micro-inverters or optimizers when shading is major issue ?

[nwdiver]

As i said pv modules diodes do not ingage at the slightest effect of a shadow.

I posted pretty clear evidence they do... and if the small shadow isn't enough to trigger the bypass diodes then it's not enough to effect the other panels... MPP is a curve and there's typically more than one MPP within <1% of each other. If the current drops slightly because of a shadow too small to trigger the bypass diodes then voltage increases and power remains the ~same...

Where did you show there was no cost difference??? You disputed my numbers but never provided yours. RES isn't the only place -41 inverters are available for ~$1200... The Powerstore and Renvu also offer a 5kW SMA -41 inverter for <$1200. The difference is even bigger if rapid shutdown isn't required.

screen-shot-2018-07-12-at-11-47-44-am-png.316409.png

[ButchDeal]

.... yeah.... if 1 panel in a 10 panel string is shaded it goes down ~10%... math. Sure... an optimizer might reduce that to ~7% since the shaded panel can produce what it can instead of being deleted but is it really worth ~$60 to get power from a shaded panel?

As i said pv modules diodes do not ingage at the slightest effect of a shadow. A little shadow will not activate it and thus it effects the string. Also shadows rarely affect just one pv module, they are odd shapes generally and hit a little of multiple modules, some don't have enough to engage the diodes, this the string is affected.
then you have operating range of the inverters, without buck/boost on the optimizers, they often can go in and out of range as diodes start dropping modules out.
remember op is asking about a lot of shadows...

also as we already showed it is not a $60 difference but closer to $20 and even less ( to zero) if OP wants to have secure power and rapid shutdown

[nwdiver]

But you have seen a string be reduced by up to 10%. This will vary by pv modules used of course but 10% of a whole string is a lot more than you are letting on.

.... yeah.... if 1 panel in a 10 panel string is shaded it goes down ~10%... math. Sure... an optimizer might reduce that to ~7% since the shaded panel can produce what it can instead of being deleted but is it really worth ~$60 to get power from a shaded panel? And this is assuming shade is cast across all cell groups. If only 1 cell group is shaded then that cell group is removed with an optimizer too... So optimizers really only provide a small benefit in a narrow use case most of the time.

[ButchDeal]

No... I've watched this first had. Shade creeps in power dips to the point that the bypass diode trips. I've never seen a string of 10 get reduced by >10% due to shade on a panel.

But you have seen a string be reduced by up to 10%. This will vary by pv modules used of course but 10% of a whole string is a lot more than you are letting on.

[nwdiver]

The disconnect is yours. The bypass diodes do not operate on slightest shaddow and most shadows are partial, leaving diodes unaffected and the string at something other than MPPT. Your arguments are based on too binary thinking of the results.

No... I've watched this first hand. Shade creeps in power dips to the point that the bypass diode trips. I've never seen a string of 10 get reduced by >10% due to shade on a panel.

Here's an image I took of a SMA system with TIGO. Two of the panels have fingers of shade cast by a vent. One cell group in each panel has been 'deleted' by the bypass diodes. The other panels are unaffected.

screen-shot-2018-07-12-at-11-47-44-am-png.316409.png

[ButchDeal]

RES lists a brand new current -41 SMA inverter at $1121. The same site lists a 5kW Solar Edge SD Wave at $1482. They list the TS4-F at ~$28 and P320 optimizers at $70. If there's a better source for Solar Edge I'd love to know... if I can get SE equipment for less than SMA equipment I would. I'm not arguing that SMA is 'better'... it's just a better value.

Physics isn't an opinion. If a panel is shaded the bypass diodes activate and 'delete' the shaded section => it cannot effect unshaded portions. It's physically impossible for shade on a panel to negatively effect unshaded sections (If that string is on an independent MPPT and voltage doesn't drop below the MPPT band).

The section of the video showing a 'traffic jam' was misleading. I think some of this is because of a disconnect between marketing and engineering. The 'traffic' would just bypass the shaded section...

The disconnect is yours. The bypass diodes do not operate on slightest shaddow and most shadows are partial, leaving diodes unaffected and the string at something other than MPPT. Your arguments are based on too binary thinking of the results.

as for the prices, most resellers have the new SMAs at higher prices, i would highly suspect that one as an error since it is so far off from others but maybe a good deal if you can get it.

[nwdiver]

They are only misleading in your opinion

BTW, here is one from SMA which of course has both sides with and without optimizers but they explain it pretty similarly

https://www.youtube.com/watch?v=VA--pcs_bl8

RES lists a brand new current -41 SMA inverter at $1121. The same site lists a 5kW Solar Edge SD Wave at $1482. They list the TS4-F at ~$28 and P320 optimizers at $70. If there's a better source for Solar Edge I'd love to know... if I can get SE equipment for less than SMA equipment I would. I'm not arguing that SMA is 'better'... it's just a better value.

Physics isn't an opinion. If a panel is shaded the bypass diodes activate and 'delete' the shaded section => it cannot effect unshaded portions. It's physically impossible for shade on a panel to negatively effect unshaded sections (If that string is on an independent MPPT and voltage doesn't drop below the MPPT band).

The section of the video showing a 'traffic jam' was misleading. I think some of this is because of a disconnect between marketing and engineering. The 'traffic' would just bypass the shaded section...

[nwdiver]

You don't seem to be though. The Current SMA 5kW inverter is the Sunny boy 5.0-US actually runs over $1400 NOT some old model you can get for $1120.

No... Brand New current -41 model of SMA 5kW inverter runs ~$1121. Same site lists a 5kW SE for $1482.

I'm open to the idea my sources are not correct.... what's your price comparison?

[RShackleford]

The TS4-R-O devices being obtainable for as low as $40, that is virtually lost in the noise of the variability in panel per watt costs (30 cents to a dollar or more). How the heck do I decide that ?

Also, somebody at the beginning suggest "half-cell panels" being better for shade.

[SunEagle]

Now my posts are being flagged for moderator approval.

It is an automatic flagging due to multiple web links.

[RShackleford]

Of course, in order to implement rapid shutdown, maybe I have to have SOME kind of TS4 on every panel - or do I ? So if I do F's, and then decide I need O's, I have to discard the F's ?

Though I'm thinking of ground-mounted, which doesn't need rapid shutdown, or carport/shed-mounted, which may or may not.

Ok, just talked to a guy who seems to know his stuff at SMA. He says if I want the "secure power" to work, I need to put an 'O' on EVERY panel, and use a -41 inverter.

If I want rapid shutdown to work, I need to put a TS4 of some flavor on every panel. So the marketing that you don't need to put an optimizer (or some kind of TS4) on every panel is a bit misleading, because this is only an option if you don't need either "secure power" or rapid shutdown.

And you also need the "rooftop communication kit", at least for rapid shutdown.

A lot of this information can be discerned from: https://www.tigoenergy.com/products/ ... although I don't see the "secure power needs TS4-O on every panel" bit. I find this a bit less forthcoming than I would prefer.

And yet this page sows more confusion, and appears to have responses written by an SMA person (maybe the same guy I talked to): http://www.smainverted.com/sma-redef...ower-solution/ It seems to imply that rapid-shutdown and secure-power cannot co-exist in a system, period. Which kind of makes sense: if you're relying on the absence of grid power to initiate rapid shutdown. This is pretty darn exasperating.

[RShackleford]

Regarding 'Major' shading... can you estimate how many 'panel-hours' we're talking? For example... I have 4 panels that get shaded in the evening for a couple hours in the summer so I'd estimate ~1 panel-hour/day (an hour after 4pm is less valuable than an hour at noon) for 4 months of the year so... ~120 'panel-hours' per year of shade. How 'major' is your shading issue?

I just don't have a clue at this point.

[RShackleford]

This is why I'm leaning heavily towards string inverters, and Tigo optimizers IF I have optimizers. Tigo gives one the opportunity to decide later to include optimizers, and to optimize only "problem" panels.

Of course, in order to implement rapid shutdown, maybe I have to have SOME kind of TS4 on every panel - or do I ? So if I do F's, and then decide I need O's, I have to discard the F's ?

Though I'm thinking of ground-mounted, which doesn't need rapid shutdown, or carport/shed-mounted, which may or may not.

[ButchDeal]

I was comparing apples-apples. I can get a 5kW SMA system that's NEC 2017 compliant for ~$1600.

You don't seem to be though. The Current SMA 5kW inverter is the Sunny boy 5.0-US actually runs over $1400 NOT some old model you can get for $1120.

If you get special volume pricing from SolarEdge that's not really available to @RShackelford and a bit of a moot point... for him it's ~$1600 for SMA vs ~$2400 for SolarEdge.

If you are talking retail it is SMA WITHOUT optimizers for $2040 or SMA WITH optimizers for $2360 or SolarEdge for about the same.
What you CAN get for some discount price doesn't do @RShackeford any good.

Now that you mention installer discounts. SMA has had to cut their prices considerably in the past few years to compete with SolarEdge so their installer discounts are smaller. This makes the choice much simpler if you are buying a turn key system from an installer.

I don't think he's gonna get $800 more energy from the SE system... not in ~20 years...

Well the price difference is much closer and the production difference as well as ease of design and layout with optimizers is easily going to pay for the slight difference.

My point is that with string level MPPT the cost of optimizers is not worth the benefit. You do not need module level optimization if all the panels on each string can face the same direction.

And no Shadows AND no need for NEC 2017 rapid shutdown. But if you do have a need for NEC 2017 rapid shutdown then you do need module level electronics and if you do you might as well go for optimizers rather than non-optimizers.
If you have shadows or a complex layout with multiple azimuths complex shadows you should go for optimizers, and they will pay for themselves.

The only real benefit to module level optimization is recovering generation from shaded areas... if the shade persists long enough to make that worth while then it's probably not a good location for solar to begin with.

There are other benefits as already listed but everyone doesn't have the luxury of a shadow free roof.

I'm sick of the misleading graphics from SolarEdge and Enphase

They are only misleading in your opinion

BTW, here is one from SMA which of course has both sides with and without optimizers but they explain it pretty similarly

https://www.youtube.com/watch?v=VA--pcs_bl8

[nwdiver]

This is why I'm leaning heavily towards string inverters, and Tigo optimizers IF I have optimizers. Tigo gives one the opportunity to decide later to include optimizers, and to optimize only "problem" panels. With SE, you gotta buy into the whole system from the get-go.

Also, with the non-SE plan, I have the option of the SMA inverter with "secure power", meeting my desire for a little backup power during grid outages. Though the jury still seems to be out, here, over whether using optimizers will defeat the "secure power" feature.

P.S. I can include my EV in the backup power scheme. I'm already using an inverter connected to its 12v system for backup power, so maybe I just use the SMA to charge the Leaf's battery using the L1 cable, and don't backup from the SMA directly.

Please check with SMA (not a distributor) on which TS4s are compatible with Secure Power Supply. I've seen some conflicting info on what works and what doesn't. Most sources seem to suggest the S, O and L work but the Fs don't. Which is odd because the Fs are the most simple. I agree that one big benefit with Tigo is you can selectively 'optimize' only the panels that need it. The Os are ~2x more than the Ss.

I haven't used the new -41 version that incorporates some of the TIGO hardware but I have used TIGO with the -40. I believe you still need a rooftop comm box that runs ~$100 since the S,O and L TIGO units don't communicate via the DC line (The Fs do). So the system cost jumps a bit even if you only want to optimize a couple panels.

Regarding 'Major' shading... can you estimate how many 'panel-hours' we're talking? For example... I have 4 panels that get shaded in the evening for a couple hours in the summer so I'd estimate ~1 panel-hour/day (an hour after 4pm is less valuable than an hour at noon) for 4 months of the year so... ~120 'panel-hours' per year of shade. How 'major' is your shading issue?