installer
Still unclear if you are showing a separate backup panel (I see a label but not a drawing) and where the relocated circuits are tied in. But this looks better.
Analog's idea also works, but requires 2 backup panels. ATS1 could be manual.
Personally I think a manual generator start and transfer might be better for this client. But maybe that's not what you're selling, or maybe they bought the house with the solar and just don't care.
jaggedben
Senior Member
- Location
- Northern California
- Occupation
- Solar and Energy Storage Installer
No, during normal function the energy from the solar/battery would go wherever there is load, before going out the meter to the utility. Not to worry.
Another C10
Electrical Contractor 1987 - present
- Location
- Southern Cal
- Occupation
- Electrician NEC 2020
I guess what confuses me with the solar is there are 2 connections to/ and or from the inverter. 1 appears connected through the solar meter landing on a 40A breaker of the meter main, the other to and or from the inverter, going to the branch distribution.
My idea of the Manual transfer switch after the ATS is to assure solar and generated never work in unison.
So if I was to disengage the solar at the branch circuit connected side of the inverter Im am thinking there would be no back feeding, although
the branch circuits would only see the inverters contribution when the manual transfer switch turns off the generated power.
It almost seems the fool proof solution is to have 2 groups of distribution for 2 different backup methods. although not too practical.
My idea of the Manual transfer switch after the ATS is to assure solar and generated never work in unison.
So if I was to disengage the solar at the branch circuit connected side of the inverter Im am thinking there would be no back feeding, although
the branch circuits would only see the inverters contribution when the manual transfer switch turns off the generated power.
It almost seems the fool proof solution is to have 2 groups of distribution for 2 different backup methods. although not too practical.
Another C10
Electrical Contractor 1987 - present
- Location
- Southern Cal
- Occupation
- Electrician NEC 2020
1 back up panel which would be the 200A rated manual transfer, the original meter main will have no branch circuits connected to its distribution fins other than the initial 200A supply to the automatic transfer switch and the 40A connected to the solar inverter .
Another C10
Electrical Contractor 1987 - present
- Location
- Southern Cal
- Occupation
- Electrician NEC 2020
The home owner decided to buy a 110A generac and asked if I could connect it to their main electrical which has an older solar system connected already, installed 6 years ago.
analog8484
Senior Member
- Location
- CA
- Occupation
- Tech
I don't see how solar would be isolated from the genset when it's feeding the meter main via the MTS.
analog8484
Senior Member
- Location
- CA
- Occupation
- Tech
Also, how would it isolate from the grid in the meter main?
Another C10
Electrical Contractor 1987 - present
- Location
- Southern Cal
- Occupation
- Electrician NEC 2020
The Automatic switch would tell the generator to kick in, only until the manual switch is physically engaged would the generated power supply the branch circuits affiliated within the MTS.
At the same time breaking the solar and or battery supply intended for any connected branch circuits from that inverter.
The only solar / inverter connection at that point would be the 40A connection of the downed grid of the meter main, no power from the generator would ever see the downed meter main bussing.
jaggedben
Senior Member
- Location
- Northern California
- Occupation
- Solar and Energy Storage Installer
When the grid is operating, the inverter outputs as much power as it wants (as a current source) and it goes to both connections.
When the grid goes down, the inverter has an internal contactor that disconnects the connection to the main panel. Then it changes modes to a voltage source and outputs as much power as the backup connection draws.
Yes this works as long as the loads on the load side of the manual transfer can't possibly be connected to anything else. Your sketches showing this going back to the main panel had me worried.
If the manual transfer is switched to the generator side, then...
On grid, the inverter will still output to the main panel, and the power will in turn flow to the generator ATS and then to the loads, along with utility power as needed.
Off-grid, only the generator will power the loads.
In other words, it's okay.
Another C10
Electrical Contractor 1987 - present
- Location
- Southern Cal
- Occupation
- Electrician NEC 2020
All branch circuits of the home would be attached to the MTS bussing a 200A / 60A ( if possible ) manual switch breakers will independently energize the bussings within the MTS provided distribution fin method.
jaggedben
Senior Member
- Location
- Northern California
- Occupation
- Solar and Energy Storage Installer
Ok good.
The remaining issue is that you're limited to 40A passing through the inverter, and I think only 5kW continuous on the backup panel off-grid. So if you're planning to move all the large loads off the main panel to the backup panel, this could be a problem in both situations, especially if the customer wants the solar to be the primary backup. Because there's a decent chance that at some point during normal-grid tied operation, they'll draw more than 40A on the backup panel and trip breakers. Or that they'll overpower the inverter when off-grid. So the solar can't really be the primary backup for the whole house, and the client shouldn't leave the manual transfer set to the inverter side during normal times if you're moving all the loads to the backup panel. The other thing I don't like about it is that the generator will still turn on and make noise and waste fuel while not powering anything. (Say the outage occurs when the homeowner is not around and the manual switch is set to solar; generator turns on for no reason.)
If the customer wants the generator to be the primary backup, then it's more okay. Because the solar should still work okay on-grid if you don't mess with the Solaredge meter CTs. And if the customer wants to switch to the solar/battery and turn off the generator, they can manually turn off the large loads when they do that. They are just not taking advantage of the battery they have unless they do that.
Another C10
Electrical Contractor 1987 - present
- Location
- Southern Cal
- Occupation
- Electrician NEC 2020
I'm sure glad there are well experienced people within this forum to give me a considerate heads up on this curious installation design.
I think now I can provide this drawing for a city plan check and re adjust the estimate to the customer.
Thank you.
Sincerely, Mark
Another C10
Electrical Contractor 1987 - present
- Location
- Southern Cal
- Occupation
- Electrician NEC 2020
This seems to be the customers vision, they got the generator because the solar system wasn't strong enough or would last long enough during the occasional 2-3 day outage based on high winds,
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