Van Build-out - First Questions

[liandri]

Hi all. This will be my first post here, I figure I'll get all the silly n00b questions out of the way before starting down the road of specifics. My questions are marked by (#), but feel free to weigh in on anything.

I'm planning to build out a van myself, hopefully at around $15k or less. My eyes are currently set on a 2003 Ford E350. It's 12ft cargo area should provide plenty of space for amenities. After the van is acquired, my plan is to drive down to LA to get a 24" Fiberine top installed to give us standing room. A family friend is a cabinetry and tile wholesaler and installer, so hopefully that part can be done well and pretty cheaply.

My biggest questions lie around the topic of electronics. My girlfriend and I both work in high-tech, and the ability to be connected all 24/7 is a must. Specifically it means, at minimum, 2 laptops and a 3G/4G modem and a router. Probably also means an extra external monitor and probably some Ok speakers.

I've read the electronic section here and it's been very helpful, but hasn't been able to answer my questions below: http://newboatbuilders.com/pages/electricity1.html

What I've settled on so far are the SolarFlex panels for the roof--(1) at least 200W worth. (2) I'm leaning toward at least 400Ah battery bank. (3) LiFePO4s are powerful and small, but seem to be at least $3k (!!!) for that capacity. I've found a 4kW pure-sine AC inverter on Amazon (http://www.amazon.com/PowerTech-Advanced-Technology-Terminals-Protection/dp/B0131PZ9J2) for $340, but (4) I'm concerned with how it's different from the $1k one from GoPower. It's suspiciously cheaper.

As a computer engineer, I also have the urge to connect everything, likely with a raspberry pi. Specifically, I want to know the current power draw (and how much the energy is left), and which socket (and the appliance attached to it) is being the most power-hungry. I've seen these guys (https://www.sparkfun.com/products/11005), but (5) how the heck do I connect multiple sensors for more than one outlet... say 4 or 5 outlets? Also, (6) what's the best way to extend the obligatory 2 outlets on inverters to more around the cabin? Can all cabin outlets be on one plug or should the cabin plugs be divided between the two inverter plugs? Keep in mind there will also be a small frig, water heater (maybe), and microwave ((7) though maybe I connect the frig and water heater to propane). (8) Should those be on the separate AC plugs? I'm having a hell of a time finding DC water heaters online. With how much everyone seems to want DC for the efficiency, I'm surprised so many RV/marine things are AC only.


Also, (9) what's everyone's experience with electrical needing to match legal requirements? I know boats have a good amount of regulations, and it's probably for good reason, and I don't want to explode.

Thanks, all. I could have made an individual thread for each of these topics, but since everything in electrical relies on everything else, it seemed best to lump it all together and just refer to the question numbers.

 

[SternWake]

1, you will need way more than 200 watts of solar for 400AH of capacity.  a 1 to 1 ratio might not even be enough depending on how deeply you discharge that 400Ah of capacity.


Plug all your intended electrical consumers into a power strip, plug the power strip into this:

http://www.p3international.com/products/p4400.html


After 24 hours of you intended usage, divide the KWH number by 12 to get the AH consumption.  then add 20% for inverter inefficiency.

Once you know your 24hr electrical consumption, we can recommend battery capacity and the charging sources which can keep that amount happy in Ideal, and less than ideal solar conditions.

You do not need a 4kw inverter for powering the items you describe.

4000 watts is a 333 amp load at 12 volts.  That much of an electrical load would deplete a healthy fully charged 400 AH battery bank to 50% in under 20 minutes, and even with a 100 amp charging source, a full charge cannot be completed in less than 6 hours, and returning to a full charge quickly and often is the key to lead acid battery longevity

For your laptops, goto amazon electronics and type in make and model number of laptop and add 'car adapter'.  These products are much more efficient than using the inverter just to power the original power transformer provided with laptop.  If the laptops consume more than 60 watts regularly the ciggy plug connectors will eventually cause issues.  not a huge issue to overcome.

Lifepo4 batteries are not a simple lead acid drop in replacement.  They can be damaged instantly if overcharged or overdischarged.  They are a superior battery compared to lead acid, but they require more accoutrements to be an effective safe system which will not allow a human to easily kill them.

Not that it cannot be done.

http://www.cruisersforum.com/forums...or-those-using-them-as-house-banks-65069.html

Whatever amount of battery capacity you end up needing, getting the batteries to last an acceptable number of deep cycles is dependent on how well they are recharged.  getting to true 100% can easily double the number of cycles compared to only getting them to 97%.  And that last 3% takes hours as the lead acid batteries simply are slow to fill when near full, and there is no way around this.

So Solar+ alternator+ 120Vac charger plugged into the grid and/or a generator are likely all going to be required to keep the batteries happy enough to give decent service life.

Getting the most from these individual charging sources is a topic for another thread.  But you are limited in solar wattage due to roof space, and there is a balamce between solar wattage and battery capacity, depending on depth of discharge, which can make a system or kill the batteries quickly.

Cycling to 50% daily, and solar as the only charging source, then a 2 solar watts to 1 AH of capacity will not be enough.

When employing AGM batteries, the solar/capacity ratio should be even higher as AGMS prefer higher initial charge rates, and it is even more important to get them to a 100% charged state, compared to flooded batteries.

So limiting factors are roof space, unless portable panels to set up are an option.

How much battery capacity you get, should be determined by your available charging sources.  Like if one drives an hour each morning, one can get away with much less solar, but if solar only, then one needs a lot more solar to keep the battery happy.

In many cases, it is simply easier to learn/figure out how to to use less electricity, than it is to say this is how much I use, I need a system to power it.  The median lying somewhere in between. 

Living on battery power, and having the batteries give you your moneys worth, is not just a slap an inverter and some solar on it and off you go. Well perhaps if replacing batteries often and prematurely is of no consequence to your sanity or bank account.

it gets very annoying when battery capacity quickly declines to the point where one is always having to ration their usage and worrying about charging them to their maximum remaining capacity.  Once battery capacity has diminished, it is pretty much gone for good, never to return.  A diminished capacity battery also becomes even harder to fully charge, requiring more time to reach its remaining 100% charged level, and of course during discharge, reach 50% that much quicker.  if depleting the same amount, then the battery is being cycled below 50%, which degrades capacity even faster.

So, Not trying to scare you or put you off, but a well balanced system which can meet your needs, and batteries which can last at least 500  deep cycles to 50% is not so easy to achieve. The number of cycles achieved is directly related to how deeply they are discharged, and how often and quickly they are returned to a true 100% state of charge.

Achieving absolute maximum battery longevity can be taken to extremes.  One should at least know what the batteries would require for Ideal battery longevity, then find some acceptable number below that.

Like say Ideal is 800 total cycles to 50%.  Is 600 cycles acceptable?  what about 400?  what if the battery capacity diminishes by cycle 220 to the point where your low voltage alarm starts screaming at you by 8:30 PM, can you deal with that.  What about the finances?  What if you are hours from the nearest place to get new batteries, and the batteries they can get are just marine batteries, or starting batteries?

The point at which battery capacity diminishes to an unacceptable level, often comes as a surprise to the battery cycler.  For most people, the battery is 'performing good as new', 'still going strong', and Just Fine( when it is not), and abruptly one day it 'no longer takes a charge', and they freak out, and usually blame the battery.  In reality the battery capacity was diminishing from cycle number one, diminished faster than it needed to due to substandard recharging or perhaps overdischarging, and only became noticeable when it no longer had enough capacity to meet their overnight needs.

The hail mary recharge at this point is too little too late.  Equalization charges (forced overcharges of flooded batteries) could have greatly slowed the diminishing of battery capacity if performed monthly or at some interval dictated by the hydrometer and battery itself.

but when the battery one day, mysteriously 'no longer takes a charge'  an EQ charge at that point might return some capacity, but it will quickly flee the scene when the regular electrical consumption is resumed.

So, if your source of income is dependent on your ability to use as much electricity as you need, then you have to think surplus of  battery capacity, surplus of solar wattage, and surplus of other available charging sources to keep the batteries as as high a state of charge as possible, when possible, to get an acceptable number of deep cycles from them.

It could come down to carrying a generator too, to power a high amp converter/charger, if you run into many cloudy days and do not drive anywhere.

 

[BradKW]

Welcome to the forums!
Random thoughts follow:

1) 200W is probably low for your usage, definitely too low to keep a 400Ah bank happy. Flex panels are more expensive, less efficient.
2) 6v golf cart batteries are a good bet, flooded or AGM (more expensive with more knowledge about charging and higher amps needed). LiPO4 would be great, its just not "there" yet for me...
3) I'm going flooded to a) learn batteries/charging, b) least initial outlay, and c) watching for Tesla's Powerwall to become available to DIY consumers in not distant future.
4) You get what you pay for with inverters. You can't go wrong using Magnum as at least a fair metric to compare to, its acknowledged to be one of the best. I think you haven't really figured out your needs yet, and I bet 3000W is way overkill. Likely you would be fine with this: http://www.wholesalesolar.com/2901242/magnum-energy/inverters/magnum-energy-mms1012-inverter ...also is a charger which you may need to supplement solar for your bank.
5) no idea...sounds boring
6) Good inverters allow you to directly wire off them to a sub-panel, or just use a power strip. here's a good 12v one: https://www.amazon.com/dp/B001DPK63...TF8&colid=1GWENKU8U6NBD&coliid=I10HLLRKW8EYTM
7) go electric for fridge, no reason to go propane or 3-way if starting fresh.
8) umm...eh? you buy a 12v fridge for a RV, not AC.
8.5) only way to really heat water via DC is with a resistance diode in something like a 5gal tank...wait 40min till hot, then shower. Amp draw just too huge to run a normal instahot electric water heater. Propane is a good bet, something like this: http://www.amazon.com/Eccotemp-L5-P...ater heater&qid=1460322907&ref_=sr_1_6&sr=8-6
9) It's the USA, we are free to blow ourselves up as often as we want, so long as it doesn't effect anyone else's happiness

 

[cognitive dissonance]

First, you will need more than 200 watts of PV to charge a 400 amp battery bank - particularly since you know you will be using a lot of power every day.  Off the cuff, 400 watts of PV sounds a bit closer to me. You may need to go to rigid panels, which put out more watts per square foot of roof space used.

"I've found a 4kW pure-sine AC inverter on Amazon (http://www.amazon.com/PowerTech-Advanced...B0131PZ9J2) for $340, but (4) I'm concerned with how it's different from the $1k one from GoPower. It's suspiciously cheaper."

It's junk.  A good quality 4kw sine wave inverter will be around two grand. Here's the 2000 watt inverter I use:

http://www.amazon.com/Magnum-MS2012...id=1460323347&sr=8-1&keywords=magnum+inverter 

The 4000 watt inverter you linked weighs 9.9 pounds, shipped. My 2000 watt Magnum ships at 50 pounds (actually weight is about 40).

Which inverter do you think would run my power tools and not die?

Fortunately, you will rarely need that kind of power.  Your hotspot, laptops (and probably your monitor) already run on dc.  Why would you want to convert solar dc to ac, then plug in the laptopadaptor that converts it back to the dc it runs on, with losses at each step? There should be a cigarette lighter adaptor for all these items.  In the case of the hotspot, it's already a usb charger!

A good quality AC fridge can run on a very small inverter.  Here's what I use - it's very high quality, high efficiency no noisy cooling fans and has extremely low standby/idle draw:
 
http://www.amazon.com/Morningstar-F...sr=8-3&keywords=morningstar+300+watt+inverter 

This little inverter runs my 10 cu. ft. Vissani fridge with power to spare. I looked at 12v RV fridges, but went with the Vissani with the defrost heater disconnected.  It's astonishingly efficient.

You might think about buying a second Morningstar 300 watt inverter if you want to run some nicer audio.

If you don't want to re-think power consumption a bit, you might also want to consider a Honda EU1000 or EU2000 generator.

 

[cognitive dissonance]

It is critical to know how your batteries are actually doing. Most RV house batteries are never fully charged/recharged, which in turn causes most of the problems people ever have with battery power. Without a battery meter, you will be in the same boat as everyone else.  I use this: http://www.solar-electric.com/batte...t-engineering-tm-2030-rv-battery-monitor.html

 

[Reducto]

DC and propane are your friends. Inverters are inefficient and some are noisy. Propane is ideal for heating water and your interior. Whether you need a bulk tank or just disposable 1lb bottles depends on how much you wind up using.

You can get 12v adapters to run your laptops and many external monitors use a 19v adapter so you can use a car adapter for that too. A hotspot will give you 3G/4G with built-in router.

I'm using this speaker which sounds great and runs straight off my 12v:
http://www.amazon.com/dp/B008VMT2HQ

Ditto what others have said about the flex panels - flat panels will give you more wattage per square foot and you could mount them to tilt towards the sun when you're parked.

 

[liandri]

Nice, much to work through here, thanks guys.

Ok, so more PV. With the van roof, I'm sure I can get at least 5 Solarflex on there, possibly a sixth (41.7"x21.3"x0.1"). I understand rigid PV functions better, but the flex seems to not interfere with the function of the car. It won't put a giant wing on the roof, nor does it spoil the stealthiness of the vehicle. So say we can do 5, that's 500W. (And also $2500)

Also looking at charging the batters with the car alternator is good, and may be a must. I'm not sure, is a generator necessarily better than just using the car engine? My guess is it's much more efficient...

Ok, so definitely dropping that cheap inverter then. Also, you guys seem to be suggesting getting multiple smaller inverters for the individual appliances. My assumption was that could be more costly than a single quality inverter that could share the load. Also, the 3000W number was a maximum "just-in-case" number, so my girlfriend or other friends don't need to worry about looking at what else is plugged in before frying the van (as smart as they are, it just wouldn't be on their radar). Assuming we do just a 1000W inverter, we'd have to turn off like everything else to use the microwave (which is also a question... only thing we microwave is leftovers and sweet potatoes. Potatoes we could boil, leftovers... idk, pop it in the pan or something). But then we could also get a small

I have been looking almost exclusively at LiFePO4 due to more cycles, longer/deeper cycles. One 400Ah pack I found was $3k and fits in a 17"x17" box. AGM is fine too, but what would be the equivalent cost and size for equivalent available Ah? Storage space will also be super valuable in the van. Also, opinions on Firefly Oasis AGMs? Four of them would be ~$2k for 464Ah.

And nobody seems to be complaining about my goal for 400Ah.

I initially wanted to do everything possible on DC, but with 95% efficient 3kW ones, it seemed easier to simplify on AC side. For laptops, we're all on MacBook Pros. My searches for recommended DC alternatives weren't fruitful, especially with Apple's MagSafe connectors. I do realize those little bricks are all just DC converters. Instead of doing a cigarette lighter plug, could I just wire it into a circuit box? Seems like it'd look nice that way, and it's stuff that stays in the van. And skipping the dedicated inverter, why not a Truck Fridge?

But to SternWake's point, our source of income is not exactly unlimited electricity as much as it is just having Internet to our laptops during the day, and our source of comfort is being able to cook meals or reheat them in a pinch (and keep fresh ingredients cold). And boiling water for tea. Gotta have that. Hot water heater is essentially just to wash dishes (for some reason it helps, but I guess we could skip it). But yea, we currently do not eat out. But when we do cook, it's always for a couple days worth, so the next 2 days just involve reheating, and maybe frying up some fresh eggs in the morning.

And feel free to reply randomly to anything... I'm reading everything and organizing it internally.

Thanks again

 

[BradKW]

If you completely cover your roof with solar, you won't have space for vents, which are pretty necessary.

What exactly are your AC requirements? At this point you're just guessing at stuff...back up, slow down, focus on single aspects, and work through the options. You can't plan around a claim of 95% inverter efficiency either...A 3Kw inverter may typically draw around 20 watts from your batteries when no AC current is being used. It would then follow that if you are using 20 watts of AC power, the inverter will be drawing 40 watts from the batteries and the efficiency will only be 50%. A small 200W inverter may on the other hand only draw 25 watts from the battery to give an AC outpur of 20 watts, resulting in an efficiency of 80%.

Please post the LiPO4 batteries you've found at that price point. At this stage in that game, there's a lot of possible mistakes to make, even just at the point of ordering. There's a few people here who are quite knowledgable about them....I'm not one. I do know enough to be a bit suspicious about 400Ah for $3k tho.

Like the panels vs vents, everything is a trade-off...much of what you want to know can be found reading through with the "search" function. It takes time

 

[Optimistic Paranoid]

9) It's the USA, we are free to blow ourselves up as often as we want, so long as it doesn't effect anyone else's happiness  

Actually, if you do it TOO often, I'm sure the authorities would insist on locking you in a padded room where you could spend hours and hours talking to the nice man about your mother.

Regards
John

 

[GotSmart]

Hi all. This will be my first post here, I figure I'll get all the silly n00b questions out of the way before starting down the road of specifics. My questions are marked by (#), but feel free to weigh in on anything.

I'm planning to build out a van myself, hopefully at around $15k or less. My eyes are currently set on a 2003 Ford E350. It's 12ft cargo area should provide plenty of space for amenities. After the van is acquired, my plan is to drive down to LA to get a 24" Fiberine top installed to give us standing room. 

Lets start with the van.  The one you are looking at has had a number of recalls.  If you get that one, realize you will be putting 3 X the value of the vehicle into the body.  

Flex panels are not something I would ever trust when the need is for reliability.

You might look into box vans for your needs.  Something with a flat roof for conventional panels.  JMHO.

 

[akrvbob]

I've been using this Xantrex 2000 Prowatt Pure Sine for several years, it runs my microwave almost daily and it runs extremely well for $350 See it here:
http://amzn.to/1RNBVbB


bob

 

[SternWake]

Yes, the macbooks seem to be the exception to the rule of laptop 'car adapters'.  

A smaller inverter 'might' be more efficient powering those laptops than a larger inverter that can power them and more at the same time.  My 400 watt PSW inverter powering a 50 watt heating pad consumes 20% less power than my 800watt MSW inverter powering that same heating pad.  Inverters will vary widely in how efficient they are powering a certain % of their rated wattage.

Not sure, But i've also read macbooks are finicky about the inverter, with some saying a PSW inverter is necessary.

And CD's report of a 300 watt inverter being able to handle the start up surge of his fridge is impressive.  Many reports of much smaller fridges requiring 1250 watt inverters with 2500 watt surge capability, even if the fridge only requires 80 watts once the compressor is already running.

Truck fridge's use the Danfoss/Secop compressor bd35f.  Which in my experience is more efficient and much quieter than the Sawafuji compressor that came in my Norcold.  I went with a Vitrifrigo fridge when the Norcold failed at 5 years,  over the truck fridge as it is Italian made, and its fit and finish are a notch above.  The coolant plumbing on the cooling unit uses a larger condenser, and a larger 120mm fan to remove the heat, and allowed me to modify the cooling unit ventilation for more efficiency, the TFs plumbing would not have allowed that.

Check this site for VF's or TF's with free shipping:

http://www.westyventures.com/parts.html#cart_restore

The alternator can be a very effective charging source, but with a whole bunch of asterix's involved.

One is that many do not produce much current when hot at idle.  Their amp rating is only achieved in a lab, when cold, spinning at super high rpm.  Never to occur in actual usage. but a higher rated alternator likely can better dissipate the heat it generates.

Two is that even if they are capable of sustaining high amperage at idle speeds, the internal fan is not spinning fast enough to dissipate the heat generated, and can cook the alternator when it is asked to feed a thirsty bank of batteries.  If internally voltage regulated, this might have a simple thermistor which reduces target voltage as the alternator warms, reducing its ability to charge a depleted battery.

Three is the Vehicles voltage regulator.  These can be internal to the alternator, or external.  To recharge without wasting fuel, the voltage regulator will ideally seek 14.4+ volts, and hold it until the battery is full, then drop to 13.2 to 13.6v.

THIS NEVER happens.  Usually a vehicle's voltage regulator will seek and hold 14.4+ volts briefly, then quickly  revert to 13.7 to 13.8, which slows recharging by a huge degree.  Many variables here with different platforms being better than others. I recently rigged up an adjustable voltage regulator that has a dial on the dashboard so I choose the target voltage manually.

4th is that  the original alternator to battery charge circuit is only thick enough to safely ( barely) carry enough current, to power original  vehicle loads, and to top off a starting battery kept at 80% charged.  When more depleted batteries are tacked onto this circuit, more amps need to flow over the same cabling, causing more voltage drop, slowing charging in the upto 80% charged range, greatly.  From 80% to 100% is always going to be slow and take around 4 hours, no matter how powerful the charging source might be, but getting to 80% from 50% or less, can be done quickly with a charging source capable of producing high amperage.

4 can be mitigated with thick copper directly from alternator(+() to house bank(+), with appropriate isolation device and fuses on that thick copper cable and a thick ground path too.

So a generator powering a high amp charger/converter is better, whenever parked, but when driving( not just idling), one should obviously take advantage of the fast spinning alternator that has lot of underhood airflow to keep cooler and last longer while producing more amperage to fill that battery bank fuller in shorter drives.  

Most automatic charging sources also suffer the premature drop to float voltage when the battery still needs more time at absorption voltage, to reach 100% charge in the minimum time required. Having a charging source which can seek and hold 14.4v + the whole time the generator is running, can mean shorter generator run times, or just significantly more recharging occurring while the generator is running. Generally that 80% to 100% charge will take 4 hours.  Most people will not bother running a generator to get to 100%, as the generator is barely working/ accomplishing anything, but this is a great time for solar to take over and finish the job, silently.  Once the batteries get upto absorption voltage, the amperage needed to hold them at absorption voltage keeps decreasing until the batteries re fully charged.  Once the flooded batteries can only accept 2 to 3% of their capacity at absorption voltage, can they be in the full charge range. So when 100Ah of flooded battery only needs 2 to 3 amps to be held at 14.4 to 14.8v is in in the 100% range, but double check flooded batteries with a Hydrometer.

AGM batteries are considered fully charged when only 0.5 amps per 100Ah of capacity are required to hold absorption voltage.  (14.2 to 14.7v, depending on AGM manufacturer)




Regarding the  solar panels and stealth, well flex panels do not fit compound curves very well, and most raised roofs are not as flat as one thinks.  Thinking 5 panels will lay down nicely conforming to rooftop, could be a pipe dream.  Also these flex panels, adhered to a roof, are going to be much less efficient just because they will be that much hotter than a framed panel with airflow underneath.

Aerodynamics, well hard to argue that.  My panels are not stealthy, I tried though, can't say it is not a consideration..  Most people never look up anyway.  Most are surprised when I say I have 200 watts on my roof.  Some really nice installs on this forum with panels submerged into what appears to be a ladder rack.  Such panels shade the roof keeping van interior cooler, and  allow one to put a vent under them.  Flex panels adhered to the roof will transmit heat to the interior.  I only have 1/2 inch foamboard insulation on my roof, and the white ceiling, under the adhered unisolar panel is significantly hotter than the white roof next to it, and significantly hotter again compared to the shaded white roof under my framed panel.

Some flex panels are reporting longevity problems/ early failure. They've not really been out for long.

If you are really trying to maximize wattage on the roof, framed panels could allow you to harvest 25% more juice.  Not an insignificant number.  The price savings of framed panels might pay for the custom roofrack that allows one to really maximize the wattage.  MPGs do take a hit at highway speeds.  One could just drive slower to get them back.

Your actual battery consumption is still unknown until you have tools to measure what you intend to use for as long as you need to use it, but we can guess. 

For reference:
My Dell laptop requires a 90 watt DC to DC adapter, but averages half of that in actual use.  I have 198 watts flat on my roof, and only 90AH of AGM battery.   The AGM would be happier with 250+ watts and shallower cycles.  I use 35 to 45Ah each night.

In summer I can basically use the laptop 6+ hours a day, no issues.  In winter, issues, and I've been at 32' north in a coastal desert most winters( lots of sunlight).  Other charging sources are needed in winter, or I need to use less.  My AGm requires the high amp recharge every so many cycles( 4 to 5).  It will easily and happily  initially gobble up 65+ alternator amps when depleted to 50% , but with most other lead acid batteries this ~ 70% charge rate is likely abusive if performed often.  Trojan 'recommends' a 10 to 13% rate, assuming a plug in charger and 8 to 12 hours to reach full charge. A 10% rate is more than 2 solar watts to 1AH of battery capacity.

Lifepo4 batteries can easily overwhelm an alternator, frying it, as they are so low resistance and only at the very end of charge do they begin limiting what they can accept. All other charging sources also  need to confirm to Lifepo4  voltage requirements.


I never worry about My fridge or its consumption.  1.8 cubic feet is plenty  enough volume for just me.  It rarely consumes more than 18Ah per day at 68F ambient average, but it has extra insulation and the condenser is very well ventilated for maximum efficiency.  It will still run even if I deplete the battery to 25%.  Worrying about it shutting down due to insufficient battery has never been an issue.

The Firefly AGMS are reported to be great, but there is not much feedback on them from those who are not paid to test them or possibly get a kickback from praising them.  Both AGm and GEL batteries made similar claims when they first came out, and many years later their deficiencies of character in actual usage reveal those initial performance claims to be fraudulent

The flooded 6v gc-2 golf cart battery is hard to beat in terms of reliability, but they offgas and are tall, heavy and take up a good amount of interior space, and if placed below the floor, will compromise ground clearance to some degree.

If you are driving into LA for the fiberine roof, there are a Few Lifepo4 importers there. They all come from China.  Recent changes in laws regarding Lithium batteries and Airlines might bump up the cost of Lifepo4 cells.

Concorde is also there, they make Lifeline AGM's which are top quality AGM batteries, but these require the occasional high amp recharge to keep happy.

 

[cognitive dissonance]

...My 400 watt PSW inverter powering a 50 watt heating pad consumes 20% less power than my 800watt MSW inverter powering that same heating pad.  Inverters will vary widely in how efficient they are powering a certain % of their rated wattage...

Inverters consume some electricity on their own.  (Thermodynmics rears its head again!) A good rule of thumb is they will use 10% of their rated power to operate, even if their only AC load is a 4 watt LED bulb. This is exactly why I recommended a small inverter for small loads - less "overhead".  Never measured this myself, but knew it was the case and always planned systems accordingly. Thanks for putting some hard numbers out here. 

...And CD's report of a 300 watt inverter being able to handle the start up surge of his fridge is impressive.  Many reports of much smaller fridges requiring 1250 watt inverters with 2500 watt surge capability, even if the fridge only requires 80 watts once the compressor is already running. Newer refrigerators are quite efficient. The label on an appliance only shows the maximum wattage or amperage an appliance might use. In reality, most appliances use considerably less. I went around to appliance stores with an extension cord and my Kill-A-Watt and actually tested several of them, starting them from room temperature.

At 10 cu. ft., I expected the Vissani to be a little hungrier, but the starting surge was under 200 watts. After 30-45 seconds, it was running at about 75 watts. Once cold, starting surge is closer to 150 than 200.  

The PV and the batteries are temporarily installed on/in my school bus, even though I haven't begun the conversion. The fridge is already running on the Morningstar. When the project is complete, I will be able to plug a Samsung 40" LED flat screen and a Samsung DVD/Blue Ray player into that same inverter, using a power strip to eliminate the phantom load when not in use. I've already tested it - with all 3 connected, the total load is still well under 300 watts! 

[b...Flex panels adhered to the roof will transmit heat to the interior.  I only have 1/2 inch foamboard insulation on my roof, and the white ceiling, under the adhered unisolar panel is significantly hotter than the white roof next to it, and significantly hotter again compared to the shaded white roof under my framed panel.

Some flex panels are reporting longevity problems/ early failure. They've not really been out for long.

So let's tally this up: five times the price, less power for a given roof area. transfers massive heat, doesn't last as long. 

What's not to like?

Unisolar already went bankrupt. So much for their warranty!

I believe the flex panels liandri mentioned have only a 10 year performance warranty, whereas flat laminated glass rigid panels are generally performance warranted for 20 years. You can count on bankruptcies to negate most warranties, but this certainly gives an insight into longevity of various types of PV modules.

 

[GotSmart]

Aerodynamics, well hard to argue that.  My panels are not stealthy, I tried though, can't say it is not a consideration..  Most people never look up anyway.  Most are surprised when I say I have 200 watts on my roof.  Some really nice installs on this forum with panels submerged into what appears to be a ladder rack.  Such panels shade the roof keeping van interior cooler, and  allow one to put a vent under them.

I currently have 200W inside my ladder rack, and plan on adding a 3rd panel later by extending the rack another 2 feet, and turning the panels sideways.  

I lost about 1/2 MPG when I first put up the racks, but nothing further since I added the panels the way they are. They range from 3/4 inch to 2 inch of clearance.

I have 448 AH of battery storage.  (Fullriver DC224-6) I bought those at a discount from a company that supplies batteries to the state DOT.  They change them out on a schedule.  The thinking is that the first set of batteries is going to be destroyed by misuse, and getting something to learn by is much cheaper than destroying new top of the line batteries.  I have about $250 invested in the batteries.

 

[SternWake]

Don;t want to stray off topic too much, but the Vissani fridge start up surge is impressively low. What's the duty cycle like?

My VF for example runs about 15 minutes per hour, but in 5 minute bursts On for 5, off for ~20. The compressor starts at about 42 watts but tapers to about 26 watts at the end of those 5 minutes.

Pretty nice install GS.

Here's my Kyocera GT-130 purchased in 2007, for 735$ !!!!!! Installed on my fiberglass roof.

I added the Unisolar pvl-68 in 2012. It seems to produce fairly well at low sun angles levels, perhaps due to the rather large space it consumes for just a 68 watt rating. I was harvesting more than expected when i added it, which was/is nice. Anything to get battery(s) to absorption voltage via solar ,faster, helps Lead acid batteries live longer.

For maximum lifespan, Do not fully charge Lifepo4. Need to retrain the LEad acid mindset when switching to Lifepo4.

 

[amwbox]

To really maximize your solar panel coverage, you could spring for a roof rack like this:

This is significantly wider than the roof, and will actually allow you to install full size grid tie solar panels sideways between those side rails. With some careful planning for spacing, you could possibly fit close to 900 watts of solar up there and still have room for a fantastic vent. Of course, these higher voltage panels will necessitate an MPPT charge controller.

 

[Optimistic Paranoid]

To really maximize your solar panel coverage, you could spring for a roof rack like this:

This is significantly wider than the roof, and will actually allow you to install full size grid tie solar panels sideways between those side rails. With some careful planning for spacing, you could possibly fit close to 900 watts of solar up there and still have room for a fantastic vent. Of course, these higher voltage panels will necessitate an MPPT charge controller.

The thing that concerns me with racks like that is this:

I get the impression that they are designed to support the weight of ladders and such pushing down.  What happens when you fill it with flat panels?  Can the air get between the roof and panels as you drive down the road at 60 mph and exert a LIFT on the rack?  And will the mounting points hold if they are dealing with a lifting force instead of opposing gravity?

Regards
John

 

[GotSmart]

The thing that concerns me with racks like that is this:

I get the impression that they are designed to support the weight of ladders and such pushing down.  What happens when you fill it with flat panels?  Can the air get between the roof and panels as you drive down the road at 60 mph and exert a LIFT on the rack?  And will the mounting points hold if they are dealing with a lifting force instead of opposing gravity?

Regards
John

The way they are clamped on the roof channel, they stand up to all kinds of forces.  I see people with the racks over loaded and pushing 75 down the highway with no thought to the fact that their front end is lifting from the wind.  

Personally, I have had panels mounted to a sheet of plywood and regretted it.  That is why I went the way I did.  Low profile.

 

[SternWake]

As long as the roof gutters are not all rusted out, like they like to do, and the Hooks which go around the gutters are not loose, I would have no concerns with that large roofrack creating enough lift to separate from the van. But the OP is having a fiberglass roof installed, and the legs to reach the drip rails would have to be longer, reducing their strength and ridigity. Enough to compromise the panel's well being at highway speed? I can't guess without seeing the final product in place.

If going for the super large high voltage household panels, I would support the middle of the panel better from underneath, to prevent any harmonics developing in the slipstream at highway speeds, that might fatigue the panel's glass, frame, or internal cell connectors.

 

[cognitive dissonance]

Don;t want to stray off topic too much, but the Vissani fridge start up surge is impressively low.  What's the duty cycle like?

Never checked. After I bought it, I left it plugged into the Kill-A-Watt for 24 hours and the usage was trivial. I don't remember the number, but I remember thinking that even if power use doubled in a non-air conditioned RV in the summer it would be no problem.

Remember, too, that I have since disabled the defrost heat, which is a big power saver.