i need help designing a solar / dual battery / inverter setup

[tjohns1006]

hello there. i have been lurking a while in a few different categories. currently i am thinking about doing a full on solar / dual battery with inverter setup in my 2001 4.7L tundra. i want something that is VERY user friendly, uncomplicated, low maintenance, reliable, etc. i also want to hear your recommendations as far as product suggestions and items that have 'proven themselves' in the field.

i have a fair understanding of electricity but i don't want to piece together a system on my own with all of the 'little' pieces. based on what i know, i need the following items - two batteries (should they match or use a different accessory battery), isolator, dual battery control system (i want ease of use and guages), solar panel (i want to go the rollup route, any brand suggestions ?), an inverter (enough to charge and power a netbook, LED lighting, cell phone, future fridge, etc).

what am i missing ? what size inverter will i need ? what size solar panel ? do i need a separate solar charge controller ? will i need an upgraded from stock alternator ?

anyone willing to draw up a wiring diagram and parts list ? or is there a thread on this already ?

thank you all in advance for your input and suggestions. ballpark of what all this will cost ?

tom

 

[Martyn]

The system we install is very straight forward.

For your needs a 60 watt, 3.6 amp foldable solar panel

Connected to a charge controller via waterproof connectors

Either a simple 4 amp charge controller if it's going under the hood, or a larger 20 amp controller with digital display in the dash.

The controller is wired to the secondary battery.

Primary and secondary batteries joined using the National Luna Dual battery Management System.

A modified sine wave inverter 300 - 600 watts, connected to the secondary battery. You want to aim to run as much as you can direct from 12 volt as an inverter is inefficient, i.e. the LED lights, the cell phone, the fridge.

For batteries we use the Deka AGM Deep cycles.

There is more information here.

 

[Rando]

One thing to consider is whether a rollable/foldable solar panel is really the right choice. If you have space to mount either a rigid framed solar panel, or a semi flexible panel to a roof rack or a topper these offer several advantageous. Firstly they are always out and charging your battery, if you are parked at a trail head, the pub or on the road, there is also nothing to be done to set them up. For travel styles like mine, where I spend very little time hanging out by my car, packable panels are not practical as they are difficult to secure against theft/wind while I am out hiking/rafting/climbing or whatever. The times you would be most likely to deploy a packable panel (in evenings and mornings when you are hanging out at camp) are also when there is the least usable insolation. Additionally packable panels are incredibly expensive for the power they produce, about $10 - $20/watt, where as framed panels can be had for $3 - $5/watt. They are also much less efficient than rigid panels, and require 2-3 the area for the same amount of power.

That all being said, if you don't have some where to mount or carry a rigid panel a packable panel maybe your only option.

 

[shogun]

I am a little suspicious of the efficiency of these things. I have a solar charge controller that indicates solar power available, and maximum charging, by led's.

It came with a small, ridgid, 5w panel that is very heavy. I have noticed that this, no doubt cheap, panel will keep the power available light lit pretty much in daylight, not even direct sunlight. The other day it was still it after sunset with the sky still light.

I also have a small Global Solar panel that is supposed to be very high-end, flexible, lightweight, fold up stuff. It will not light the power available light unless it is in direct, and very strong, sunlight.

If this situation is to be believed, why would I spend so much more for the high-end panel when I will not get even 8 hrs of charging from it? I am starting to consider options for in-camp battery charging (60w?). Is this stuff really junk?

 

[tjohns1006]

very valid points from two people. thank you. keep them coming. i kind of had the same idea. i have heard of solar collectors made into shingles and siding for homes that are very inefficient and these collectors seem to be similar.

i do love criticism. first of all to save me money and frustration and second of all to push the industry and technology. i know there is no perfect setup otherwise there would be no new products. but....

keep it coming.

ETA - yes i am also very 'outdoorsy' and hike, climb, fish, 'spend time away from the truck', etc. i do have a possible plan to mount a 2' X 4' or 2' X 6' panel on a hinge / moveable mount that i am capable of welding / setting up on my roof rack. i can also move/park my truck to orient the panel towards the sun. in everyones opinion, is a solid panel more efficient than a 'rollable / foldable' panel ? it sounds like it. and then, what brand/models are the best/most efficient ?

how about the other components ? what batteries ? what inverter ? what controller ?

thank you....

 

[Martyn]

I am a little suspicious of the efficiency of these things. I have a solar charge controller that indicates solar power available, and maximum charging, by led's.

It came with a small, ridgid, 5w panel that is very heavy. I have noticed that this, no doubt cheap, panel will keep the power available light lit pretty much in daylight, not even direct sunlight. The other day it was still it after sunset with the sky still light.

I also have a small Global Solar panel that is supposed to be very high-end, flexible, lightweight, fold up stuff. It will not light the power available light unless it is in direct, and very strong, sunlight.

If this situation is to be believed, why would I spend so much more for the high-end panel when I will not get even 8 hrs of charging from it? I am starting to consider options for in-camp battery charging (60w?). Is this stuff really junk?

The small compact controllers with LED's red and green lights can be problematic as the lights don't tell you much, and although you may be getting a reading of amperage being produced by the panel it may be negligible, there is no real way of telling.

The LED controller I mentioned gives a digital read out of amps coming in from the solar panel and volt stored in the battery. Some real data you can work with.

The foldable solar panels have consistent power output in full sun, cloudy skies, early morning, late afternoon, direct sunlight and partial sunlight. We worked for years with solid panels and the power output we observed was very dependent on the panel being oriented toward the sun, and varied considerably from full sun to partial sun. But that's only data you can review if you have a controller that's producing real time quantitative values.

 

[Corey]

I have the 60 watt foldable panel I bought from Martyn last year, not a problem with it, and it kept the battery charged while using the fridge.

 

[Rando]

If you have a place to mount it (and it sounds like you do) I think you will do better with the rigid panels. 80W rigid panels go for less than $250 and would easily fit in a 2' x 4' area. I have mine mounted to some Yakima bars with quick release pins and integrated prop, so I can either prop it at an angle for high solar zenith angles, or remove it all together and set it up remotely if I am parked in the shade. In the summer I usually just leave it flat and it is always charging my battery. All up, with mounting hardware (I already had the Yakima racks) and charge controller the entire system cost me under $300.

very valid points from two people. thank you. keep them coming. i kind of had the same idea. i have heard of solar collectors made into shingles and siding for homes that are very inefficient and these collectors seem to be similar.

i do love criticism. first of all to save me money and frustration and second of all to push the industry and technology. i know there is no perfect setup otherwise there would be no new products. but....

keep it coming.

ETA - yes i am also very 'outdoorsy' and hike, climb, fish, 'spend time away from the truck', etc. i do have a possible plan to mount a 2' X 4' or 2' X 6' panel on a hinge / moveable mount that i am capable of welding / setting up on my roof rack. i can also move/park my truck to orient the panel towards the sun. in everyones opinion, is a solid panel more efficient than a 'rollable / foldable' panel ? it sounds like it. and then, what brand/models are the best/most efficient ?

how about the other components ? what batteries ? what inverter ? what controller ?

thank you....

 

[Rando]

Here is a (bad) photo of how my 80W panel mounts to the roof bars:

 

[teotwaki]

I have a variety of different panels including a rigid 54 watt panel and a Global Solar 64 watt foldable. The larger surface area of the foldable means that it is less sensitive to sun direction and intensity. It also has a higher short circuit current ahn the rigid panel.

For a transportable application such as in this discussion it may be better to buy a newer MPPT style charge controller rather than more panels.

martyn,

Have you looked at the MPPT (Maximum Power Point Tracking) style yet? The price points overall are still fairly high but there is one from BZ Products that has a voltage/current display that is not too bad

 

[wrcsixeight]

The BZ units do not have a great reputation.
http://www.wind-sun.com/ForumVB/showthread.php?t=6152

I have a Bluesky SB2512i. The 2512ix has a battery temp sensor capability that I wish I had. It also has load diversion to send extra juice to another battery when the auxiliary battery is full

I also have the IPN pro remote which has the ability to adjust the above charge controller, and acts as a battery monitor. An amp hour counter, not just a voltage display. It is the best way to know how much you are using. Voltage is not a very accurate method except on a well rested battery, one that has not had any charge or discharge for several hours.

I am happy with these products and my Kyocera 130 watt panel.

Measure the distance of any roof racks and get a ridgid panel which fits nicely in between, and is easily storable when inside.

You might only need 60 watts now. But you should, in theory, have almost a hundred watts for every 100 amp hours of battery, to keep the batteries happiest over the long term. Having more wattage allows higher bulk and acceptance voltages to be kept when the fridge's compressor kicks on.

I have a manual switch for battery isolation, but I like to be able to divert starter demand and alternator amperage where and when I want.

Mainly I do not want the fridge's compressor to be operating and hooked to the which ever battery is starting the engine, and I like to wait a little while before asking the alternator to supply amperage to the house batteries.

There are some automatic systems which compensate for the above variables. But I am only familiar with mine, and simple solenoids.
Good luck

 

[teotwaki]

Good thread, not only for the BZ but other info such as the MPPT kit from Rogue. So far it seems that MPPT technology is great but the costs are still fairly high for decent units

EDIT: Rogue no longer offers kits

 

[Rando]

At this point, I am not sure if MPPT is worth the cost. Given the high temperatures that a panel on a vehicle is likely to be operating, and the linear inverse relationship between temperature and voltage an MPPT controller will probably only provide a 10% or so increase in output. In winter it could do a little better. For example, with my 80W panel, I get an effective output of about 5A at 13.4V into my battery or about 67W. With a MPPT controller I could bump that up to 80W, and gain 13W at a cost of about $200. Alternatively I could buy another 60W panel for $180 and get an extra 50W or so of increased power.

It may make sense if you have a larger (say 200W+) array and use it at high latitudes and cold temperatures.

 

[wrcsixeight]

My Monitor displays solar amps in, and out.

Now that we are near the solstice, with my 130 watt panel flat on the roof, around noon, I will see 7.5 amps in, and 7.9 to 8.8 amps out, depending on temps, and battery voltage. In the winter the difference is about the same, but I'm living near the ocean in S cal, so I am not seeing blistering temperatures, nor bitter cold.

The more depleted my batteries are, the bigger the difference has been between amps in and amps out.

While they claim MPPT can produce up to 30% more than a PWM, It must be relatively cool and the battery voltage must be pretty low for that 30% over a PWM controller to be realized.
I painted the frame of my panel white, more to blend in with my white roof than for temperature, but it keeps the anodized aluminum about 35 degrees cooler.

When I bought my system in June '07 My controller was 35 bucks less, and my panel was 40% more than todays prices, so going MPPT was a no brainer for me then, and if I were to do it now, Even fitting 30 to 50 more watts on my roof, I would still go MPPT, and I'm broke, but I live off 12 volts.
But I would get a MPPT controller designed to handle higher voltages, as My SB2512i can only handle 12 volt nominally rated panels.

 

[teotwaki]

The SB2512i can be found for $170
http://www.infinigi.com/blue-sky-energy-sb2512i-solar-boost-2512i-controller-p-1685.html?ref=100
The controller costs about as much though