The Survival Podcast Forum

Energy Options => Solar Power => Topic started by: surfivor on June 01, 2018, 07:57:18 AM

Title: Portable solar system to run electric fans
Post by: surfivor on June 01, 2018, 07:57:18 AM
I am interested in a portable solar system to run a couple of fans at my camp when it’s very hot out. I would like to have one fan that blows air out the window and another fan that blows air on me. When it’s warm out sometimes my yurt gets very hot in the afternoon such that it is too hot to take a nap, cook or do anything

I have this little fan that uses 6 D batteries but it doesn’t push enough air when it gets really hot

Would I be looking at one 12 V battery and some panels? How long will the battery run the fans for roughly?  On a hot day it can be too hot from about 11:00 to 4:30. It is not hot every day and if I am not inside the yurt then I don’t need to run fans. It would be nice if such a system could run fairly powerful fans for 2 or 3 hours. There is some sun here but much of it is partial sun or direct sun only during certain parts of the day. If the system is not too heavy or bulky I could possibly place it in a more open area 1/10 of a mile back onto my property for charging

What are some good systems?

This would also be a good backup system to have. I would be Interested  in something portable so I could move it back-and-forth between my camp and my house if I wanted to
Title: Re: Portable solar system to run electric fans
Post by: armymars on June 01, 2018, 09:27:46 AM
  It depends on how big the fans are. It's all about voltage and current needed to run them. I once read ther was a tent design that lowered the temp. by 20 degrees. It involved a tarp above the tent with a one foot spacing. This would cause an air flow between the tent and tarp.
Title: Re: Portable solar system to run electric fans
Post by: Carl on June 01, 2018, 10:12:09 AM
 :popcorn:  Just getting some fresh popcorn ,for now.BUT ,air circulation makes up for a lot of sweat and many good fans are made for RV's that run from solar direct or 12 volt battery. A small fan directed across you can do a lot and maybe you should look into a roof vent to open more circulation as hot air naturally rises and ventilation can often be fixed without use of power ...HINT for some I use are just auxiliary auto radiator cooling fans from a scrap yard.
Title: Re: Portable solar system to run electric fans
Post by: surfivor on June 01, 2018, 12:13:48 PM
:popcorn:  Just getting some fresh popcorn ,for now.BUT ,air circulation makes up for a lot of sweat and many good fans are made for RV's that run from solar direct or 12 volt battery. A small fan directed across you can do a lot and maybe you should look into a roof vent to open more circulation as hot air naturally rises and ventilation can often be fixed without use of power ...HINT for some I use are just auxiliary auto radiator cooling fans from a scrap yard.

There is a large skylight but it does not have many clean edges so that installing a screen would be complicated. There are various springs and a gear where are you open it using a stick Turner.  All those things create a jagged area.
Title: Re: Portable solar system to run electric fans
Post by: Bolomark on June 01, 2018, 04:28:16 PM
I installed an attic fan in gable end of my house, solar panel is mounted on an old direct TV satellite arm adjustable both ways.The sun hits it at 10 am runs until sun goes down.
it is controlled by thermostat  (72deg.)  and fuse and works great.I picked up my fan and panel from backwoods solar. no batt. 8)
Title: Re: Portable solar system to run electric fans
Post by: surfivor on June 01, 2018, 04:33:19 PM
I know it was mentioned in another post that the goal zero system may be overpriced but this one for $600 (just battery) can charge a laptop 3 to 5 times. I am familiar with these so it is a place to start.

https://www.goalzero.com/shop/power-stations/yeti-400-lithium-portable-power-station/


This one will charge a laptop 17 times and cost $1300 but that is just for the battery

https://www.goalzero.com/shop/power-stations/goal-zero-yeti-1000-lithium-portable-power-station/

What are some similar alternatives and is hooking such systems to panels a simple matter?
Title: Re: Portable solar system to run electric fans
Post by: Carl on June 01, 2018, 05:05:27 PM
  You shop in a higher end market than I as 100 amp hour battery can be had in the $75 to $100 range and a 100 watt panel with controller well under $200 and this would run several fans and lights for several years before needing to replace the battery and let me add that AMP HOURS is the measure to look for ....not how many times you can charge a laptop or electronic cigarette...
Title: Re: Portable solar system to run electric fans
Post by: surfivor on June 01, 2018, 05:52:03 PM
  You shop in a higher end market than I as 100 amp hour battery can be had in the $75 to $100 range and a 100 watt panel with controller well under $200 and this would run several fans and lights for several years before needing to replace the battery and let me add that AMP HOURS is the measure to look for ....not how many times you can charge a laptop or electronic cigarette...

Post some links or recommend brands

I guess maybe anker was the better priced brand.

Also found this

https://bestportablesolargenerators.com/goal-zero-yeti-alternative/
Title: Re: Portable solar system to run electric fans
Post by: surfivor on June 01, 2018, 06:40:20 PM

This unit looks interesting. It weighs 12 pounds and sounds like it has a lot of power for its size

https://www.chargerharbor.com/review-suaoki-120000mah-portable-power-supply/
Title: Re: Portable solar system to run electric fans
Post by: Carl on June 02, 2018, 06:45:47 AM
This unit looks interesting. It weighs 12 pounds and sounds like it has a lot of power for its size

https://www.chargerharbor.com/review-suaoki-120000mah-portable-power-supply/

About 30 amp hours,if compared to a 12 volt battery, as the 120,000 mah rating is very deceptive because it is a 3.7 volt main storage cell and depends on inverters to produce usable voltages for other devices  with this you basically have 300 Watt Hours (I know that it claims 400 Watt Hours) of available power...300 watts for one hour....30 watts for 10 hours....enough to run one small (say 6 to 8 inch) fan for 10 to 20 hours or a good 20 inch fan for maybe two hours.

Fans require a fair amount of power to move quantities of air and few quality fns are designed for 12 volt battery use.


May I suggest you find the fans that you want to use for the job and work towards a power unit that will give 10 hours run time ,or more and maybe allow for a light or two ....though flashlights and portable lamps do work great also. You will have a far greater chance for success this way.

Title: Re: Portable solar system to run electric fans
Post by: Carl on June 02, 2018, 10:05:22 AM
I use fans like the links below and they do move a good bit of air for 'personal' use as while in a chair or in bed on a hot,power-outage night and they run off most any 12 volt battery BUT use about 1 amp so you get about the same number of hours use as the rated amp hours of a good battery or jump pack....for TWO of this fan I would suggest an 18 AMP HOUR battery though better to use one fan per 18 Amp hours of battery to add longer life to the battery as flattening them each day is not so healthy for the chemistry. During a power outage I used a 12 amp hour sealed lead acid battery to run one fan all night and was comfortable with a recharge in the morning from my larger solar panels/battery set-up.

https://www.amazon.com/12v-Oscillating-Fan-Car-Universal/dp/B0719JVTW4/ref=sr_1_30?ie=UTF8&qid=1527954786&sr=8-30&keywords=12+volt+auto+fan

https://www.amazon.com/Zento-Deals-Portable-Oscillating-Fan-Universal/dp/B01HMV9CX0/ref=sr_1_11?ie=UTF8&qid=1527954644&sr=8-11&keywords=12+volt+auto+fan

https://www.amazon.com/Hopkins-SP570804-Go-Gear-Oscillating/dp/B003SS62PS/ref=sr_1_1?ie=UTF8&qid=1527954644&sr=8-1&keywords=12+volt+auto+fan

I don't know that one fan is better than the other and usually just buy the lower cost of these links as I usually keep a couple spares as I use some daily in my Ham shack for circulation.
Title: Re: Portable solar system to run electric fans
Post by: kid_couteau on June 02, 2018, 05:54:19 PM
Hi All

Surfvivor may I ask a personal question?

Do you have any electronics experience? Please forgive I do not mean that in a catty way but as an honest question. I ask because then we know where to start.

It is only my opinion and again please forgive my bluntness but it seems that in your posts you always tend towards the Goal Zero type equipment. From what I have read and what I have built it may be good stuff but you could build an equivalent setup yourself for a lot less.

From Carl's post: https://www.amazon.com/12v-Oscillating-Fan-Car-Universal/dp/B0719JVTW4/ref=sr_1_30?ie=UTF8&qid=1527954786&sr=8-30&keywords=12+volt+auto+fan

https://www.amazon.com/HQST-Monocrystalline-Connectors-Battery-Charging/dp/B018BMGTTO/ref=sr_1_5?ie=UTF8&qid=1527983429&sr=8-5&keywords=solar+panel+100watts

https://www.amazon.com/EDECOA-Inverter-Modified-Display-Remote/dp/B074VY2RGS/ref=sr_1_23?s=lawn-garden&ie=UTF8&qid=1527983504&sr=1-23&keywords=power+inverter+sine+wave

https://www.amazon.com/Universal-UB121000-45978-100AH-Cycle-Battery/dp/B00S1RT58C/ref=sr_1_3?s=electronics&ie=UTF8&qid=1527983590&sr=1-3&keywords=12+volt+sla+battery+100ah

Heck you dont even need the inverter if you just want 12 volt stuff

Just a thought
Kid Couteau
Title: Re: Portable solar system to run electric fans
Post by: FreeLancer on June 04, 2018, 01:27:39 AM
I got one of these Vornado Energy Smart fans last summer that has a high-efficiency brushless DC motor that runs off 24VDC transformer that plugs into the fan with a standard barrel connector.  It's expensive but it does move air well and can be dialed down to really low speeds to reduce noise and energy consumption.

(https://www.vornado.com/wp-content/uploads/2017/03/783DC_Hero-570x708.jpg)


Today I made up a DC power cord and played with running it off of 12V batteries and power supplies through a DC converter to measure the fan's current draw.  At full speed it pulled 2.2A x 24.0V ~ 53W from the converter, which corresponded to 4.2A x 13.8V ~ 58W from the power supply I was using.  At about 75% fan speed, which seems like the sweet spot in terms of noise and air flow, the fan pulled 1A x 24V = 24W.   I have the exact same design with the traditional AC motor and it pulls 72W from the wall socket at full speed, although the DC model feels like it may move a bit more air at top speed.


You could hook up two deep-cycle 12v batteries in series with a 24V solar charge controller and then run the fan directly off batteries with no conversion losses from a DC-AC inverter or a DC-DC converter. 
Title: Re: Portable solar system to run electric fans
Post by: Carl on June 05, 2018, 08:40:37 AM
Looks like a good fan choice though I would not run it on high for extended periods.

https://www.amazon.com/Ceiling-Battery-Power-ceiling-Portable/dp/B06XP58PSB/ref=sr_1_60?ie=UTF8&qid=1528200811&sr=8-60&keywords=12+volt
Title: Re: Portable solar system to run electric fans
Post by: surfivor on June 06, 2018, 09:59:33 AM
Hi All

Surfvivor may I ask a personal question?

Do you have any electronics experience? Please forgive I do not mean that in a catty way but as an honest question. I ask because then we know where to start.

It is only my opinion and again please forgive my bluntness but it seems that in your posts you always tend towards the Goal Zero type equipment. From what I have read and what I have built it may be good stuff but you could build an equivalent setup yourself for a lot less.

From Carl's post: https://www.amazon.com/12v-Oscillating-Fan-Car-Universal/dp/B0719JVTW4/ref=sr_1_30?ie=UTF8&qid=1527954786&sr=8-30&keywords=12+volt+auto+fan

https://www.amazon.com/HQST-Monocrystalline-Connectors-Battery-Charging/dp/B018BMGTTO/ref=sr_1_5?ie=UTF8&qid=1527983429&sr=8-5&keywords=solar+panel+100watts

https://www.amazon.com/EDECOA-Inverter-Modified-Display-Remote/dp/B074VY2RGS/ref=sr_1_23?s=lawn-garden&ie=UTF8&qid=1527983504&sr=1-23&keywords=power+inverter+sine+wave

https://www.amazon.com/Universal-UB121000-45978-100AH-Cycle-Battery/dp/B00S1RT58C/ref=sr_1_3?s=electronics&ie=UTF8&qid=1527983590&sr=1-3&keywords=12+volt+sla+battery+100ah

Heck you dont even need the inverter if you just want 12 volt stuff

Just a thought
Kid Couteau

 Yes, I mentioned goal zero may be over priced but it is something I am familiar with. I didn't say I was buying that necessarily but using it as starting point for comparisons. I took a digital electronics course 30 years ago, but I don't remember much of it. It may seem like easy stuff to grasp but I have so many hobbies, friendships, things to do and research all the way from trying to do martial arts, gardening, practicing guitar, going out with friends, keeping up with old friends, going surfing, cleaning my house, working out, shopping, going camping, band practice, fixing my car, working, learning new stuff for my profession, canoeing, going to church or temple, finding time to meditate, I am always juggling something and have limited time to figure anything out.
Title: Re: Portable solar system to run electric fans
Post by: Carl on June 07, 2018, 05:39:59 AM
  When you get time ,you really need to add to your skill on such important things...until then,I would suggest you pay the high cost of the commercial made products  and hope for the best....in this (power needs) case get the largest capacity and as many options to charge the system as you can and give us reports of the use,care,and advantages as I personally know of no one who uses the pre-packaged option...except for the USB/phone chargers.
Title: Re: Portable solar system to run electric fans
Post by: surfivor on June 07, 2018, 08:15:17 AM
I already posted a link to a unit that I thought looked interesting and it was not a goal zero system. I was on vacation last week and we had a couple of hot days that got me thinking about fans. Right now I am back at work and thinking about other things but I appreciate the links and will look at them when I have time
Title: Re: Portable solar system to run electric fans
Post by: surfivor on June 16, 2018, 06:53:01 AM
I may order the Suaoki 400Wh/120,000mAh Portable Power Supply this week as well as one of the cheap DC fans Carl posted and maybe the smart fan as well. Then if I am up at my camp in the hot weather and want to take a nap in the afternoon, I will be able to stay cool
Title: Re: Portable solar system to run electric fans
Post by: Carl on June 17, 2018, 07:14:00 AM
I may order the Suaoki 400Wh/120,000mAh Portable Power Supply this week as well as one of the cheap DC fans Carl posted and maybe the smart fan as well. Then if I am up at my camp in the hot weather and want to take a nap in the afternoon, I will be able to stay cool

400 watt hours is good capacity for most any of the 12 Volt DC operated fans as long as the 12 volt outlet is capable of 1 amp per fan used as many of the current power units do not use a 12 volt battery and electronics must 'step up' the voltage . I would suggest the 15 watt listed power level for fans as that power is needed to actually move a usable quantity of air.I used a small 12 amp hour battery to run a 6 inch oscillating fan for over 10 hours successfully and this is equal to about 140 Watt Hours of the rating on one of the power pack units ....so two fans over night is not out of the question with 'reserve ' power for LED lighting or cell phone recharge and I would use the recharge while mobile option or about 30 to 50 watt solar (costly) for daily planned use of the unit.
Title: Re: Portable solar system to run electric fans
Post by: surfivor on June 18, 2018, 06:57:41 AM
Quote
.so two fans over night is not out of the question

 I don't need to run fans overnight. It's usually cooler at night and my camp has good ventilation. It's usually the afternoon hours that are too hot to take a nap or be inside the yurt. I generally only would need to run a fan or fans for 2 or 3 hours at the most
Title: Re: Portable solar system to run electric fans
Post by: surfivor on June 22, 2018, 05:27:03 PM
 The 12 volt lithium battery arrived today and the smart fan a few days ago. I have the smart fan plugged in to the battery AC plug right now and the fan is running. Depending on the fan speed it shows 40W output at medium speed or about 77W at high speed. It is a very strong fan with a great deal of airflow.

  I also have the other much smaller fan that Carl recommended that runs on DC, but I don't think it is supposed to be used for DC and AC at the same time. This AC fan puts out plenty however as it is and would be good when it is very hot and the DC fan when the heat is more moderate.

 I will probably take a vacation to my camp in Maine at the end of August. Sometime before then I will most likely order solar panels to charge the battery with. The one they seem to recommend is this 100W solar panel https://www.gearbest.com/chargers-cables/pp_640785.html
for $169. There is no electricity at my camp of course

Any other recommendations for solar panels to use ?
Title: Re: Portable solar system to run electric fans
Post by: chad on June 23, 2018, 11:53:05 AM


I just added this to my system








https://www.amazon.com/Newpowa-Monocrystalline-Efficiency-Module-Marine/dp/B01LY02BOA/ref=redir_mobile_desktop?_encoding=UTF8&psc=1&ref=yo_pop_d_pd_title
Title: Re: Portable solar system to run electric fans
Post by: Carl on June 23, 2018, 01:23:34 PM
Nice panel Chad.
Title: Re: Portable solar system to run electric fans
Post by: chad on June 23, 2018, 01:47:03 PM
Thanks Carl, I'm up to 330 watts now.
Title: Re: Portable solar system to run electric fans
Post by: surfivor on July 11, 2018, 01:52:15 PM

 Today is the first day I have worked from home from my camper. I am using my 12 volt Suaoki lithium battery to power my laptop inside the camper. It is almost 4 o'clock and it's used about 3/5 of it's power to run my laptop all day based on the panel readout.

 It is hot out and I am running the fan on the camper skylight on low, however that fan is running off of the truck RV battery which is a totally separate battery from the lithium battery and also currently disconnected from the truck battery.

 I have been sitting in this little tiny camper all day using my IPhone as a hotspot. it hasn't been too bad but if it was much hotter out it would be difficult. I think it must have reached a high of about 80 and there is a sea breeze

What I do is I shut off the lithium battery and when my laptop goes down to about 75% or 80% I turn it back on and then turn it off when it gets close to 100%

This wasn't the original plan of why I bought the battery but it has all sorts of uses
Title: Re: Portable solar system to run electric fans
Post by: surfivor on July 18, 2018, 11:13:24 AM

I bought this 60W solar panel. When I hook it up to the battery, the battery shows 4 Watts of input. I wonder how long it will take to charge the battery. I ran the battery down 20% and then put it out in the back yard with the solar panel to see how long it would take. I am guessing it may take a long time

https://www.amazon.com/gp/product/B018TY8ZYQ/ref=od_aui_detailpages01?ie=UTF8&psc=1
Title: Re: Portable solar system to run electric fans
Post by: kid_couteau on July 18, 2018, 11:42:13 AM
May I suggest that you allow us to teach you some basic electronics?

I mean respectfully if you are going to be a survivor and use this sort of equipment it would truly benefit you to learn the fundamentals.

Here is a micro lesson. I offer it in friendship. [Guys feel free to correct me if I make any errors]

With a 60W solar panel, I am assuming you are in Maine like I am, to get the best power input place it about 45 degrees from the earth. You want it to be as close to 90 degrees to the sun as possible. This time of year you should get about 4.5 hours of optimum sunlight per day in Maine.

Now if your battery is in Watts then the math is easy. Say a 240 watt battery receiving 60 watts an hour should charge in roughly 4 hours of optimum sun.

If your battery is in Amp Hours then you can use this:

W/E=I where W-watts  E-voltage and  I-current or Amps

say a 60W 12 volt panel 60/12=5 Amps so roughly 5 amps per hour [of course it is not that clear cut usually it will be round 4 amps per hour with a 60 watt panel]

Anyways I hope this helps unfortunately there is a bit of guess work with solar.

Kid Couteau
Title: Re: Portable solar system to run electric fans
Post by: surfivor on July 18, 2018, 01:08:30 PM
 I was going by what the console readout on the battery looked like when it was charging from the wall which took quite a while but showed much more watts of input. I thought I had it angled kind of towards the sun, but then I realized the sun was a bit more to the west possibly from where I had aimed it. I got the console to show 27 watts of input from the solar panel after further adjustments which seems much better.

I have so many adapters and input options that this thing came with as well as the lithium battery, I was screwing around for quite a while trying to figure out why it appeared the solar panels were connected but the battery console was not registering anything.
 
 The lithium battery has a special solar panel input with +/- and an adapter for that and then a different input for single adapter. I ended up doing the charge on the single adapter.
Title: Re: Portable solar system to run electric fans
Post by: Carl on July 24, 2018, 05:42:06 PM
  I am back from the dead....Sometimes you have to jiggle the handle as most 60 watt panels will only output 50 watts with the charge controller as the panel is usually rated at maximum current TIMES Maximum voltage and as we use 12 volt batteries with 20 volt panels ,,,the math will always be FUZZY. Also your indicator may be 4% charging PLUS powering of the device. Numbers can get in the way of enjoying solar power as they still don't add up.
Title: Re: Portable solar system to run electric fans
Post by: Alan Georges on July 24, 2018, 09:18:33 PM
  I am back from the dead....
No strange cravings, I hope?  For say... BRAINS?!?   :zombie:


Good to see you back, Carl.  Back to the thread topic...
Title: Re: Portable solar system to run electric fans
Post by: idelphic on July 25, 2018, 08:13:22 AM
I'm rather late to this but the o2Cool 10inch fan works on both Dcell batteries and 12v adapter.

Title: Re: Portable solar system to run electric fans
Post by: surfivor on July 25, 2018, 11:57:59 AM
I'm rather late to this but the o2Cool 10inch fan works on both Dcell batteries and 12v adapter.

 I have had those types of fans for years. This 12 volt setup allows me to run a more powerful fan but I still use those other types sometimes also
Title: Re: Portable solar system to run electric fans
Post by: antsyaunt on July 25, 2018, 12:20:50 PM
  I am back from the dead....
So good to hear, Carl!  Hoping you are feeling better every day. 

And thanks to those who are providing good explanations.  Knowledge from college physics hasn’t stayed with me, unfortunately.    Refreshers are needed!
Title: Re: Portable solar system to run electric fans
Post by: Carl on July 25, 2018, 01:15:35 PM
  I find that effecting air motion ,as with air temperature,that more power is needed than often planned for. I find favor with the 8 inch ,12 volt fans in the 15 watt class that require about ONE AMP to give motion to air and as there is little innovation in propeller...one can well judge the average fan with the power consumed. Being able to recognize the need to oil bushings can add to the useful life of these fans as they are  simple and fairly tough. Also keeping the moving and non-moving parts free from dust will greatly effect their usefulness. 

  I have used 120 volt fans in the 8 to 10 in (about 30 watt) table top size and will use them with an inverter as I have good supply of solar to power stuff and while an inverter driven fan does work well,they are less efficient than a directly driven 12 volt fan . Of the battery operated fans I like best are thee one or two speed 12 volt ,with cigarette plug...often advertised as 15 to 20 watt and often requiring ONE AMP or there abouts of power. I will link one or two below with the fact that brand name offers little in decision here as cost is my guide....most appear to be made to the same quality anyway.

  A final note is the OH 2 COOL battery fans is that they are good fans ,though they lack the power to move as much air as the 12 volt ,plug in fans and would not be my first suggestion unless battery only (internal batteries) is a requirement as they tend to not move as much air...though they are quite effective...I like the more common looking dash board fans as below.

https://www.amazon.com/gp/product/B01BFLQKLK/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

https://www.amazon.com/gp/product/B0719JVTW4/ref=oh_aui_search_detailpage?ie=UTF8&psc=1


Note that COST,not brand name,is more my guide to purchase these and I also look at options as speed,and oscillating to be good to better aid motion in a somewhat larger than 'personal' room.
Title: Re: Portable solar system to run electric fans
Post by: idelphic on September 09, 2018, 10:19:39 AM
Small... but if you can pull them from old Server Power supplies - or old Servers period,.. try looking for something similar to this:

https://www.sager.com/9crb0412p5s201-3676235.html?utm_source=googlemerchant&utm_medium=click&utm_campaign=sager-brand&gclid=EAIaIQobChMIkr2Gsqiu3QIVB9bACh3TTgw6EAQYBCABEgKWv_D_BwE

I have a San Ace 40, it's a two stage fan that runs at 12v 1.1a.. It's a pretty powerful fan for the size...  but they do have a bit of a bite on cost.

Title: Re: Portable solar system to run electric fans
Post by: fratermus on September 13, 2018, 08:31:09 AM
> most 60 watt panels will only output 50 watts

The difference usually has more to do with voltage suppression due to cell temp above lab conditions (25F, about 0F ambient).

>  with the charge controller

Even without a controller.  A panel attached to a battery the panel will be run at battery voltage.  This is why PWM is said to "waste power" and the secret to how MPPT controllers maniupulate panel voltage (and therefore power).


> as the panel is usually rated at maximum current TIMES Maximum voltage

The panel is rated at Vmpp:  voltage at which the panel puts out max power under lab conditions.  This is usually far away from Vmax (max voltage, open circuit) but generally in the neighborhood of Imax (max current) because current is usually pretty flat across the power curve.


> and as we use 12 volt batteries with 20 volt panels

Hence MPPT. 


>  ,,,the math will always be FUZZY....  they still don't add up.

A look at the panel's power curve will clarify the situation greatly. 

OP:  non-controller or pwm controller scenarios work best when the panel's Vmpp is close to Vbatt (battery voltage).  A mono panel (higher than usual voltage) and lithium pack (lower than usual voltage) are not matched very well.   This is one of those situations where more expensive (or more mindshare) is actually counterproductive.*

related info: 


* that and AGM charged by solar, but don't get me started


Title: Re: Portable solar system to run electric fans
Post by: fratermus on September 13, 2018, 10:15:56 AM
Quote
This time of year you should get about 4.5 hours of optimum sunlight per day in Maine.

This idea is correct;  the unit of measurement is Hours of Full Sun Equivalent (FSE).   It's the amount of light a flat-mounted panel will receive n a given location at a given time of year on average.  IOW, the amount of sun received throughout the day will be equivalent to 4.5hrs of sun under perfect/lab conditions. 

I point this out because it might help people predict the amount of average sun available where they are.  It also allows us to see how much gain we can get from tilting/tracking. Here's one example of FSE data by month:

http://solarinsolation.org/wp-content/uploads/2012/01/Solar_insolation.jpg <-- having troubles inlining images from this browser


Quote
say a 60W 12 volt panel 60/12=5 Amps so roughly 5 amps per hour [of course it is not that clear cut usually it will be round 4 amps per hour with a 60 watt panel

Temperature derating can be calculated here (http://digivation.com.au/solar/tempderate.php). 

Controller losses will be:


This means that in special cases PWM can actually put more power into the bank than MPPT.   

I've started a gentle intro to solar for beginers on this wiki (http://rvwiki.mousetrap.net/doku.php?id=electrical:solar:gentle_intro) page.  It's proving harder than I thought.  I welcome corrections and additions.