Solar power vs.

[dredman]

Originally Posted by mikeypj

Ive done alot of research about running your AC off of just solar , and besides one couple who say they are doing it right now, everywhere else that i read says no way can it happen.

If you have enough PV, you can run anything till the sun goes down, then you need PV + Storage(battery bank), and that is a restriction when you are mobile, or confined to <300 sq ft. I have seen a few people demo their "solar AC systems", one was in Canada

My solution: Move to cooler climates in the summer - it WORKS!

[DoubleO7]

For a skoolie, forget about inverters.
The PV panels are putting out DC voltage.
Use it to charge a battery bank and DC appliances and DC whatever else.
Any device like an DC to AC inverter that generates or gives off heat is wasting watts into thin air.

[jazty]

It's all about size (isn't it always? ). I have 600w worth of solar panels and a 455Ah battery bank. When the sun is coming in nice and strong the panels are putting between 30 and 40 amps into the batteries. I played around with running a 5000Btu window air conditioner that I picked up at the local garbage dump. It would run off of my 2000w MSW inverter and pull 50 amps from the DC side.

Remember that the A/C unit isn't running constantly. It'll run constant until the temperature is within range, then it will cycle on and off. After the initial cool down it could be assumed that the A/C unit runs 50% of the time out of each hour. As in it'd consume 25Ah. Staying within 50% use of my 455Ah battery bank gives me 227.5Ah to play with. 227.5Ah / 25Ah = 9.1 hours directly running from the battery.

But of course, the panels aren't keeping up with it so the calculation needs to be in favour of the panels. On a summer day it's typical that I'll be harnessing between 120-180Ah from the sun. 120Ah / 25Ah = 4.8 hours. Not much run time there.. It could be good for reducing temperatures before going to bed, but not much else. To go 24 hours you'd need 25Ah * 24 = 600Ah from solar. 600Ah / 5 hours of good sunlight a day = 120A. 120A @ 12v = 1440 watts. Plus inefficiencies you'd probably want 1600 to 2000 watts of solar panels for that one A/C unit running 24 hours... And of course a suitable battery bank. Say a 1200Ah battery bank?

I'm sure these energy demands can be reduced with insulation... Either way, it's gonna be expensive.

Great bit of ramblin' there ol' man Jazty....

[jazty]

Originally Posted by DoubleO7

For a skoolie, forget about inverters.
The PV panels are putting out DC voltage.
Use it to charge a battery bank and DC appliances and DC whatever else.
Any device like an DC to AC inverter that generates or gives off heat is wasting watts into thin air.

Yeh, I toyed around with the idea of creating a variable speed DC driven air conditioner. Still may when I have time for tinkering. That 5000Btu air conditioner I was mentioning is probably as inefficient as they come.. It was from the garbage dump, after all!

[dredman]

Originally Posted by DoubleO7

For a skoolie, forget about inverters.
The PV panels are putting out DC voltage.
Use it to charge a battery bank and DC appliances and DC whatever else.
Any device like an DC to AC inverter that generates or gives off heat is wasting watts into thin air.

I strongly disagree with this comment(respectfully). If you want efficiency, by all means, go straight DC - BUT, if you don't care as much (like me) about efficiency, then get an inverter.

I run an AC dorm fridge, flat-screen TV/computer monitor, desktop computer, a rack of battery chargers (camera batteries, toothbrush, haircare, etc.) 8-10 hours every day, and the cost to convert all that crap far outweighs any lost electrons

This thread has inspired me to produce a WHY YOU NEED SOLAR in YOUR BUS video - look for that soon!

[mikeypj]

So what is the best panel , battery count? Im going to spend as much as is needed to keep my batteries full, bus cool and enough juice for what im running. Any input on lithium batteries? Besides they cook galaxy phones..lol

[jazty]

There are some things I think are completely worthwhile going straight DC for those boondocking folk, especially.

- LED lights. LEDs are low-voltage, low-amp DC devices. It's silly to take low-voltage DC, convert it to high-voltage AC (loss), then convert it to low-voltage DC (loss).
- USB chargers. USB charging is also low-voltage (5v) and low-amps. Same things applies as with LED lights. I installed a handful of 12v USB charging ports all over the bus. I disabled the LEDs because they were annoying. Without the LEDs the parasitic draw is something like 10 milli-amps.

- Water pumps. There are many good RV water pumps and they're already set up for 12vdc.
- Fans. Permanently installed type. Aside from table-top fans you might as well go DC here. Roof vent fans, range hood fans..
- Tool battery chargers. My DeWalt 20vMax 120vac battery charger died some time back. I purchased a 12vdc charger instead and I'm glad I did! If you full time in your bus then why not. Being able to easily charge while in the car has been handy, too.
- Laptop. Most laptops run at 20vdc. I picked up a 12vdc charger for my Thinkpad for $25. It works great.
- Sound system. Just install a kickass car stereo!

Now for things I have no desire in converting to DC:
- Plug-in tools. Jig saw, impact wrench, air compressor.. They can stay AC. I don't use them enough to care.
- My coffee grinder It's small, works great and is turned on for all of 20 seconds per day. I'm not messing with it. There's no return on invested time there..

The inverter in our bus is completely turned off 99% of the time. Most days it only comes on for morning coffee, but it's always there for when we do need it.

[Iceni John]

For real-world info on lithium batteries in a bus conversion, read Technomadia's blog. Those folk have been using theirs for a while now and are familiar with their pros and cons.

John

[dredman]

Originally Posted by mikeypj

So what is the best panel , battery count? Im going to spend as much as is needed to keep my batteries full, bus cool and enough juice for what im running. Any input on lithium batteries? Besides they cook galaxy phones..lol

I will weigh in, since I have real-world experience with solar(not just theoretical). First let me state that I am NO EXPERT - but a simple soldier in the front lines of the Energy War. But, my advice is to have someone DEMONSTRATE their fancy Solar Powered RV/Bus/Igloo, meaning (a)here is what I have done, (b)here are the specs & costs, (c)here is where I live, (d)average temps in the summer are ___, (d) this is the insulation I use, (e) and here are the all the drawbacks, misconceptions, and pitfalls.

Once you have this real-world data, you can make the hard choices. Drawing stuff on a chalk board is not sufficient.

[mikeypj]

Originally Posted by Iceni John

For real-world info on lithium batteries in a bus conversion, read Technomadia's blog. Those folk have been using theirs for a while now and are familiar with their pros and cons.

John

Ive read a little of the blog, what they say is pretty much all ive heard about them.

[mikeypj]

Originally Posted by warewolff

I do this for a living. Solar power is far superior. You'll still need the battery backups with wind and to do it right you'd be looking at a minimum 2k investment on equipment that is in no way meant to be installed on a vehicle. Then you'd have to break down a system that's meant to be permanent every time you want to drive. If you're thinking about driving with it on, don't. You'd have a negative ROI as you're burning fuel to make the turbine spin. Wind is most effective on sprawling farm properties. You can find 24v 305w panels on eBay right now for $100 a piece. Combine that with even the cheapest charge controller, battery bank, and inverter ... you'll be infinitely more happy.

Sorry to burst your bubble. If wind was more efficient for regular people like us I'd love to sell more wind systems. But it's not. And then the zoning ....

I had no bubble to burst, just curious as to why no one ever mentioned it, when talking about being off grid power. Now i know. And trust me i will have many more questions in the months to come. Thanks for your input!