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Optimizers... what are they good for?
- Thread starter nwdiver
- Start date
The combiner box is an extra item that isn't typically required with a string inverter and it doesn't include the gateway. The gateway is another ~$2k. Pretty sure the IQ series doesn't come with cables. I know the M215s didn't. That's extra. The PW 2 was AC coupled but it looks like the PW 3 is essentially a hybrid inverter. It also includes PV inputs.
If the longevity of SE is a real concern then it applies to all solar inverter companies in the US. SE is the biggest solar inverter company in the US after Enphase with similar market share.
Huh? Because one company used bad capacitors every other company should be treated as if they did too, even with a lack of evidence?
My non-profit installer provided an itemized invoice list a decade ago for my M215 system, everything was listed at their (wholesale) cost, as their overhead/profit was charged separately at a flat $/watt rate. The only things needed were the M215 itself at $126.40 per panel (per micro), and the interconnect cable at $18.54 per drop (per micro). A combiner box was not needed, nor a gateway (which I think the IQ8 only need for optional Sunlight backup), neither even existed then on M-series. The rest of the wiring was just four standard wires down to a 30A breaker.
I did opt for the Envoy box for per-panel monitoring, but that was my choice and was $427.50. It has no wiring, just plugs into an outlet and uses PLC for comms, plus Ethernet cable. No CT's back then.
That was 10 years ago, I don't know how it compares to string inverter pricing back then; nor how it compares to a "modern" IQ7/IQ8 system, since none of the parts are compatible. But the micro's were 30% of the total wholesale cost of materials for my install (excluding the Envoy monitoring, since that was optional).
However, I still believe the micro's were the only feasible solution for my shading, as I have separate east, west, and seasonally south tree's rolling across the arrays separately, each over 2-hour intervals. I think this forum would have concluded upfront that I was not a viable candidate for solar, yet I managed a 6.5-year payback period, and am going strong into Year 11 now.
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Enphase also had lots of failures in their earlier model inverters due to bad capacitors.
That was probably true ~5 years ago. But today the vast majority of string inverters have 3 or 4 trackers. So you can have 3 strings facing different directions with different shading at different times and your annual production will be about the ~same. I am a huge proponent of each string on its own tracker.
I believe with the new IQ series if you want monitoring you need the combiner box. But it's probably not required for a single string if you don't want monitoring...
CrazyRabbit
Active Member
This discussion still points back to cost as really the only benefit of strings. From my own install, that was negligible when you add the 26% tax credit (it's 30% now) and my own install with limited panels (~7 kW). I'll monitor the solar reddit and current quotes if I see them, but never found the price that different in a full install when both were options provided (like $1k-$2k).
I suppose without any cost difference, would anyone use strings? Note that 1 dead central inverter and a person will probably be jaded against strings from that point on if they were offline for a month or support took a very long time to replace it (sometimes, 3-6 months). I've certainly seen more string inverter failure complaint posts in general. Old SE inverters were also 10 year warranty. Most solar folks aren't owners with any know how to diagnose or replace the inverter. I do agree putting a new one in the garage is easier than going on one's roof.
I suppose without any cost difference, would anyone use strings? Note that 1 dead central inverter and a person will probably be jaded against strings from that point on if they were offline for a month or support took a very long time to replace it (sometimes, 3-6 months). I've certainly seen more string inverter failure complaint posts in general. Old SE inverters were also 10 year warranty. Most solar folks aren't owners with any know how to diagnose or replace the inverter. I do agree putting a new one in the garage is easier than going on one's roof.
The cost difference is ~$0.30 - $0.40/w. For example the 16.5kW ground mount we did was (36) 460w panels tied to a $1500 11.4kW inverter. $1500. Let's add up all the stuff we would need for micro inverters. (36)IQ8M @ $180ea = $6480; (36) connection cables @ $20ea = $720. Combiner Box $500. $500 + 6480 + 720 = $7700. $7700 - $1500 = $6200 for a difference of $0.37/w. $0.37/w is not a small difference.
AND then there's wire and line loss. This ground mount was a ~200' run. With a string inverter it's ~30A at 380vdc. So 8 runs of #10 ~$400 in wire. With micro inverters you need 48A at 240v. So ~400' of #3 for ~$1000. So that's another ~$600 in wire. PLUS when the string inverter is saturated at ~11.4kW the line losses are zero.
The customer I'm helping has a ~9kW ground mount with micros but no smart panel. He wants batteries. It's going to be cheaper to AC couple his micros to a hybrid inverter. He'll have ~$5k in redundant equipment because his installer didn't want to hire people that knew how to add panel voltages.... his system also isn't online because another corner they cut was understanding which areas require production meters and which ones don't
Another benefit to string inverters is flexibility. We repaired a hail damaged ~12kW ground mount that used M215s. It would have been great to use newer, better panels to increase the capacity a bit but we were locked into what was compatible with the M215s. So we installed refurbished 260w panels when ~340w panels would have easily fit for about the same price.
... AND... system expansion. We've got ~3 expansion projects in the next few weeks taking advantage of some $0.23/w panels. Adding ~12kW to one system. Panel cost is ~$3500. The micros alone would be ~$6k. But since we're just oversizing an existing inverter the cost is $0. Sure... a lot of generation on a sunny day between 11am and 3pm will be lost but there's almost no value to that these days anyway. What you want is to double production in the mornings and evening.
.... sure.... if you wanted to ignore cost every panel would just have it's own embedded AC inverter. But if you're going to go down the road of ignoring cost we'd all just be using nuclear power and not fuss with batteries or solar.
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Who makes that? Doubt that's a tier 1 grid-tied solar inverter vendor in the US. A cost comparison of same tier vendors would be more useful. Also, the Enphase cost includes 25 year warranty. Does the string inverter cost include that?
'Tier 1' applies to solar panels not inverters and it's more an indication of the financial ability of the manufacturer to honor a future warranty claim than the quality of the panel. I don't think there's anyone that would dispute SunPower made some of the best panels but they were not 'tier 1' due to their precarious financial situation. Solar Edge would probably be considered 'Tier 1' but their failure rate is atrocious right now.
It's a GroWatt inverter. It only has a 10 year warranty but is it really worth paying ~5x more for 2.5x more years of warranty?
This is the first GroWatt we've installed since SMA and Fronius have fallen behind. Really impressed so far.
What makes it even more incredible is it's a hybrid inverter. So you can add 20kWh of batteries and recover some of the energy that is clipped due to inverter saturation.
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The cost difference is ~$0.30 - $0.40/w. For example the 16.5kW ground mount we did was (36) 460w panels tied to a $1500 11.4kW inverter. $1500. Let's add up all the stuff we would need for micro inverters. (36)IQ8M @ $180ea = $6480; (36) connection cables @ $20ea = $720. Combiner Box $500. $500 + 6480 + 720 = $7700. $7700 - $1500 = $6200 for a difference of $0.37/w. $0.37/w is not a small difference.
AND then there's wire and line loss. This ground mount was a ~200' run. With a string inverter it's ~30A at 380vdc. So 8 runs of #10 ~$400 in wire. With micro inverters you need 48A at 240v. So ~400' of #3 for ~$1000. So that's another ~$600 in wire. PLUS when the string inverter is saturated at ~11.4kW the line losses are zero.
The customer I'm helping has a ~9kW ground mount with micros but no smart panel. He wants batteries. It's going to be cheaper to AC couple his micros to a hybrid inverter. He'll have ~$5k in redundant equipment because his installer didn't want to hire people that knew how to add panel voltages.... his system also isn't online because another corner they cut was understanding which areas require production meters and which ones don't
Another benefit to string inverters is flexibility. We repaired a hail damaged ~12kW ground mount that used M215s. It would have been great to use newer, better panels to increase the capacity a bit but we were locked into what was compatible with the M215s. So we installed refurbished 260w panels when ~340w panels would have easily fit for about the same price.
... AND... system expansion. We've got ~3 expansion projects in the next few weeks taking advantage of some $0.23/w panels. Adding ~12kW to one system. Panel cost is ~$3500. The micros alone would be ~$6k. But since we're just oversizing an existing inverter the cost is $0. Sure... a lot of generation on a sunny day between 11am and 3pm will be lost but there's almost no value to that these days anyway. What you want is to double production in the mornings and evening.
.... sure.... if you wanted to ignore cost every panel would just have it's own embedded AC inverter. But if you're going to go down the road of ignoring cost we'd all just be using nuclear power and not fuss with batteries or solar.
I'll keep an eye on posts from other people I see on here and the solar reddit, but most end consumers don't care about all the cost you/installer has and just wants the end number of what it costs them. Again, I didn't see $5-$6k less $$ to go string during my install. I got like 15 quotes too.
Maybe string/central inverter sales "pads" an installers profits more so they push it more under the guise of saving people $$ a bit (the installer pockets a bit more).
I assume you do this full time then, but even at the prices you quote, I'm not sold even at the $0.30-$0.40/W more. I paid close to $2.5/W. I'd have no issue with $2.8/W for micros still and that's pre-tax credit.
My system is like half as big as the one you quoted so my costs won't be as much overall, but for people paying $2.50 - $3.00/W, the answer then is $0.30 - $0.40 more worth it for Micros? That's about 10-15% of the cost not even adding ESS. That's also before tax credits.
I still think 1 dead SE/central inverter and no one will sweat the $$, but your cost argument isn't sold on me still.
I'd say it's worth it assuming the company is still in business for 25 year warranties. With tech, there's almost always a reason warranties are what they are. Hard drives are 2-3 years cause they break in 2-3 years often. We see the mess SE was in with all those. We'll see about Growatt, but if it's so reliable, why not just come out and give 25 year warranties? Companies evaluate and test their products and if it's 10 years, they probably expect it to fail at year 11. I don't think that's an unfair comment.
Here's a recent SB SMA complaint:
What would I have gained spending >$6k more for micros?
Finishing a 12kW project this weekend. Micros would have added >$4k to that project. What would ~$4k have bought me?
Another 15 years of warranty coverage? Is that worth $4k?
Slightly increased redundancy to maybe avoid losing ~a month of production? Spend ~$4k to maybe save ~$300?
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I would beg to differ
Not sure it's practical to separate.
Not worth 5x but Enphase vs Growatt is not really a good comparison. One main reason that people pay for Enphase is the support. Owners can easily contact Enphase to get warranty replacement. Can you do that with Growatt?
A more useful same tier comparison for Growatt would be Hoymiles micro/mini-inverters which can be 50%+ less than Enphase but still have 25 year warranty. Frankly, I like Hoymiles' mini-inverter technology, openness and cost. However, solar is a 20+ year investment so long term support is just as important as technical merits. Are you confident that Growatt (or Hoymiles for that matter) will still be in the US market actively supporting customers even in 10 years? Just look at all the LG solar panel customers that got left hanging after they pulled out of the US market.
'Tier 1' is defined by Bloomberg. It's based on financial stability of the company not the quality of the product. That's just the definition. SunPower produced the best panels. Had very poor financials. Does that mean you should avoid the best panels?
You don't think $4k saved is worth the risk of possibly needing to pay ~$2k out of pocket for an inverter swap out of warranty?
And at the rate inverters are advancing it would likely be a huge upgrade anyway. Compare an inverter today to what was available just 5 years ago.
CrazyRabbit
Active Member
Is GroWatt compatible with any MCI? But really is a example of china dumping practices. Not saying I wouldn’t use gowatt in off grid solution, but I would keep a spare inverter.
I do appreciate the reliability and fail safe of enphase.
I do appreciate the reliability and fail safe of enphase.
It could worthwhile but only if "all else being equal". I would need the same level of cost savings but with 25 year warranty, owner accessible support and panel level monitoring to seriously consider it.
How much is that really worth? I don't think I have a single customer that routinely checks their systems anymore. It's fun for the first month, then they almost never look again. I actually get texts occasionally from customers for me to check their system because it's been too long since they last logged in and forgot how to.
Like I posted earlier. You don't need panel level monitors to spot, diagnose or find an issue. $300 IR camera or $4k for panel level monitoring....
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