SunPower AC w Microinverter or SunPower DC w SolarEdge

[ButchDeal]

Thanks Butch, I'll have to look into these (bimodal inverters) in more detail.

Sorry, by "FLA" I meant flooded lead acid -- not the Sunshine state. I wasn't intending to suggest that Tesla was the bees knees from a technology perspective. But rather that grid connected, residential storage was a relatively new and fledgling product offering which was only just starting to come into its own. Companies like Tesla, LG, SolarEdge, Enphase, etc. with their brand recognition, all in one turnkey solutions, and modern, compact high energy density storage offerings are what is needed to drive the necessary consumer adoption to bring these technologies into wider acceptance and implementation. Additionally, my expectation is that a novel bimodal system from a company like any one of these would be an AC coupled solution which could co-exist with the homeowners existing PV investment be it Micro, Optimizer, or String.

As I said most bimodal systems can AC couple NOW. and can work with different battery technologies.

SolarEdge is the one exception where you can install a StorEdge inverter without batteries and add the battery latter as well as they have an upgrade program to upgrade/trade up a solaredge inverter for Storedge

I view AC coupling as a poor technological choice particularly when not used for retrofits. EG. tesla and enphase. This is a solution engineered solely as a compromise to fit their existing products. DC coupled solutions are more efficient, simple and better controls.

My concern with a conventional bimodal solution is that these are all / mostly string inverters, correct? Typically with large, heavy, expensive battery banks for off grid / rural / or unreliable grid environments. To which you would then need to add rapid shutdown solutions as needed to meet the various NEC revision requirements. yes, it can be done. But you end up having to piece together a number of different partial solutions to make the whole.

StorEdge is definitely not a string inverter. Almost all will work with optimizers as in Tigo.

For simplicity and cost effectiveness (and the high volume of units needed to make this a reality) you really want a simple all in one solution from a single vendor. I had hoped that StoreEdge would pan out. But SE seems to have dropped it like a hot potato. Perhaps Enphase will eat there lunch in this regard with there AC coupled solution.

Why do you think SolarEdge has dropped the StorEdge? it is in the new HDWave inverters and on multipls as well:

https://www.solaredge.com/us/solaredge-introduces-storedge-backup-solution-for-the-entire-home

[jnook]

Thanks for all the info. I think I'm going to move this forward with the DC panels and SolarEdge, will get the Consumption meter to see that side too. All the battery talk can anyone confirm I should be going with the SolarEdge 7600A style inverter to be future compatible to a battery system, not the 10000H for example?

Based on my reading I should also request the P505 optimizers instead of the P400 to avoid voltage blocking? Thoughts?

I forgot to mention I'm going with pole mount (2/3rds) and rack mount (1/3rd) due to layout, avoiding roof even though this is costing a premium to mount on ground. Few reasons our roof isn't ideal... Any other considerations to think of for this SunPower X22 45 AC panels and SolarEdge optimizers/inverters before I pull the trigger?

Thanks for all the help!!

[Mike90250]

I believe pole mount removes the rapid shutdown requirement ! ( not on a roof that firemen will be walking on)

And you need to insure your AC wiring from pole to main panel, can handle the array output without faulting the inverters. (from high resistance)

[jnook]

I believe pole mount removes the rapid shutdown requirement ! ( not on a roof that firemen will be walking on)

And you need to insure your AC wiring from pole to main panel, can handle the array output without faulting the inverters. (from high resistance)

Thanks Mike, can you give more detail on the AC wiring. Do you mean from the pole mount/array to the inverters? How can you tell, does it need to be a certain gauge?

[Mike90250]

AC wiring is from the inverters, thru the main panel, and to the Grid. Every connection, length of wire, gauge of wire, has resistance. Resistance & amps = voltage.

The problem arises when a perfectly adequate 200A house service, from your color TV, back to the power pole (Grid) has some resistance, and your TV (and fridge, and lights....) see 115V instead of 120V from the grid. 5v droop, not a big problem.
Until you add some grid tie inverters, and then THEY see resistance. The grid (which is really 240V) is (for all purposes) is always 240V, but that 5V droop your TV saw, becomes 10V going the other way, when the 240V inverter is cranking all day. now your inverter starts to see 250VAC and stands a chance to go offline because of improper Grid voltage. Folks with micro inverters often see this, around noon, a couple units (with low voltage calibration) trip offline for an hour or two, because of the 7Kw being pumped into the grid. Houses seldom consume 7Kw, and so the voltage droop never really gets noticed, till the inverter goes overvoltage and shuts down.

The longer the AC runs are, the more susceptible your system is. The DC runs do not affect this.

[jnook]

QQ... is two 7600A SolarEdge inverters enough for the system? Seems too low? (45x360 panels = 16,200 vs 15,200 on inverters?)

We're going with the 7600A style inverters in case we add batteries in the future...

Thanks

[nanewnanew]

Unfortunately strings are not a code compliant solution for new installations unless rapid shutdown electronics are installed on the roof. These have just as much complication and reliability concerns if not more. So we are left with what is the best that remains viable after a poor code provision. My opinion is that if the Enphase grid-independent operation promised for IQ8 turns out to be legitimate (and backward compatible to light up current IQ6/IQ7 micro-inverters), Enphase will move to the front in value proposition. If SolarEdge announces something similar, look for it to be available in 3+ years.

Is this true? Is there no way to get a simple string system with high reliability anymore that is up to code? I am looking to install solar on my roof in Southern California and get plenty of sun, just don't want to deal with all the constant microinverter/optimiser worry. What string system options are there? I don't know much about it all just trying to learn from others who have shared their horror stories with SunPower and the like.

[Mike90250]

Unfortunately strings are not a code compliant solution for new installations unless rapid shutdown electronics are installed on the roof. These have just as much complication and reliability concerns if not more.........

I think you are oversimplifying and glossing over a couple factors. Rapid shutdown electronics on the roof, are quite simple, low power circuits, and much less complex than microinverters, and even less power density that optimizers.
Things that fail are High Power, Complexity, and Density.

here's a link to one such system. These have to be designed into a system, it's not an easy afterthought to add on.

http://www.midnitesolar.com/rapidShutdown/rapidShutdown.php

[ButchDeal]

I think you are oversimplifying and glossing over a couple factors. Rapid shutdown electronics on the roof, are quite simple, low power circuits, and much less complex than microinverters, and even less power density that optimizers.
Things that fail are High Power, Complexity, and Density.

here's a link to one such system. These have to be designed into a system, it's not an easy afterthought to add on.

http://www.midnitesolar.com/rapidShutdown/rapidShutdown.php

The birdhouse system is not cheap and works with disconnecting combiners.
It also does not provide any monitoring or performance improvements for the added costs, just shutdown capabilities.

[nanewnanew]

So does anyone have a system that has not had problems in say 5 years, much less 20 or 25?

[bcroe]

So does anyone have a system that has not had problems in say 5 years, much less 20 or 25?

There is a a ground mounted string system here running over 5 years with no component
failures. There were a couple wiring issues in the first couple years, which seem to have
been cleaned up now. Bruce Roe

[J.P.M.]

So does anyone have a system that has not had problems in say 5 years, much less 20 or 25?

FWIW, the first PV system went into my HOA in 2006. It's one of the systems I informally monitor. It has not had an issue. There are currently ~ 130 systems now in my HOA with probably over 2,000 panels among them. To the best of my knowledge, there have been 2 panel failures, both infant mortality early on, one on startup. There have been maybe a dozen micro failures, with most of those of the M190 micro. I do not believe any string inverters have failed. My system will have its 5th anniv. on 10/17/2018. It has not missed a beat.

A corollary to Murphy's law: KISS. Less complicated things fail less.

[jflorey2]

So does anyone have a system that has not had problems in say 5 years, much less 20 or 25?

Let's see - I put up an SMA based system in 2002, expanded it in 2005. It is still working fine; no required maintenance other than cleaning panels occasionally. Only problem is that the plastic over the display has gotten so yellow that I can barely see the LCD. (Secondary problem is that neighbor planted trees, but that's not a problem with the system.)

When we bought our most recent house they had put solar on it in 2008. That is also still working fine. The two Sunpower (actually Fronius) inverters are showing their age, and they are noisy, but they are still working well. If they go south they will likely be replaced with two SMA inverters.

[littleharbor]

[QUOTE=jflorey2;n385229]
Only problem is that the plastic over the display has gotten so yellow that I can barely see the LCD.



Is the inverter mounted outdoors, in a sunny location? These SMA inverters are built like tanks and can handle the weather. If outdoors it would always be better to locate in a shaded location but it just goes to show how well their products are made.

[jflorey2]

Is the inverter mounted outdoors, in a sunny location?

Yep, side of the house. Knowing what I know now, I would have put an overhang to shade it (with a long cutout to allow heat to escape.)