First system - offgrid advice needed please

Started by vikkip, August 07, 2023, 10:34:40 PM

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vikkip

I'm weeks away from needing to order my solar system, and I'm having doubts about every system I've researched.  We're building a new off grid vacation home.  Peak load will be about 6kW and max daily usage in winter about 17kWh.  However, most of our use will be in summer, with the house up on a ridge and clear sky views to south and west. 

We have the option of installing rooftop on a standing seam metal roof 8:12 pitch, south facing, or pole mounts.

I met with a local solar installer, who quoted MidNite Solar Rosie with Hawke's Bay 90, 12 365w panels on two pole mounts, and 6-75AH 48v LifePO4 batteries.

Compared to other brands, I find MidNite's available information to be sparse, and features to be thin (no web monitoring?  I live 2.5 hours away, and need to know if there is an issue that needs my attention).  Though it looks like a solid system for the money, I want to be sure I'm buying a system that I won't find huge gaps in after installation.

With this setup, where would I connect a generator's AC output for emergency charging?

I haven't yet found a battery system that makes me happy.  If you were looking for 24kWh-30kWh of affordable battery storage, what would you choose?

My Renogy Rover 20, which powers lights and a small inverter and phone chargers in my barn, warns that if the batteries are disconnected from the charge controller while the PV is active, system damage will result.  I haven't yet used LifePO4 or other large format lithium batteries - if the controller or battery BMS shut down the batteries on a detected low voltage, high temp, low temp, overcurrent or other fault, will the MidNite controller be damaged?  Can a system be reset remotely?
**SEEKING KNOWLEDGE for my new off-grid homebuild**  Renogy Rover 20, 2x100 HE

qrper

Hi, and welcome to the MidNite Solar forum.

It sounds like a nice system you're planning. I don't see any mention of a dc to ac inverter, so I'm wondering if that's in the works?

I, personally, like pole and or ground mounted solar panels. It makes it so much easier for maintenance on the panels, if needed.

There is web monitoring, the mymidnite (get the software from the MidNite webpage) for the classic controllers. I don't have a Hawke's Bay controller, so maybe it works with the mymidnite software. BoB will have to chirp in to give you a thumb's up or down. There are some slick new software coming out, yeah, you need it now, and personally, I can hardly wait myself. If you're looking for over the air internet stuff like Outback and Schneider, it is in the works for MidNite Solar.

i'm going to assume you're using some sort of dc to ac inverter, and 99% of them have an external ac input, usually designed for a generator. Some, not all, inverters have the ability to start an exteranl generator. I know the MidNite Rosie has that feature. The guy who specified the components for your system should have told you where the generator would connect.

I'm old school. So I personally lean toward lead-acid batteries. Yes, I know, but I haven't drank the lithium tainted Kool-aid yet. And being 2.5 hours out, you might want to pass on flooded lead acid batteries as they do require some maintenance. AGM lead acid perhaps?

The rack mount lithium batteries are quite popular. They usually come in 5.xx kWh and run about $1700 depending on brand. Your 75Ah at 48 is around 3.6kWh. Six would be just shy of 22kWh. You'd need about five of the rack batteries (25kWh) so about $8500. Only you know the price of the batteries the dealer quoted.

I can't say with 100% positivity about disconnection of the batteries from the MidNite controller will damage it. I've done it here with my classic, and didn't let out any of the magic smoke.

And as far as I know, you can't remote reset the classic (or Hawke's bay) remotely, at least as of today.

Hope I was of some help, sounds like a nice system

There's plenty of smarter people here and more a tune with the interworking of MidNite solar.

Mike

System one: 7kWp w/ Trina 250 W panels @90 Vdc. Classic 150 to 16-6 V U.S batteries. Trace 5548 sine wave inverter.
System two: 6kWp grid tie with solaredge inverter.
System three: Midnite Brat, two 120 W Astropower modules, 100 Ah battery. Runs the LED streetlight in the back yard.

vikkip

Thanks for the thoughtful reply.  Yes, Rosie was the name of the inverter (drew a blank while typing and forgot to fill it in before posting).

I'm leaning toward the rack mount batteries due to increased capacity for the $ over the brand he recommended that I never heard of and can't find info on.  I'm a bit leery about buying product that will be with me for 10+ years best case, or flush the money away worst case, if the vendor isn't truly behind their products.

EG4 LL appear to be good...are they better than the much cheaper EG4 Lifepower?
**SEEKING KNOWLEDGE for my new off-grid homebuild**  Renogy Rover 20, 2x100 HE

ClassicCrazy

Quote from: vikkip on August 08, 2023, 11:18:06 AMThanks for the thoughtful reply.  Yes, Rosie was the name of the inverter (drew a blank while typing and forgot to fill it in before posting).

I'm leaning toward the rack mount batteries due to increased capacity for the $ over the brand he recommended that I never heard of and can't find info on.  I'm a bit leery about buying product that will be with me for 10+ years best case, or flush the money away worst case, if the vendor isn't truly behind their products.

EG4 LL appear to be good...are they better than the much cheaper EG4 Lifepower?
EG4 , SOK, Jakiper all batteries in the same price point and with similar cells and warranties. EG4 and SOK have US dealers for support . Also look up Trophy batteries.
Lithium battery systems are ever evolving as are the bms in them. Look up Off Grid Garage on you tube because he goes very in depth into all the details ( maybe too much for a general consumer).
 
The Midnite Hawkes Bay and Rosie are newer products that are recently on the market and still evolving in their firmware and monitoring. The Midnite Classic over the years got a lot of major firmware upgrades that gave it much more capability ( Whizbang addition being one of them that gave very precise SOC monitoring and control ).
Not sure how long it will take for new features of the new products to roll out. Better monitoring options are supposed to be on the horizon.  Midnite does have very good customer support and warranty. Their products are built rugged and solid and in USA. Over the years Midnite has always been active on the forums to take direct feedback of issues and to take suggestions and add new features that have been suggested. Not a lot of companies do this on a public forum.
I think if you went for that option might be worth the cost to go with a Hawkes Bay 120 instead of 90 in case you ever want to add more PV in future ?

I dont' have a Rosie but pretty sure that will take generator input to charge batteries.
 
Not sure where your location is. If snow is a thing , then ground mounts make it a lot easier to sweep off snow, as well as QRPer said to do and troubleshooting or maintenance.

Larry

 
system 1
Classic 150 , 5s3p  Kyocera 135watt , 12s Soneil 2v 540amp lead crystal for 24v pack , Outback 3524 inverter
system 2
 5s 135w Kyocero , 3s3p 270w Kyocera  to Classic 150 ,   8s Kyocera 225w to Hawkes Bay Jakiper 48v 15kwh LiFePO4 , Outback VFX 3648 inverter
system 3
KID / Brat portable

qrper

Quote from: vikkip on August 08, 2023, 11:18:06 AMThanks for the thoughtful reply.  Yes, Rosie was the name of the inverter (drew a blank while typing and forgot to fill it in before posting).

I'm leaning toward the rack mount batteries due to increased capacity for the $ over the brand he recommended that I never heard of and can't find info on.  I'm a bit leery about buying product that will be with me for 10+ years best case, or flush the money away worst case, if the vendor isn't truly behind their products.

EG4 LL appear to be good...are they better than the much cheaper EG4 Lifepower?

That sounds like a good plan!

I have a Rosie that I've been beta testing, and so far she's handled it all without issues. I use the grid as my backup generator, so i can't say how Rosie handles a generator.Yes, you can connect a generator, and the last time I looked on the menus, there is an automatic generator start for two wire generators, which is the most common type.

As far as the lithium server rack batteries, I'd suggest you log into the DIY solar forum (google 'em) and read the reviews on all the server rack batteries as well as the suppliers.

Like Larry mentioned, 'Andy's off grid garage' on YouTube has a lot of info on BMSs. The guy certainly loves his BMSs!

Mike

System one: 7kWp w/ Trina 250 W panels @90 Vdc. Classic 150 to 16-6 V U.S batteries. Trace 5548 sine wave inverter.
System two: 6kWp grid tie with solaredge inverter.
System three: Midnite Brat, two 120 W Astropower modules, 100 Ah battery. Runs the LED streetlight in the back yard.