Need solar advice for student in minivan

[TinaTomato]

Hi CRVL!

I’m a student about to move into my minivan (can't afford the cost of living in my city), with daily access to campus facilities (showers, charging for my laptop and camera batteries, WIFI access, etc). When I’m in the van, it will be primarily to sleep, or to run an errand or two a few miles here and there. I have the Luci solar light and a rechargeable battery headlamp for nighttime reading.

I’m trying to put together a solar package that would be sufficient to run two specific appliances that would be impossible to drag into school and plug into a power outlet without being completely and conspicuously insane.

I live in Wisconsin, and it’s winter. I pray I won't need to worry about running an electric heater, as I have 0-degree rated camping bivvy and lots of blankets, cold weather gear, etc., and if I realize before too long that I need a heater, I will opt for the Mr. Heater Little Buddy for emergency warmth.

The two appliances in question:

--I have a Dometic 12v 47w thermoelectric cooler (has AC 120v plug too) I’d like to probably run a couple of hours per day if at all, just to keep veggies cool. No other perishables involved.

--My biggest concern is my juicer. It’s not a beast by any stretch, but it is 120V 200W and I’d run it once a day for 2-3 minutes at a stretch.

This is the system I’m looking into:

100w solar kit (comes with PWM charge controller) - 329.99
1000w inverter -189.99
battery AGM 12v 100ah - 168.99
battery case - 18.34
________________________________
TOTAL:   707.31

My questions are:

1: Is the above-mentioned system powerful enough for my scenario, as described, and/or does this setup seem totally whack?
2: Are these quoted prices decent? Should I be paying less than what I’ve been able to put together from my research?

Any comments and/or advice is greatly welcomed and appreciated. Thank you all!

 

[Trebor English]

Thermoelectric coolers are bad.  In Wisconsin in February it will be fine.  There are two problems.  They only cool to a temperature that is about 30 degrees below ambient.  When the van is 90 degrees the food is 60 degrees, too warm for food.  The second is that the quantity of electricity used is huge.  The watts may not seem too bad but it doesn't stop.  A compressor fridge thermostat turns it on and off.  It varies with temperature but only 10% on is not unreasonable to expect.  An Alpicool C20 mini fridge is about $250 but uses very little power.  There are you tube videos.  

Search on Amazon.  The HQST 100 watt polycrystalline solar panel I have is $98 and the PWM controller I have is under $10.  You shouldn't need a 1000 watt inverter for a 200 watt juicer.  

AGM batteries are more expensive than flooded.  I use a flooded battery.  The hydrolysis that makes hydrogen happens when the battery is charging and is getting full.  If you are in class in the afternoon you won't even be there.  You should not smoke near batteries.  You should not smoke far from batteries either.  

$100  Solar panel
 $10 PWM controller
$100 inverter
$100 flooded battery
  $20 battery box
   $10 multimeter
  $50 Crimper, terminals, AWG #8 wire
  $10 fuse holder & 30 amp fuse
Total about $400 to $500  

Operating your own electric utility is not like the electric company.  If you get 3 warm rainy days in a row you will need to not use the juicer else you injure the battery.  When the battery gets low the fridge quits.   You have to monitor the system.  

Anything that can use 12 volts will take 20% to 40% more power to convert the 12 to 120 then convert the 120 to 12.

 

[Homeless in Canada]

Since you have access to shore power get a couple of lithium batteries you can carry one in your backpack and charge it while studying in the library.

 

[TinaTomato]

Since you have access to shore power get a couple of lithium batteries you can carry one in your backpack and charge it while studying in the library.

Thanks for the advice - this sounds completely do-able. Do you have any further advice and/or experience with this? I'm wondering what sort of battery size(s)/capabilities I would need for the juicer (120V 200W running 2-3 minutes once per day). Thanks again for your kind consideration.

 

[TinaTomato]

Wow, Alpicool for the win! I checked out the C15 and it seems decent.

I swear, this "journey" is really guiding me toward the idea of a more minimalistic approach than the one I had originally mapped out. I mean, I'm going down a rabbit hole here - it seems the more I think I need, the less I realize I actually need. So interesting.

 

[tx2sturgis]

Buy a hand powered juicer....and save a lot of money by not purchasing an inverter that wont be needed.

Then put that money towards a decent 12v compressor fridge...NOT a thermoelectric cooler. 

You still need 100-200 watts of solar with controller to power that fridge, depending on a lot of things, such as solar exposure, roof-mounted vs portable panels, plus the AGM battery.

I don't recommend flooded batteries for interior living space and also because they require some occasional distilled water, which if ignored, is a problem for the battery if it dries the plates from neglect.

 

[jonyjoe303]

100 watt panel will get you about 5 amps of charge power in the best (sunny) conditions. My advice get the biggest panel that will fit on your roof, I got a 240 watt panel on my small astrovan, that gets me 12 amps of charge power in the best conditions and still gets me about 5 amps when it gets cloudy. I got mine off craiglist for 200 dollars. In your area the bigger panel will work better for you. A small panel will disappoint you. With the 240 watt panel, I have practically unlimited power, my batteries are always charged back up the following day. Better to have more power then you need, you won't regret it.

I use to power a 12 volt fridge 24/7 from a 120 watt panel and a 75 ah agm battery, but I had great sunlight in southern california. So your plans are doable if you can get a larger panel. The juicer shouldnt be a big problem, 200 watts for 3 minutes is not a big deal for a fully charge agm.

You mention cold weather, in an uninsulated van you will need that mr.heater especially in the morning. If you havent spend a night in your van yet, I get the mr heater ready. But also start thinking about insulating your van. Its easy to do and not that expensive for your comfort level. At one time I tried using a 12 volt heater but it was useless when it got cold, only the mr.heater was able to help me.

Solar sounds complicated but you can do it. Its easy to wire the panel 2 wires plus/neg, controller has 2 wires solar input plus/neg, and 2 wires to battery plus/neg. All controllers have same connections. No need to buy an expensive kit.

 

[Master Mechanic]

wisconsin winter even if clothing kept u warm wearing all that stuff will get old fast.

using propane makes moisture = mold
so u have damp clothing, bedding and mold that can kill ya and need windows down a bit so carbon monoxide does not kill ya.

two options i can think of. i would mount on trailer hitch cargo carrier. me id have both.

Diesel Air Heater 5KW 12/24V
https://www.amazon.com/dp/B07KGBJY8V/ref=twister_B07KFFV9N3?_encoding=UTF8&psc=1

electric heater with Dual Fuel Inverter Generator
https://www.amazon.com/dp/B076CWJZH...olid=2REYPDGM9883F&psc=0&ref_=lv_ov_lig_dp_it

 

[Trebor English]

In post number 2 I suggested a 100 watt panel and a cheap PWM controller.  That kind of controller is good for a 36 cell "12 volt" panel.  When it turns on it just connects the panel to the battery.  If you are considering a bigger solar panel they are different.  Typically they are 60 cells or 72 cells so their voltage is higher and not compatible with the way a PWM controller works with a 12 volt battery.  For those you need an MPPT controller to step down the voltage and step up the amps.  The "12 volt" 36 cell panels have an open circuit, no load, voltage, Voc, of 20 to 24 volts.  

Beware of internet, eBay, and Amazon ads for controllers called MPPT.  If they are under $65 they are not MPPT.  Look for products over a pound with a fan for cooling.  MPPT controllers have substantial electronics that cannot be done in a 3 ounce product.  The electronics will dissipate heat.  It is possible to dissipate the heat with good fins and no fan.  My cheap controller is PWM, doesn't dissipate much heat yet it has real looking cooling fins.  They are plastic and not functional.  An actual fan costs money and it is unlikely they'll put one in if it isn't needed.  

Just because a controller 1) claims to be MPPT, 2) weighs two pounds, 3) has a fan, 4) has a price over $65, meeting all the points on my list, doesn't assure that it really is MPPT.  If it misses any one point I can assure you it is not MPPT and you will be disappointed.  Victron and Epever make some real MPPT controllers at low prices, $120 and up.  

If you start with a minimum system, 100 watt panel, cheap PWM controller, and want more power the first step is to get a second panel.  A second "12 volt" panel will double the power and costs $100. You will also need a 20 amp PWM controller, $15 instead of $10 for a total of $105.  A real MPPT controller, just the controller,  for a 60 or 72 cell panel will cost that much.  The higher wattage panel might fit your roof better than 2 100 watt panels.  There are lots of things to consider and it gets complicated.  

You can use an MPPT controller with a "12 volt" solar panel and it will improve system performance.  The lower the battery state of charge or the higher the loading like the fridge compressor, the better the improvement.  According to the vendors it is up to 30% better while the battery voltage is low.  The improvement reduces as the battery voltage rises.  So, for the price of another panel, 100% increase, the MPPT will give less than a 30% increase.  As system sizes increase MPPT becomes a better deal because it is 30% of a bigger number.  

Conservation is key.  Every watt hour or amp hour you save is a watt hour you don't have to generate with panels and store with batteries.  The challenge is to get enough electricity at a low cost.  

I just looked at Amazon.  I searched for "240 watt solar panel" and looked at the first one.  That's not necessarily the best deal or even a good deal, just the first one.  It was $531 plus $30 shipping.  The Voc is 36.6 volts.  The maximum power voltage (Vmp) is 30V.  At .5 volts per cell, that makes it 60 cells.  With a PWM controller it will work, with great waste, and it will be better than one 100 watt "12 volt" panel but not as good as two.  MPPT  will make it significantly better than two 100 watt panels.

 

[jimindenver]

There are MPPT controllers that sell for under $100. My favorite is the Eco-Worthy 20a MPPT controller that can be had for $69. I have used them for over 5 years.

 

[Tbaldwin]

I’m from Iowa and not killing my house battery in my minivan seems like a year round challenge no matter how light the load. On the other hand, I’m wintering in AZ/CA with all systems go. Minivans (and solar power when you have the sun) rocks!