Solar Newbie S.O.S.

[pnwexplorer]

Hey All,

I'm just creeping into the realm of all things solar, and I've discovered that I just opened up a huge can of worms! haha.

I watched the Youtube video that was posted on here about calculating the total number of watts needed per day... My biggest concern is the fridge that I currently have. It's an R/V & boat fridge, a Norcold DE-351D, and it's quite old. After calculating the wattage for a 24hr period I was a bit shocked, so here's the break down :
12v*3.5A*24 = 1008 watts per day!

After briefly looking at the spec's for a Renogy 100 Watts 12 Volts Monocrystalline Solar Panel it looks like a MAX out put of 500 watt hrs per day.

So then I started to think... "wait don't fridges cycle on and off?" Is that the case, if so do I need to factor in this duty cycle?


Along with the fridge I'm planning on charging both my laptop & phone once per day. I also have an old Sharp Carousel microwave oven in the van.. Who uses a microwave? Reheating things would be nice, but I'm not sure If I'll really need it.

Than van is equipped with a Magnetek power converter, see photo.

This converter goes to the Auxiliary battery (which is junk). Right now it has one Aux battery, I'm thinking that I'll be better off with the two 6V batteries, like most folks have been doing.


Another news flash for me, Inverts & Converters are two different things.. Converters are for A/C to D/C, and Inverters are for D/C to A/C. I also found that you need to be careful when selecting an inverter, as there are cheaper ones that are not pure sine wave.

 

[AngryVanMan]

Definitely factor in the duty cycle of the refrigerator, but remember to try and simulate your worst case conditions with a hot interior room temperature, proper food items in the fridge, and opening and closing the door the "normal" amount. You can record the duty cycle while plugged into 120V since that's a dual voltage fridge if you don't have battery power to test with, the duty cycle/run time should be close on either power source. Also, you might get lucky and the fridge pulls less than the nameplate amperage while it's running, this is fairly common. If you have a wattmeter or a multimeter with a DC amps setting you could test it.

Microwaves are great if you know you'll use it - it takes a pretty big inverter ($$$) to run one, but the total power use per day is usually low as they don't run for that many minutes in a 24 hour period. We are going to have a microwave, but I think most will not have one in a van.

I'm going to see if I can find the YouTube video you mentioned about the power calculations.

 

[jimindenver]

With 750w of solar and 675 Ah of battery I couldn't run that fridge day and night in good weather. 35 amp at 12v times 24 hours and a 50% duty cycle = 420 Ah a day. That fridge is a pig. How big is it?

 

[TMG51]

Buy a 12v compressor refrigerator from this century and get rid of that headache.

 

[Spaceman Spiff]

I use an old (1982) Norcold DE-251D 12/110 volt refrigerator in my camper.  It uses ~5 amps on startup at 12 volts and tapers to ~3 amps at end of cycle.  I run it off of 200 watts of solar and 208 AH of battery (2 X GC2 6V batteries in series).  I also run a MaxxFan for ~ 6 hour a day, charge an iPhone 5S, MacBook Pro and an InReach SE, run a WeBoose 4G-M when on the phone or internet, have LED lighting, and run various other small 12V fans.  The refrigerator is wrapped with 2" of polyiso and is well vented in the back with an exhaust fan.  I seldom get below 80% battery capacity and am usually back to 100% by 11:00 AM.  The refrigerator maintains 35F even in 90+ degree temps.  On very hot days my frig runs ~40% of the time (but I am also getting max output from my solar panels, so it is not drawing from the batteries during the hottest part of the day).  I keep the frig and freezer full, which helps.

Get a Kill-A-Watt meter and run your frig for a while on shore power and see how it does.  If it will hold temperature and not run over 50% duty cycle, i'd use it.  Make sure the door seals are good.  Make sure the condenser in back is clean and well ventilated.  Forcing air out of the condenser compartment will improve efficiency.

 -- Spiff

 

[AngryVanMan]

Dang, you don't get much better than a custom tailored report with someone using a very similar rig! Is there any major differences between the 251 and the 351? Size?

Another thing to consider is where you might setup camp vs Spiff. If you spend a good deal of your time in the PNW, you might get less sun than someone in the SW does. I wasn't sure where you each camp/plan on camping.

 

[pnwexplorer]

Slowly piecing together this puzzle...

Since my sing Aux battery is toast, I'll definitely be replacing it with two 6V batteries. The battery guy in town has Trojan T105's @ $139.95 I've seen some better deals online, but the web sites didn't look all that official, so I don't think I'll end up going that route.

I'm pretty sure I found the inverter, but I'm not totally sure if that's the case. It's up in the front of the van, back behind the grill under the passenger side headlight... Seems like a good spot for corrosion.

At this point I'm not super worried about whether my fridge draws all that much current, or not. I'm just going to base it on the numbers that Spaceman Spiff supplied. My thinking is that I can always get a more efficient unit down the road if need be.

Next question. With my high top Van, and Roof top A/C unit I don't have all that much real estate to devote to Solar panels. I'm living in the PNW in the valley, it can get somewhat hot here 90's are about max with a bit of humidity.. My rooftop A/C has to be run on shore power, so I'm thinking maybe I should just delete that to do two things: lower the overall height of van approximately 10", makes more room for solar panels. For all you full timers, and stealth guys how are you fairing without an A/C? Lately I've been waking up at 5:30 and going to bed around 12:00am, around these times it's been fairly cool which is definitely nice.

I'm thinking Two 100 watt panels would be plenty, but more is always better right?

 

[SternWake]

It could be argued The pre 90's Norcolds were made better than later models.  This was before the 'cheapen everything as much as possible, increase the marketing, sales, and maximum profit' mindset that has completely taken over.

The electronics which control the compressor are not as efficient as today. I have a electronic wizard friend that plans on upgrading capacitors and some other electronic gizmos on his older model Norcold before restarting it after a long rest, but he is also budgeting for a new fridge in case he is not happy with its performance/battery consumption.

One thing to check on an old fridge is the door seals, and door warpage.  See if a dollar bill closed in the door presents the same resistance all the way around when pulled out.  The seal on the bottom of the door is especially important as the locking mechanism is at top, and one time of trying to force the door shut with too much inside can warp the door, leaving a gap, and forcing the compressor to run much more often for longer.

 Magnatec converters are junk.  Replace it with a pd9245 or Iota DLS-45 and if and when you plug in, your batteries will actually be able to reach full charge in 6 to 10 hours.  With that magnatec converter it would take days, or weeks or even never, and after they were fully charged and still plugged in, they would be overcharged until they are dry and useless.  There are other converter options and amperages, but these two are pretty good.  If you never plan on plugging in to recharge then don't bother, If you do, then these are good for a pair of GC-2 batteries in series for 12v.  I'd give the nod toward the PD9245-14.8 model as one can force it into seeking and holding certain voltages manually, while still being automatic if one does not want to bother.


Fridge electrical consumption can vary widely depending on usage and ambient temperatures.  In 2007 I was afraid my fridge would need more than the 130 watts of solar I had gotten.  I added more insulation to the fridge and cabinet, made sure the coils on the back had more than adequate ventilation, and then found in my usage I could easily have run 2 of these fridges on 130 watts in my climate.

I now have a better fridge( the Norcold failed after 5 years of use) and 200 watts of solar and only 90Ah of AGM battery for both engine starting and house duties.  With a capable alternator well wired, and the ability to plug in and recharge with an adjustable voltage 40 amp power supply, I need no more battery capacity than I currently have, currently.

But I have enough tools and experience to know pretty much where my battery is, state of charge wise, and what it is capable of, and what it requires to retain as much of its capacity as possible being worked hard.

Newb's to living on battery power are usually fairly clueless in these regards, so more battery capacity is required to give the best chance of not overdischarging them and giving them more time before battery capacity declines to the point they can't help but notice something is wrong.

A pair of gc-2 batteries is about as good as a van dweller can do in the durable battery department.  However, If one discharges them to 50% nightly, then 200 watts of solar is nowhere near enough as 200 watts harvests only 55 to 75AH on a good sunny day in summer.  It is very difficult to have too much solar, and quite easy to have to little.

Electrical loads tend to increase with more time living in this fashion, so 300 watts might cost you a bit more time and frustration and $$ now, but your batteries will live a lot longer and you will have more buffer for less than perfect conditions.  Upgrading later is not just as easy as slapping on another panel as the charge controller might not be able to handle it, or the wiring might have to be thickened, and rerouting wiring is not very fun, so this yet another case where it is beneficial to get more than enough, rather than just enough, and having to upgrade later at a much higher expense than having done it right he first time.

Especially in the PNW.  I would definitely make sure the alternator can charge the batteries when driving over adequate thickness of copper, and if plugging in you want the Converter to be able to take over all DC loads and top off the batteries, and the PD9245 or Iota converters in the 45 amp flavors can recharge them quickly and float them correctly to keep them fully charged.

If you replace the fridge, I am of the opinion that the fridges that employ danfoss/secop BD35f compressor are most efficient, and quietest, and allow for some extra fine tuning with another computer fan hooked to the compressor controller to evacuate the heat from the condenser and the area where the compressor resides.

Many poor fridge performance or failures are caused by improper installation where the compressor and condenser cannot adequately breathe and release the heat they have pulled from the box. NOrcold developed the nickname Nevercold, as their earlier design allowed installers to simply mash it into a cabinet without thought to evacuating the heat generated by the cooling unit.  Later designs remedied this, but by then it was cost cutting 101+ marketing 101 in the manufacturing stage, and instead of thicker plumbing on the refrigerant lines, they decided they could save 30 cents per unit by going thinner and figure it would still last the warranty period.

Another low CFM low amp draw computer fan evacuating the heat generated by the cooling unit will greatly increase efficiency of the fridge, and the benefits increase exponentially the hotter it is outside and the harder the fridge is asked to work.

 

[pnwexplorer]

Sternwake, Thanks for the very in depth reply. That's more than I could have asked for!

Today being Amazon Prime day, the Renology 100w solar panels are on sale for $120 a piece... I'm debating on whether or not to snag two, what do you guys think?

At this point I yet to really need any electrical. Yeah, I've got a fantastic Fan & fridge... they both haven't been on since I've bought the rig. I've been going out and camping in the mountains every weekend. I'm loving the van life so far, it's so simple, and stress free. which has me thinking about whether or not I actuality want solar.

If I went solar I'll probably just go with the simplest solution, and replace the single 12v aux battery, and add a single 100w panel.

I haven't really spent alot of time looking at all the other equipment needed to run the solar set up such as Inverters, battery monitors, and heavier cables. I guess the simplest thing would be to track down another members build. I'm all for piecing together the components needed, as the kits do seem to have quite a mark up on them.

 

[SternWake]

I think Home Despot is still currently selling 100 Watt panels for 10$ less than the 100 watt Renogy panels on Amazon.

 

[GotSmart]

I think Home Despot is still currently selling 100 Watt panels for 10$ less than the 100 watt Renogy panels on Amazon.

What brand?  OK, Grape Solar.

The Renogy monocrystalline panels I have continue to generate power until the sun is completely down.  Where I am parked now, the panels are shaded for the last 3 hours of light.  I have parked under trees, and had my batteries completely filled by 11 am. 

Spend the extra few $ for Monocrystalline panels.  They do make a difference