Advice on solar power? for camper van.

[Bbasso]

I'm starting from scratch so I could use some advice, please.

Here's what I'd like to have,
fully off the grid power any time in my soon to be camper van. No generator- hopefully.

I know I'll need a hefty budget for this, but just how much?

What my power needs are:
LED TV, draws just under 40 watts
laptop, 65 watts
Engel fridge
a furnace, but not sure which yet or the draw.
water heater, also not sure what yet.
a hand full of LED lighting, shouldn't draw much to worry about.
a MaxxFan Deluxe, but I can't find the power demands.
A microwave, Yeah the killer but eating is important lol. Suggestions on which model?

As for what I was thinking to buy.
two 230 watt solar panels.
controller
inverter
one maybe two 4d deep cycle batteries, not sure about all the weight...

If I'm way off on my thoughts, please chime in so I can start planning this correctly.
I'd like to get my project going soon and I'll be doing all the work.

Thank you, I really appreciate the help.

 

[Bbasso]

to add some info, so I could get better help...

Panels I'm considering. http://www.wholesalesolar.com/products.folder/module-folder/Trina/TrinaTSM-230PA05.html

possibly instead of the 4d size batteries, I'd consider two of these. http://www.lifelinebatteries.com/marineflyer.php?id=14

Inverter. http://www.powerinverters.org/products/Go-Power-GP-SW1500-12-Inverter-1500-Watt.html

controller. http://www.altestore.com/store/Char...DL-Solar-Charge-Controller-with-Display/p245/

just some of the items I think might be necessary to run what I need, But I'm probably way off.

 

[rsbones]

I think you'll find this page interesting (I did):

http://handybobsolar.wordpress.com/the-rv-battery-charging-puzzle-2/

 

[4x4junkie]

But I'm probably way off.

I don't think you're all that far off, however a lot will depend on how much you want to run that power-hungry TV & laptop.
If only an hour a day each, you'll only use maybe 8AH or so. But for 5 hours each, then it jumps to 40 AH.

Fridge consumption varies with temp (and how big your fridge is). A 45qt unit should be around 40-45AH a day in an 80° environment, less if it's cooler, more if the sun beats down on it at all.

Furnace fans are energy hogs, and mostly at night when there's no outside energy going into your batteries (unless it's really really windy and you have a wind turbine to throw up lol). I'd figure on 20AH or so a night for that (or just bundle up in a nice warm sleeping bag instead).

Water heater should be negligible, it mostly runs off the propane.

LED lights = negligible if run directly off 12V.

Guessing that vent fan has a current draw around 2-3 amps. Doubting it's less than 1.5A, or more than 5A. So maybe around 2-3 AH for each hour it's used.

Microwave oven: I don't see total AH amounting to much, typical use is only a few minutes a day. However power demand while it is running will be through the roof. Your battery setup will have to be capable of dumping lots current without too much voltage sag (tripping the cutout on your inverter).
A 700W oven will draw approx 70A off the batts running through the inverter (figuring in for some conversion inefficiency, and a half volt or so drop on the cables between the batteries and the inverter).
Run for 8 minutes total power should be somewhere around 10AH.
(I'd cook as much as possible on the stove and/or barbeque instead) :chef:

All that looks to be around 85 - maybe up to 100AH total for a day (this assumes a hour each for the comp & TV).

I'd say the two 230W panels should be enough to keep up with that if you have good conservation abilities (and the days are perfectly clear for the 5 hours or so the sun actually hits the panels directly). However, use more power than usual one day (or if the days are a little cloudy), you could be playing catch-up for awhile.
I'd add in a 3rd panel myself (plus as you probably know, solar panels almost never live up to their ratings in real-world conditions anyway).

That charge controller you picked out appears decent just looking at it's specs, and should work with up to 3 of those panels.

Batteries: To prevent getting close to (or even going over) 50% DoD on a regular basis, I'd use a minimum of 250AH. Because of the microwave though, the more battery you have, the better off you're gonna be when that demand come on. If it were me, I'd invest in at least 400AH of batteries (four of those 6V you linked would be fine, as would four or five 12V group 27 or 31 automotive deep-cycle batteries @ 100-120AH each in parallel).

And as for having the generator...
I would never be without one myself having that much power demand going on. 2-3 cloudy days in a row and you could be having to run your engine to charge your batteries back up, and that'll use tons more fuel than something like a little 1500 watt Honda will (get an inverter/charger with a built-in transfer switch instead of an inverter-only unit so you can plug it into the gen. You can then run the microwave off the gen while it's charging your batteries at the same time).
Inverter/charger unit w/built-in xfer switch:
http://www.xantrex.com/power-products/inverter-chargers/freedom-hf.aspx



.

 

[Bbasso]

that's some great info, thank you. and lots to read!
As for the laptop, yeah... it would be running a lot, sadly. it's how I make money and it's my entertainment system too
funny you mention the wind turbine, I was looking into a small one.. but even the small ones are $ and not really that small.
A third solar panel,,, I might not have the room on the roof for one. I'll have to see how the roof rack sets up once I get it.

 

[Bbasso]

http://www.lifelinebatteries.com/rvflyer.php?id=15
That one is listed at 300, so two of those would be 600. Would you think that would be better then four mid size? I'm a little concerned about weight and size.

 

[IdaSHO]

I think you'll find this page interesting (I did):

http://handybobsolar.wordpress.com/the-rv-battery-charging-puzzle-2/

Very good read.

That guy sure like to talk! Some very good info in there though.

 

[wrcsixeight]

Laptop DC DC converter

If you have a PC, you can get a car adapter which converts 12.xx battery voltage to 16 to 21.5 v DC.

This is much more efficient than using a power inverter to power the original laptop power brick. It is as much as 45% more efficient on my Newer Dell, according to my battery monitor.

Goto Amazon electronics, type in your laptop brand and model number and add "car adapter'

I would not trust the universal models for providing more than 60 watts. Get a specific one for a few bucks more.
---------
You are looking at some very nice, very pricey batteries. Unfortunately in a new system, most users greatly overestimate the amount of electricity stored in a battery, underestimate how much their devices draw, and think the alternator can fully recharge the batteries quickly.

This usually leads to chronic undercharging, sulfation and premature battery death. LifeLine batteries are the Mac daddy of batteries, but they will still be damaged by chronic undercharging. I'd recommend building a battery box/ tray much larger than you think you need, and consider your first set of batteries to be " practice batteries" whose lower initial price will not hurt so much when they die prematurely due to abuse. You can get dual purpose batteries that can handle some abuse, but for about the same price you can get flooded 6v golf cart batteries which are probably the best bang for the buck. I just bought new Crown deep cycle Group 27's for 40% more than 2 Golf cart batteries would have cost at Sams or Costco, Similar A/H rating, but the GC's likely are more HD and can handle more abuse. The 12 volts likely will drop less voltage under a heavy load like the microwave though.

Do note that GC batteries are much taller than a group 27/29/31 automotive style battery.

While there are a few peak hours where the solar might deliver 90% of it's rated output, most solar newbies act as if the full rating is possible at all daylight hours. You should really squeeze as much in as you can on your roof, it's hard to have too much but all too easy to have too little.

Remember it is easier to use less electricity than to build large systems to create and store it, so Insulation, propane, and low draw devices are your friends. Don't forget to beef up your vehicle's charging circuit. The original wiring is too thin to pass enough current to a bank of thirsty house batteries.

Also Get yourself a minimum 25 amp battery charger/ converter, so that when you do have access to Grid power, you can blast your batteries with enough amps to fill them as quickly as possible.

 

[Bbasso]

Sadly my budget won't allow for mistakes, so I'll have to do this right, once. I won't mind spending the $, but it's gotta be on point first time. This is why I'm asking so many questions, sorry to pick everyone's brain so much... I'm reading, learning, reading, learning and more.

So if I can't fit three of the same size panels on the roof, can I use two of the same and one smaller and some how wire it to not effect the larger one's performance?
As for the 25amp charger for grid fill ups, thanks! that missed my radar...

Oh... would traveling down a road during daylight allow the panels to produce power? or do they get shut off for safety (or some other reason)?

I think I'd rather have taller batteries to allow for more floor space, and neg effects of them? Considering building a shelf/cabinet to house them vertically.

I was given this link, http://www.jackdanmayer.com/rv_electrical_and_solar.htm Do you think it's of considerable value?

 

[wrcsixeight]

You can run an unmatched solar panel, but the voltage at max amperage and open circuit voltage should be as similar as possible for maximum efficiency.

Look into battery trays which bold/weld to the frame. Batteries take up a lot of room, and the lower they are( within reason of course), the better. Mine are in a steel homemade box under a hatch in the floor inside my fridge/ electrical cabinet.

 

[4x4junkie]

So if I can't fit three of the same size panels on the roof, can I use two of the same and one smaller and some how wire it to not effect the larger one's performance?

As long as it's Vmp (volts at max power) rating is similar to that of your other panels (+/- 5% or so), it can be paralleled up with them no problem. Maybe instead of 3 big huge panels, you might be able to fit a greater number of smaller ones up there? (like four 180 watters or six 120 watters). The smaller panels would probably fare better with the vibrations and what-not from driving too I would think (that's a lot of glass on those big ones)

As for the 25amp charger for grid fill ups, thanks! that missed my radar...

I mentioned that at the bottom of my post also (I'd get the 40A/1800W one).

Oh... would traveling down a road during daylight allow the panels to produce power? or do they get shut off for safety (or some other reason)?

The solar system can charge while you're under way, however the available energy coming from your engine's alternator will be many times what you could possibly get from the panels. I'd look into a higher-power alternator maybe, something "rated" around 150-200A that actually puts out around 100-130A (or maybe dual alts). You'll need to use some nice fat cables from the alt to get that amount of current to go into your batts though (probably #2 or even #0 gauge depending on how long they are), however you'll then be able to have your batteries close to fully topped off with just a few hours of driving.

I was given this link, http://www.jackdanmayer.com/rv_electrical_and_solar.htm Do you think it's of considerable value?

Another wonderful, but extremely long read lol. I read the first little bit of it, and it seems to be well written and spot-on (and better organized too, much less 'wordy' that the 1st one above)

That was very good advice for the laptop converter. The more stuff you can run directly off 12 volts, the better. If your TV has a 12V input, USE IT. If your TV does not have a 12V input, I'd suggest trying to find one that does.
For your LED lighting, take a look at lo-cost household 12V MR-16 tracklighting fixtures. Using LED MR-16 lamps (4 watts is about equivalent to 25 watts of halogen incandescent light) you can totally flood the inside of that camper with light if you want with little impact on your batteries. Many such lights can be dimmed successfully just by putting a dropping resistor in series with the lamp too (I did this in my own RV and it works wonderful. I wired a 3-position switch on them so it has Off, Low & Hi settings).

 

[wrcsixeight]

My solar will contribute to amperage into my house bank only when the batteries are very low, and the alternator has not yet gotten the batteries upto 14.5 volts.

When the alternator has gotten the voltage up to 14.8, my solar charge controller goes open circuit and contributes nothing.

I wish I had a 40 amp charger. I'm glad mine is at least 25.

This one is what I would buy today.
http://www.amazon.com/Black-Decker-VEC1093DBD-Battery-Charger/dp/B000EJQJ1G

In the RV world there are devices called converters which are designed to power all 12v devices as well as charging the battery. I can use my battery charger as a converter, but cycling loads, like my compressor fridge, or mattress heating pad can cause bouncing voltages and thre charger might shut itself off. A converter is designed to handle cycling loads.

 

[Bbasso]

I forgot to mention that I'd like to keep my van's electrical system separate from the solar setup, two reasons.
So there is less wiring/cost and second so when I need to turn the key to start it will without any possible issues.

And yes, my TV, laptop and other small items can be 12volt powered.

I'll have to wait to know what size and how many panels I'll be using. I need to find a roof rack first.



THANKS SO Much

 

[wrcsixeight]

You should take advantage of the alternator's output.

You can certainly keep solar/house separate from the vehicles existing system, but don't think you will save much money in wiring costs. There are simple ways to assure your engine battery always has enough juice to start the vehicle, but it requires 2 or more separate batteries. There are also low voltage disconnects that remove the complexity of wiring up a solenoid to parallel the batteries only when the engine is running.

You can also just hook up the alternator to charge your house batteries at a later date when you understand the system better, and have more fundage.

 

[Bbasso]

http://www.blueskyenergyinc.com/products/details/solar_boost_2000e/

Been told it's one of the best, true?