I'm back ... where is roof mount pricing nowadays in San Diego area

[CharlieEscCA]

What's the consensus on string inverter brands? If SolarEdge is considered high quality, who and what products are the SolarEdge of string inverters? More specifically, what are the better string inverters for an 8.4 Kw DC system?

Between SMA SunnyBoy and Fronius Primo, is one better than the other? Are either any good quality wise? I was offered my choice at the $2.59 price point and my quick research had me leaning to the Fronius.

I told my 2017 company about my bid for the new house, and asked for a string inverter bid. Thus far, rather than get a bid, I got told I was comparing apples to oranges / rock bottom equipment to premium equipment. And then a big knock to Fronius being the lowest quality material. Not the exact reply I was looking for -- I'd rather see an alternative bid to the $3.65 bid and then tell me why it's better than the "rock bottom bid" -- which I know would let me choose different panels or inverters and would then adjust their price.

Having been away for a while, I'm not posting vendor names (one is a Solar Review member, one is not -- I've been told you pay to be a member and the second one said they chose to not be a member because they found it was not worth the cost -- there is however a significant quantity of reviews I could find in other places to feel confident in getting a quality installation) as I'm not sure of the current forum rules.

[J.P.M.]

What's the consensus on string inverter brands? If SolarEdge is considered high quality, who and what products are the SolarEdge of string inverters? More specifically, what are the better string inverters for an 8.4 Kw DC system?

Between SMA SunnyBoy and Fronius Primo, is one better than the other? Are either any good quality wise? I was offered my choice at the $2.59 price point and my quick research had me leaning to the Fronius.

I told my 2017 company about my bid for the new house, and asked for a string inverter bid. Thus far, rather than get a bid, I got told I was comparing apples to oranges / rock bottom equipment to premium equipment. And then a big knock to Fronius being the lowest quality material. Not the exact reply I was looking for -- I'd rather see an alternative bid to the $3.65 bid and then tell me why it's better than the "rock bottom bid" -- which I know would let me choose different panels or inverters and would then adjust their price.

Having been away for a while, I'm not posting vendor names (one is a Solar Review member, one is not -- I've been told you pay to be a member and the second one said they chose to not be a member because they found it was not worth the cost -- there is however a significant quantity of reviews I could find in other places to feel confident in getting a quality installation) as I'm not sure of the current forum rules.

SMA was the inverter of choice 10 or so yrs. ago. They still seem fit for purpose if maybe a bit less overdesigned now. Fronius seems OK and the acquisition by ABB didn't seem to hurt their quality much.

This is part of why it's important to chose vendors wisely. You've probably read my spiel ad nauseum about spending as much time evaluating vendors as evaluating equipment. Vendors who've been around and plan on being around tend to try to avoid poor equipment. Poster Solarix comes to mind as does Solar Pete for two examples. Quality vendors also don't want the headaches of service calls associated with poor equipment (and which BTW, may say something about their desire to stay in business, and also how they value their reputation). Lots of trucks in front of houses with arrays don't help with reputation. People do notice. Vendors with longevity know this. Stick with known vendors. Probably worth a (slight) premium.

FWIW, my (limited) personal in my HOA experience has been that inverters don't fail much. Drive around my HOA and you'll see about a 25 % PV penetration. I'm pretty familiar with all of the installs and know that to the best of my knowledge, one string inverter had infant mortality (an SMA 5 kW in 2009 I think) with the rest going strong, and several Enphase micros failed, mostly the old M190's and M215's. In spite of what seems like about half the system problems I read about on this forum being associated with SolarEdge equipment (check the latest posts and see how many of those describing system problems are about SolarEdge equipped systems), the SolarEdge equipped systems in my HOA don't seem to be problematic aside from those of poor installation quality done by Larry with a ladder type vendors, or the SolarCity/Vivant/Sunrun bandits. The 3 quality vendors I mentioned in a prior post do have occasional problems, but they usually manage to resolve them with one call, maybe two and quickly, most of the time with one service call - and their systems seem to be less problematic. FWIW, string inverters seem to have fewer service calls. But, in all honesty, all of that is not much better than anecdotal. I review/recommend PV systems for the HOA Board, and I take it seriously, but it ain't a vocation. It does seem however, pretty good experience.

I'm not sure it's worth considering micros or optimizers based on the idea that their warranties may be 20-25 years vs. a 10-12 yr. string inverter warranty if the micros or optimizers need more service, even if the cost of such service is covered under warranty claims. Opinions probably vary on that one.

For me only, keeping things no more complicated than absolutely necessary with fewer part to fail make for more reliable systems with a higher probability of fewer problems. For no/low shade, that means a string inverter.

As for which string (or other for that matter type) inverter is best, I'd suggest a string inverter in a well designed and constructed array that's fit for the duty will have the highest probability of trouble free operation for at least as long as the warranty period.

[CharlieEscCA]

Much has changed since my last post.

Got a quote from new vendor on same 300 watt 60 cell panels but with SolarEdge w/optimizers. Added 0.27 per watt, or $2.86 per watt.

Got a quote from my known installer of my 2017 ground mount system to give me a straight up string inverter proposal, which they did. Much closer to the "new" aggressive vendor, but above. Got a quote using SolarEdge and same 300 watt 60 cell panels of other vendor. Close but above other vendor. They did point out that they use QuickMount roof mounts, which are the "best and most expensive" but the only mounting system my roofing contractor (who they know and work with) accepts as not voiding the roofing contractors warranty. I countered the SolarEdge proposal to an even 24K for an 8400 DC watt system, and this was accepted.

So, ended up being $2200 more than a straight up string inverter ($1540 after tax credit). But for this, I get known vendor who did my 2017 review, money goes to VC owned business, get a better roof mount put in by a solar company who works closely with my roofing contractor, keep my roof warranty intact on detached garage, and I probably get a couple of percent better production and I can continue to have per panel monitoring (which I do look at and keep track of).

All's well that ends well.

I still question that I may be oversizing kWH production wise but probably not revenue wise as being a new house its a bit of a crap shoot on electric use.

[J.P.M.]

Much has changed since my last post.

Got a quote from new vendor on same 300 watt 60 cell panels but with SolarEdge w/optimizers. Added 0.27 per watt, or $2.86 per watt.

Got a quote from my known installer of my 2017 ground mount system to give me a straight up string inverter proposal, which they did. Much closer to the "new" aggressive vendor, but above. Got a quote using SolarEdge and same 300 watt 60 cell panels of other vendor. Close but above other vendor. They did point out that they use QuickMount roof mounts, which are the "best and most expensive" but the only mounting system my roofing contractor (who they know and work with) accepts as not voiding the roofing contractors warranty. I countered the SolarEdge proposal to an even 24K for an 8400 DC watt system, and this was accepted.

So, ended up being $2200 more than a straight up string inverter ($1540 after tax credit). But for this, I get known vendor who did my 2017 review, money goes to VC owned business, get a better roof mount put in by a solar company who works closely with my roofing contractor, keep my roof warranty intact on detached garage, and I probably get a couple of percent better production and I can continue to have per panel monitoring (which I do look at and keep track of).

All's well that ends well.

I still question that I may be oversizing kWH production wise but probably not revenue wise as being a new house its a bit of a crap shoot on electric use.

Understood. Thank you for the update. Ever wonder if they'd have bit on $22K ?

As maybe an example of how things have changed pricewise, a short story: In 2013, I'd been gathering quotes. I knew the pricing avail. from my HOA activity and the CSI database, and also knew I would buy Sunpower to compare their output to other panels for myself, and for reasons unrelated to their B.S. Anyway, 08/14/13 I paid $4.50/W and got the lowest per STC W price on the entire CSI database for Sunpower stuff at that time. Other quality stuff like LG was running ~ $3.60 - $3.75/STC W at the time. Panasonic and Kyocera were a bit higher, ~ $3.75 - $4.00/STC W. Prices have come down, but, because of the T.O.U. rate and time adjustment, so has system cost effectiveness by about the same amount.

Good luck.

[nwdiver]

What's the consensus on string inverter brands? If SolarEdge is considered high quality, who and what products are the SolarEdge of string inverters? More specifically, what are the better string inverters for an 8.4 Kw DC system?

I've used mostly SMA inverters. Not sure it it's just luck of the draw or what but both Fronius installs I've done had issues with the inverter. I've installed ~10 SMA inverters and from what I've seen they're rock solid. No issues. I'm doing my first Solar Edge project this week. I've heard good things but I'm not crazy about the price. IMO there's little/no benefit from module level optimization. String level is really all you need and the new SMA inverters do this. My last project used 6 independent strings and (2) 7.7kW SMA inverters. IMO in terms of value SMA inverters are currently WAAAY ahead of Fronius or Solar Edge.

I can't find the link now but I read a report recently examining the performance and durability of several inverters. SMA wasn't the best in any one category but it did best overall.

[ButchDeal]

IMO there's little/no benefit from module level optimization. String level is really all you need and the new SMA inverters do this. My last project used 6 independent strings and (2) 7.7kW SMA inverters. IMO in terms of value SMA inverters are currently WAAAY ahead of Fronius or Solar Edge.

SO you think 6 MPPTs is good then why wouldn't 7, or 12, or 30 be better? That is all that Module level optimization is, full MPPT everyplace. as well as monitoring and NEC2017 rapid shutdown.

Now you mention price but to get NEC2017 from SMA you would have to use their tigo optimizers and SolarEdge optimizer are cheaper and much more effective there.

[nwdiver]

SO you think 6 MPPTs is good then why wouldn't 7, or 12, or 30 be better? That is all that Module level optimization is, full MPPT everyplace. as well as monitoring and NEC2017 rapid shutdown.

Now you mention price but to get NEC2017 from SMA you would have to use their tigo optimizers and SolarEdge optimizer are cheaper and much more effective there.

The reason string level optimization is more effective (if you have 2 or more strings) is because if you have parallel strings and one panel is shaded the other unshaded strings AND unshaded panels in the shaded string are forced off their MPP. This occurs at my house. I have a 6 year old system with an older 8kW SMA. I have 3 strings of 14. The panels on the rear of my house get shade ~3pm in the summer. Once ~3 panels are shaded system voltage drops from ~370 => 350 all panels are now operating off their MPP and my output drops ~20%. If I had a newer inverter with string optimization those three panels would just be 'deleted' from the array when the bypass diodes active and I would lose ~7% not ~20%. Sure... module level would do the same but you're paying a lot more....

I agree that SE is a bit more cost effective for roof mount due to rapid shutdown requirements but TS4-Fs are compliant with rapid shutdown and cost ~$30 compared to $60 for an optimizer. I'm using SE for my current install. Even with rapid shutdown a SMA system with TS4-Fs would have cost ~$3500k. I paid ~$5k for Solar Edge

[ButchDeal]

The reason string level optimization is more effective (if you have 2 or more strings) is because if you have parallel strings and one panel is shaded the other unshaded strings AND unshaded panels in the shaded string are forced off their MPP.

that is a reason module level MPPT is more efficient not string. Each module is kept at their OWN MPP with SolarEdge optizers. With strings some of the modules would be OFF MPP, I.E, less efficient than module level optimization.

This occurs at my house. I have a 6 year old system with an older 8kW SMA. I have 3 strings of 14. The panels on the rear of my house get shade ~3pm in the summer. Once ~3 panels are shaded system voltage drops from ~370 => 350 all panels are now operating off their MPP and my output drops ~20%. If I had a newer inverter with string optimization those three panels would just be 'deleted' from the array when the bypass diodes active and I would lose ~7% not ~20%. Sure... module level would do the same but you're paying a lot more....

With SolarEdge you would lose much less as every module would produce its max possible production related to the light on it.

I agree that SE is a bit more cost effective for roof mount due to rapid shutdown requirements but TS4-Fs are compliant with rapid shutdown and cost ~$30 compared to $60 for an optimizer. I'm using SE for my current install. Even with rapid shutdown a SMA system with TS4-Fs would have cost ~$3500k. I paid ~$5k for Solar Edge

But the inverter costs more to use the TS4-Fs than the SolarEdge inverter as the SMA inverter has to do Buck/boost as well as MPPT but the SolarEdge inverter doesn't.
Also the TS4-Fs does rapid shutdown and some monitoring but zero optimization so you are getting a lot more for the optimizer.

[nwdiver]

that is a reason module level MPPT is more efficient not string. Each module is kept at their OWN MPP with SolarEdge optizers. With strings some of the modules would be OFF MPP, I.E, less efficient than module level optimization.

Sure... maybe there's a narrow set of conditions where you'll get noticeably more output from a shaded panel with an optimizer than one that's been 'deleted' from the array by bypass diodes but at that point it's blood from a stone. Depending on how the shade falls only 1/3rd of the panel can be removed and the effect would be the same with a string or with optimizers.

With SolarEdge you would lose much less as every module would produce its max possible production related to the light on it.

Or if I had 3 MPPs.... the difference between 1 MPPT and 3MPPT would be <5% and cost ~nothing. 3 => 42 (for every panel) increases the cost ~30% and the improvement in production <3% over 3 MPPTs...

But the inverter costs more to use the TS4-Fs than the SolarEdge inverter as the SMA inverter has to do Buck/boost as well as MPPT but the SolarEdge inverter doesn't.
Also the TS4-Fs does rapid shutdown and some monitoring but zero optimization so you are getting a lot more for the optimizer.

I just bought a couple 7.7kW SMAs for $1420ea ( ~$0.18/w) and a 11.4kW HD-Wave for $2100 (~$0.18/w). So the inverters are roughly the same price.

[ButchDeal]

You will always get more production from a shaded module with an optimizer than from one that has been "deleted" by bypass diodes, every time , always optimizers will get some production and deleted gets less than zero.

[nwdiver]

You will always get more production from a shaded module with an optimizer than from one that has been "deleted" by bypass diodes, every time , always optimizers will get some production and deleted gets less than zero.

I agree. The question is... is it worth spending $60 on an optimizer to harvest ~20w from a shaded panel. That's $60 for ~$2/yr of electricity....

Also; If a cell group is shaded there there won't be much if any difference since the optimizer would 'delete' the cell group in the same way a string would.

[ButchDeal]

I agree. The question is... is it worth spending $60 on an optimizer to harvest ~20w from a shaded panel. That's $60 for ~$2/yr of electricity....

Also; If a cell group is shaded there there won't be much if any difference since the optimizer would 'delete' the cell group in the same way a string would.

I think you don't understand how solaredge optimizers work. Your keep quoting $60 and minimal 20w ...

As for cost in a NEC 2017 region the costs are about the same. And performance is more than a little more . You might want to try a few more than one ( not yet installed) and see or read how they work.

[nwdiver]

As for cost in a NEC 2017 region the costs are about the same. And performance is more than a little more . You might want to try a few more than one ( not yet installed) and see or read how they work.

I did; The last SMA system I installed I optimized one panel since Tigo allows a mixture; 14 panels with 'shutdowns' and 1 with an optimizer. So that one panel is allowed to operate at its peak MPP. The difference between the 'optimized' panel and the others that just operate with the string is negligible.

One of these panels is optimized.... can you tell which one? Hint: It's not the best producing module.

Screen Shot 2019-06-20 at 10.51.01 PM.png

[ButchDeal]

I did; The last SMA system I installed I optimized one panel since Tigo allows a mixture; 14 panels with 'shutdowns' and 1 with an optimizer. So that one panel is allowed to operate at its peak MPP. The difference between the 'optimized' panel and the others that just operate with the string is negligible.

well here is the thing. Tigo optimizers are NOT even close to SolarEdge Optimizers. SolarEdge optimizers have MPPT & Buck/Boost, Tigo does not have MPPT or boost, just buck.

So the ONE that you put a tigo on is not working at ITs best MPP but the strings MPP since there is just one MPPT for the string.

[nwdiver]

well here is the thing. Tigo optimizers are NOT even close to SolarEdge Optimizers. SolarEdge optimizers have MPPT & Buck/Boost, Tigo does not have MPPT or boost, just buck.

So the ONE that you put a tigo on is not working at ITs best MPP but the strings MPP since there is just one MPPT for the string.

Tigo has both. The 'L' is used if you want longer strings (buck) and the 'O' is used for all other optimization (boost). The string MPP is irrelevant. The purpose of the Tigo optimizer is to allow an individual panel to operate at its MPP. The point here is that ~99% of the time panel MPP IS string MPP or close enough to not matter.

The only efficiency benefit to optimizers is allowing current to vary in a series circuit. But each panel will usually have multiple MPPs for the same reason strings have multiple MPPs. Sure, only one is the highest at any given point but the difference is a rounding error and likely too small to even be distinguishable by the tracker. Voltage can still vary panel to panel and that 'naturally' follows the MPP for the string current because physics. If string current is 8A but one the MPP of a panel is closer to 8.2A then the panel voltage will be slightly higher with that panel running at 8A.

If you watch the current and voltage of a string inverter it's interesting how consistent power output is even with fluctuations in voltage and current.

This is two 11.4 kW arrays located next to each other on an old Fronius string inverter. 4 strings, 1 MPPT. Shading can cause issues but that would be almost completely eliminated with string level MPPT.

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