Diagram for solar project on home

[bfaubion]

Hi all.. I originally posted this in a different forum, maybe it was the wrong one (couldn't figure out how to delete that post) anyways, I've been digging around, looking at what it takes to setup a solar/battery system in my home. I'm In northeast San Diego county, on a 200 amp main panel breaker. It all started with one of those PPA Sunrun guys and their sales pitch...you know the ones! I thought, how in the world is a solar system on this home going to be worth over 40k?! I did get a few quotes from other local installers, anywhere from mid upper 20K (Tesla) to mid 30K. Anyways, I've just been trying to inform myself and see what it's going to take if I don't go through an installer and work with an electrician instead, while doing some of the work myself.

Incentives include 30% federal, California SGIP $0.15 per watt on battery, and the Rewiring America 50% of electrical rewiring and panel work. After those incentives, I've got the tally of the solar panels, inverter (1 6000xp), and battery(EG4 PowerPro), down to about $3,000. That doesn't include the other misc. parts, and of course the cost of help with an electrician. FYI, I can dig and fill the posts for the ground-mount panel brackets, and then run the pvc for the solar panel wiring myself. I'm just not going to mess with severing my main service line near the sub-panel to install the solar components. I wanted to get some advice from people here on the forums.. curious if this diagram makes sense, and what else I should be planning for. Or, if I need to totally reconsider what I'm doing here.

 

[OffGridForGood]

best to start with an audit of the loads, your monthly electrical bill will tell you totals per month, and all the bills for a year will tell you how your loads change with the seasons. There are spreadsheets in the resources section of the forum to help with this.
next plug your area and panel info into PVWATTS to see what you can generally expect from 8 panels in your area.
Reconsider things like your oven running on one 6kW output inverter - for each load you need to know its' running and start up power requirements, ie motors draw a lot more power to start than to run. Even a fridge can have a surprising start up load.
A killowatt P3 meter (look it up) can tell you what a cycling load actually draws per day - ie fridge freezer window A/C unit. very handy.
for start up loads, a meter with an in-rush capture is the best (these tend to be expensive though) or find someone with a meter and get some data.
Most important - read over the resources and similar builds in the forum to see what you can run with what equipment.
I found a modular approach worked well for us, and spread out the work and the cost over a few years, allowed us to do it all ourselves.

 

[chrisski]

I think I understand the diagram now. The subpanel only runs a portion of your loads, and the others are not listed.

Looking at the diagram, any two loads you have could exceed your 6 kW inverter, and only one may be less than 6 kW.

I estimate a 5 ton will run at 5 kW, but that is highly dependent on the SEER rating. My 220 V oven is on a 50 amp circuit, which 50 amps exceeds what a 6 kW inverter will provide, but perhaps runs at less wattage. Also, my Tesla car charger can run at 48 amps, 11 kW, full out.

I had a similar decision and for a critical loads panel I run battery power every day,

how in the world is a solar system on this home going to be worth over 40k?!

Without a decent Net Metering plan, this will be very hard. POCOs have been dealing with solar for over. Decade and know how to get their money back.

Over the last 10 years, our utility has added many additional charges that now account for over half the bill five months of the year. This seems to make up for their losses on solar, and at selling excess back at $.075 per kWh and no kWh credit into the bank, makes payback periods very long.

Also, I have a 4 ton and a 5 ton AC and from 4pm -7pm this year one will be ruin off battery, but the other will be run at an electric rate 3 X what my non solar rate was. Without solar, I was paying a fixed rate all day at around $.13 per KwH, and with solar got changed to a rate a couple cents an hour less except for peak hours where the rate is $.33 per hour.

 

[OffGridForGood]

A system needs to be realistic, things like an EV charger may work for a dump load when the batteries are full and excess solar is available, but will be unlikely to charge an EV and run a home on 3.2 kW of solar panels, even in a good solar area.

Lets see what PVWatts shows us for your locale:
plugging in Fallbrook CA, 3.2kW PV set 33 degrees from horizontal and due South we see: 380-500kWh per month potential something like 12-16kWh per day on average, depending on the season.

This would run some typical house loads fine - like your fridge and freezer (critical loads) lights and some typical things like computer/electronics.
Unlikely to run any A/C or not very long, and as I noted above, the EV as a dump load would work on sunny days but not for daily commute likely (we need about 18kWh/day avg for a Kona EV).
You need to choose either a net-zero export type of set up (solar puts what it can into your panel, but limits to ensure no export to grid) if this can be permitted in your area; or set up the CLP (critical loads panel) like your diagram with fridge, freezer, alarm system, stuff that you don't ever want off-line, and plan for some items that you toggle on CLP or Grid depending on season/sunny days.
You can plan for future PV expansion to increase the average incoming energy and add things to your solar side.

 

[bfaubion]

@OffGridForGood @chrisski thanks for the replies! I'll look at that kilowatt meter. And this will be a net-zero export. SDGE has such low compensation for energy, so I don't want to send it back to them, plus I won't have the hassle of permits If I don't have a fully interactive on-grid system.

A few notes on my system.

• I use about 8 - 10 kWh per day in my home when not using heating or cooling. If I use the gas heating or central cooling, then about twice as much energy is used. However, I don't use either of those very often, as I live in a somewhat mild climate.
• My appliances are:
  • Fridge 6 amps,
  • Gas Dryer 6 amps,
  • Washer 6-10 amps,
  • Gas water heater 0
  • Dishwasher: 12 amps
  • Oven range fan (not sure).
  • 220 Oven as stated on a 50 amp circuit breaker, not exactly sure what it uses.
  • Also tools are a 120v welder for occasional hobby projects, sometimes an angle grinder too.
  • Other usage of energy throughout the home - charging phones and several laptops, occasional TV usage, that's it.
  • Lighting is all LED.
• PVWATTS - 3.2 kWh system (8 x 400 watt panels) is 5,400 kWh a year (so 15 kWh produced per day with that solar setup)
• No electrical vehicle yet, but would like to plan for one - maybe a Hyundai Tucson PHEV - I can charge it with 120v at 12 amps.

Based on that data, that's why I'm looking at not planning to have the heating/cooling on solar, and just use grid for it. And same for the 220 oven. If I put the oven and HVAC on grid, then I'm thinking I could get by with one 6000XP if I don't have the electric vehicle?

If so, I wonder what two 6000XPs would get me, and at what point would I max out that second 6000XP?

 

[MisterSandals]

plus I won't have the hassle of permits If I don't have a fully interactive on-grid system.

Unless you are doing this COMPLETELY on the sly, you'll need permits, utility sign off and UL approved hardware.

 

[bfaubion]

If it’s required that I still have a permit for not grid tied system, then I’ll definitely get a permit. I know at least for solar ground mount under 5 feet no building permit is required for us. Fortunately it is an instant permit process now for system specs within my range. I’ll have to dig around and see what the specifics are for systems that don’t send energy back to the grid.. they don’t seem indicate if there is a difference there.

 

[chrisski]

Unless you are doing this COMPLETELY on the sly, you'll need permits, utility sign off and UL approved hardware.

My AOH does things slightly different, as each AOH can do.Plans approved and needs permit might be the same step. Commissioning is the turn on, programming and adjusting after utility approval.

Plans Approved by the city with UL Equipment—>need permits—>Build—>Fire Inspection—>City Inspection—> utility sign off —>Comissioning

If San Diego is easier than Arizona for the permitting and inspection, I’d be surprised.

 

[bfaubion]

@chrisski @MisterSandals @OffGridForGood I think I'm going to go with the 18Kpv.

1. A big benefit is that I can run the whole house through a single unit, and take advantage of my HVAC unit on solar, which is where the outrageous electricity bill comes from. Also this will facilitate EV charging in the future
2. I can designate a single point between my meter and the sub-panel that will be severed and then reconnected with the manual transfer switch and the 18Kpv.
3. I don't have to rewire the existing sup-panel and separate them for critical loads as I would with the 6000XP.
4. The 18KPV is approved from the California energy commission
5. Even though the buy-back rates are so paltry, there may be a few times a year like late summer where rates seem to be a bit higher, and I can at least take advantage of that if I want to.

 

[MisterSandals]

The 18KPV is approved from the California energy commission

I don’t know what this means but you should ask in a specifically title thread, what others in this state have experienced.

Your reasoning on all points seems sound. Leaving room to progress to next step of self consumption with a battery bank would be wise as the state is prodding solar in that direction.

 

[bfaubion]

@MisterSandals Just means that POCOs are authorized to permit them. I would consider two 6000XPs, but they do not have that certification, although I might just ask and confirm (again, no need to sell back energy to utility)

• Likely going with the 1 EG4 PowerPro battery, or 3 of the EG4 rack batteries.
• Also about the actual installation, the one other rather expensive part is hiring an electrician to install and wire up the ATS or MTS and feeder tap. I guess I need an ATS/MTS, or maybe that's just recommended, not sure. That unit itself is around $500 - $600.
• I don't mind doing the work for PVC wiring and actually installing the inverter on the wall as well as the battery, and then installing the ground mount solar units, panels, and pvc/wiring for them.

I've included the 18Kpv diagram here, as well as a picture of my existing meter box. Thanks everyone for your advice so far, the forums have been a great place to get feedback and read what others are doing.

 

[bfaubion]

18Kpv is looking like the best choice.. thought I'd ask here about the transfer switch or interlock load panel to add. Instead of going for a 200 amp double throw, I was considering a 200 amp panel, with 2 x 200 amp breakers + a breaker interlock to switch between grid or inverter, that then goes to the whole house sub-panel. The benefit is it's much cheaper, and flexible with more breaker spaces if I need them in the future. I see that most 200 amp panels are quite large, I don't really need all of those spaces.. wondering if there is an option out there to facilitate the 200 amp and breaker interlock, but a bit smaller.. I found this on amazon that seems like it could work. Unless I'm missing something here?

https://www.amazon.com/Siemens-PNW0816B1200TC-8-Space-16-Circuit-Breaker/dp/B08Y59RB2L?source=ps-sl-shoppingads-lpcontext&ref_=fplfs&smid=A2G633VAWDS005&th=1

 

[zanydroid]

Just means that POCOs are authorized to permit them.

It is on the CEC list but EG4 missed a few steps and some forum members got blocked during PG&E review due to missing PCS certification, and it’s clear either the EG4 reps here don’t understand the issue or don’t have access to a runbook of paperwork to give PG&E to clear it. There are complaints about it distributed across a few recent threads (unfortunately not centralized). I am very skeptical how many customers have actually installed on grid in California.

 

[zanydroid]

Instead of going for a 200 amp double throw, I was considering a 200 amp panel, with 2 x 200 amp breakers + a breaker interlock to switch between grid or inverter, that then goes to the whole house sub-panel.

Where are you seeing these 200A branch breakers? I have a Siemens panel and spent a while looking, I don’t think they exist for standard residential Siemens panels.

If they did, it would be the type that spans 4 spaces so it can engage on more bus stabs.

My assumption has been that you would either need to use 400A ranchbus with 2x200 Siemens main breakers plugged onto them (and hopefully there is an interlock available for this breaker combo) or just suck up the 200A DPDT switch

 

[bfaubion]

Where are you seeing these 200A branch breakers? I have a Siemens panel and spent a while looking, I don’t think they exist for standard residential Siemens panels.

If they did, it would be the type that spans 4 spaces so it can engage on more bus stabs.

My assumption has been that you would either need to use 400A ranchbus with 2x200 Siemens main breakers plugged onto them (and hopefully there is an interlock available for this breaker combo) or just suck up the 200A DPDT switch

Ok, I’ll keep a lookout on the certification.. i thought recently they were getting certified here in California. I’m on SDGE, will check with them. If the 18kpv ultimately doesn’t get certification, I’ll just go with two 6000xps.. since no export, no cert required.

About those breakers, ok.. yep I see what you are saying about 2 200 amp breakers.. that’s my lack of electrical knowledge. FYI, I do plan to hire an electrician to disconnect and add breakers along with the 2/0.. so not planning DIY install on that one. So what are the options for a grid interlock with the grid and inverter if it’s a 200 amp service with the 18k?

1. Suck it up with the 200 amp DPDT
   
2. Downgrade service to 100 amps but use that 200 amp sub-panel , not sure its even possible with the 5-ton ac system, although everything else beside 220 oven is gas.
3. Skip DPDT, keep 200 amps and go directly from 18k to the existing 200 amp whole house sub-panel.

 

[zanydroid]

Ok, I’ll keep a lookout on the certification.. i thought recently they were getting certified here in California. I’m on SDGE, will check with them. If the 18kpv ultimately doesn’t get certification, I’ll just go with two 6000xps.. since no export, no cert required.

The review with PG&E was blocked on a storage with export setup. There are extra behavior requirements for that specific to different classes of systems. So one person getting it through might have a different SLD with fewer restrictions. Or got lucky.

The way you express the difference as 6000XP/no export = no cert sounds imprecise or wrong. You can have parallel zero export set up, still subject to lots of rules and checking. Off grid, same (but fewer).

FWIW you still need to pay for interconnection fee and review with any parallel output setup (grid and inverter support load at the same time). The 6000XP is off grid so it will not have both the same time.

Did you get confirmation with your AHJ that 6000xp is fine? AFAIK it does not have 9540 and that is a residential code requirement. I would not buy anything until full permit set is approved and permit is in hand. And I’m not convinced full permit set being approved is enough, if you are in an AHJ where they actually check UL stickers (minority).

And that 5 ton AC (if it’s single stage) would be obvious ok to run on a parallel zero export because the grid will fill in the unsatisfied surge if the inverters are not up to it. But in an off grid setup the inverter has to carry the surge.

About those breakers

100A is probably fine for one big AC. What’s the breaker rating feeding it right now? Have you don’t a load calculation?

Another approach is to require manually reconfiguring some conductors to bypass. For instance you could stick a Polaris or lug block in front of L1/L2/N to the inverter, with a spare port. And move the output onto this when bypassing. It would take 30 min, tools and materials nicely organized, and qualified person to be home.

Also given that the inverter stacks under discussion are 50A-60A output, you can use 100A bypass switch and not degrade the critical loads capability of the inverter (actually you can do 125A with interlocks, those branch breakers are available on some brands). You could add a second 200A panel and feed it directly from the main for future electrical loads. Note that if you want to offset loads on this second panel you will need to pull CT sensors up to the main. And the main will have to be able to fit those sensors. This is a question of how the factory wiring is laid out, many combo meter mains make it hard or impossible to mount sensors. It’s very easy for someone to check for you online with a photo of the panel internals.

Note that you will have to do some 705.12 calculations to verify that the load side connection to the main are OK. 18kpv counts for 60A solar breaker and 120% rule will require derating of the main. Or you may qualify under sum of breakers rule

 

[bfaubion]

I’ll check with SDGE and see what my options are for the 18k. Ideally that’s what I’d want, I have no concerns about it being able to handle everything in the home.

Since the 6000xp is considered off-grid with no export to grid features, I didn’t think it required any inverter certification.. I was having a hard time understanding that aspect since having solar is often assumed to be export capable and not “off-grid” for residential. I don’t want to do anything non code compliant for insurance or safety purposes though.. not worth it for me.

Good to check on all this before pulling the trigger.. thanks for the info. I have some more homework to do. I’ll see if I can get an 18k setup with the 125 breakers and an interlock. That would be ideal.

 

[zanydroid]

Since the 6000xp is considered off-grid with no export to grid features, I didn’t think it required any inverter certification.

It is still electrical equipment and that always needs to be listed. It just is exempt from grid interactive listing.

The ESS part is governed by fire adjacent code in California Residential Code and those risks are independent of being grid connected

 

[zanydroid]

18kpv for parallel zero export is most likely ok. Because EG4 has the paper trail workflow for it. Basically they lock your system’s AC limiter and sign a paper for the POCO.

The authoritative answer comes as part of the interconnection review. Worst case you back out and go off grid or change equipment.

You could consider buying a clamp meter with surge measurement and see what the AC draws when starting.

Couple fine points about the 125A branch approach.

On the bus with multiple outputs (non interlocked) you may be limited to 100A/125A on a 225A busbar panel unless you want to pony up for a 320A. Now I guess since you said you will only ever have one 18kpv this actually will work on 225A with no limit (if you went to more AC output it gets tricky).

For a panel you are manhandling into a cheap 125A interlock you can go to 125/125 no problem since only one output is active.

100A transfer switch is a little more friendly for someone without knowledge to switch. May be a tiny bit cheaper than a subpanel and two 120As but the $100 difference is peanuts in this project.

If you split your house loads feeder load calculations will be trickier down the road, and your AHJ may force you to balance loads between the two panels. If they are next to each other then no big deal.

Anyway the next step is probably for you to come back with another line diagram for your next idea

 

[bfaubion]

@zanydroid After talking with online sales for the 18kpv, I found that the unit has the built in ATS with 200-amp bypass, that will still function even if the inverter is down or dead.. so I may just skip that manual transfer switch, and just opt for a Siemens disconnect switch, although it is not required by poco. I'm satisfied with the unit's ability to still transfer power even if the inverter is down. I've attached another diagram here, it's about as simple as I can make it. The 18K is also approved by PG&E, I think it would be as well from SDG&E. So really, it doesn't make sense for to go with the 6000xps, if I can make this setup more simple anyways.

The thing I'm wondering is if I can go ahead and set up the 18kpv without solar/batter, and just have it run in standby mode until I actually get all the PV/Battery installed and an electrical inspection on it. Otherwise, I can't legally run it if it's generating power.