Building a Skoolie

sasquatters · December 2016

Hello everyone!

I come here seeking help. I was previously on another forum (not worth mentioning) full of rude "experts" that were anything but willing to help. Someone over there posted a link to this site stating that this crowd here is way more inclined to help, and then his post got deleted. So...

I am working on building a skoolie that we will be living in full time because we are tired of paying bills and we would like to travel. I am completely new to solar but have read about panels, and loads, and batteries, and it is still all very much a foreign language. My buddy is also building a bus at the same time so we are getting a lot of the same parts. Our bus will have smart home functionality while his will not. So if someone, or multiple people, could help me figure out what solar setup we would need that we be really great. I would like to have this complete by spring. The bus is fully gutted at this point, spray insulation is coming soon and solar and wiring is after that.

Products going into the RV:

Eccotemp LP on Demand Water Heater (This only needs a spark for ignition)
Refrigerator (24/7) (Not 100% set on this one)
Water Pump 12v (<10 minutes a day)
Water Pump 24v (<10 minutes a day)

I am unsure about which pump because from what I understand a <1000w solar setup should use the 12v and >1000w should use the 24v. Without knowing how much solar I will need I will not know which pump to get.

Macbook Pro (7 hours a day) (Charger says 60w 16.5V 3.65A)
Samsung TV (<3 hours a day)
Projector (For watching things outside under the awning. Weekend use? Cannot really give an amount of hours)
Lights x8 (8 hours a day but not all will be on at once)

Smart Home Items: (the switches and outlets have small green lights that always stay on which is why they are labeled 24/7)

Router (24/7)
Insteon Hub (24/7)
Light Switch x7 (24/7)
6 Button Switch (24/7)
Outlets x16 (24/7)
Amazon Echo Dot (24/7)
Sonos Speakers x2-3 (5 or so hours a day)

I believe this is everything. All help appreciated!

mcgivor · December 2016

Welcome to the forum sasquarrers

Living off grid has its challenges and being mobile and off grid will only add to these challenges, it's all about sacrifices and economizing, shaving every little bit of fat off, so to speak. To put this in context, take for example the refrigerator proposed, the Energy Star rating is not bad, 357Kw per annum, this equates to almost 1Kw per day. My refrigerator which has about the same consumption, requires an array of 1.5Kw (although never produces that amount ) and a battery of 260Ah @ 24v to confortablly accommodate it's demand without depleting the batteries below 80% state of charge, I could double the storage capacity but that would mean on the overcast days, they may not reach full charge, you will learn more on this as the responses and calculations come rolling in. The size of the array is around 24 × 5.5 feet or 132 square feet, land based and in full tropical sun, your real estate, the roof of your Skoolie is limited. Please understand there is no negativity intended and all here, I'm sure, want you to succeed, the first step is put on paper all your proposed loads, operating times, and as accurate as possible, to come up with a base load, from this base load a rough calculation, taking into consideration losses, location etc. etc. can begin. My advice for what it's worth, is don't buy anything until the calculations have been completed. And one additional thing, anything that is used to produce heat is not recommended, but I see you are off to a good start with the LP demand water heater.
Good luck, this process will obviously take some time, there are some really helpful people here to help you on your quest.

sasquatters · December 2016

Thanks for the response. I tried to put the times down as best as I could. It is hard to do without it actually being done and living in it. I was told to stay away from anything that generates heat like you said which is why we have no coffee maker, toaster, microwave, etc. For that 132sq ft array size you mention, are those 100w panels? I am hoping to go with 250 watt panels and also have them on some sort of tilting mechanism.

Thanks

DConlyGuy · December 2016

being in a bus i would look into one of the isolation things for your battery so you can charge your battery's going down the road that will make a big difference in charging your stuff as and alternator can charge more than any solar panel can

sasquatters · December 2016

DConlyGuy said:

being in a bus i would look into one of the isolation things for your battery so you can charge your battery's going down the road that will make a big difference in charging your stuff as and alternator can charge more than any solar panel can

Yes I would like to do that but also have solar. We will be driving to places but we will also be staying places for weeks at a time without moving the bus.

mike95490 · December 2016

sasquatters said:

Yes I would like to do that but also have solar. We will be driving to places but we will also be staying places for weeks at a time without moving the bus.

You will likely need a generator and charger to supplement when you don't have good sun.

Another thought for "weeks at a time", is to make a portable, deployable array to expand the roof top panels.

Estragon · December 2016

I'd go so far as to say you WILL need a generator, unless you're okay with running the bus engine for charging. It's probably unrealistic to expect to cover charging and loads with solar alone given space limitations. You could do portables to supplement but 250w panels are awkward to handle and store, and are pretty fragile. I assume there are racks made for RVs that handle wind and vibration - don't know about tilting though. You will want to get the racking figured out early as this will drive panelling choices.

For fridge you might want to consider a marine/rv unit such as NovaKool, either a ready built unit you can add insulation to, or a kit for a DIY box. From your list of loads it looks like this will be what drives inverter and battery choices.

Estragon · December 2016

Also, you mentioned spray insulation, but not space heating or cooling. Heating with diesel or propane won't change much for the solar system but air conditioning will.

sasquatters · December 2016

I am planning on wiring for AC but not actually installing one because of the heavy draw. My buddy traveled a lot with panels on his RV and they were fine but they had a much smaller fridge. Like I said, I am not set on this fridge since it seems like it is going to be the highest demand on my unit. I have looked at smaller units but not really committed.

This process has been challenging for me because I cannot determine what to buy until I know what solar setup I will need and I cannot buy the solar setup I need until I know what products are going in. Aside from the fridge, the rest of the products are set in stone.

WaterWheel · December 2016

Like was mentioned on the other forum grab a calculator and figure how many watt hours you need per day.     Using your tv as an example if your tv uses 60 watts and you figure on using it for 3 hrs a day 60w x 3 hrs = 180 watt hours.
Do this with each of the items you listed above and that is how many watt hours a day you'll need, maybe plan for a little more just for safety.
At the end you may come back with a number like 4200 watt hrs a day (4.2 kw/day),     Then you can see exactly how much system you need and start to play with how many panels you need.

With the right inverter you can hook your auto-start generator to come on if needed so you run off batteries as long as practical and if needed the generator can come on covering heavy loads and charging the batteries if needed.

oil pan 4 · December 2016

Check the reviews on your electronic spark only tank less propane heater.
I have seen people complain about these simple type tank less heaters not being able to handle varying amounts of water very well.
You may want one that has a blower and modulating gas valve.
From what I have been reading I would even try a spark only tankless heater on most applications.

I don't care what any one says, get a generator, at some point you will need one.

Estragon · December 2016

@WaterWheel - there are two numbers needed for inverter and battery choices. The first, as noted is total wh/day. The other is peak draw.

OP didn't say what might be plugged into "outlets" aside from stuff listed, but seems to get the no heating stuff electrically rule. That leaves pumps and fridge as likely candidates for larger peak loads.

@sasquatters - you really do have to estimate these two numbers. I know it's hard to do without real-world experience but we have to start somewhere. Note that many small ac fridges are surprisingly inefficient. The advantage to the dc units is they have low start and running draw and don't need a large inverter to handle. A large inverter is not only more costly it also takes more power just to be on, which increases daily watt hours.

Assuming you either won't have a fridge or will use a dc one, it looks to me like you might be able to use a really efficient small inverter such as the Morningstar 300w12v. With no large draws on the inverter, 12v is probably your best bet, and bank sizing will depend on total daily watt-hour budget.

WaterWheel · December 2016

Estrogon, Yes, we all realize that inverter size will be defined by his peak loads but... I suspect that ssquaters is going to quickly wish he had enough inverter to make a cup of coffee or run a 700 watt microwave, especially if the generator will run through the inverter/ charger to top the batteries off during bad weather... Or do you expect him to manually switch between solar and generator every time he wants a cup of coffee?

DC refrigerators tend to be very expensive, 20 years ago they were the way to go if you could afford one but modern energy efficient appliances, especially inverter based refrigerators, are a better choice in my opinion. Let's say that ssquaters puts three 340 watt panels on his roof and receives an average of only 3 hrs of good sun a day (almost wintertime in much of the US). Even after assuming a 77% charge efficiency he'll pull 2350 watts per day (and more on most days with 4+ hrs average sunshine like most of the US gets), plenty for a 1500 watt inverter (or a Magnum 2012) that goes into search mode. And that's enough panels to charge a 12v 400 amp/hr battery bank at a C/10 rate using only about 12' of his roof.

I suspect that ssquaters wants to minimize power and generator use but not at the expense of constantly focusing on his electrical system, the man and his wife will want some additional power occasionally and a 300 watt inverter isn't going to do it.

But at this point we need to wait until he tells us more about his projected energy needs and budget.

Estragon · December 2016

@WaterWheel

His list of loads includes some on 24/7 so no search mode. He didn't list a microwave and I make coffee with a kettle and french press.

There are trade-offs in any off-grid setup. We're just trying to help the OP understand the options.

sasquatters · December 2016

Thank you all for the replies. In the original post I listed as best as I could all of the times items will be used. We also plan on not having a microwave or coffee maker. Simply the items listed up not. As far as other items that will be plugged in, an iPhone or two for charging ever day. As far as the tankless hot water heater, it is an eccotemp and all of the reviews have been wonderful. I got this one. All of the items in the main posts are links.

Image: https://cdn1.bigcommerce.com/server3400/401e1/products/366/images/1512/Eccotemp_i12_Indoor_Tankless_Water_Heater__90660.1438878159.1280.1280.jpg?c=2

Tricksailing · December 2016

My goals were similar but with a sailboat. No problem with a refrigerator (details later). An additional challenge for me was the 17 amp draw of a reverse osmosis watermaker that needed to run for a couple of hours each day. We also use a small (800w) microwave. Our system has been running for about 10 years - when cost were higher, output lower and before recent technological advances. Nevertheless, the details/hints may help/encourage.
A common question from other sailors is why we never run our generator (Honda 2000 - yes, you should have one for backup, along with a high output battery charger-especially if you visit cloudy climes). The answer is that we never need to run it because our solar system provides everything we need. The caveat here may be that we usually operate close to the tropics when there is lots of sun almost every day.
We use 4 ~135w panels with 2 Pro Star 30 PWM controllers each receiving input from 2 panels connected in parallel. I suspect your roof would easily accommodate 4 of the newer 250 w panels which would require a different controller setup. The redundancy of 2 controllers leaves me with power if one ever fails. The controllers charge a bank of 3 gel batteries (~400 Ah - awkward access on a boat favors maintenance-free batteries). Some lasted 10 years. We also use a Xantrex 2000 watt pure sine wave inverter for AC.
We eventually ran 2 refrigerators (redundancy again). The first was a custom installation using vacuum insulation panels for the box and a then Adler Barbour Coldmachine (now Waeco/Dometic) cooling system kit based on the Danfoss compressor running on 12 volts. Parts cost over $1,000 ten years ago. Our second refrigerator is an ARB chest type refrigerator that operates on 12 or 110v. It is about the size of a cooler with a Danfoss compressor for cooling. Cost 6 years ago was almost $800. I like it much more than the more popular Engel. Quality is outstanding, it shows few signs of age and still freezes down to its max -18C. Propane refrigerators are even more expensive and don't work too well in temperatures over 90F. I recently helped a friend install a solar system to run a standard 110 refrigerator. Total cost, including refrigerator was about the same as a propane refrigerator.
Two of the solar panels are on 2-axis manually adjustable mounts, the others are on single axis mounts. At around 23 degrees north, I usually leave the panels flat and the batteries are still fully charged mid-morning. The mounts have been damaged in hurricanes and I would be inclined to make any future design permanently flat to minimize damage potential. This choice may be different at higher latitudes.
Not sure what you gain from Smart House functionality in a mobile home. I was involved in software development for the X-10 system many years ago and loved it for my house but I never felt the need for anything like it on the boat.
Also in the process of installing new lighting with LED fixtures purchased at trucker's stores. These stores are a great source for on-the-move living supplies without the price markup often found a 'luxury' RV and marine supply stores. These new generation LED light fixtures are as bright as standard house light fixtures.
Good luck with your project.

sasquatters · December 2016

Thanks for the post. While this is all still a foreign language to me, what you wrote seems to make sense. As far as smart home functionality, it is merely for convenience. I will be able to stand in the bus anywhere and say, "Alexa play classic rock" or "Alexa turn on the bedroom TV." This voice control will also be accompanies by a smart remote that will also control everything so that you do not have to lay in bed and say to turn the TV volume up or late at night when my significant other is sleeping I won't have to say out loud, "turn off the lights." I believe this will be quite beneficial in tight living quarters. Plus it is kind of cool to be able to ask the bus to put on music while your hands are covered in rabbit blood while preparing that nights dinner. :P

mcgivor · December 2016

@sasquatters Understandable that this is a foreign language and the dilemma you face not knowing which to go for first, the load or the system that will support it. Quiet simply it is the load which should come first, and the system size will be based on the calculation of the basic load, adjustments can be made either way. As many have said you need to do this calculation yourself or at very least, provide the numbers as it takes time and effort to search links etc. until then everyone can only speculate, not very productive. The more involved you are with the calculation, the more able you will become at understanding how it all works. As I said the first time it's all about sacrifices and economizing, you might find in order to fit within size or budget, something has to be adjusted, it's a tradeoff, but without the figures.......

sasquatters · December 2016

With some assistance I have come up with a daily consumption of 3Kwh for my project, this includes a refrigerator and various loads specified in my OP. My proposition is to use a Morningstar 60A MPPT controller, with remote meter, charging a bank of 8 Trojan AGM golf cart batteries in 48v series string with a 3000W pure sine wave inverter, Cotek, Samlex or similar. As for the array, I am considering 12× 24V 250W poly panels, size permitting, as this is in the development stage. A Honda 3000W generator is planed, for low solar days and backup as required. Any suggestions would be greatly appreciated.

Estragon · December 2016

A Samlex 48v3000w inverter will use almost 1kwh/day plus loads. Is this in your 3kwh estimate?

Assuming it is, battery capacity is a bit light, but workable. You would plan on charging with genny on the second really cloudy day, maybe the third with lighter cloud.

You could get by with less panel. Output won't be much anyway on really gloomy days and will be wasted on sunny days unless you have opportunity loads. Getting that much panel mounted might be a challenge anyway.

mike95490 · December 2016

How do you plan to charge the batteries from the generator? Does the inverter have an integral charger ?
And why a 3kw inverter, 1,500w ought to be plenty to start the fridge, unless there are a lot of other loads.

oil pan 4 · December 2016

What's your generator to battery charger going to be?

sasquatters · December 2016

I have no idea how I am planning on charging the batteries from a generator. I'm just trying to figure out what panel setup I need first. There is some sort of relay where the wheelchair lift was connected to the batteries. I was told this would work for charging the batteries off of the bus engine, but it would need some sort of device to tell it when it is done charging.

As far as a 3kw inverter, I do not know why that one was chosen. I am new to this and getting help from members.

Also, I got on the bus roof earlier and measured since there is an emergency hatch upfront. Here are the dimensions. I am trying to save the space between front of the back hatch and the back of the bus for a small deck/ or just roof sittin'

Image: http://i68.tinypic.com/el1c20.png

Thank you

mcgivor · December 2016

For roof mounting with the dimensions given you could get 4× 250W panels, loose the front hatch add one more.
The rooftop is prime real estate, if you go with a deck, some panels on the side, over the windows which can be tilted up when parked, will shade the windows like an awning. Have the roof panels tilt to the same side and this would be the sunny side of the bus when parked.

sasquatters · December 2016

I definitely do not want to lose the hatch since it will be good for ventilation. I did consider side panels but am slightly worried that someone may mess with them. The bus is flat nosed so there's no roof access for anyone that does not have entry into the bus itself.

cupcake · December 2016

1) Calculate your loads (ex: 400ah per day)
2) Find a battery(s) that match this load (ex: 400ah battery)
3) DOUBLE #2 (ex: 800ah battery) this is now your new 'load' and new battery requirement
4) Find solar panel(s) that match your load (ex: 1kw of panels)
5) Multiply this factor by 3 (ex: 3kw of panels)

mcgivor · December 2016

sasquatters said:

I definitely do not want to lose the hatch since it will be good for ventilation. I did consider side panels but am slightly worried that someone may mess with them. The bus is flat nosed so there's no roof access for anyone that does not have entry into the bus itself.

What is the total length and height ? Mounting sideways could be high enough, a 250W panel is about 40" wide, so total height, I'm guessing 10', minus 3.5' would be 6.5' above the ground, mounting this way would probably be high enough to eliminate the possibility of anyone messing with them. You have to have somewhere to mount panels, and since the roof has other priorities, the side looks to be a viable option. Moving a portable array would be more trouble than its worth, my opinions.

sasquatters · December 2016

I definitely do not want a portable array. I was hoping to be able to arrange the panels around the hatch. The bus is 27' total length.

littleharbor2 · December 2016

mcgivor said:

For roof mounting with the dimensions given you could get 4× 250W panels, loose the front hatch add one more.
The rooftop is prime real estate, if you go with a deck, some panels on the side, over the windows which can be tilted up when parked, will shade the windows like an awning. Have the roof panels tilt to the same side and this would be the sunny side of the bus when parked.

Seems to me side mounted panels could be easily set up to pivot up and over to lay flat on the roof, although upside down, when traveling, and tilted anywhere around up to 270 degrees to the side windows of the bus. You would need to get creative with the tilt support but you would have the ability to set about any angle you want when stationary.

Estragon · December 2016

It looks to me like you might get 5 large (2 forward of escape hatch + 3 between hatches). You could use monocrystaline panels which may give you a bit more watt per sq.ft. at a bit higher $/watt. So something like LG 315w mono x 5 gives you ~1500w (STC) of panel. Tilting is likely to cause shade problems so assuming flat mounting actual output may be significantly less.

Depending on where you're located and time of year that may cover your 3kw daily budget on a sunny day. 3kwh/day (or more like 4kwh if you hadn't included inverter tare losses in you budget) is pretty high for a mobile application, so you'll have to make some trade-offs. Either lower the kwh or accept you'll be running the genny a fair bit, or a bit of both.

sasquatters · December 2016

I have looked for more efficient refrigerators but the few I have chosen are the best for power consumption. It's amazing how much that still is though.

Building a Skoolie

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