Outbuilding system configuration & component questions:

mike1919

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Sep 4, 2022
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First post--Appreciate the forum, learning a lot, however I'm in need of some guidance on setting up a small system for a shed and outbuilding. I'm running into some questions. First off, this system is for utility and occasional use. It will not draw power with the exception of a motion sensing flood light that is on a 5min timer. By occasional use, I mean some to all of the loads listed below drawing power perhaps 3-4 days per month and only for 4-5 hours per day. Based on those loads, I'm not sure if it's worth spending a bit more or not, if a pure sine wave inverter is needed, or if I can make due with a lead acid 12v 50-ish amp hour battery or if I should be looking at deep cycle lithium or 100 amp hr batteries to scale it up in the future. There are some smaller "systems" from Northern Tool and Harbor Freight that people have suggested, but I'm not convinced on their quality although the reviews on the 100w panels seem decent.

Loads:
4x 11w LED floodlights
4x 5w to 8w LED bulbs
1x 12w LED work light (infrequent use)
1x Laptop charger (infrequent use)
1x 1.5 amp 120v Bathroom fan/light (infrequent use)
1x 120v 18" industrial fan -- I believe this would be the largest draw in summer

Looking for suggestions on a packaged system or the components to include panel(s), charge controller, battery and inverter. Here are some of the products that were suggested to me by a neighbor:

Panels https://www.harborfreight.com/100-watt-monocrystalline-solar-panel-57325.html

Carge controller https://www.amazon.com/SUNYIMA-Cont...sprefix=charge+controller,aps,116&sr=8-5&th=1

Battery https://www.amazon.com/ML55-12-Batt...amp+hour+solar+battery&qid=1663876119&sr=8-29

Inverter https://www.amazon.com/BESTEK-Inverter-Converter-Charger-Listed/dp/B07JJSW48V/ref=sr_1_18?crid=JQ6ECL9592YC&keywords=solar+inverter&qid=1663876506&sprefix=solar+inverter,aps,103&sr=8-18

Or would I be better off with a kit of this type, or similar:
https://www.amazon.com/ExpertPower-Panels-Controller-Trailer-Projects/dp/B096LJNR99/ref=sr_1_19?crid=37O0XN1ORC52T&keywords=solar+inverter+200w&qid=1663876459&sprefix=solar+inverter&sr=8-19&th=1

https://www.amazon.com/ECI-Power-LiFePO4-Controller-Projects/dp/B09HW4758N/ref=sr_1_16?crid=37O0XN1ORC52T&keywords=solar+inverter+200w&qid=1663876301&sprefix=solar+inverter&sr=8-16&th=1

https://www.amazon.com/Renogy-200W-12V-Monocrystalline-Controller/dp/B08T24Z7J1/ref=sr_1_10?crid=37O0XN1ORC52T&keywords=solar+inverter+200w&qid=1663876372&sprefix=solar+inverter&sr=8-10&th=1

I'd like to keep my total budget around $400-500 and have the option to add another battery in the future, if needed; to keep initial cost down. I belive I need 100-200w in panels, 2x 30 amp hr batts or 1x 50-70 amp hr batt, and a 500w+ sine wave inverter/charge controller. All the loads will be plugged directly into the inverter or via extension cord (50' max length). The shed is not insulated and not heated/cooled, only 80sf so space is limited. Final question; should I add a fusible link or in-lin fuse and if so, where?

Greatly appreciate all the help and any guidance. -Mike
 

12VoltInstalls

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like to keep my total budget around $400-500
A 50Ah-usable deep cycle lead acid battery from walmartha is $100, $200 for 200W of windyNation 100W panels, $60 for an Epever charge controller, and $110 for a Giandel pure-sine inverter barely leaves any cash enough to buy cables.
I tend to not buy bottom of barrel equipment because replacing it is more expensive than just buying something with a track record.
 
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Al D

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Jul 23, 2022
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Certainly go for the pure sine wave inverter dealing with inductive loads (fans) and computer chargers. If you use a 12V battery, the current draw will be 10 times higher than the rated current on your 120V devices. That fan/light combo will draw 15A from your 12V batteries. Keep that in mind for the big industrial fan. Also, you'll need to size your wires accordingly. In my opinion, it's best to go with a 24V system if you can manage it.
 

mike1919

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Certainly go for the pure sine wave inverter dealing with inductive loads (fans) and computer chargers. If you use a 12V battery, the current draw will be 10 times higher than the rated current on your 120V devices. That fan/light combo will draw 15A from your 12V batteries. Keep that in mind for the big industrial fan. Also, you'll need to size your wires accordingly. In my opinion, it's best to go with a 24V system if you can manage it.
Going with a 24v system, what components would you suggest, specifically? I've only looked into 12v options so far.
 

Al D

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Two of those panels you listed in series,

A 24V MPPT solar charge controller capable of handling an input voltage >48V and at least 10A (the one you listed is rated at 24V, but doesnt seem to be a true MPPT, read the reviews, especially the 1 stars, for more information),

A 24V pure sine wave inverter, recommending 1kW due to your inductive loads,

Two 12V deep cycle batteries around 100Ah each, in series to form a 24V 100Ah battery. With these types of batteries, you only want to use half of the capacity. This gives you a bit more than 1kWh. Using more will degrade the lifetime of the battery.

Those are the basic major components.
 

12VoltInstalls

…myself everything do I…
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Going with a 24v system, what components would you suggest, specifically? I've only looked into 12v options so far.
A 50Ah-usable deep cycle lead acid battery from walmartha is $100, $200 for 200W of windyNation 100W panels, $60 for an Epever charge controller, and $110 for a Giandel pure-sine inverter barely leaves any cash enough to buy cables.
I tend to not buy bottom of barrel equipment because replacing it is more expensive than just buying something with a track record.
The above should meet your budget constraints.

A few more bucks and this inverter with this kit and two walmartha “group 29” deep cycle batteries is close to the budget.

The solar panels and pwm you posted are similar to what I suggest except that I used those for two years- known successful products. I own that inverter, too, with 3 years(?) of use on it without troubles. It’s big watts for your needs but it’s only 26W idle consumption so not critical and it’s growth-ready.

You’re tight on watthours, though. But better than the kit from the brand you suggested which only includes a 20Ah battery. Which is near useless.

More money buys more panels- that little P30L controller is a pwm and will do like 4-6 100W panels iirc

More than 400- or 500W of panels and this is another lower-priced item that works well: an mppt charge controller. I’ve sold others I’ve had but kept this one.
 

Al D

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Using a 12V system may be slightly cheaper, but the cost of wires might eat away at those savings. Also, a 12V system leaves little room for upgrading. If OP ever wants to use power tools or put in a window AC unit, a 24V system, or higher, will be better purposed.

The power consumption of the industrial fan is probably going to be the deciding factor in whether 100Ah or 50Ah batteries will suffice for now.
 

12VoltInstalls

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Using a 12V system may be slightly cheaper, but the cost of wires might eat away at those savings. Also, a 12V system leaves little room for upgrading
The cost of 2/0 IS a lot more than the cost of cabling for 24V for equal wattage, but on the grand scale of things it’s just a pizza or a couple pizzas different.

2/0 and 12V handles 2000W fine, probably up to 2500W or 3000W as the absolute ceiling for practical 12V.

But OP is describing a smaller system with budget constraints. With the plethora of 12V lighting and charging devices etc. from the automotive and RV sectors 12V makes sense in a smaller system. And with the cost of LiFePo recently a couple kWh of lithium batteries only adds ~$600 more than 1/2 that storage in lead acid. Well as long as sub- 33*F charging isn’t needed.

I recently contemplated 24V again myself. But my needs are heavy on 12V devices including the furnace, and my “heavy”120VAC consideration is 5 minutes of 700W for a coffeemaker and weekly or twice weekly vacuum cleaner use. A 24V-12V converter is just one more thing to fail, buy, and the current fridge at 80W doesn’t tax the system at all.

If someone was wanting to run a ‘normal’ urban or country house with a family, or a shop or something, 24V might not even make sense- just jump into 48V and move along. But with small solar the redundancy of batteries, easy and inexpensive backup inverters and SCCs, and low amperage; 12V is fine and in an emergency you could even use a vehicle to boost the system. (In five years on 12V I haven’t had an actual emergency)
 

Al D

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Jul 23, 2022
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Renogy RNG-100D-SSX2-US 100W panels (Qty:2) - $200 (& free shipping)

Epever 2210AN MPPT SCC - $80

WZRELB 24V 800W (RBP80024B1) pure sine wave inverter - $95

EverStart lead acid marine & rv deep cycle battery, group size 29DC (12V/845 MCA) - (Qty:2) - $180 (+state core charge)

Total price for main components: $555

This is not a recommendation, just a way to get a 24V system for around your budget. There's still wires, fuses, and switches you need to consider. I highly encourage you to do some research into these components before making any purchases. Also research the pros and cons of 12V vs 24V systems.
 

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