Solar Edge [from: help me design the most efficient system]

PhilS

Re: Solar Edge [from: help me design the most efficient system]

Initially I was thinking like niel (spam) but solaredge kept answering the concerns voiced. From what I've seen the true spammers never continue posting.

So solaredge (and Powers) seem to me to be legit IMHO. And this group has thrown hard questions at them both.

And I hope you all have a WONDERFUL Christmas... I'll be away from a computer for a week or so.

Phil

BB.

Re: Solar Edge [from: help me design the most efficient system]

Cariboocoot wrote: »

I'm glad Bill split this out; an interesting discussion that was getting far, far away from the OP.

Just to be clear--I was trying to be nice and not take the positive credit for splitting the thread and really extend thanks to Solar Guppy and Niel.

There was no "complaining" involved by anyone to me.

And since the original post asked about Solar Edge--I was perfectly fine in letting the conversation go on in the original thread--But I was (am/is/are) very happy to split it off into its own since the vendor representative was kind enough to answer many of the questions raised here.

Merry Christmas, Happy Hanuka to Solar Edge (and our other friends here), and a great Festivus to all.

-Bill "can't win for trying" B. :roll:

PS: This post will self destruct in a few days...

westbranch

Re: Solar Edge [from: help me design the most efficient system]

Hmmm....been a month but no response to the last posted questions.
Too bad I was hoping for some good responses..
too tough maybe? pity.
Eric

westbranch

Re: Solar Edge [from: help me design the most efficient system]

Danya, here is the part I felt was an unanswered , almost , question.... CaribooCoot made it as a statement...

"I think I've come to the conclusion that this product tries to get a partially shaded panel to behave like a lower Wattage panel but at the same Vmp as the rest of the string by boosting the output Voltage from the 'shaded Vmp' point to match that of 'unshaded Vmp'. I'm not convinced it would work, much less that it would be practical. And I don't think SolarEdge did a very good job of explaining how his product supposedly function"

Can you please clarify his deduction of how the system works.

thanks
Eric

SolarEdge

Re: Solar Edge [from: help me design the most efficient system]

Hi Eric,

The way our system works is that there is no string-Vmp at all, as a matter of fact.
Our power optimizers, which we call PowerBoxes, are embedded to each and every panel, determining Vmp and Imp individually for each panel, independently of all other panels. This way every panel works at its own maximum wattage and is not affected by any other panel in the array. After tracking the optimal MPP for their respective panel, the PowerBoxes perform a DC-DC conversion (at a 97.7% weighted efficiency). Each panel is connected only to its PowerBox and the PowerBoxes are connected in series to form a string, so that each PowerBox produces an output voltage (that varies dynamically) that sums up to the inverter's optimal working voltage (which is constant). The SolarEdge inverter is a single stage current source – it continuously adapts the current it draws from the PV array in order to keep the input voltage constant.

The fact that panels in our installations are not connected to each other but are working separately as single units in their own optimal conditions, dependent on irradiation, shading, temperature, etc., allows us to connect panels on different facades and panels of different make and model to the same inverter.

A detailed theoretical example (with numbers…) can be found in the concept of operation (pages 6-7) of our architecture overview here http://bit.ly/Architecture_Overview

I hope I managed to answer your question. Please let me know if you need any further explanations/clarifications.
Regards,
Danya

solarix

Re: Solar Edge [from: help me design the most efficient system]

Just found this thread after learning about SolarEdge from one of my distributer's new catalog. I for one am quite interested with this new technology and want to thank the company rep for his explanations. Beyond the efficiency advantages, (which make sense to me), the big advantage this system has to my designs is that it makes possible any size system and efficiently handles the many difficult roofs I run into. With the present high-wattage modules, the gaps in allowable system sizes due to input voltage limitations of central inverters is getting pretty bad. For instance, using CSI 230W modules on a SMA inverter greater that 3kW, you can't do array sizes between 13 and 21 modules. I just quoted a system last week with two 3kw inverters as the best way to do his desired 4kW size. From what I've seen so far with SolarEdge prices, it is very comparable to a standard inverter - and a lot better than dual inverter alternative options.

My only reservation to these Power Boxes, is their reliability. It is what has kept me away from Emphase. Just have a hard time believing that electronics will survive a rooftop environment here in Arizona. However, I like what I hear about the SolarEdge warranty. The bottom line to me though, is whether these powerboxes use any electrolytic caps. I very much suspect (unlike Emphase) they don't. Because these are just DC-DC converters operating at higher freqs, I bet they use ceramic or film caps. - Please tell me this is so. Because Emphase is an inverter too, they have to run at 60hz and need big caps. Just wait about 5 years, there will be failures galore. I don't care what anybody says, electrolytic caps - no matter what the ratings - are not long term reliable in switching supplies. SolarEdge - do you need a rep in my area?

SolarEdge

Re: Solar Edge [from: help me design the most efficient system]

Hi Solarix,

You are absolutely right. Indeed we steer clear of electrolytic caps for all the reasons mentioned. We only use ceramics which have virtually no aging problems. We have tested these caps technology in our labs under environmental stress for the equivalent of over 150 years in order to prove its reliability. Moreover, 100% of the capacitors are electrically tested in the production line.
For further inquiries, please don't hesitate to contact us through this forum or fill-in the form http://bit.ly/agh30T

boB

Re: Solar Edge [from: help me design the most efficient system]

SolarEdge wrote: »

Hi Solarix,

You are absolutely right. Indeed we steer clear of electrolytic caps for all the reasons mentioned. We only use ceramics which have virtually no aging problems. We have tested these caps technology in our labs under environmental stress for the equivalent of over 150 years in order to prove its reliability. Moreover, 100% of the capacitors are electrically tested in the production line.
For further inquiries, please don't hesitate to contact us through this forum or fill-in the form http://bit.ly/agh30T

On the Power box... It says

"OUTPUT DURING OPERATION (Inverter is Operatin g) Maximum Output Current 16.4 A"

What voltage is thies 16 Amps at ? 120VAC ? 240 VAC ? I don't think I saw an output voltage spec. And, it really runs down to 5 V Mpp ?? That must be with the 14 Amps maximum input ?


EDIT: Nevermind... I guess that these are DC to DC modules rather than an inverter.

boB


PS, OK, how much to these boxes cost ? How does their MPPT tracking work when an MPPT tracking inverter is connected to the array ?? Do they interfere with each other ?

boB (again)

SolarEdge

Re: Solar Edge [from: help me design the most efficient system]

Hi boB,

As you noted the PowerBoxes are DC-DC converters connected to each panel, answering your questions:

• PowerBox Input: Each PowerBox performs MPP tracking per panel, so its input (=panel output) will equal to its panel’s Vmpp and Impp.
• Indeed, the PowerBox can track MPP between 5v - 60v. This unique, wide MPP voltage range allows us to keep optimizing partially shaded panels even if one or two substrings are bypassed (in which case the typical panel’s voltage drops by a 1/3 or 2/3).
• PowerBox Output: When a string of PowerBoxes is connected to an activated inverter, the output DC voltages of different PowerBoxes may vary, but will sum up to a fixed string voltage (the fixed string voltage principle was explained earlier in this thread.) If the inverter is disconnected from the grid or turned off, the PowerBox output will decrease to a 1v “safety voltage”.
• Cost: a full SolarEdge system includes Inverter + PowerBox per panel + panel-level monitoring, and the total package is priced equivalently to a standard inverter of a leading brand. For example, find package prices at the new AEE Solar catalogue http://aeesolar.com/catalog/products/H_ASW_IN_GT_SEG_R.htm
• The SolarEdge PowerBox works optimally in unison with the SolarEdge inverter, which was specifically designed and optimized to work with the PowerBoxes at a fixed string voltage and without MPP tracking. Therefore, there is no interference.

Let me know if you require any further information.
Danya

boB

Re: Solar Edge [from: help me design the most efficient system]

OK, Danya.
So, it looks like the power box really requires your inverter for the MPP to stay within high degree of accuracy, system wise.

This is like the National Semiconductor Solar Magic box, which, last I heard, costs around $200 each. That's too much in my book. Now, maybe 50 bucks a panel might be better. I don't know if you can even buy the Solar Magic box yet ?

How about a one box per string solution. I know that there is a unit out there that does that. Not quite as good as one per module, but maybe cheaper and certainly fills a void.

Thanks for the info,
boB

drees

Re: Solar Edge [from: help me design the most efficient system]

boB wrote: »

This is like the National Semiconductor Solar Magic box, which, last I heard, costs around $200 each. That's too much in my book. Now, maybe 50 bucks a panel might be better. I don't know if you can even buy the Solar Magic box yet ?

Looks like they're $250-$300 searching Google Products.

SolarEdge

Re: Solar Edge [from: help me design the most efficient system]

The price of the full SolarEdge system is comparable to the price of other leading inverters, but it includes all the following: SolarEdge PowerBoxes per module, SolarEdge inverters (3.3kW – 6kW), SolarEdge Monitoring hardware and web portal, and additional features.
Please refer to AEE Solar's new catalogue http://aeesolar.com/catalog/products/H_ASW_IN_GT_SEG_R.htm for further details.

solarix

Re: Solar Edge [from: help me design the most efficient system]

An update after 6 months of installing SolarEdge inverters. I have nothing but good comments to report after doing 10 of these systems. We are seeing the efficiencies claimed, support from the company has been good although they are having some difficulty ramping up production, ease of installation is good, installation safety is great - no more HV DC, and the best thing is that I can design any size of array with any size module or even mix of modules.
I now stock an inventory of PV modules, confident that I will not be stuck with a few extra or odd sized modules. There are a lot of games played in PV module distribution - it seems like I can never get the price I want on modules I design in when the time comes to order them. Now I buy modules when they are available at a good price, and know that I won't be stuck with them because the SolarEdge system is flexible enough to use anything. No more designing in 230W modules then 6 months later (when the powers that be actually allow us to build it) find that only 235's are available which changes the string sizes ... Arrrggh
I think there needs to be some clarification on how the SolarEdge strings work. The Powerboxes (DC-DC converters) adjust their output voltages so that their ouput currents all are the same (since they are in series). The main inverter adjusts its input impedance so that its input voltage is right about 350Vdc. This sets the string current, and the Powerboxes adjust themselves to transform the PV panel's mppt IV to whatever voltage produces this string current. You may have one module at 13V and another one somewhat shaded only at 10V but both supplying 15A to the Inverter.
Having a two-stage conversion (DC-DC Powerbox and then DC-AC Inverter) is not a disadvantage as central inverters all do the same two stages internally as well. The SolarEdge inverter is actually better because the DC-AC stage is presented with a set input voltage making its job easier and the circuit design more efficient. I still say this is the best system design for Grid-tied applications.

vtgoingsolar

Solar Edge Reliability methodology

I received this document a while ago but figured some might find it an interesting read.

My install is to be end of march / beginning of April (weather dependent) and I will be using 18x240 Solarworld mono panels with solaredge powerboxes and the 5000W inverter.. Hoping for the best.

I just got a TED and am playing with that now.. entertaining to watch certain devices I did not monitor with the kill-a-watt monitor (like my furnace / hot water heat zones ).. The house gets down to approx 100W when nothing big is running (just router, cordless phones, modem, laptop plugged in but charged).. With the TV on.. fridge on.. perhaps a head zone.. 700W right now .. fun stuff.

ggunn

Re: Solar Edge [from: help me design the most efficient system]

Cariboocoot wrote: »

Despite being foggy this week, I think I've come to the conclusion that this product tries to get a partially shaded panel to behave like a lower Wattage panel but at the same Vmp as the rest of the string by boosting the output Voltage from the 'shaded Vmp' point to match that of 'unshaded Vmp'. I'm not convinced it would work, much less that it would be practical. And I don't think SolarEdge did a very good job of explaining how his product supposedly functions.

My understanding is that it reduces the voltage on the shaded panel so that its current goes up. The current is the same in any point in a series circuit, so if a panel in a string is only producing 1A, you are only getting 1A from the whole string.

solarix

Re: Solar Edge [from: help me design the most efficient system]

I asked the SolarEdge engineer at a convention last week about how the powerboxes control their output. It is pretty tricky as there is no continuous communication with the main inverter and they essentially sense the string impedance and autonomously stay in balance with it. If the string voltage goes too high then the inverter turns on harder increasing the string current to compensate. Then the power boxes sense the bigger load and turn on harder as well which increases their current for a lower voltage. The control loop on the powerboxes has to be much higher speed than that of the inverter for this to be stable. The loop in the powerboxes runs at about 10khz which is super fast compared to other MPPT algorithms which is one of the reasons for their superior efficiency. The bottom line was that it is pretty close to magic but is the key to making this technology such a good solution.