Please critique my plans

ZebraStripes · July 2019

I am planning on self-installing some solar equipment and would like some extra eyes on my plan to make sure I'm not doing something stupid. The immediate needs are a battery bank to protect us from black outs and brown outs (Which are frequent), and to provide us some normalcy in the event of an other Maria. I have picked a battery capacity that should take care of us in both of these scenarios. I also plan on expanding this in the future to our casita, so I want to plan for this as well. I have the ability to add more battery storage and more MPPTs and inverters with this system, which should take care of us for future expansion, I think. Here is what I'm looking at now:

Storage: Fortress Power 16.5kWh Lithium Battery

Inverter/Charger: Schneider XW+ 6848

Panels: 24 Canadian Solar 355W Poly Panels in two strings of 12

MPPT: Schneider XW 80A MPPT (I believe I only require 1, because the total voltage going down the line will only be 12*24=288V, right? And if so, that's well within the parameters of the MPPT)

Conext Gateway, Power Distribution Panel, Genstart, Battery Monitor - The gateway to make configuring everything easier, the PDP to make wiring a lot easier because it has built-in disconnects, Genstart because we have a generator to start, the battery monitor for ... monitoring the batteries

Racking: IronRidge

Other: Extra breakers for PDP, wire

Questions:

1. I am also considering these Peimar panels (https://www.altestore.com/store/productos-solares-en-puerto-rico/pr-paneles-solares/peimar-grid-tie-solar-panels-puerto-rico-p41241/#PR-PEI330P-EACH) because of their lower price and immediate availability (Have to wait on Canadian Solar panels to get here). Thoughts? Worth the wait on Canadian or will the Peimar suit me just fine?

2. The inverter manual suggests that it only be used with battery banks of at least 440Ah, but the Fortress battery only has a capacity of 360Ah. Will this be a problem / Why does the ah capacity of the bank matter here? The manual says that if the batteries fall below 40V that the inverter won't turn on, but the datasheet for the Fortress says that it's minimal voltage is 45V.

3. What's the most foolproof way to make sure I am buying exactly what racking I require? The altE warehouse is quite a drive from here, so I only want to make the trip once if I can.

Photowhit · July 2019

ZebraStripes said:

I have picked a battery capacity that should take care of us in both of these scenarios.

Storage: Fortress Power 16.5kWh Lithium Battery

Inverter/Charger: Schneider XW+ 6848

It doesn't appear to be a balanced system. you will have about 13 kWhs of available storage. What do your daily loads run? Do you have something that has a high peak starting that would require this size inverter? Running near capacity, you would empty your reserves in about 2 hours. Usually an indicator or an imbalance.

ZebraStripes said:
Panels: 24 Canadian Solar 355W Poly Panels in two strings of 12
MPPT: Schneider XW 80A MPPT (I believe I only require 1,...

Charge controllers are based on the output current, so 24panels at 355 watts = 8520watts x .75 (to give good effective size from the array as there is a difference between the rated and actual output) = 6130 watts ÷ 50 volts (rough guess at charging voltage for your battery bank) = 122.5 amps, so at least 2 charge controllers.

ZebraStripes said:

1. I am also considering these Peimar panels (https://www.altestore.com/store/productos-solares-en-puerto-rico/pr-paneles-solares/peimar-grid-tie-solar-panels-puerto-rico-p41241/#PR-PEI330P-EACH) because of their lower price and immediate availability (Have to wait on Canadian Solar panels to get here). Thoughts? Worth the wait on Canadian or will the Peimar suit me just fine?

I pretty much buy Poly and mono crystalline solar panels by the watt, if it's close go with mono...

ZebraStripes said:

2. The inverter manual suggests that it only be used with battery banks of at least 440Ah, but the Fortress battery only has a capacity of 360Ah. Will this be a problem / Why does the ah capacity of the bank matter here?

I think you will be fine with Lithium batteries, I suspect the reasoning is based on lead acid and it's ability to deliver/service a 6500 watt load, 6500watt ÷ 48 volt= 135 amps from a 48 volt battery bank at 440 amps is almost 1/3rd of it's capacity, lead acid would see a huge voltage sag as this is more than a third of capacity at that discharge rate.

Lithium's don't suffer from this voltage sag, so I think you would be okay, granted the minimal capacity already discussed.

ZebraStripes said:

3. What's the most foolproof way to make sure I am buying exactly what racking I require? The altE warehouse is quite a drive from here, so I only want to make the trip once if I can.

Gosh, I wish there was a foolproof method. I guess lay it out on paper with every lift of the pen writing down what you have just drawn.

Draw wire> write length, gauge of wire AND CONNECTORS!!!
draw junction box> write the junction box down, INCLUDING THE CONNECTIONS

When you are all done, buy an extra30% of each wire as well as connectors and crimping tool!

Then, make friends with someone at altE or where ever you buy stuff, so they can send you the 3 water proof wire restraints you forgot...lol.

Seriously you might have a 'pre wired' power center built, expensive, heavy, but more likely 'plug and play'.

ZebraStripes · July 2019

Thank you for your well thought-out reply.

1. We have a 1HP well pump that I'm a bit worried about, and we plan to also run some mini splits during the day when capacity allows (IE excess energy being produced). At night, our needs are very minimal and the battery should have no problems keeping up with us. The battery is supposed to have 16.5 usable kWh (18.5 total).

2. Right now, our daily use fluctuates between 11 and 13 kWh. But we don't use our AC much at all. We are *HOPING* that during the hottest part of the day, once the battery is charged back up, we can use our excess production to power a mini split.

3. We plan on expanding our energy generation/storage to our casita next year, and I was hoping we might be able to tie that into this inverter rather than going with a second one. However, if we would be better off with the smaller inverter and just adding a second inverter for the casita, I'm definitely open to that.

4. Thank you for explaining the charge controller sizing. I originally had planned on two (One per string) but then talked myself into needing only 1 due to the voltage requirements. I didn't really understand what the 80A represented in their specs.

5. Pen and paper was my plan for the racking. Glad to hear someone else say it.

I know I can go with a pre-wired system, but this is a learning experience for me. Once I have my parts picked out and sized correctly (With the help of you very very smart people here), I have no problem doing the installation. This is the part that makes my head spin

littleharbor2 · July 2019

You are talking about the 600 volt version of their charge controller aren't you.

QUOTE: "Schneider XW 80A MPPT (I believe I only require 1, because the total voltage going down the line will only be 12*24=288V, right? And if so, that's well within the parameters of the MPPT" Where are you getting your numbers from?. While these may be considered 24 volt nominal panels that's not the way you calculate your input voltage.

Canadian Solar 355 watt panel, 46.8 Voc. x 12= 561.6 volts. Add a chilly bright morning and you are watching lots of very expensive magic smoke float away.

ZebraStripes · July 2019

littleharbor2 said:

You are talking about the 600 volt version of their charge controller aren't you.

QUOTE: "Schneider XW 80A MPPT (I believe I only require 1, because the total voltage going down the line will only be 12*24=288V, right? And if so, that's well within the parameters of the MPPT" Where are you getting your numbers from?. While these may be considered 24 volt nominal panels that's not the way you calculate your input voltage.

Canadian Solar 355 watt panel, 46.8 Voc. x 12= 561.6 volts. Add a chilly bright morning and you are watching lots of very expensive magic smoke float away.

See, this is why I'm here - To learn

I had originally written down that I wanted two of the 80A 600V charge controllers. Then today, while going back over the plan, I couldn't figure out why I wanted two, so I changed it back to one. So just to clarify - I would be good with two strings of 12 each, each running into their own MPPT, right?

littleharbor2 · July 2019

Absolutely not! The voltage I just showed you in a series string of 12 will be lethal . You could run TWO strings of 6 panels into each controller. Whether it is cost effective for you to use such high voltage controllers is something you need to figure There's plenty of 80 amp controllers on the market with Voc. limits of 150, 200 and 250 volts. You will, With two strings save on fusing and combiner boxes but you pay a premium for the 600 volt controller. The 150, 200, 250 Voc. controllers will require fusing and combiners.

ZebraStripes · July 2019

I really appreciate you taking the time to try to help me. I apologize if my questions sound stupid - I am still learning and realize that I have a ton to learn.

Can you explain why having two strings of 12 would be bad? If the CC is rated for 600V and the string is putting out 561V, what is the problem?

Additionally, the smaller Schneider CC, it seemed like even at 6 panels per string, I'd be over the limits for it, as it states the maximum input voltage from the array is 150V.

Again, I do appreciate the help, just trying to figure out all of the little things that go along with this.

Photowhit · July 2019

ZebraStripes said:

1. We have a 1HP well pump that I'm a bit worried about, and we plan to also run some mini splits during the day when capacity allows (IE excess energy being produced). At night, our needs are very minimal and the battery should have no problems keeping up with us. The battery is supposed to have 16.5 usable kWh (18.5 total).

1hp should equate to 800 watts +/- after the starting surge. I'm sure it would run on an inverter half that size. But I understand the 'buy once' and use for the future home.

ZebraStripes said:

2. Right now, our daily use fluctuates between 11 and 13 kWh. But we don't use our AC much at all. We are *HOPING* that during the hottest part of the day, once the battery is charged back up, we can use our excess production to power a mini split.

I don't have or use lithium, yet, but you should read through the recent post about someone having issues 'dialing in' a charge controller to use lithium batteries. In the past the inefficiency of lead acid made it easy for the charge controller to determine when to allow energy to come from the solar array to make up for energy outgoing to the battery, Even at 'float' a small load will create a difference and the charge controller will allow more current to pass to allow you to draw energy from the system that is pretty much directly off the array...

...whit lithium, there is minimal to no voltage drop, so it looks like this will be an interesting problem to overcome. Many people with lithium avoid charging to 100% and stay between 15 or 20% and 90%. There is very little voltage drop so this person was having his battery drained and not having the charge controller pickup the increased demand.

https://forum.solar-electric.com/discussion/354791/why-isnt-the-charge-controller-using-the-panel-to-feed-loads-when-the-battery-is-charged#latest

Yeah, I've enjoyed wiring up the system's I've done, and even when helping others. I always grab some 'S' clips and grounding lugs (not used as often these days, people going with WEEB(?) systems) When I go and check out other peoples systems being installed. Something you might consider are the wiring clips to keep the wiring clean, There are UL black wire ties, but they may only last 8-10 years, Stainless Steel 'S' clips will clip 2-4 wires to the frame of a solar panel and are made different if you are using PVwire or USE2(which is thinner) They are hand to have around, I have always heard that even the UL nylon Zipties become brittle and fail after 8-10 years, but I admit to using them for keeping wires coiled and things neat.

Wiley Electronics PV- Cable Clip ACC-PV Stainless Steel

Wiley Electronics PV- Cable Clip ACC-PV Stainless Steel

https://www.altestore.com/search/go?w=Search+Products&p=Q&ts=v2&w=clips&p=Q&ts=v2&x=0&y=0

Estragon · July 2019

You need to adjust the 561voc string voltage for record low temp at your location. Max voc is usually at ~dawn, which is also about when record low temps are recorded. In PR, maybe not a big issue (though a <10% buffer is skinny to me), but certainly a potential issue in colder climates.

ZebraStripes · July 2019

Estragon said:

You need to adjust the 561voc string voltage for record low temp at your location. Max voc is usually at ~dawn, which is also about when record low temps are recorded. In PR, maybe not a big issue (though a <10% buffer is skinny to me), but certainly a potential issue in colder climates.

Well now I'm really confused. I thought voc was the maximum voltage the panel could produce, period. Ie I thought it was a measure of maximum sunlight, minimum temperature type scenario. But you're saying the panel can actually produce more than that number when conditions are right?

Edit: Just found an article describing how to calculate Max VOC. Somehow this is the first time I'm coming across this. Thanks @Estragon

littleharbor2 · July 2019

The colder the panel the higher the voltage. It's not that the panels are potting out any massive amounts of power first thing in the morning. They are putting out very little actually BUT, they will put out very high voltage first thing in the morning. You need to find the temp. coefficient stats for whatever panels you are going to use. Then you need to find the coldest typical temps for your area. Look up ASHRAE, I believe to get the weather info and calculate the voc. @ that low temp.

ZebraStripes · July 2019

So I just did the maximum VOC calculations for those canadian solar panels and the record low for this spot, and came up with 595.08 maximum VOC. Cutting it a little close I guess

So what's the solution? 4 strings instead of two? And then two 80A charge controllers, each handling two strings?

littleharbor2 · July 2019

That would work. I don't know how those charge controllers work on 250ish. vmp. I would hope they don't need max smoke to operate efficiently. What is the voltage range on them?

Photowhit · July 2019

Not sure if you will be making your own cables?

Officially you should use the Code compliant tools, but I know what a good crimp looks like and choose to use a cheaper tool. These days they make cheap tools that function similar to the code compliant tools. with the dies being pressed together straight up and down. These work better than the tools that are hinged (like the cheap tool I bought 10+ years ago) I know I've used them both!

Don't buy this!

Go for something like this instead;

Image: https://images-na.ssl-images-amazon.com/images/I/41qqoHe4myL.jpg

Link;
https://www.amazon.com/VIKOCELL-Crimping-Connector-Terminal-Crimper/dp/B0727P5PK7/ref=sr_1_8

Shows the 2 different types in operation;

https://youtu.be/fTUWW1sXJf8

Also important if you are going to make your own cables, be sure to get the higher strand wire, The cheapest stuff is often USE2 7 strand wire, it's a PITA to crimp, I got to the point I just fanned the wire out clipped 1 of the strands, then careful made sure the others were 3 x 3 into each side of the crimp.... Seriously! PVwire is typically(always?) 21 strand and much easier to crimp.

ZebraStripes · July 2019

littleharbor2 said:

That would work. I don't know how those charge controllers work on 250ish. vmp. I would hope they don't need max smoke to operate efficiently. What is the voltage range on them?

The datasheet for the MPPT 80 600 says "PV Array operating voltage: 195 to 550 V"

ZebraStripes · July 2019

Photowhit said:

Not sure if you will be making your own cables?

Officially you should use the Code compliant tools, but I know what a good crimp looks like and choose to use a cheaper tool. These days they make cheap tools that function similar to the code compliant tools. with the dies being pressed together straight up and down. These work better than the tools that are hinged (like the cheap tool I bought 10+ years ago) I know I've used them both!

Don't buy this!

Go for something like this instead;

Link;
https://www.amazon.com/VIKOCELL-Crimping-Connector-Terminal-Crimper/dp/B0727P5PK7/ref=sr_1_8

Shows the 2 different types in operation;
https://youtu.be/fTUWW1sXJf8

Also important if you are going to make your own cables, be sure to get the higher strand wire, The cheapest stuff is often USE2 7 strand wire, it's a PITA to crimp, I got to the point I just fanned the wire out clipped 1 of the strands, then careful made sure the others were 3 x 3 into each side of the crimp.... Seriously! PVwire is typically(always?) 21 strand and much easier to crimp.

Thanks for the tip on the crimper. I did intend on doing my own crimps because if this works out, I'll likely do it again at least once or twice...

littleharbor2 · July 2019

The blue one works great. Done many hundreds of crimps, if not tens of hundreds. Photowhit is right about the other type. They don't work as well. There's some tutorials on youtube walking you through crimping the MC-4 connectors. Good thing they're cheap because you're bound to do a few wrong while you're getting the hang of them. Once you snap in the contact you cannot get it back out. Remember, Male contact into female MC-4 housing and Female contact into male housing. I say male and female housings because the male isn't necessarily the positive and vice-versa. The male on the back of the solar panels is the positive but when you are making extensions the female connector connects into the male output and has a male connector on the other end or whatever type on termination you require for the combiner, charge controller, etc..

mcgivor · July 2019

@ZebraStripes
Attached is instructions on how to set up the Schneider for use with Fortress batteries if you don't already have info.
Question, why the 600V controller, is there a large distance between the array and controller? That apart from minor savings in wiring and combiner equipment would be the only benifits, the cost is ~ 3 times that of a 60-150's having the redundancy of multiple controllers can have benifits albeit at the expense of minor complexity, also consider multiple arrays at different orientations to extend solar hours, this will be less taxing on the batteries.

VERY IMPORTANT
Budget for lightning protection, SPD devices are essential in tropical climates and make sure the clamping voltages are suitable for the equipment, both AC and DC sides

Dave Angelini · July 2019

An unfair comparison of an 80 amp controller and a 60 amp. The price difference is more like 2/1. The OP will need at least 2 controllers either way. The 80 amp also has multiple fans and fan speeds that may help in a hot climate. Either way they both are excellent products.
The 80 amp is just far easier to install and change later. A good case for having one of each also!

ZebraStripes · July 2019

mcgivor said:

@ZebraStripes
Attached is instructions on how to set up the Schneider for use with Fortress batteries if you don't already have info.
Question, why the 600V controller, is there a large distance between the array and controller? That apart from minor savings in wiring and combiner equipment would be the only benifits, the cost is ~ 3 times that of a 60-150's having the redundancy of multiple controllers can have benifits albeit at the expense of minor complexity, also consider multiple arrays at different orientations to extend solar hours, this will be less taxing on the batteries.

VERY IMPORTANT
Budget for lightning protection, SPD devices are essential in tropical climates and make sure the clamping voltages are suitable for the equipment, both AC and DC sides

Thank you! I had seen that Fortress says it works with Schneider MPPTs, but couldn't find the numbers. Had planned on just calling them for it.

Please critique my plans

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