Author Topic: MidNite E-Panel vs Magnum MP Panel  (Read 182 times)

ICPete

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MidNite E-Panel vs Magnum MP Panel
« on: March 29, 2019, 04:03:54 AM »
Hi,
I'm a new forum member but have lurked here before searching for information about the charge controllers etc.
I'm a degreed mechanical engineer with some solar PV experience reaching back to the early '80s. But this is not my business activity, only personal.
I have extensive mechanical expertise and quite a bit on the electrical side; I do plan to engage a licensed electrician and/or solar installer to help with the installation, and the county building department requires a PE-stamped electrical design for the PV system. So at this point I'm just trying to understand the major component choices and compile a cost estimate.

I'm designing a residential system to be constructed late this year or early next year; I'm in the early planning stages.
I've done the whole load analysis around the design of our new home where this system will be installed. Panels will be ground mounted so RSD is not required. I definitely want to include PV GFP and AFP however. I'm not looking for input on the overall system design, but here are the basic parameters:

40 panels, 60-cell, 305W Canadian Solar; wired as 8 strings of 5 in series; two strings connected in parallel to each CC
4 Classic 250 Charge Controllers
48 KWHr of LTO batteries (lithium titanate) @ 48V nominal
Off-grid inverters: leaning towards four (4) Magnum MS4448PAE stacked to provide 240/120 split-phase output
Also considering two OB Radian GS8048A
Operating mode will be "Mini-Grid", where the system attempts to power all loads through the inverters, and only sucks grid power when required to recharge the batteries.
I'm not planning to sell back power to the grid; I just want to buy as little as possible and be quasi-independent of it.
Backup for "grid-down & low-solar" days will be either a generator OR eliminating HVAC loads via an LP boiler (heating system will be hydronic, and our summers are generally mild enough here at 5000 ft that we could go several days without A/C if necessary).

So with that introduction out of the way (and thank you for reading this far!), here is my question:

Given the 5-yr warranty on Magnum inverters if installed on their own MP panels, is that generally considered a good enough reason to spend the higher price, compared to using the MidNite E-Panel solution?

I've studied both their installation manuals to get a feeling for what's involved with each of them. They both appear to be well thought-out products.
What I haven't really seen, even in photos, is how the E-Panel solution would accommodate 4 inverters; though I have read that they are designed to stack either vertically or horizontally (I will install in a shed and should have plenty of room for four E-Panels horizontally arranged on one wall).
I think one major issue will be how to implement AC bypass, to operate from grid power directly in the event one or more inverters fail; perhaps I would simply disconnect the AC output of any failed inverter(s), but when the last one fails, bypass is required. With four of them, perhaps total failure is extremely unlikely.

My local dealer is NAWS, so of course in the end I will spend time discussing this with them in detail to make the decision.
But if anyone on this forum can offer the "voice of experience" regarding this tradeoff (MN E-Panels vs Magnum MP Panels), I'd love to hear it.

Pete

ralph day

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Re: MidNite E-Panel vs Magnum MP Panel
« Reply #1 on: March 29, 2019, 08:56:35 AM »
I'd do a little math to check the economics of using a generator on low solar days.  Any fuel consuming charging system is going to cost more than using utility power to charge when it's available.  I have  10kw diesel and 2.8 kw gas generators, and there's so way they're cheaper for charging than the utility.  That might not be true in Hawaii or SOCAL time of use.

For outages, if it's not long term, like your usual overnight solar outages, then a generator is good to have around.  I haven't seen a long utility outage in my locality since 2003 (half of North America out).  Usually windstorm damage, ice storm or some knob hitting a pole with their car puts things out for hours only.   We still answer "maybe" when neighbours ask if our power is out.  (Off grid with utility as backup generator and battery system)

Ralph

ICPete

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Re: MidNite E-Panel vs Magnum MP Panel
« Reply #2 on: March 29, 2019, 03:04:48 PM »
Hi Ralph, thanks for your comments.
I wasn't clear enough, that the backup I listed was only for days that are BOTH "grid-down" AND "low solar".
For "low-solar" days when the grid is UP, the grid will provide juice to recharge the batteries.
For "grid-down" days when there is adequate sun, well, PV is providing all we need anyway.
When both "low-solar" AND "grid-down" occur at the same time, then I will have a generator, but my main plan is to reduce demand by burning LP in a high-efficiency boiler; the hot water will provide both winter space heating and domestic hot water. All other electrical loads can be minimized so that even on an extremely overcast day, we should get enough PV input for the truly critical loads (refrigerator for example). And if this event were to occur during hot weather, well, we can go several days without A/C here (the house will be built with a huge amount of thermal mass as in concrete walls and floor).

Still looking for comments regarding experience with the E-Panel vs the MP Panel...

Peter

Westbranch

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Re: MidNite E-Panel vs Magnum MP Panel
« Reply #3 on: March 29, 2019, 09:21:02 PM »
You might have to post over on the NAWS BB as most here are MidNite fans/devotees...  you may find some other comments/suggestions about building houses and systems too...

Q?, is it the LTO batteries that makes you have to have 4 controllers?
KID FW1811 560W >C&D 24V 900Ah AGM
CL150 29032 FW V.2126-NW2097-GP2133 175A E-Panel WBjr, 3Px4s 140W > 24V 900Ah AGM,
2 Cisco WRT54GL i/c DD-WRT Rtr, NetGr DS104Hub
Cotek ST1500 Inv  want a 24V  ROSIE Inverter
OmniCharge3024  Eu1/2/3000iGens
West Chilcotin 1680+W to come

ICPete

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Re: MidNite E-Panel vs Magnum MP Panel
« Reply #4 on: April 06, 2019, 03:15:29 AM »
NO, the reason for needing 4 controllers is the max amperage of each one. With 10 panels on each CC the peak power to the batteries could reach 3000 watts, or 60 amps at 50 volts. That's right at the limit of the Classic 250 on a warm day. I've spent a lot of time with the Midnite string calculator online, as well as creating my own spreadsheet to compare many different makes and models of CC.

I've concluded the Midnite Classics are the best bang for the buck, especially since they include built-in AFCI and GFI. I'm concerned about AFCI because we are in an area of grasslands where fires happen almost every summer. I wouldn't want to be the cause of one!

My peak open circuit voltage gets very close to 45 v at the coldest temperatures here. So with five panels in series that's 225V, ruling out the Classic 200. Yeah, I know it can actually withstand 200 + battery voltage, but I also want it to start up and reach MPPT when it's very cold out, and I want some headroom in these expensive electronic devices.

SolarMusher

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Re: MidNite E-Panel vs Magnum MP Panel
« Reply #5 on: April 18, 2019, 03:36:07 PM »
For a quad system, you'd better use magnum panel. Reasons are: only 1x 125A bypass, 4x 175A disconnects in a small space, 5 years warranty, and it will take less time to mount the system, less space on your wall and a better look at the end.
For three inverters, same things...
For dual inverters, I prefer to work with 2x Midnite Epanel side by side.
Pro reasons are: all disconnect are reachable, easier to mount 2x CL controllers, a bit less expensive, better cooling, better design, PV bus, nice look on your wall, and I love Midniteā€¦
Cons are: Midnite backplate is not great, Grey color, really too expensive for its quality, only 3 years warranty for the inverters and one or two years for the rest of components.
A+
Erik
 
« Last Edit: April 18, 2019, 03:46:03 PM by SolarMusher »
Off Grid with 3.2kw PV | Classic 200/WBjr + Classic lite 200 | 2x Outback VFX3648 Epanel | 3x SPD300 + 1x Schneider HEPD80 | Hub + Mate + PSX-240 | 750Ah Rolls S-480 battery bank + Trimetric | 1200 watts DC water heater | 8000 Generac and 7200 watts Champion gas generators

ICPete

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Re: MidNite E-Panel vs Magnum MP Panel
« Reply #6 on: April 21, 2019, 04:54:47 PM »
Hi Erik,
Thank you for a very informative answer; just what I was looking for.
Great photo of your dual-inverter installation.
Peter

Kent0

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Re: MidNite E-Panel vs Magnum MP Panel
« Reply #7 on: April 21, 2019, 11:19:42 PM »
If you are doing a quad Magnum inverter setup with four charge controllers, consider the MPDH panel. Plenty of room for all the breakers you'll be installing and you get a 125-amp system bypass switch.

This is a big system:
4 Magnum 4448 PAE
4 x 4400= 17600W, rated surge capacity of 34000W, and 240 amps of battery charging

Did you consider this alternative:
3 Schneider Electric XW+ 6848 inverters with the Schneider Electric XW+ PDP
3 x 6800 = 20400W with a surge capacity of 36000W, and 420 amps of battery charging

ICPete

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Re: MidNite E-Panel vs Magnum MP Panel
« Reply #8 on: Today at 01:56:45 AM »
Hi Kent,
Thanks for that alternative.
For the 4 Magnums, yes, the MPDH and accessories was what I was considering for the Magnum "MP" panel system.

The XW+ or newer XW Pro 6800W inverters definitely sound like beasts.
As you point out, the surge capacity would be 36 KW, and that is rated for 60 seconds, whereas Magnum's 34 KW is their 5-second surge rating. Magnum doesn't show a 60-second rating, but does state 24 KW for 30 seconds (for 4 inverters).

In terms of cost, of course, the Schneider solution would be around $10K, whereas the Magnum would be around $7200 (just for the inverters, going by some published online pricing). I haven't looked into whether the PDP mounting/distribution system would end up costing similar to, or greater than, the MPDH mounting system, when comparing apples-to-apples for the full system.

I'm definitely not set on any particular inverter manufacturer, and am still trying to learn their pros and cons.
In fact I'm still somewhat considering AC coupling instead of DC coupling, i.e., using frequency control from the inverter/charger to reduce the output of string inverters, as opposed to using charge controllers.
My reasons for possibly leaning towards string inverters are their higher net efficiency when using the power real-time (during the day), as opposed to the efficiency when battery storage gets involved (night-time usage).
My loads SHOULD work out to be maximized during daylight hours, and my home's energy usage at night should be minimal (base loads like the fridge, computer, some lighting, and some water heating). But given the thermal storage of the house itself, I plan to avoid significant overnight energy use for HVAC. This means I should be trying to maximize efficiency for daytime usage of the PV output.

Using string inverters I could have adequate battery inverting power using just two of the Schneider XW+ (or Pro) 6848 inverters, as their power would be added to what the array is producing at any given moment. When there is insufficient sun, or after dark, I can probably limit consumption to 13,600 W. It might end up being a question of intelligent load control, in order to minimize grid usage.

It appears that the Schneider system, especially the new XW Pro inverter, is designed to be programmable for AC coupling, and would work with SMA or Fronius string inverters, which can respond to frequency control.
But I'm definitely out of my wheelhouse when it comes to this level of architectural design for the inverter system. So I really need to find a suitable installer I can work with; possibly NAZ Wind & Sun.

Anyway I'm definitely open to the Schneider options.

Peter

SolarMusher

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Re: MidNite E-Panel vs Magnum MP Panel
« Reply #9 on: Today at 07:51:29 AM »
Hi Peter,
For large system,  I will go with the Schneider XW (or wait for Midnite B17 with Classic) even if more expensive.
Best of luck,
Erik
Off Grid with 3.2kw PV | Classic 200/WBjr + Classic lite 200 | 2x Outback VFX3648 Epanel | 3x SPD300 + 1x Schneider HEPD80 | Hub + Mate + PSX-240 | 750Ah Rolls S-480 battery bank + Trimetric | 1200 watts DC water heater | 8000 Generac and 7200 watts Champion gas generators