Lean-to Shed Solar Power for Year Round Use

nicorellius

Troubleshooter
I've got an 8' x 15' shed, with a single pitch roof facing west, but at a 1/4 slope. The roof area is about 150 square feet. I can probably install the panels so they face more southward if needed... It gets pretty darn good sun in the spring/summer months. But I'm in Portland, Oregon, so the rest of the year it's cloudy.

I want to install a solar system that powers lights, chargers, a small computer, but also handles power tools (6-12 A saws, sanders, drills, maybe a 15 A compressor, etc). These will likely only ever be used one at a time, for short bursts. For example, in the spring/summer, I might use them heavily on some of the weekends, but on the cold months, hardly at all. In the fall and winter, it'll need to power only lights, radio, maybe chargers with the rare power tool use.

Based on my initial estimates, I was thinking of a 400 watt system (4 x 100 W panels), with a couple 12 V 100 A h batteries. But I'm new to solar, so I'm not sure if this makes sense (or if it's even in the right ballpark). Also, I've got no real idea on what vendors/manufacturers offer the best gear.

Thoughts, recommendations? Thanks in advance.
 

OffGridInTheCity

Solar Addict
Hey There - I lived in Portland for 10yrs in the 80s but these days I'm in Southern OR. There's quite a few more sunny days down here :)

My opinion - I think you'll find 4 x 100w panels is a bit small. I use a utility called PVWatts https://pvwatts.nrel.gov/pvwatts.php. It will give you good estimates for Portland.

Meanwhile, let me share that I have a 7 x 14 cargo trailer with 4 x 300w used panels mounted flat (1200w). You're shed is big enough for 1200w. Here's the PV input curve for today (hot / sunny all day) - somewhere around 5kwh total for the day. If tilted, then 6.5kwh for the day. Winter time is aprox 25% of this - so aprox 2kwh would be a good day for cloudy Portland when the clouds aren't too thick.
1626226275624.png

Portland is cloudy region - here's what PV watts shows for 1200w, 20deg angle - consistent with my experience outlined above for the trailer:
1626227893928.png
That's around 5.8kwh/day in July and 1.5khw/day in winter.



Inverter wise I went with an all-in-one (PV input, Bat Charger, Inverter, UPS, ATS) MPP Solar PIP 3048 (3000w inverter / 48vdc battery) - https://watts247.com/product/pip-3048lv-mk/. Its handles up to 25a@120v circuits (with surge). You're saws would run. They make a 2000w / 24v version as well - it might be enough for saws.

I'm sure you'll get a ton of comments - look forward to hearing more about what you decide :)
 
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nicorellius

Troubleshooter
Thanks @OffGridInTheCity. Great advice on the all-in-one inverter. That thing seems very robust. And thanks for the resource to evaluate solar radiation. I've read that a common mistake beginners make is underestimating the requirements, so this it's good to hear you confirm that. My goals are to power the things I need to, but also fit into a budget. I just built this shed I'm describing and, as we all know, lumber has been super expensive lately. I was over budget by about 30%.

The idea to use solar to power this shed was somewhat inspirational, as I originally thought I'd run power from a workshop to the shed. But then I thought, why do that, when I can install a more sustainable power source? And since I've been wanting to learn more about solar energy anyway for future installations (eg, larger systems), I thought this would be a great stepping stone.

If I understand correctly, the main reason the originally proposed system might be too small is that it would not handle the peak power consumption of the saws or compressor? I've seen ranges of startup power use vs steady state, so I'm not sure what the maximums would be when I start these saws or the compressor. Assuming a saw is rated at 12 A (~1400 W), how much will it use when it first starts? Twice that?

How much would a system like you describe cost in total?
 

OffGridInTheCity

Solar Addict
If I understand correctly, the main reason the originally proposed system might be too small is that it would not handle the peak power consumption of the saws or compressor?
You can never heave enough solar panels - so if you plan for 4 x 300 or 4 x 350 you can start with 2 (perhaps) and then expand to 4 kind of thing.

I've seen ranges of startup power use vs steady state, so I'm not sure what the maximums would be when I start these saws or the compressor. Assuming a saw is rated at 12 A (~1400 W), how much will it use when it first starts? Twice that?
Its not the solar panels its the battery -> inverter that provides the power. A 15a US circuit @ 120v is 15a * 120v = 1800watts. You can test your saw(s) on a house circuit that is 15a and see if they run. Some equipment - such as my stone saw - need 20a circuts. 20a * 120v = 2400w.

You need an inverter that can 1) deliver the 1800w for 15a circuit OR 2400w for the 20a circuit AND 2) that has 2x or 3x surge for X seconds as saws have a second or 2 of surge power.

Its that 20a circuit for larger saws that lead me to suggest a 3000w (level) inverter with surge. 3000w / 120v = 25a. 20a + a bit if head-room.

How much would a system like you describe cost in total?
MPP Solar PIP 3000w @48vdc OR Growatt 3000w @ 24vdc are in the $700-$800 range.
Panels - Used panels such as from ebay Santansolar - https://www.ebay.com/itm/New-Talesun-330W-120-Cell-Black-on-Black-Mono-Warranty/265131150012 - ... (this is just an example, you can search for more or less + $200 shipping is likely). Let's say $500.
Battery! Lets say you just buy one from BigBattery.com such as this smaller 24dc one - https://bigbattery.com/products/24v-mule-lifepo4-120ah-3kwh/ for $1300.
Rails/Hookup/Wire/Panels - $500?

At a minimum for a functioning shop it adds up to $800+$500+$1300+$500 = $3100.

$3100 for a serious, operational system that would run your shed/tools and even a small AC unit to keep the shed cool while working in it.
This could double over time. There is 20%? US tax credit.

Do you need to spend $3100? - this is such a judgement call. You 'could' do a couple of 100w panels, a couple of used batteries, a cheap charge controller, and a cheap inverter and maybe $1500?

*Take all this with a HUGE grain of salt as I don't know you, your-skills, interest, scrounge abilities etc.

Suggest you want some of @Will's recent youtubes (last 6 months) on GroWatt inverter reviews, powering his shed, BigBattery (and other) reviews, etc. After some time, this should give you better prespective on things.

Also - happy to answer more questions personally and I'm sure you'll get *many* comments on the board here :)
 

nicorellius

Troubleshooter
Its not the solar panels its the battery -> inverter that provides the power. A 15a US circuit @ 120v is 15a * 120v = 1800watts. You can test your saw(s) on a house circuit that is 15a and see if they run. Some equipment - such as my stone saw - need 20a circuts. 20a * 120v = 2400w.

You need an inverter that can 1) deliver the 1800w for 15a circuit OR 2400w for the 20a circuit AND 2) that has 2x or 3x surge for X seconds as saws have a second or 2 of surge power.

Its that 20a circuit for larger saws that lead me to suggest a 3000w (level) inverter with surge. 3000w / 120v = 25a. 20a + a bit if head-room.

Your analysis is spot on. This makes good sense. Thanks for breaking it down. I really like the idea of buying something like 2 panels now, then maybe adding more later. So long as I get the right battery + inverter setup to handle my power tool surges.

And thanks for the YT recommendation. I found Will's channel and watched some videos. He knows his shit, that's for sure.

I think my main concern at this point is the overall cost. I'm pretty handy, so I'm not too worried about the installation. On the one hand, I don't want to buy low quality equipment, but on the other, I don't have $3K to spend. Thus, my adventure of compromise begins ;-)
 
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nicorellius

Troubleshooter
Follow up questions. If I start with, say, 2 x 250/300 W panels, can I still use an all-in-one like the PIP LV2424 MSD 24V 2.4kW, 120V Output, 2kW Solar Input 80A Mppt? To shave some cost on batteries, would it make sense to go with, say, 2 x 12 V 100 A h and then add more in parallel if I need more capacity (like the Weize for $175 each)? The differences in battery cost is hard to wrap my head around ($150-1000 per battery).

Regarding solar power equipment in general, I've seen the stock at my local Harbor Freight grow over the years. Is any of this worth buying? Or what about the kits on Amazon?

I've been seeing videos on bifacial panels. Seems they function better in cooler environments. Being in Portland, Oregon, would I benefit from this technology?
 
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Brassburnz

New Member
Follow up questions. If I start with, say, 2 x 250/300 W panels, can I still use an all-in-one like the PIP LV2424 MSD 24V 2.4kW, 120V Output, 2kW Solar Input 80A Mppt? To shave some cost on batteries, would it make sense to go with, say, 2 x 12 V 100 A h and then add more in parallel if I need more capacity (like the Weize for $175 each)? The differences in battery cost is hard to wrap my head around ($150-1000 per battery).

Regarding solar power equipment in general, I've seen the stock at my local Harbor Freight grow over the years. Is any of this worth buying? Or what about the kits on Amazon?
I am new to all this as well, but I learned early that Harbor Freight solar products are to be avoided. I use Harbor Freight products for other things and I am a member of their discount club. I do like some of their insulated hand-tools and their pneumatic crimper. Try to find a 20% off coupon.
 

OffGridInTheCity

Solar Addict
Follow up questions. If I start with, say, 2 x 250/300 W panels, can I still use an all-in-one like the PIP LV2424 MSD 24V 2.4kW, 120V Output, 2kW Solar Input 80A Mppt?
Yes - if you start with this all-in-one it will set the tone for the rest which is a good strategy.
Yes - 2 x 250/300w panels in series should be just fine for PV input specs of an LV2424. Then later, you can parallel in 2 more panels.
In fact - here's a nice youtube on how this all-in-one can be hooked up by @Will Prowse

To shave some cost on batteries, would it make sense to go with, say, 2 x 12 V 100 A h and then add more in parallel if I need more capacity (like the Weize for $175 each)?
Yes - you could start with 2 x Weize batteries. They're lead-acid so 50% DOD (depth of discharge) is a limitation if you want them last. The LV2424 will let you do custom settings so you can make sure you only do 50% DOD - this is good!

To give you a perspective let's try this.
2 in series would be 2 x 12v = 24v @ 100ah. At 50% DOD this would be 50ah @ 24v. This is 1,200wh of useable 'battery' - e.g. you can run 1200 watts for 1 hour. 1200w / 120v = 10a. So you could run a medium saw for an hour continuously. (FYI - this web site is useful for battery -> watt-hour calculations - https://milliamps-watts.appspot.com/)

Recap
- PIP LV2424
- 600w panels
- 24v@100ah lead-acid

In July this will give you up to 3kwh (3000 watt hours) / day. After the sun goes down and you're on battery only - you'll have about 1,200wh of useable stored energy. In winter you'll have up to 750wh/day total - it will take 2 days to charge up the 24v battery.

This would be a complete system - and later on you can add panels, swap out to different batteries, all is user settable, it will educate you on all this. My advice - think about expansion as you start smaller - e.g. don't plop the 1st 2 panels right in the middle of the roof but on 1/2 the roof so you can just add 2 more some day :)

The differences in battery cost is hard to wrap my head around ($150-1000 per battery).
The battery type and size is a complex question. The system above will educate you on many things and help make this clearer after you operate if for a while. For example:
1) In my case I want my house to run all night... 12-20hrs... inbetween sun-down and sun-up the next day. For my case this takes A LOT of battery capacity.
2) Lead-acid and Lithium-ion will have much longer life-spans if you don't try to use them to 100% of their storage capabilities. LifePo4 are the best at long life + pretty deep depth of discharge.
3) DIY battery builds can save *massive* $ instead of buying a battery premade - but it takes time / info / experience.

In your case above with 2 x Weize batteries - to run your shed all night - it would be 1200w / 12hrs? = 100w/hour. But if you use the saw after the sun goes down - then you won't have much left for 'other' thru the night. Maybe this is OK for you. Maybe you can time your work so you only use the shed when it has enough power so a small system is OK. Its all about your operational goals / what you want to be able to do.

Regarding solar power equipment in general, I've seen the stock at my local Harbor Freight grow over the years. Is any of this worth buying? Or what about the kits on Amazon?
Personally, I wouldn't go this route - even for a 'base' system.
 
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nicorellius

Troubleshooter
Thanks a lot for all the feedback. It's been very useful. And the videos on Will's channel. They're packed with good information.

I'm leaning towards the following to start:

- MPP LV2424 -- $700
- 4 x Rich Solar 160 W 12 V polycrystalline panels -- $700
- Lynx Battery 24 V 100 A h LiFePO4 -- $1000

I can get the panels and battery shipped for free. I'd like a battery with cold temp cutoff since part of the year it gets pretty cold here. I found these Lynx batteries on Amazon. Anyone try these? Might still go with a couple lead acid batteries to save some money. Do lead acid generally do well in cold climates? The Weize 12 V 100 A h LiFePO4 caught my eye as well.

For the panels, it would be 720 W (48 V in series) coming in to the system. Does this seem sensible? Or would I configure these to deliver 24 V (assuming this is possible)?

After looking into used panels I encountered two potential drawbacks. First, the used panels seem to be hit or miss on quality and often the efficiency is really low (like 70-80%). Second, if I'm only looking to buy two, I'm looking at 50% in shipping. So two older 250 watt panels for $50-100 apiece, come with a $150-200 freight charge (from eBay, for example). At a buck a watt, it seems new panels is the way to go, at least for my initial starting point.

I'm still actively researching this; the above is where I'm at right now. This might all change (well, the LV2424 is definitely making the list!).

PS - Anyone know of a solar power system online configurator? Something that takes as input all the variables (number and rating of panels, inverters, batteries, system voltage, etc) and gives recommendations or suggest changes? Not a calculator that asks for devices or appliances you want to run and tells you what size system you need in watts...
 

OffGridInTheCity

Solar Addict
Bascially the total voltage (of panel or panels in series) should be higher than the battery max voltage - e.g. at least 30v for a 24v battery. 40v+ is probably better - some say 20-30% higher than max battery voltage - but this actually depends on the PV charge curve which is specific for the MPPT algorithm for MPP Solar LV2424 and I couldn't find one. So 2 in series I'm guessing at least. Maybe all 4 in series (up to about 100v'ish) if none will be in shade.

Here's a thread on solar panel sizing for the LV2424 - https://diysolarforum.com/threads/sizing-an-array-for-mpp-solar-lv2424.1395/ - that may help you.

And congratulations - sounds like you're narrowing in on making some decisions/progress :)
 

MisterSandals

Participation Medalist
I was thinking of a 400 watt system (4 x 100 W panels),
Instead of messing with tiny panels, you should strongly consider big cheap panels from craigslist. A quick search found this and others:
 

nicorellius

Troubleshooter
I've placed orders for the 2424LV-MSD and two (2) ExpertPower 12 V 100 Ah Lithium LiFePO4 batteries. After seeing Will's review, I was hesitant on these batteries. But then after researching the issue and confirming with the manufacturer that they had faulty temperature probes during the bad reviews, I'm feeling better about these. The recent reviews I've read claim that the low temp cutoff is working as expected. Obviously I'll test this when I get them.

For panels, I went with four (4) used 240 W (VOC ~35 V, ICS ~8 A). These seem like a good place to start, and they were very reasonably priced and delivered to boot! Only problem is that I fried my multimeter fuse while testing. Total newbie mistake. I am researching clamp multimeters now that can handle 400-500 A DC.

Based on the max PV voltage of the LV2424 (145 V), I think setting these panels up in series will be good (~35 V x 4 = 140 V), or is that too close? Which values do I use to determine whether to put these in series, VOC or voltage Pmax/VMP (35 V -> 140 V or 30 V -> 120 V)? Specifications here...

Thanks @MisterSandals for urging me to go with higher output panels. Saved me money and will get me closer to my end goals.
 

MisterSandals

Participation Medalist
(~35 V x 4 = 140 V), or is that too close?
Way to close. It would only have to drop a couple degrees below 25C (77F) to up the voltage to fry your SCC.

2S2P for your array is a good solution.
3 in series would be very good but you'd need 2 more panels to go 3S2P (sorry about upping the budget again).
 

nicorellius

Troubleshooter
I want to thank everyone for all the great help so far. It's been super informative. In only a week, I've learned more about solar than I could have imagined. Super cool...

I received my LV2424 and have my panels ready. Still waiting on the batteries, but I thought I get started on planning the layout. I need to purchase wiring and hardware, as well. From my research, it seems most people connect wire straight into the LV2424. Does anyone install MC4 tails that hang off the LV2424 for easy connection to the array?

Wire gauge is also a topic I've encountered some ambiguity. Is there any reason to not just play it safe and get much thicker wire than needed in pretty much all cases? Or should I get as close to the rating as possible? For example, for array wiring, I'm looking at 10 gauge, which handles 30 A. Since I'm going with a 2S2P, my panels will deliver at most about 15-17 A. Or should I go with 12 gauge?

Likewise with battery to battery and battery to inverter. Most of the videos on Will's channel use pretty beefy wire (2-4 gauge). I'm thinking 2 gauge for battery to battery (2 x 12 V 100 A h batteries in series) and 4 gauge for battery to LV2424. All based on the information here.

For the panel layout and configuration, I'm probably going to configure them vertically, side by side, in a single row ([] [] [] []). I thought I could put them in two rows (and 2 columns) but the length of the panels is more than 1/2 the width of the roof so they will not fit. Because I'm at 45 degrees latitude, it seems a panel tilt of about 45 degrees is good for year round? I do have some trees in the path for the winter months so I worry that without tilt, I might not get all that much sun. In the summer months, the path of the sun clears the trees, and March/September will have some obstruction.

Temperature and insulation are a consideration, as well. I'm in Portland, Oregon, so pretty hot summers and pretty cold winters. The shed is not insulated, but is enclosed, with a door, etc. It'll be hotter than ambient inside in the summer and likely a bit warmer than ambient inside during the winter. My question is whether I should build insulated enclosures for the batteries and LV2424? The LV2424 manual says ambient temperature specs are 0-55 C (32-131 F). It seems like I'll be good without enclosures, but I wanted to hear from the pros on this. Or maybe I should just insulate and drywall the interior? This was not part of my original budget, but neither was solar, so hey...

On to fuses/breakers, etc... In reviewing this page for a blueprint (though using a 2S2P configuration), I see a combiner box/circuit breaker and an inline fuse on the positive battery lead. I'm assuming this is the right thing to do here? I had not considered these bits until now (oops). I guess I was thinking the system was small enough to not need them. And what about inline fuses for the solar wiring since I'm going in parallel?

Finally, wire length seems to be a question that most system audit apps ask for. If I lay out my panels as described above and aim for shortest possible wire run lengths, I'm looking at a segment from one end of the array to the LV2424 that is 25 feet. That's the long end; the short end (the side of the array closest to the LV2424 and batteries) is closer to 15 feet. This is all assuming I arbitrarily choose one side for the LV2424 and battery bank and run wire accordingly. Any tips for this?
 
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OffGridInTheCity

Solar Addict
Congratulations on taking the plunge... I so much enjoy capturing power from the Sun on my own. Its just a gift that keeps on giving and I suspect you'll become addicted as well - fair warning! :)

I want to thank everyone for all the great help so far. It's been super informative. In only a week, I've learned more about solar than I could have imagined. Super cool...

I received my LV2424 and have my panels ready. Still waiting on the batteries, but I thought I get started on planning the layout. I need to purchase wiring and hardware, as well. From my research, it seems most people connect wire straight into the LV2424. Does anyone install MC4 tails that hang off the LV2424 for easy connection to the array?
I usually do Panel -> mc4 | mc4 -------> circuit-breaker-near-LV2424 --> LV2424 (see comment below). The circuit breaker is to turn off the incoming power within arms reach of the PIP LV2424 to work on things and to turn on/off each individual string to verify they are working.

Wire gauge is also a topic I've encountered some ambiguity. Is there any reason to not just play it safe and get much thicker wire than needed in pretty much all cases? Or should I get as close to the rating as possible? For example, for array wiring, I'm looking at 10 gauge, which handles 30 A. Since I'm going with a 2S2P, my panels will deliver at most about 15-17 A. Or should I go with 12 gauge?
12 is OK. Some do 10 awg if the distance is long to limit wire-transmission losses as much as possible. You mention 12ft (below) - I wouldn't bat an eye this short distance. Some may disagree and I won't argue it - thicker wire is perfectly OK.

Likewise with battery to battery and battery to inverter. Most of the videos on Will's channel use pretty beefy wire (2-4 gauge). I'm thinking 2 gauge for battery to battery (2 x 12 V 100 A h batteries in series) and 4 gauge for battery to LV2424. All based on the information here.
The LV2424 inverter is 2000w? 2000w/24v = 83a. So 4 awg would be the smallest (assuming you're only running a few feet). I'd go a little thicker myself.

For the panel layout and configuration, I'm probably going to configure them vertically, side by side, in a single row ([] [] [] []). I thought I could put them in two rows (and 2 columns) but the length of the panels is more than 1/2 the width of the roof so they will not fit. Because I'm at 45 degrees latitude, it seems a panel tilt of about 45 degrees is good for year round? I do have some trees in the path for the winter months so I worry that without tilt, I might not get all that much sun. In the summer months, the path of the sun clears the trees, and March/September will have some obstruction.
45deg is perfectly sane - a bit better for winter vs summer. I do 25deg - better for summer than winter.

Most important - avoid shading as much as possible. Any shade (even 2sq inches) will bring down *severely* (like 80-90% of the power will be lost) all the panels of that string.

There are several web pages on tilt and relative % such as this - https://www.solarpaneltilt.com/
You get more power (20%?) if you can adjust the tilt to be optimal for different times of the year - but that's just too much for me. I'd rather add 20% panels to make up for the losses and just not add that chore to my list :)

Temperature and insulation are a consideration, as well. I'm in Portland, Oregon, so pretty hot summers and pretty cold winters. The shed is not insulated, but is enclosed, with a door, etc. It'll be hotter than ambient inside in the summer and likely a bit warmer than ambient inside during the winter. My question is whether I should build insulated enclosures for the batteries and LV2424? The LV2424 manual says ambient temperature specs are 0-55 C (32-131 F). It seems like I'll be good without enclosures, but I wanted to hear from the pros on this. Or maybe I should just insulate and drywall the interior? This was not part of my original budget, but neither was solar, so hey...
Its better (longer life) if you try to keep them more between 60-90F/15-32C. Its not that 1 day will 'kill them' - it's more like several months in a row would start to be stressful. Fan's perhaps for heat or even a window heat-pump. @Will did some youtubes on low power 'shed cooling' - here's one

On to fuses/breakers, etc... In reviewing this page for a blueprint (though using a @S2P configuration), I see a combiner box/circuit breaker and an inline fuse on the positive battery lead. I'm assuming this is the right thing to do here? I had not considered these bits until now (oops). I guess I was thinking the system was small enough to not need them. And what about inline fuses for the solar wiring since I'm going in parallel?
I like having a 'central box' with circuit breakers and bus-bars ... to tie everything together and give on/off to isolate things to work on things.
This is my trailer and you'll see 6 circuit breakers...
1) 1st 2 panel string
2) 2nd 2 panel string (#1 and #2 are combined as 2s2p - routed to the MPP Solar)
3) Battery on/off
4) BMS on/off
5) Heat-pads (I have RV water tank heat-pads under the packs for winter time - they kick in at 45F? or so and keep batteries warm)
6) ....
1626825355970.png


Finally, wire length seems to be a question that most system audit apps ask for. If I lay out my panels as described above and aim for shortest possible wire run lengths, I'm looking at a segment from one end of the array to the LV2424 that is 25 feet. That's the long end; the short end (the side of the array closest to the LV2424 and batteries) is closer to 15 feet. This is all assuming I arbitrarily choose one side for the LV2424 and battery bank and run wire accordingly. Any tips for this?
15/20ft is not big deal in my experience. If you get 100ft, 200ft - then its significant as I said above.
 
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nicorellius

Troubleshooter
Thanks for the reply and recommendations, @OffGridInTheCity. I'm looking into breaker boxes and/or combiner boxes. Any specific recommendations here? For my first run at this, I'd prefer more of an all-in-one. Would the 4-1 listed on watts247.com work for my system (63 A max output)? If going to Lowe's or Home Depot to buy breaker box, breakers, etc, what should I look for?

I'm still a bit unclear on how to gel all these amp ratings:

1. Solar array will be delivering 15-17 A at 25-30 V (950 W)
2. LV2424 is 2.4 kW (24 V) so it's an 100 A system
3. Batteries are 2 x 12 V in series (24 V) at 100 A h (2400 W h)

If I stick a combiner box or breaker box in there, what should it be rated at? About 100 A? And what should each circuit be rated at (15 A)? This is the part that confuses me... My inexperience working with electricity has me a bit lost in these final stretches.
 

MisterSandals

Participation Medalist
I'm still a bit unclear on how to gel all these amp ratings:

1. Solar array will be delivering 15-17 A at 25-30 V (950 W)
2. LV2424 is 2.4 kW (24 V) so it's an 100 A system
3. Batteries are 2 x 12 V in series (24 V) at 100 A h (2400 W h)
Your solar array, as 2S2P (the 2P part in particular) doubles your panel Isc amperage. That is the array amperage.

The LV2424 can only create amps from your array which produces 950W
950W / 25.6V = 37.1A

Your batteries "amp" ratings... assuming you mean charge and discharge limits? Those will be specified by your battery maker. This rating is usually a "C" rating where 1C = the Ah rating of your battery. So 1C charge/discharge rate (common for LiFePO4) would be 100A at 25.6V.
 

OffGridInTheCity

Solar Addict
Thanks for the reply and recommendations, @OffGridInTheCity. I'm looking into breaker boxes and/or combiner boxes. Any specific recommendations here? For my first run at this, I'd prefer more of an all-in-one. Would the 4-1 listed on watts247.com work for my system (63 A max output)? If going to Lowe's or Home Depot to buy breaker box, breakers, etc, what should I look for?
I use Midnite Solar MNPV6 (6 circuit breaker) box - https://www.solar-electric.com/mnpv6.html - but they make 3 position as well. You just cut that top plate (combiner buss) to 2 circuit breakers for your 2s2p. That leaves the other 4 circuit breaker slots open. The box also has bus bars - I use the one on the left for negative and the other for ground... but you could mount it with spacers and use it as a + busbar. I use the extra space in the box... maybe you have a shunt (for example).

Here's a 'combiner diagram' example for your 4 panels arranged in 2s2p + 24v Battery going thru a circuit breaker for ON/OFF. Crude/messy but hopefully get's the idea across.
1626890232841.png
Midnite Solar makes DC circuit breakers from 5a thru 120a that snap in on the DIN rail. Here's a 15a as an example - https://www.amazon.com/MidNite-Solar-Breaker-150VDC-MNEPV60/dp/B00BSYSLXU/ref=sr_1_4
They also make a 100a (2 slot) - https://www.amazon.com/Midnite-Solar-Circuit-Breaker-MNEPV100/dp/B06XHW4R16


The 4-1 listed on watts247.com is not what I was recommending. That's a dedicated combiner. I'm just saying it's nice to have a 'control box' where you can mount circuit breakers and put your wiring. It so happens that Midnite Solar boxes work OK for me for my trailer. ANY box with bus-bars and circuit breaker mounts will work :)


I'm still a bit unclear on how to gel all these amp ratings:

1. Solar array will be delivering 15-17 A at 25-30 V (950 W)
You'll likely have about 40v @ 8a on each string. Its the panel voltage * 2 but the amps stay the same as 1 panel.

2. LV2424 is 2.4 kW (24 V) so it's an 100 A system
2400w inverter max output / 24v battery = 100a max draw from the battery.

3. Batteries are 2 x 12 V in series (24 V) at 100 A h (2400 W h
If I stick a combiner box or breaker box in there, what should it be rated at? About 100 A? And what should each circuit be rated at (15 A)? This is the part that confuses me... My inexperience working with electricity has me a bit lost in these final stretches.
Hopefully the diagram above will clarify things a bit. This 'control box' is only DC / Circuit Breakers + maybe a shunt and has nothing to do with AC distribution. Its a place to have bus-bars, consolidate control, and protect wiring - a physical place for wiring to terminate. :)
 
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