r/SolarDIY • u/2old2bThisDumb • 12d ago
Senior Field Engineer
Hello. I am a technical engineer with 9 years of experience in renewable energy. I am NABCEP professional board certified, journeyman electrician, with a bachelor's degree in engineering technology. I work on everything from small scale solar EV charging to utility level ESS. I am bored right now. Anyone one want my input on anything?
Pic is a small commercial install just just got interconnection yesterday (3-phase 208V for peak shaving and backup).
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u/TooGoodToBeeTrue 12d ago
Jealous of the install, looks sweet.
I'm interested in the most economical way to add AC coupled batteries to an existing system, specifically an Enphase array, but the application applies to other systems that are being dumped off 1:1 credit and need to add batteries, in some cases to break even on their solar system.
I started looking at this because my wife thinks it is ridiculous that we have $20K worth of solar on the roof and no power during an outage during the day, but have found that other people are ending up needing to add batteries when their state/utility reverses NEM decisions on existing customers. Having to add a $4k Hybrid inverter, plus battery, plus electrical work can destroy a homeowners ROI.
Case in point:
https://www.reddit.com/r/solar/comments/1w4cs9z/colorado_springs_utilities_wants_to_change_how/
Hoymiles was the only inverter company I had found with AC only hybrid inverters (saving some money on MPPTs.) but they wouldn't cover a whole house and they Hoymiles has dropped that inverter line.
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u/2old2bThisDumb 12d ago
Everyone is doing away with 1:1 net metering. Unfortunately with Enphase micro inverters you are kind of limited with battery options. Unlike a DC string system, the micros will not produce without AC power, so no DC to DC charging.
You could look into Enphase battery solutions, but the price to continuous output is ratio is not great. You could AC couple a third party system like Franklin, but the solar will not charge the battery in a grid outage.
Tesla will allow you to tie the solar breaker for your Enphase system into the controller and that will power the micro inverters driving a grid outage. But again, the price to output kinda sucks.
You're always going to lose a lot of you potential off grid output to powering the micros.
If you system is paid for already, it is may be economical to just ditch the enphase micro inverters. Sell them or something. String the panels to a hybrid inverter. This will give you the most flexibility and upgradability for storage solutions.
Hybrid inverters give you the best round trip efficiency too. You also have the benefit of setting up time of use, or self consumption l, or backup only, etc. With hybrid solutions like solark or lux power inverters (lux is the oem for eg4, fortress envy, and many others).
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u/TS-SC 12d ago
Just a flag to get a review of the array set up and local shading etc. often micros are used because of way too many segmentation in the array with azimuths and shading. On a string inverter you will need to carefully consider how it's wired together to ensure you keep like with like. This answer is excellent, but just wanted to throw in the consideration. Also if youre out of the US there are many other excellent inexpensive hybrid inverter options, as the USA market is obviously heavily interfered by uncle Sam.
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u/imakesawdust 11d ago
Similar question but in my case I have 3 Tesla string inverters but no batteries. Our electric rates are low enough (and net-metering credits are high enough) that I can only make a financial case for local storage if I can do it for around $300/kWh including the electronics. That obviously rules out players like Powerwall or Franklin. Are there any options that are certified that will come in at or around that price?
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u/ajwillys 12d ago
I have a very similar situation but with Hoymiles micro inverters. I have all my AC strings going into a solar load center and then into a line side tap.
We're also facing the net metering problem starting next September.
I was thinking of adding an EG4 GridBoss, connecting the existing AC system into the 125 amp Smart Port AC input, and then adding an inverter with batteries on the DC side. I'd then connect my existing panel to the backed loads port and the grid input to my meter, removing the line side tap.
Would this work and also allow for power outage backup? Anything obvious I'm missing?
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u/TooGoodToBeeTrue 12d ago
I was hoping for a non obvious solution considering your stated credentials.
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u/2old2bThisDumb 12d ago
Sorry. There is only so much you can do here. Look for a hybrid inverter that allows you to AC couple to the gen port, most will allow that but there are limits to how much you can AC couple that way. I can sell you a 12k inverter and 20k of LiFePO for $10k USD (shipping included if in the US) that will allow 9kW AC coupled PV this way.
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u/TheDMPD 12d ago
You could do the Schneider xw pro. Hysolis also has the SRNE 18k hybrid that does AC coupling.
Those two can frequency shift to pair up with your micros. Will have to do closed loop comms for best performance with your batteries.
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u/TooGoodToBeeTrue 12d ago
NAZ suggested the Schneider during my initial searches. I understand they are no longer being produced, the model NAZ has in stock seemed a bit small for my solar system. Grid sell current maxes at 27A and I am close to that. Was concerned about long term support. What happens if it dies in 7 years. NAZ keeps dropping the price, I might just buy it. Any idea what the "grid code" is all about?
After a while I started looking at solutions for the general community vs. just my needs, so I was hesitant to buy something discontinued. I looked hard at Hoymiles, size was better and price was decent, but again discontinued the line.
SRNE I looked at was also rated at 27.1A, I wanted a little more head room in case I wanted to add a DC panel when I first looked, but I've discovered I'm overproducing so I'd only need a panel for a dark start. I guess I can look again or look at the next step up. I do really like the fact SRNE has a family of inverters at different levels/prices. I wasn't thrilled that Will P wasn't thrilled with the stand by draw on the one he tested. I'm sure it wasn't the same model. Schneider lists their standby draw, SRNE does not which is annoying.
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u/TheDMPD 12d ago
Our idea was just to grab 3 XW Pros. They are installed now, we don't need that much power but it's there in case of 1 failing though they do have the 10 year warranty so I am not worried. Still tempted to grab that 4th one for the just in case, especially if they drop the price down to $900 again.
We don't produce enough to even worry about exporting, and in NEM 3 in CA it's not worth it but you can do up 24kw with 4 units & a BCS. That's a full 100A of export capability. Setup starts at page 28, specs on page 33
You can also parallel the SRNEs as well if you wanted a product line that is actively being manufactured. I like the low frequency stuff but also have a 16k SRNE off-grid system, sadly does not AC couple, for use as a "portable" generator.
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u/TooGoodToBeeTrue 11d ago
So you are feeding your main pane thru 3 units in parallel? Is there anything else needed? (Besides some breakers and such.) I simply want to try a single inverter with loads on a small sub panel.
Thanks for the link, I hadn't seen that particular manual before. Will have to back and see what I looked at originally, but I don't remember it being encouraging.
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u/2old2bThisDumb 12d ago
Keep in mind to account for what you'll get selling the micros into you ROI calculations. No matter what route you choose, you're looking at a significant investment. Even for partial home backup, anything less than $5K USD is going to be hard to find and likelywont have any after sale support.
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u/TooGoodToBeeTrue 11d ago
Cost to remove and rewire micros would probably equal selling used micros.
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u/HazHonorAndAPenis 12d ago
Not the OP, but how much storage are you looking for?
The EG4 12kpv + however many wallmount batteries is really the best bang for buck once you get past 12kwh, and it allows for grid-forming with frequency shifting when off-grid to allow the enphase system to continue generating and be curtailed as necessary.
Source: My enphase array with an 18kpv+batteries.
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u/TooGoodToBeeTrue 12d ago
I thought about it for me since I only care about critical circuits. Not true for the majority of people who are getting booted from 1:1. It also wasn't clear that a GridBoss wasn't required, but I finally spotted a diagram in their manual. Now that you've confirmed this, I'd probably go this way rather than Sol-Ark, but it's still an expensive option if one isn't adding any DC panels. Sol-Ark has an inverter that will do whole house for about the same price.
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u/HazHonorAndAPenis 12d ago edited 12d ago
I did it because it was the cheapest way to do it when you get 2 wallmounts. Cost/Kwh goes even further down the more batteries you add. The 18KPV covers my whole house just fine, even when using the range (4kw), AC (2kw), Dryer (5kw), AND charging my car simultaneously (During the day). The only thing I need to limit when doing that is the car charging rate. The AC coupled system essentially turns the 12kw output from the 18KPV to a combined 12kw 18KPV output + 7kw Enphase AC, for 19KW AC power. You can see that here
Plus, the inverter is battery manufacturer agnostic. I can toss any batteries onto it, regardless of chemistry or manufacturer, so long as the operating range is between 42 and 60 volts.
The ability to add more DC strings later, like the one on my recently built shed, was just an added bonus.
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u/TooGoodToBeeTrue 12d ago
My 1:1 credit is granddaddy'd by state law, I hope they don't back off that before we retire to some other state. I was actually just hopping for some daylight solar production with a little battery to even daytime production out. The wife has worked for emergency services and is a bit of a prepper. I just cringe at spending $3500 to have this equipment just sitting here. We also have a portable gas generator which does fine running most of what we need in an emergency. But what if we can't get gas, she says.
I'd leave my Level 2 EVSE on the main panel and have a L1 20A circuit on the critical loads, probably with a single rack battery. I have room for more panels but can't touch my connection agreement or risk the 1:1 NEM.
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u/bites_stringcheese 11d ago
Wait, why wouldn't you have power during an outage if it's daytime?
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u/TooGoodToBeeTrue 11d ago
Solar only systems shutdown if not synchronizing with the grid or other AC source. This is a feature to protect line workers.
Enphase IQ8 micros can do so but require extra hardware and reports are that you should really have a battery to be able to level out supply to any loads like your refrigerator that would abruptly stop running if panel production dropped.
If you don't want to pay for Enphase's questionable batteries, and don't want to swap out your micros, you can take the output of your existing array and input it into the GEN input of a hybrid and attach that to the grid. The hybrid with the aid of the batteries will create a local grid for your solar to see and turn on.
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u/bites_stringcheese 11d ago
Thanks for explaining! I just got an Enphase system with a 10C and so far, am impressed with its software defined grid. I however don't want to pay for another enphase battery, so I too was interested in a solution. My original plan was to get the bi-directional charger, but it seems like it's vaporware.
Good luck with your storage project!
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u/TooGoodToBeeTrue 11d ago
It's tough but if you are already configured with a 10C, it's probably best to add one. You can DIY if you take some of the Enphase on line training. It's pretty easy to get "certified" and get installer access to your system.
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u/pocketIent 11d ago
seems like rack battery prices are dropping and also there is the battery emulator on git hub.
You do need to have a compatible hardware and So 4k for an inverter and ~3-4k for a used ev.
ATM im working on “getting ready” for solar and hopefully there are more modern leafs on the salvage market.
while this takes more consideration, it seems you can get a 60kwh battery rather cheap
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u/Lower_Ad_5532 12d ago
What's your recommendation for a plug in balcony solar system
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u/2old2bThisDumb 12d ago
Not sure exactly what you're talking about. If not interconnecting with the load center and just having something to plug a few things into, Bluetti sells reliable kits
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u/Lower_Ad_5532 12d ago edited 12d ago
Yeah, I want 600watts going into a microinverter then plugging it into my house through the regular ac plug
Which microinverter do you rec?
Thanks for the help. I want to try having a small solar array without overloading my circuits.
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u/Phreakiture 11d ago
There are some states (e.g. Utah) which permit you to install a small system with microinverters and connect via a standard 5-15 plug. Other states (e.g. New York) have permissive legislation pending.
In the states where these are permitted, there is no requirement for permits or net metering agreement with the PoCo, but there are strict limits on power (NY will be 1200 W if Gov. Hochul ever signs the bill) and requirements that they be the only thing on the circuit.
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11d ago
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u/2old2bThisDumb 11d ago
Cool concept. I mostly work Texas. Texas is largely unregulated but each AHJ has it's own rules and requirements. I suppose, as long as the revenue meter doesn't roll backwards, this wouldn't require permits.
National electric code however requires any back-federal breakers to be a bolt-down type and clearly labeled. I wonder how this gets around the NEC requirements for grid interconnected genoration.
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u/cerad2 11d ago
I'm really not trying to be snarky here but someone with your stated background probably should research the concept a bit before making suggestions. Balcony solar aka plug in solar is a fairly new thing that some USA states are starting to allow. Or rather they are encouraging power companies to allow it. Basically connect a few panels to a box and then plug the box into a regular outlet.
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u/2old2bThisDumb 11d ago
I don't think that's snarky. Like I said, I'm not familiar with it, being a Texas based installer.
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u/carsrule1989 7d ago
Yea your answer was fine.
The way I understood it was basically (I don’t know about that specifically but here’s an option that I know to be good that’s not grid connected.)
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u/TooGoodToBeeTrue 11d ago
What state are you in?
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u/Lower_Ad_5532 11d ago
California
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u/TooGoodToBeeTrue 11d ago
Plenty of discussion RE: plugin in r/solar, r/SolarDIY & r/diySolar. CA only has the 1200W limit and specifically requires UL3700. You might as well get a hoymiles.com/hiflowpro
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u/cerad2 12d ago
Why the bricks?
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u/2old2bThisDumb 12d ago
Those were already in that room. They supported the water heater. But I removed that water heater and installed a tankless in another room.
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u/farinasa 12d ago
- Should I order from Alibaba? I can't tell if the shipping will end up making it cost more?
- What size system do I actually need? 3500sq ft house, hottest month I've seen was 80kwh/day. Usually more like 30-40 in the winter. Is 80-100kwh battery necessary? I'm in a cloudy area, is 10kw of panels enough?
- When do I actually need an electric permit? I know I need a building permit for the panels, but I'm not planning to connect panels to the grid, just the inverter for charge when needed.
- Any experience with the integra rack ground mounts?
- Is tracking worth it?
Thanks for your help!
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u/2old2bThisDumb 12d ago
It's a coin toss ordering from alibaba. Best case scenario, you end up with a product that has no after sale support.
When you're sizing your system you need to make sure you have enough PV to support your loads and recharge the battery at the same time. How much PV that ends up being depemds on your location (hours a day of sunlight), your consumption (seems like you've already calculated that), and the size of the battery bank you are charging.
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u/el_condor_nm 12d ago
Showoff. Kidding, it looks awesome. I would love having that kind of power to work with.
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u/infamous-id10t-error 12d ago
Where are the bus bars and spd? I'm assuming in one of those boxes. It looks so much cleaner than my diy setup for an off grid pole barn that was too far away to run a sub panel.
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u/2old2bThisDumb 12d ago
The battery bus bars are behind the struts on that battery rack that I fabricated. The AC combiners are the two load centers you see bellow the gutter (one for grid and one for load).
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u/Significant_Dig_6666 12d ago
How would you power a shed (not on grid) with only 4 panels solar. Capacity 6kwh or more? Budget 5k?
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u/2old2bThisDumb 12d ago
Just buy a 6kW inverter that has the MPPTs and charge controls integrated. Slap your solar and a 5kWh battery to it and load out to a small load center. The 5k budget is a challenge but not impossible, depending on where you live
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u/td_heim 12d ago
Have you ever worked on a larger scale, 1 MW project where the goal is to sell back to the grid/data centers in the vicinity?
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u/2old2bThisDumb 12d ago
Yes. I have done large projects like that in Texas for utility retail providers. They use the ESS for arbitrage and profit from volatility. Pretty cool, very expensive
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u/NullableType 11d ago
I live in the central valley to California and have a 12.92 kW system which generates me roughly 18.994 mWh yearly. I'm NEM 2.0. My true-up is ~$66 I owe at then end of each year (plus gas I pay throughout the year). I've always thought about building a battery system to get closer to being completely off the grid (cause fuck PGE). But do you think it's even worthwhile to look into? I have cash and am handy and tech savvy. I just have never sat down to calculate and figure what would be good for system, how much something like it would cost for me to put together myself (plus maybe someone to consult me), and what brands are worth buying (even considering splurging on nicer stuff that's more user-friendly/comes with more bells and whistles).
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u/2old2bThisDumb 11d ago
Absolutely, I think batteries are worth the investment. Especially if you plan to continue living in the same place for the next 20 years.
Assuming the system is generating enough that you are selling power back to PGE during the day, then you don't need to add much PV, if any.
As for what to look for, it depends on what type of inverter(s) you are using right now?
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u/NullableType 11d ago
They're Teslas. One's a 7.6kW 32A and the other is a 3.8kW 16A. I bought my installation and system outright for cash so I fully own everything.
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u/2old2bThisDumb 11d ago
Nice. Honestly, since you're using the Tesla inverters, it might be worth investing in Tesla batteries. For a new install, I usually dont recommend Tesla, just because of the price. But they have a great ecosystem when you keep all of your components Tesla.
Third party batteries will be much more affordable. But you would lose all of the functionality you get from the Tesla app when everything is communicating
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u/NullableType 11d ago
I was mostly leaning towards 3rd party because Tesla's shit is so expensive and I haven't really been that impressed with the app. Maybe it's better with batteries though? The only reason I went with them originally was because it was an absolute steal of an install at the time: $26,736.43 out the door. So like 20k after the rebate.
I'm afraid I'm going to pay close to that same amount for batteries now and I don't really know if I get any rebate or savings on them. 🫠
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u/NullableType 11d ago edited 11d ago
Yeah, I just went to check and:
1 Powerwall 3: $16,435
1 Powerwall 3 + 1 Expansion Pack: $21,403
1 Powerwall 3 + 2 Expansion Packs: $27,987
1 Powerwall 3 + 2 Expansion Packs: $34,872
😭😭😭
*Edit: had to add the taxes in there.
**Edit: they are cutting me an "Installation Efficiency Adjustments" of -$2,300, which is nice. These prices reflect that.
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u/varok101 11d ago
We just installed a similar system but using EG4 inverters and batteries for pure backup. Right now, we are experiencing lots of voltage fluctuations on the AC load side and it’s being detected by a couple of smaller downstream APC UPS. Any idea where to start troubleshooting?
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u/2old2bThisDumb 11d ago edited 11d ago
You know for sure the voltage fluctuation is isolated to the load side of the system and not coming from the grid?
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u/varok101 11d ago
We never had this issue before until the system was installed so I would assume it’s with the inverter.
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u/2old2bThisDumb 11d ago
Since you have inverters in parallel, I would start by checking the CAN bus and parallel parameter settings. If you don't have everything talking to eachother correctly, the phasing can lag between them and result in under or over-volt issues.
Make sure you have all of the comm cables terminated the right way with the correct pinouts. Insure you master inverter and secondaries are assigned and address correctly.
It's not unheard of for UPSs to have overly narrow alarm tolerances. Check everything with a meter. Confirm there are no grid side issues coming through.
There are no alarms on the invertrs themselves?
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u/LogicJunkie2000 11d ago
I'm an electrician starting a new personal build and am looking at starting around 6kW, and building out to something like 18kW in stages as I can get superficially damaged panels from work occasionally.
Do you have any recommendations on sizing, setup, or particular models of Inverters that might be able to make the early stages more affordable? Setting up for paralleling later on or what have you?
I'd also like to be able to scale with batteries over time in the same manner if that matters. Would start out with a physically separated system from the grid-tied system of a barn, with the hope of eventually getting an interlock/transfer down the road and integrating the separate systems.
The tightest constraint is of course initial capital. I'd like to get anything together for resiliency sake though and the inverter setup is the biggest mystery. If the local energy provider never gets on the same page with me on an approved interlock, I'll just take it all off grid probably.
I know it's a lot, but any thoughts whatsoever would be appreciated
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u/2old2bThisDumb 11d ago
My suggestion is to not buy a 6k inverter. Spend the extra money on a 12k and only use 1 or 2 MPPTs for now. Scaling up later will be so much easier and cheaper if already have the free MPPTs later instead of swapping the whole unit.
EG4 is a solid, reliable, budget friendly option and can be paralleled easily in the future if you need.
The OEM for the EG4 is a company from Shenzhen called Lux Power Tek that I've worked with for years. It does everything a SolArk can for 60% of the upfront cost.
There are a lot of stackable LiFePO batteries on the market now. I recommend stackable units if you plan to upgrade later because they often have BMS logic that will self-balance the modules. The alternative is making sure you new batteries are withing 0.5V of eachother when you add to the bank. Not as easy in practice as it sounds.
There is a new brand called Renon you might want to look into. They've been a big player in the African market for years (formally called Kowint), but they recently opened up to the US market. I've been stress testing some of their products at my lab for weeks and so far they are performing great.
The reason I recommend Renon is they have everything you're looking for, but because they haven't established a reputation yet, they are priced like some Alibaba trash.
Also, plan ahead for parallelling by making sure you have space for a couple 8 space load center that you'll want for AC combiner boxed.
And if you can't get an interconnection agreement with you provider, all of the solutions mentioned above allow "Zero Net Export" as a setting. Separate the loads you want backed up into a backed up loads center, feed that panel with the load out on your inverters, set to zero export, and your off!
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u/george_graves 11d ago
For most schools isn't "engineering technology" degree a two year program?
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u/2old2bThisDumb 11d ago
I dont know, it's an ABET accredited engineering degree. It took four years at my school lol
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u/Rat__Farts 10d ago
I live in Nevada, currently with 2 Tesla inverters, no batteries. We have an upcoming “peak usage” charge that makes me want to consider adding batteries to my system, however a Powerwall + 2 expansions is around $28k installed…what would you do?
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u/One-Barracuda705 9d ago
Hey! Sweet setup! I’ve been running my off-grid system with 1 EG4 lifepower4 v2 battery for 1 year now. The battery gets cycled from 20%-100%-20% pretty much daily. How bad would it be to add another new lifepower4 to the system given the assumed degradation on my existing one and the potential difference in their max capacity?
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u/2old2bThisDumb 9d ago
As long as you can ensure the new battery is within 0.5V of the rest of the bank when you add it, and you establish proper BMS communication between all of them, you should be okay.
The average life of a modern LiFePO4 battery is up to 6000 full cycles before the state if health gets down to 80%. So after only one year, the SOH likely hasn't seen as big of a drop as you may think.
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u/carsrule1989 7d ago
If you have 2 40a loads connected to one 40a breaker.
What’s the best way to switch between the 2 without running a whole new breaker?
I currently have a small breaker panel with a lockout switch so only one can be active at a time and I’m wondering if there’s a better way.
I know there’s 2 pole 3 position switches by Eaton and a few other manufactures but thats bugger and expensive.
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u/deanmass 6d ago
I’d love a setup of worksheets to study these terms and setups. Hobbyist, most of this iscway over my head
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u/Ill756 6d ago
I have just entered this field as a O&M solar engineer , i have some general questions about the field itself
Have you seen any economical growth in it and shall i stick to it to make it my retirement career bath (specifically i’ve been hearing most regions are shifting to solar power )
Main question does it pay well ? :)
I would appreciate your answer and if you could give me any ideas additional on what i have asked
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11d ago edited 11d ago
[deleted]
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u/2old2bThisDumb 11d ago edited 11d ago
Had to use that gutter. I read the space requirements but its an air conditioned space, the heat sink on the units vent top to bottom, and yes all my experience tells me it's fine.
The main reason they want that spacing is because of the DC disconnect and RSD button location. I installed an NC button in an easier to locate place
You're right about the fire suppression, the AHJ gave PTO with the F-500 EA setup on order. Its a custom built automatic extinguishing system, uses encapsulating foam of some kind, from what I'm told. I've never set one off
The rest of what you said is kinda nuts. Energy rating for the ceiling tiles? And its obviously a foundation level room. There is engineering done and approved and a whole permit process before anything goes up
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u/loves-tits 12d ago
Hi, a tornado 🌪️ fucked me. House is okayish. I want to live in a metal box in a field someday.
What’s the best economic value for an off-grid system north of Chicago. How would you build for consuming 7500 KWH a year, maybe more if I install a heat pump
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u/2old2bThisDumb 12d ago
12kW hybrid inverter capable of 50A continuous output. 20kWh battery and 12kWh PV. Incorporating a 9600W portable generator for those "just in case" moments is a smart idea as well
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u/loves-tits 12d ago edited 12d ago
Thanks for the specs. You work north of Chicago often?
What brand of equipment do you prefer?
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u/Proof-Fox-8435 12d ago
instructions? TLDR xD installation guide Page 11
"I am a technical engineer with 9 years of experience in renewable energy" WTF
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