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Newbie to Solar - System Design Overview

SunInCo

New Member
Joined
Dec 8, 2024
Messages
8
Location
CO
Hi all, this forum has an ungodly amount of info in it, which is awesome! My background is first in software engineering, and also some experience with integration and test of fully Direct Current avionics hardware.

I'm trying to layout a first-cut at a solar system but I'm having trouble narrowing down what options I have for the components of a microinverter-based solution. I know if I go with a completely Enphase solution, then I can get the entire Enphase ecosystem to cover the rest of the system hardware, but I want to know if I can use other components from other vendors if I want to, and if so, how much additional (if any) stuff will be required to make it all play together. Also, if I mix-n-match other components, I'm guessing I'd need 1 app for monitoring the arrays, a different one for the inverter, and maybe even a different one for the battery monitoring if the batteries and AC-DC converter are not from the same manufacturer, etc.

I like the idea of using a microinverter solution because of the monitoring ability of each panel and the relatively safer running of AC from array to outbuilding compared to the high voltage run a string-inverter solution would entail. Ground mount is so I can 1) seasonally point and 2)install and maintain this system without having to be up on a building that has an 18' eave.

System info as it currently exists in my head:
~15kwh, grid-tied for now, but eventually consider going off-grid 5-10 years down the road
IntegraRack Ground Mount 45SA for seasonal pointing
36 420A REC Pure 2 panels
36 Enphase microinverters
~230' run from the panel array to the first component in the outbuilding where the components will live, including the batteries

If its a solely Enphase system, then I would include:
- Combiner
- System Controller
- 3x 5P batteries

But, what I'm trying to understand is how I'd use, say, an EG4 inverter and batteries (e.g. FlexBoss/GridBoss?). Or a Sol Ark inverter instead of EG4. And maybe Bluetti batteries instead of EG4. There's just absolutely so many options out there for inverters and batteries, these are just a few examples of non-Enphase ecosystem products and I'm not committed to any specific brand at this point.

I've spent hours gathering info about my property and the proposed layout of where things would go, looking at videos, reading about Voc, and on and on. And I fully admit, I still know maybe 1% of what so many of you on this forum know. All of this to this point has really just lead me to analysis paralysis where I can't even think straight lol.

So, this is where I thought I'd just post this message and hopefully get at least get pointed in a direction that will help me understand a non-completely Enphase microinverter system solution better. I feel like I have the string inverter system and needed components understood well-enough that I could make sensible decisions on that type of system. But, as stated above I feel like the microinverter solution is really what I'd like to have.

Any and all thoughts and input are very much appreciated by this noob.

Jeff

Oh, probably would have helped to say that I have 200A service to my house, and 200A service to my outbuilding, single power company feed into a single meter before splitting the incoming power for 200A service each to the house and outbuilding. I would be using this solar system to power both when its sunny enough or when I draw off batteries. Otherwise, it would be back-feeding to the grid.
 
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Welcome to the forums Jeff!

Enphase is a great system! It's what I have. Having all the components seamlessly integrated with one management system is worth a lot. But, in addition to being pricey they do try to lock you into their components.

It's not all corporate greed and there's enough trickiness that its not easy to be plug-n-play. As a software professional I'm sure you know that a part of the reason Microsoft has such a bad reputation is because they allow 3rd party applications and in the early days people didn't build exactly to their specs causing countless BSODs. In terms of solar, for example, there's a ratio of microinverters that can be charging one of their batteries so as to not exceed battery parameters and balancing house load against charging; if you're off-grid the amount of output power must be carefully balanced. The average home owner that hasn't invested the time you have is just going to always expect things to work and not have to do anything special, Enphase makes it so you can forget about your system, it just works.

They also do things they don't advertise because people don't understand it until they encounter it. For example one surprise people find on an 8k inverter is that they can only get 4k per leg, not the full 8k (e.g., that 120V compressor won't run). The Enphase switch (System controller) has a highly efficient built in neutral-forming transformer to fix that problem. Another little thing I like is WeatherGuard, it automatically changes my battery to full backup mode when bad weather is expected.

That said, I've frequently looked at different ways to add more battery capacity to reduce costs to something I could manage (e.g., going through the System Controller's generator port, incrementally adding AC Batteries). But to do it safely always ends up costing me more than just buying Enphase. But a few years back I heard about V2H and decided to wait ditching the generator as I realized I could more battery power than needed for very little.

Enphase is about to launch ( 🤞 ) a bidirectional EV charger. Which means you can use your EV as emergency power for your house, thus eliminating the need for expensive 3rd party batteries and providing a lot of backup power. Anyway, hope the rambling has been of some use.
 
Replying to my own thread again here, but...

After talking with some friends I've decided to abandon the microinverter route and go with a traditional string inverter setup using the FlexBOSS and GridBOSS hardware along with 2 or 3 indoor EG4 wallmount batteries. And again this would be a grid-tied system. My setup is that I have utility feed of 400 amp service (so I guess that's really 320A). I have a Milbank 320A panel that has the main utility meter that feeds 2 200A breakers. One 200A goes to my house, the other to my shop about 100` away.

I'm trying to see what it takes to get all my loads power, even during a grid outage even if at a reduced max current capacity. I was thinking that to make this work I may need to use 2 GridBOSS, as drawn here. Does this layout even make sense? If this even is legal electrically, i believe it would limit my shop to 90A max current, which is fine since that would only be the case in grid-down situation. Again, I THINK!

I could have this all 100% wrong, feeding a GridBOSS Grid output into a GridBOSS Inverter input - can that even be done? It's all AC so I thought maybe it could, but maybe there's a system control issue with that in that the 2nd GridBOSS doesn't know it's not an inverter connected to the inverter port.


1734028761652.png
 
Replying to my own thread again here, but...

After talking with some friends I've decided to abandon the microinverter route and go with a traditional string inverter setup using the FlexBOSS and GridBOSS hardware along with 2 or 3 indoor EG4 wallmount batteries. And again this would be a grid-tied system. My setup is that I have utility feed of 400 amp service (so I guess that's really 320A). I have a Milbank 320A panel that has the main utility meter that feeds 2 200A breakers. One 200A goes to my house, the other to my shop about 100` away.

I'm trying to see what it takes to get all my loads power, even during a grid outage even if at a reduced max current capacity. I was thinking that to make this work I may need to use 2 GridBOSS, as drawn here. Does this layout even make sense? If this even is legal electrically, i believe it would limit my shop to 90A max current, which is fine since that would only be the case in grid-down situation. Again, I THINK!

I could have this all 100% wrong, feeding a GridBOSS Grid output into a GridBOSS Inverter input - can that even be done? It's all AC so I thought maybe it could, but maybe there's a system control issue with that in that the 2nd GridBOSS doesn't know it's not an inverter connected to the inverter port.


View attachment 262520

We are looking at doing something similar using the Gridboss, Flexboss21 and ask for some suggestions in a post on Dec 8 titled "Setup suggestions on new solar system". Hopefully one of us will get some suggestions.
 
Time has passed, and I've come up with the attached cut at new plans. 40 panels, complete EG4 main components solution. Would love to have feedback on the high-level design. Am I on the right track here or off in the weeds?
 

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