A simple build, or so I thought; 12 panels, MidNite combiner & Classic 150, 2 LiFePo4 200Ah, Inverter …


It's not happy hour, I'm just like this.
Nov 23, 2021
Thunder Basin Wyoming
Hello folks, I am new to solar and this is my first build. I have studied quite a bit and now feel confident that I know enough to be dangerous. Any corrections, advice, “Do Not Do This”, or other input would be greatly appreciated.

Want more info, please ask and be patient, I have a dumb phone that is smarter than me.
Links to information will be studied and appreciated.
I’ve visited many sites but have not found “Solar for extra special dummies” yet.

Following is as in-depth as I could get on the first phase of my system. The second phase will just double the panels and batteries. I have tried to avoid confusion by not discussing the second phase in this post, but I am considering the expansion in all my calculations.

After reading a few responses I am editing this, and the following page so no one wastes their time.

The ARRAY of Solar panels will probably be in the 300 watt range.
Wire runs will probably be the same distances, but volts, amps and other data will change when I decide on panels.
Combiner box, Controller, Batteries will remain the same.
End Edit #1.

Edit #2, 12-12 5:30pm
Trying to get this thing cleaned up.

THE ARRAY: I am now in search of panels in the 350 watt range.
The array will be entirely composed of Newpowa NPA100S-12H.
The system is 12 12v, Voc 20.23v Isc 5.89a, 100w, panels.
There will be 6 panels in series with 2 strings of less than 26 feet to the nearby combiner box.

I believe 121.38 (Voc) volts and 5.89 (Isc) amps of current will run to the combiner from each string.

I found a good source to find out if any inline fuse(s) and/or diode(s) will be needed as I connect my panels in series or proceed to the combiner.

Additional wire and connectors will be needed to reach the combiner. The farthest panel should be less than 25 feet from the combiner. I intend to use 8 or 10 awg solar cable, for a max 2% loss up to 26’. The wire will be of appropriate color and IP68 connections will be used whenever possible.

Shading of individual panels will never be an issue, unless I am standing there scratching my head.

MidNite Solar MNPV6 Combiner will be the last exterior component of the system.

At the combiner I will combine strings to up the voltage for the 55' run to the controller.
On the combiner box I believe the MidNite Solar MNSPD-300-DC 300V Dc Surge Protector Device would be a good idea.

Breakers being considered are manufactured for MidNite and limited to 150 volts.

Am I correct in assuming my breakers will be tripped by any voltage in excess of 150?
What about those sub-zero mornings? Will I be running outside to reset breakers sometime after sunrise?

If the breakers trip at 150+ volts, my charge controller should never experience “HyperVOC” or ever be subjected to any “OVERVOLTAGE” condition. Seems as though I am adding an additional level of protection for everything downstream. I’m good with that provided I am correct.

Wires leaving the combiner will be in schedule 40 PVC conduit with 3 large radius 90 degree elbows throughout the entire run. The box will be mounted on and the conduit will pass through a 12” thick concrete wall and into a garage, across the ceiling of a bedroom (oh joy I get to do crown molding), into a very shallow attic and finally down into a closet to join the remaining components of the system.

The intent is to place the controller, batteries, inverter (not above batteries), gauges Etc. within a closet, with louvered doors, inside the living quarters of my residence. Can anyone think of a reason I should not do this?

My research leads me to believe up to 4 strands of 6 awg will live happily ever after inside ¾” conduit.

Using the initial panels, which I will not be using, and numbers from the MidNite Sizing Tool, which you can see below:
I am guessing between 102v and 150v depending on temperature and sunlight and up to 11.78 amps of current will be carried to my controller when the amps are at 100%.

On those hot days with minimum sun I need to get 102 volts 55 feet to the controller with minimal loss (2%). Again, research leads me to believe 6 awg will get almost all the volts there. I did look at a few wire/cable sizing sites and they produced conflicting numbers, so I am leaning towards 6 awg THHN THWN Stranded Copper Building Wire; Yes/No/Maybe?

I am living on the High Plains, I get snow, massive thunderstorms with a great deal of lightning, excellent sunshine, and a lot of 60+ mph winds. Larger panels are not really an option and these will be mounted pretty close to the ground with a lightning rod nearby.

Input would be appreciated before I push the buy button. Great input so far, THANKS

How I got my numbers:
I used the Classic String Sizing Tool at midnitesolar.com/sizingTool/index.php

I could NOT figure out which numbers to plug into VOC or VMP Temp Coefficient boxes, so I left them set at default.

The solar panel manufacturer has these numbers on their website: It’s over my head folks.

Temperature Coefficient Of Voc -(80+/-10)mV/ (I am assuming the little “0” means “Degrees”)C
Temperature Coefficient Of Isc (0.065+/-0.015)%/ (assuming the little “0” means “Degrees”)C
Temperature Coefficient Of Power -(0.5+/-0.05)%/ (assuming the little “0” means “Degrees”)C


Here are the other numbers from the manufacturers website. Amazon numbers differ from newpowa.com.

Monocrystalline Module

Type NPA100S-12H
Power Output(W) 100W
Voltage MPP Vmp(V) 17.0
Current MPP Imp(A) 5.89A
Voltage Open Circuit Voc(V) 20.23
Short Circuit Current Isc(A) 6.25A
Temperature Coefficient Of Voc -(80+/-10)mV/ C
Temperature Coefficient Of Isc (0.065+/-0.015)%/ C
Temperature Coefficient Of Power -(0.5+/-0.05)%/ C
NOCT (Air 20 degrees C; Sun 0.8kW/meters squared wind 1m/s) 47+/-2 degrees C

01 12-9 PhaseOne MS Tool Results.png6 x 2 24volt post -4 .png

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It's not happy hour, I'm just like this.
Nov 23, 2021
Thunder Basin Wyoming
This goes with my initial post.
Edit #1 12/10/21 5:00 (Happy Hour)

Below is a comprehensive shopping list with links to seller and manufacturer in some cases:

SOLAR PANELS: 300 watt, give or take. Make & Model undecided.
SOLAR PANELS (2 pack) Q=6:
Newpowa 100 Watts Monocrystalline 100W 12V Solar Panel High Efficiency Mono Module RV Marine Boat Off Grid(2 pcs)


MidNite Solar MNPV6 Combiner

https://www.solar-electric.com/mnpv6.html (Northern Arizona Wind & Sun)


MidNite Solar Photovoltaic DC Circuit Breaker - 20 Amp, Model# MNEPV20

https://www.solar-electric.com/mnepv.html (Northern Arizona Wind & Sun)

------------------------------------------- OR ----------------------------------------

Din Rail Mount Combiner PV Breaker - 15 Amp, 150 VDC, | MNEPV15


MidNite Solar CLASSIC 150 MPPT Charge Controller, 150 Operating Voltage, Max Current Out 96 Amps, ETL Listed to UL1741 and CSA, Type 1 Environmental Rating, Terminals are Rated for 75°C


INVERTER Q=1: This item is subject to change.
EDECOA 3500 Watt 24V Pure Sine Wave Power Inverter DC 24V to 120V 110V AC with LCD AC Terminal Block (3500W/24V V3.1 ( ET-RC Remote))

https://edecoa.com/ "Hmm this product is not listed on their site"


IP68 CONNECTOR (5 pack) Q=unknown at this time:
Witproton Solar PV Connector IP68 1500V 40A Hollow Tinned Copper Terminal Black 5 Pairs (2.5mm2~6mm2 (14AWG~10AWG))


IP68 BRANCH CONNECTOR (2 pack) Q=unknown at this time:
Witproton PV Solar Connector Branch Y T IP68 Waterproof 1000V 1500V Solid Copper Terminal 2 Male 1 Female and 2 Female 1 Male (2to1 Branch Connector)


SOLAR CRIMPING TOOL KIT Q=1: Somehow I caught this item at $19.99, Dec 6, 2021.
List Price: $49.83 Price: $19.99
IWISS Solar Crimping Tool Kit with Wire Cable Cutter, Stripper, Crimper and Connectors Assembly and Disassembly Tool Solar PV Panel Tool Kit


DC CLAMP ON METER Q=1: If this works as advertised, I will be very impressed.
AmazonCommercial 600A AC/DC Clamp Meter, True RMS, NCV, Flashlight, 6000 Count

------------------------------------------------- END SHOPPING LIST -----------------------------------

Items I already have:

LOSSIGY Lifepo4 12 Volt 200AH Deep Cycle Lithium ion Battery Perfect Replace for RV/Camper/Trailer Solar/Wind Power System Marine Battery, Maintenance-Free Built in 100A BMS

Seller: Rclithium, seem like pretty good folks.



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Participation Medalist
Nov 5, 2019
Silicon Valley
The system is 12 12v, Voc 20.23v Isc 5.89a, 100w, panels.
Is there a reason for choosing a dozen little panels instead of just a few big cheap panels (often found on Craigslist or locally for around $.50/watt?

Mounting and wiring a lot of panels is a pain and gets spendy too.

If you post your location, maybe someone can point you to big cheap panels in your area.


Solar Addict
Oct 21, 2021
Also, look beyond Amazon. I bought a Classic 150 a couple of weeks ago from Northern Arizona Wind & Sun for $635, free shipping, and an inverter from DonRowe.com for $300 less than the cheapest price on Amazon. There are still lots of stores out there that don't sell on Amazon and can reduce their prices not having to pay their fees. I'm using Samlex inverters, the EVO series, a 2kw and a 4kw, great quality and tons of features, check out their prices on DonRow.com and compare. They are a lot more attractive at those prices.

Good choices on egear, I have 3 Classics running and they've done a fantastic job for me, investing in quality gear up front is a great idea if you can afford it.

You might want to consider your panels though. I understand your environment, been there, but new larger panels aren't that much larger and are built tough. I just picked up 24 of the REC 370w panels from Santan Solar at a great price, they're only 65" tall, the same size as my older 250 watt panels and actually weigh less. If you buy a quantity of panels from someone who knows how to ship them the freight isn't an issue, it cost me $15 per panel to haul them across the country.

I've put up some huge radio communications systems in your environment and have seen corona discharge dancing off the ends of the antennas from static built up by the winds, amazing to see, but they all operated without issue due to intensive grounding and protection, you definitely want a high quality protector like the Midnite. To go with it a great ground system is critical, I'd use 3 ground rods, as long as you can drive, perhaps 6' apart and tied together with braided copper strap. For my communications systems we used 3 of those (9 rods) for each tower, and laid copper strap in the 100's of feet of 4' deep trenches dug for the cabling. The induced EMF from "mega-bolts" of lightning can be enormous, I can remember hearing the "click" of the wires in my house actually jumping when one of those hit nearby.

Good luck, you'll have fun. I've been building my system for a couple of years, still adding a bit at a time as I can.


Photon Sorcerer
Dec 30, 2019
Agree on Don Rowe and they actually answer the phone and answer questions. They even got the Mfr rep to answer a question for me.

For Northern AZ wind solar just sign up for their email list and get an additional 5% off your first purchase. They also have 5-10% off sales periodically during the year.

No sales tax for solar equipment in AZ also. I’m a satisfied customer of San Tan and the two above mentioned companies.

I always use 48v for inverter systems and avoid combiners etc. and save on wiring etc. but I know it’s not everyone taste.
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It's not happy hour, I'm just like this.
Nov 23, 2021
Thunder Basin Wyoming

Excellent input.
Had a chat with the little woman after checking recommended sites. AZ wind solar will greatly appreciate your input.
Midnight Solar products are less expensive, even without the 5% which we will sign up for, and they are not amazon.

I'm not the biggest fan of amazon but have not had any luck with my searches on the net. So again, Links or company names are appreciated.

Your input has also convinced us to purchase larger panels. Guess I had tunnel vision, it happens.
Now I have to put on my "Big Boy" pants and figure out a ground mount that won't end up on the other side of the prairie.

And to BvilleBob, great idea on the grounding. I've seen enough "Saint Elmo's Fire" to last two lifetimes, sounds as though you have as well. Yes I can and will be driving 8 or 10 foot copper and using copper strap. Gotta get a bit smarter on that subject.

A bit of research on 370w panels from Santan Solar:
The product was not in stock on the website, so I called AZ and got Georgia. AZ location was at their Christmas Party!!! Good for them.
So I spoke with Alex, a very patient and helpful chap. I was informed some of their products do not make the website because they only get a few pallets. Sounds like the phone call was worth the time.

Anyway, the MidNite Classic 150 will handle 10 of the 370w panels and take us 700 watts over our average daily use. We will save bunches of money, and get more energy with less wiring compared to a dozen or two little panels.

The upgrade to 4 200Ah batteries may be coming sooner than I thought. It would be great to start at the finish line.
The end system is intended to be 48v battery pack, and 120/240v inverter.

So, there it is. You folks threw a bit of fuel on the fire. Fire is good, spent 3 hours moving snow today.

SpongeboB Sinewave

Solar Enthusiast
Feb 25, 2021
WA State
Just a note here. The circuit breakers do not trip on over voltage. They trip on over current only. So you have to design in how many panels you connect up in series based on the coldest temperatures they will see which will raise the voltage into possibly the hypervoc region above 150 volts. You should rather not have the voltage that high as you will not be charging when it is that cold and the sun is out.

There are various string sizing tools on websites out there to help calculate the highest voltage you will see in a particular low temperature including on the Midnite Solar website


It's not happy hour, I'm just like this.
Nov 23, 2021
Thunder Basin Wyoming