My DIY 7.9 kW Enphase System

[Ampster]

We recently purchased a new home in Kenwood CA and the first priority was putting solar on the roof. My house faces Southeast with ocassional shading from some trees and a chimney. I was fortunate to find a local resource that connected me to someone who would draw a set of plans to submit to Sonoma County. We settled on a 7.9 kW system since that was the maximum we could fit on that face of the roof. I found a reasonable price on Mission 345 Watt panels from EcoDirect. Conveniently they had a supplier with a nearby warehouse. The balance of the system I purchased from CED Greentech. We used IronRidge SR1000 rails and their standoffs.
My permit from Sonoma County includes a new main service panel and two subpanels. One of those subpanels will become my essenial loads panel when I reinstall the Outback Skybox I removed from our prior home. The main service panel is a 100 Amp Zinsco panel that is a known fire hazard. Initially I had planned on a new 200 Amp service panel but susequently decided a like for like replacement would be more expedient after consulting my electrician. A like for like replacement allows me to use a 125 Amp service panel in the same location as the original Zinsco. A rule from PG&E would have required me to locate an upgraded panel 36 inches away from an existing natural gas riser. That would have required a new service drop and possibly a transformer upgrade. Those were expenses and delay causing contingencies which I wanted to avoid.
The panel installation was completed yesterday and I am still waiting for PG&E to pick a date for my electician to do the service panel swap out. I have already wired the two subpanels.

 

[Choco]

Looks nice... except the cable between arrays, why not put it through the roof space?

 

[Ampster]

why not put it through the roof space?

I looked at that option and did not want two more roof penetrations.

 

[solardad]

@Ampster nice install. I see space for one more row of panels on the left.. ;-) Do you have your battery bank reinstalled already?

 

[svetz]

Nice! Say, how are you going to hook the Skybox and the Enphase together?

 

[Ampster]

@Ampster nice install. I see space for one more row of panels on the left.. ;-) Do you have your battery bank reinstalled already?

Yes. My roof faces SouthEast and I am going to put more panels on a SouthWest pitch when I install my battery. This phase is for the GridTie with PG&E.

how are you going to hook the Skybox and the Enphase together?

I am going to AC couple them. The inverter capacity of the Enphase system is 6.6 kW which is near the max for AC coupling with a Skybox. If that is an issue I will only AC couple one string. I will have enough DC coupled solar in Phase Two to power the home and charge the batteries during the day.

 

[Ampster]

The main service panel is a 100 Amp Zinsco panel that is a known fire hazard. Initially I had planned on a new 200 Amp service panel but susequently decided a like for like replacement would be more expedient after consulting my electrician.

I just heard from my electrician that PG&E is not okay with a 125 Amp "like for like" replacement of my 100 Amp Zinsco service Panel. That means we are back to moving the location of the new service panel 36 inches away from a gas riser. That does make the coordination easier because we can set the new service panel and presumably get it inspected without disrupting service or waiting for PG&E to swing the service drop to the new weather head. The downside is that 200 Amp service may trigger the need for a new transformer. If that is the case I plan on derating the panel in the hopes of avoiding the cost of a new transformer. My Phase Two plan is to add my Skybox which I removed from my former residence. The calcs for that addition may require a larger busbar on the service panel so this may give me more flexibility. My plan is to self consume as much solar as I can or store it in my batteries. Even though I also plan on adding two heat pump split units and a heat pump water heater I don't think I will need more than 125-150 capacity.

 

[GXMnow]

This is looking great. I think about all the things I might do different if I was going to start over. Would PG&E have been okay with a 100 amp panel? Or is it any new panel must meet the new code? I can see why they might want the panel further from the gas line though. But if you still run a 100 amp main breaker, you should not need a new transformer to feed your home. Since you will be self producing and consuming your solar power, you should not ever need 100 amps from the utility. I have thought about dropping my main breaker from a 100 to an 80 so I can use a 40 amp back feed breaker instead of just a 20 that I use now. But in reality, the 20 amp is working just fine as long as my A/C is in the main panel, and not in my backup sub panel. I may be adding a mini split heat pump in the backup panel though. I will do a few more current measurements to make sure my loads are all safe. I figure 90% of the time, a small mini split will be enough, so my big Carrier central A/C will only need to run when it is stupid hot out. I may need to add some logic to the system though. If the central A/C is commanded to run, it should shut off the mini split.

 

[Ampster]

Would PG&E have been okay with a 100 amp panel?

I will find out in the next few weeks. My plans called for a 200 Amp panel so I just went for that. If there is any discussion about a transformer upgrade I am going to compare that with the cost of a smaller breaker to effectively derate my service.

 

[newbostonconst]

Nice house and panels are perfect solid black. Why did you choose enphase? The shading? I know the cost is more for enphase compare to a single inverter?

 

[Ampster]

Why did you choose enphase? The shading? I know the cost is more for enphase compare to a single inverter?

I chose Enphase for a couple of reasons, shade being one of them. Currently shade from the chimney is the only shade but some big Elms could pose an ocassional shade issue between pruning. I wanted two AC strings to give me flexibility with the AC cuopling with my Outback Skybox which is the second phase of this project. Two string inverters would not have saved enough to make a difference. The guys I hired to do the roof part of the install were more familiar with Enphase. I self installed the AC circuits from inside the attic to my sub panel..

 

[GXMnow]

For me Enphase was an easy choice for the inverters. Any power you are using when the sun is shining, Enphase is the most efficient and safest system. Adding the battery backup is not the easiest, and the Enphase battery setup is quite expensive. But their microinverters seem to work very well when AC coupled to a good solid battery inverter. I am very happy with how my system is working with the Schneider inverter AC coupled to the Enphase iQ7 micros. I did have a little glitch one my first big real power failure, but Enphase fixed it with a software update. During a power failure now, the system works great. Any extra solar goes into the batteries, and when I need more power, it seamlessly comes from the batteries. No issues at all.

My only real problem is when the grid is up, Schneider does not think it ever needs to charge. This is something that the OutBack SkyBox seems to do much better. Ampster's system with the Outback should be very smooth. In hindsight, I probably should have gone that way also.

After a lot of thought and reflection, I do think I will be adding between 6 and 9 more solar panels with a DC charge controller to provide my battery charge power. When the grid is up, the existing Enphase will just power the house all day when the sun shines, and if it over produces, the extra will be sold to So Cal Edison. The DC panels will spend all day charging the batteries at very high efficiency, better than I can with AC coupling. When the sun goes down to where the Enphase is not able to keep up, the battery inverter will seamlessly step in and provide all the power the house needs until the battery drops to about 60% charge. I will have to watch the data and see how much I want to use. I may be able to go full 24 hours on all solar if my central A/C is not running flat out. But if I do run down the battery, I will go back to buying the cheap rate grid power until the sun comes up again. If the power fails, the system is still AC coupled, and the Enphase will still power all my backup loads, but any extra power will help charge the batteries. The charge controller and DC panels will also be charging. I will very likely top out my battery bank with the small load in my backup panel. The DC charging will stop without a problem, and the Schneider should frequency shift to curtail the Enphase. I will soon have 36 kilowatt hours of battery online, so I should have no issues running 2 days, even with bad weather and minimal sun.

 

[Ampster]

Good news. I just got an Invoice for $75 for the cost of the new drop to my new service panel from PG&E. Apparently they do not need a new transformer so now I can get on with scheduling the meter changeout to the new sevice panel. That will then allow me to final the building permit and complete the application for Permissikn To Operate.

 

[Hedges]

125A QO panel with 100A main breaker, 50A PV breaker?
40A continuous PV = 9600W
Would that have been like for like?

But $75 to be allowed 225A panel with 200A main, 70A PV breaker ... I'll take that. You can't get anything for $75 these days.

 

[Ampster]

There is a shortage of service panels with local suppliers and I had to pay almost $500 for a 225 Amp panel with a 200 Amp breaker. I will include it in the cost of my PV system for the ITC.

 

[400bird]

Ouch, my main panel kit with an assortment of breakers cost less than half of that just 3 years ago.

PGE even moved my service entrance for free and no charge to go from 100a to 200a!

 

[Ampster]

I haven't updated this thread in a while. I got final inspection from my County on October 5th and submitted the paperwork to PG&E a few days later. Yesterday I got notified that I had Permission To Operate.
Now on to phase 2 of the project which is to install my Outback Skybox, 2kW of DC coupled solar panels and 42kWh of LFP. I have heard it could take a few months for PG&E to get the NEM billing right.

 

[AndyRonLI]

Would love to see a block diagram of all this.
A

 

[Ampster]

Would love to see a block diagram of all this.

I wish I had the skills to do one. I can describe the system to the best of my abilities. I have a 200 Amp service panel serving two 200 Amp subpanels. the subpanels each have 100 Amp breakers. The Enphase micros feed one of those subpanels with two 20 Amp breakers. That subpanel will also be connected to the Outback Skybox.

The Skybox will be fed by a 60 Amp breaker in the main service panel. That subpanel (essential loads) will have the feed breaker (100 Amp) from the main panel and the 60 Amp breaker from the Skybox interlocked so only one source can feed the essential loads panel. The Skybox has an automatic transfer switch and the only purpose of the interlock is to have the ability to take the Skybox offline or reboot it while allowing the essential loads panel to be powered while the Skybox is offline.

The Skybox will be run in self consumption mode which will allow me to reduce or eliminate any consumption during peak times and allow solar production to be credited at peak rates. I am on NEM 2.0 with PG&E in California.

 

[SolarPrep]

Ampster:

Nice set up! Would you mind sharing your impressions of the Skybox? Have you experienced any difficulties with it? Impression of quality? Any details would be appreciated.

Thanks!