Where's the rest of the cost?

[Ben25]

I'm dying to know if the p-800s will work with a 7600 inverter! That being said, this is why people pay me to install their solar for them. Most people just want something that is installed properly, will work for a long time, they don't have to install it and they don't have to mess with it at all. (And it will be covered by the manufacturers warranty should something go wrong)
Absolutely nothing wrong with the DIY route as long as it's done safely, but you may catch flack for crazy ideas!

[jflorey2]

our best of luck wish is going on as we speak, turns out Wholesalesolar is 25mi down the road from me, i'll talk to them tomorrow.

Great; more information is always better. Just remember - TALK but do not BUY.

[jflorey2]

One last thing, are used PV panels a waste of money... Thanks

Usually, yes, for several reasons.

1) Panel prices have been dropping for a long time. So that guy who spent $600 for his 150 watt panel 10 years ago is going to give you a "great" price on it of $200 - a savings of $400! - even though you can easily get a 300 watt panel today for $200.

2) Panel efficiencies have been going up. Same as above.

3) While crystalline panels see little degradation over time, they do see some - and so you will be buying a lower performing panel.

4) Most installs that take advantage of subsidies need warrantied parts - and used panels don't come with warranties.

All that being said, if you get a screaming deal on a panel that you want (i.e. 10 cents a watt for 5 year old panels that have been in a shipping container this whole time, and it's an odd size that you need) then great. But for me it has to be a VERY good deal to overcome the problems listed above.

[motorcyclemikie]

You might argue that we should pick a different current to operate this bizarre set of panels at. Ok, I'm game for that - what current would you like to choose? .

Yes Foo, when we increase the voltage to decrease the current, would be one way. Yeah, it all come down to operating within the devices limits naturally. I still aren't sure which PV panels and optimizers I am going to use, I will be paying close attention though Thanks

[motorcyclemikie]

Motorcycle Mikie,

I have to admire your determination and gumption. And I don't say that sarcastically, I mean it sincerely.

With that said, if I were a betting man, I would say the likelihood of your setup working is significantly less than 50%.. If it works that is awesome. But I bet that even SolarEdge may not know if it will work or not. Maybe they never intended the inverter to work with the optimizers so from their prospective it doesn't work. But **** can happen and maybe everything works fine.

However, I would stick with what works on SolarEdge's design site. https://designer.solaredge.com. If something doesn't work I wouldn't want to have to return product or spend hours trouble shooting a inverter to optimizer communications issue. I have no idea what information gets sent back and forth between an inverter an an optimizer to "Pair" them, this is beyond my pay grade and I wouldn't know where to start troubleshooting.

If you get a setup to work that is not approved of by the design tool, then you are the man and my hats off to you. I just don't have that much faith in my ability to handle engineering work arounds. And I have an engineering degree. I do know what I know and many times I would be willing to work outside the box so to speak. But I don't think there is anything that anybody could tell you about the pairing process and what signals get sent and received. I believe to really anticipate whether your system could work or not would require being the SolarEdge programmer that developed the "Pairing" protocol. and then be able to re write some of the firmware within the inverter and then flash the new code to make the items compatible.

Short of being able to do understand or re write code this is simply trial and error with who knows the likelyhood of success.

How do you plan on testing the pairing process if you don't have the minimum number of 8 optimizers? Will you plan on buying 8 optimizers?

Thanks John I appreciate the wise words, I really do realize the reality of the approach to my PV system design. I do intend to do a standard solaredge design using all their parts and in the prescribed quantities -- I will not cut corners initially with any blue sky ideas, my Mantra is to get something working and improve on it later if it's feasible. I really don't need to beat all the air out of these system prices, but getting a great bang for the WATT seems attractive to me

You know John you really do make sense by the time one were to get a firmware developers kit and spent time working to understand compatibility and so forth would be foolhardy financially and otherwise. I just can't help but to think that logically my configuration would work, it makes sense, but that can wait, you could buy a huge amount of optimizers for that time and expense. I would love to see their code though, and I'd jump at that chance were it presented. I am sure I could energize a known compatible P3XX optimizer to check "pairing", with that known, it could be scaled, or tested with a "target" part. The reality, is all that worth it to satisfy a curiosity? I think not at this point

I still have a lot to do with the permitting however I feel better knowing that I have "Wholesalesolar" in my county 25mi away. I am sure they can steer me in the right direction and profit simultaneously.

Thanks everyone for your help!

[foo1bar]

We are making these 3 X 250w panels to electrically look like 1 X 750w panel just the way the panels are built with individual cells in certain configurations that dictate what you want for voltage & current output.

Unless you're physically opening the panel and rewiring it's connections, you can't make 3 of 250W panels look like a 750W panel in the way you are proposing.

The given is the wattage, the voltage and the current is proportional but it always equals the 750w of the 3 X 250w panels.

NO!
The wattage is NOT a given.
For the below specs, the module under full sunlight will provide:
0 W at 37.5V and 0.0A
1 W at 37.45V and 0.03A
245W at 30.2V and 8.13A
2W at 0.2V and 8.65A
or
0W at 0V and 8.68A

Which of those you get (or which point inbetween) is going to be dependent on what load you have on that sytem.

This is the panel specs I have in mind.
Rated Power: 245W[
]Open circuit voltage (VOC): 37.5 V[*
]Max power voltage (VMP): 30.2 V[*
]Short circuit current (ISC): 8.68 A[*
]Max power current: 8.13 A[*
]Power Tolerance 0/+3%[*
]Maximum system voltage: 600V (UL)[*
]Fuse Rating: 15 A[*

OK - so two in parallel would be about 8.13A * 2 and 30.2V *IF* they are at their max power point.
That's 16.26A that you're going to try to shove through a single module.
The specs for the single module says "Fuse Rating 15A" - well, that sounds like it's a potential problem, since we're trying to shove 16+A through that single module.
But let's ignore that for now (even though it is a problem).
Now you've got two modules sending 16A through this 3rd module.
The third module still has a Isc of 8.68A. So if we're above 8.68A flowing through it, there is no voltage (or even a voltage drop instead of a voltage increase)
So essentially that 3rd module provides no net power to the system at that current.
You might argue that we should pick a different current to operate this bizarre set of panels at. Ok, I'm game for that - what current would you like to choose? let's say you pick 8.6A, which is where that third panel starts producing a little power. Now panel C is giving you a few watts (lets say 10W) . What are the other two panels doing? They're at 4.34A each and ~35V. So they're each giving you 151W. That plus 10W from panel C and you now have 312W from the trio of 245W modules.

Summary:
If you wired the 3 in series you'd have 735W (8.13A @ 91V ).
If you wired the 3 in parallel you'd have 735W (~24A @ ~30V)
With the horribly bad idea you're proposing the max power point is probably either around 16.26A@30.2V (490W) Or at around 8.13A@60.4V (490W)
oh - and the other really crappy thing about this choice of configuration is that these are both local maximums - there's a big dip in power output between the two. So the software in the optimizer that's trying to find that max power point is probably only going to find one of the two.


The ONLY way this would work the way you're suggesting is if you open up the solar modules and rewire them. Theoretically it'd be possible to take the 3rd panel and split up the groups of solar cells and wire it so instead of 4 groups of cells in each module you had 4 in module A, 4 in module B, and 2 sets of 2 in module C. Wire each set of two in series with one of the other modules and now you've got a system of ~16A @ ~45V. HOWEVER doing that means opening the module and breaking the existing wiring and adding new wiring. All while making sure you don't break anything sealing moisture out from the solar cells (or they'll degrade badly in 1-3 years). And you'll need to properly make connections that will hold up to continuous current of 8A or 16A. And they won't be approved modifications to the equipment, so the building dept/AHJ and/or the power company could tell you that's not allowed. Of course when you have one of these show a problem you're screwed - you can't do anything with it under warranty. Or long story short - it might be theoretically possible, but realistically it's not viable.

[John_Dumke]

Motorcycle Mikie,

I have to admire your determination and gumption. And I don't say that sarcastically, I mean it sincerely.

With that said, if I were a betting man, I would say the likelihood of your setup working is significantly less than 50%.. If it works that is awesome. But I bet that even SolarEdge may not know if it will work or not. Maybe they never intended the inverter to work with the optimizers so from their prospective it doesn't work. But **** can happen and maybe everything works fine.

However, I would stick with what works on SolarEdge's design site. https://designer.solaredge.com. If something doesn't work I wouldn't want to have to return product or spend hours trouble shooting a inverter to optimizer communications issue. I have no idea what information gets sent back and forth between an inverter an an optimizer to "Pair" them, this is beyond my pay grade and I wouldn't know where to start troubleshooting.

If you get a setup to work that is not approved of by the design tool, then you are the man and my hats off to you. I just don't have that much faith in my ability to handle engineering work arounds. And I have an engineering degree. I do know what I know and many times I would be willing to work outside the box so to speak. But I don't think there is anything that anybody could tell you about the pairing process and what signals get sent and received. I believe to really anticipate whether your system could work or not would require being the SolarEdge programmer that developed the "Pairing" protocol. and then be able to re write some of the firmware within the inverter and then flash the new code to make the items compatible.

Short of being able to do understand or re write code this is simply trial and error with who knows the likelyhood of success.

How do you plan on testing the pairing process if you don't have the minimum number of 8 optimizers? Will you plan on buying 8 optimizers?

[motorcyclemikie]

Best of luck my friend, you're going to need it.

Your best of luck wish is going on as we speak, turns out Wholesalesolar is 25mi down the road from me, i'll talk to them tomorrow. things just keep getting better

[motorcyclemikie]

This will work,

If you say so.

120 comments here on this thread and I doubt you have comprehended 10% of what is being said. You are so dead set on doing it your way while not knowing squat about what you ARE doing.

Best of luck my friend, you're going to need it.
[/QUOTE]

Thanks Little, I have to pursue this until I know differently!

[motorcyclemikie]

I believe that i have exactly the picture if what you are trying to do fine. You can stick that 9mm into the .38 but it isnt such a good idea.

We are still in agreement Butch, I used to shoot 308 winchester in my 7.62 Galil, that was cheaper also, i'm with you!

[littleharbor]

This will work,

If you say so.

120 comments here on this thread and I doubt you have comprehended 10% of what is being said. You are so dead set on doing it your way while not knowing squat about what you ARE doing.

Best of luck my friend, you're going to need it.

[ButchDeal]

You are right not eight strings, but one string of eight optimizers.

You still don't get the picture, just as all PV panels don't have a identical cell count, voltage and current specs. they are usable because they match what is needed for the application. Now break this PV panel into three pieces, and wire back together. As long as it goes back together electrically, it looks the same to the application.

This will work,

I believe that i have exactly the picture if what you are trying to do fine. You can stick that 9mm into the .38 but it isnt such a good idea.

[motorcyclemikie]

That is not a string. you are talking about 1 string of 8 PV optimizers each with a bastardized string of 2 pv modules in parallel and those two then serial with a third PV module.

Nothing in any of this will work.

You are right not eight strings, but one string of eight optimizers.

You still don't get the picture, just as all PV panels don't have a identical cell count, voltage and current specs. they are usable because they match what is needed for the application. Now break this 750w PV panel into three pieces, and wire back together the 3 X 250w panels you created. As long as it goes back together electrically, it looks the same to the application.

This will work,

[motorcyclemikie]

Then go for it! Ignore the advice given here as "marketing answers" and try it out. You'll be supporting the solar industry twice over - first when you set up a system with the P800, and then again when you buy a different system to get it to work. But you'll learn a lot in the process.

Thanks JF, yeah since I stuck my foot out this far about the aspect of cost savings, I guess you are right. I have more or less committed myself. My idea, my task. I already have the P800 on the way, I found a solar wholesaler close by -- might be he can give me a good price on panels, racking ect Their panel prices start at $.50w.

One last thing, are used PV panels a waste of money... Thanks

[ButchDeal]

John, I think that spec reflects the SE7600A, The spec for the SE7600H is 10250w I believe I read somewhere.

Yes, the plan calls for 24 panels, eight strings of 3ea.

The max string power for the SE7600H is 6kW
The Max DC power input is 11.8kW but would have to be on more than one string.