Solar powered A/C

[Ronnie]

Cheap gennies? I just was looking and cheap is about $3500 for one that would run both my rooftop a/c. This is an inverter generator, quiet running. Add a few more thousand for charger , power panel, wiring, batteries. The cost differance between a generator system and all solar is getting much smaller.

[john61ct]

Originally Posted by Ronnie

Add a few more thousand for charger , power panel, wiring, batteries.

All of which are needed in either case.

In this case I was responding to a statement of the "principle" no gennies ever.

My point is that abstract principle does not IMO translate to economically practical overall systems design.

I got a great unit, very quiet, that can puts 30A into my LFP bank whenever needed, for under $300 brand new.

I only use it about 5% of days living off the grid, but it has saved over $5000 additional capital investment I would have had to make going solar-only.

Plus gives me a lot of flexibility in where I can do so, places I simply could not live at all (for more than a few days) if I were solar only.

I don't advocate for aircon, nor large electrical systems in general when mobile.

But if your "needs" are that large, then will you need to spend (a lot) more money. In real life having **some** genny capacity in the mix will save you (some) money, in proportion to your overall needs.

But of course your rig, your choices.

[Ronnie]

What Generator did you get? For $300 to use as a backup that is reasonable.

For me I really do not expect to use ac unless I really have too. Long trips I plan in cooler weather, local use I have shore power available if I need ac. So for now I want everything solar except ac. Stove, heat, and hot water will be propane.

[kazetsukai]

Originally Posted by john61ct

To me it's silly [...] especially if you're planning on living off-grid for long periods of time.

I'd think a large solar array would be favorable to long-term off-grid living. My solution = potentially indefinite run time, your solution has definitive limits.

Originally Posted by john61ct

A cheap almost-silent fuel-sipping little inverter genny can really come in handy, even if you use it only 20 hours in a year.

I don't object to your stated conveniences, I just don't want to have to obtain, carry, and manage its needed fuel resources. Nor do I want to rely upon the availability of supply any more than I already have to.

Originally Posted by john61ct

It gives you the flexibility to camp deep in a dark forest rather than always having to park out in full-sun spots.

I wouldn't "have to" park anywhere, its just a consideration based on my use cases. My battery array should afford me some time in the shade, but yeah- optimally, I'd park in the sun.

Originally Posted by john61ct

Being dogmatic "never burn fossil fuel" will require wasting a lot of money on that last 20-40% of solar and carrying a lot of dead lead weight around both of which you won't need 95% of the time.

"never burn fossil fuel" isn't my motivation, so I object to the "dogmatic" characterization. I am not driven by enviro-dogma and I (rightfully) loathe enviro-fascism more than most people. I agree that the notion of "never burn" is nutty, especially considering we're all moving our rigs around around using large diesel engines with low fuel economies and virtually any product or service you consume is facilitated in some way by fossil fuel. Yes, even your organic produce at Whole Foods, greenies.

What I don't agree on is that I'm "wasting money", or "carrying dead weight". My position that I never want to run a generator is purely pragmatic and based on capability requirements. I don't want to have to manage the additional resources or the associated concerns of a generator. I want all systems to be capable of functioning at speed same as they would at rest- which is why I'm avoiding propane for my fridge for example. I may have propane for the oven and some little burners, a grill, maybe a water heater (undecided). But I'll also pack an induction cooktop.

Based on my research, I concluded that for my requirements, a somewhat overbuilt solar setup was a better solution than the alternative. It wasn't cost prohibitive for me, either. I'm open to better solutions, but the overarching equation goes like this:

Wood stove, or Pellet stove? Given the choice, I'd go with wood. I can procure wood myself from virtually anywhere, and I'm not relying on a resource I cannot reproduce. Minimal dependence on outside resources as practically possible given my current capabilities.

[john61ct]

Originally Posted by Ronnie

What Generator did you get?

https://www.homedepot.com/p/Ryobi-90...11LP/302703564

Champion will last longer if used more frequently.

Honda is IMO really the robust maker, actually worth fixing if it breaks.

eu2200i is the size for running an aircon or high-amp charging.

Good discussions here

https://www.google.com/search?q=site....com+generator

Also on solar A/C, highdesertranger is da man on that topic, has 800W solar driving a 5k btu unit, but only during peak insolation periods, not off batteries.

And can't recharge at the same time, need double that, still without running the aircon off the batts.

I figure 3kW solar for maybe 2-3 hours a day aircon in good weather, plus keeping the bank charged for fridge lights fans etc.

[john61ct]

An LPG conversion rather than propane-only would give dual-fuel flexibility.

If your vehicle is diesel, then obviously best to standardize on that, cummins/onan APUs can be picked up pretty cheap second-hand.

[Ronnie]

Mine is gas , not diesel. So gas genny would be better suited. Just a personal choice I would rather avoid a genny, however there are times I could use a portable one for other purposes.

For my house I have a 15kw pto driven one that I run off the tractor.

[JDOnTheGo]

Fantastic stuff kazetsukai, aaronsb, nanoplane!!! I love what each of you guys are doing!

It is fantastic how quickly solar and storage systems have come in the last five years and what we can now accomplish with them (easily and affordably). I know several folks that just want to keep on running their generator. A few of them can hardly hear or smell anything so that works ok for them. No so well for those nearby.

[john61ct]

Not being argumentative but for those that haven't used them the little inverter gennies are quiet enough to silence completely with a foam panel enclosure.

Especially Honda, much less noisy than most aircon units.

[bartthebus]

As others have said, the biggest obstacle here is efficiency. Obviously parking in sunlight where PV is most effective yields higher ambient temps where A/C is required to work much harder and vice versa. A detachable PV array would be ideal: unhitch a small trailer in the sun with some sort of fold-out panel arrangement, then go park the bus in the shade with 100 ft of generator feed cable hooked to your charge controller. You could even reposition the trailer throughout the day as the sun moves for maximum PV efficiency. Food for thought...

[Flowstatebus]

It’s really frustrating to read so many people automatically implying that it can’t be done or anything along those lines. If we said that every time someone tried something new we would still live in the Stone Age.

Constructive conversation is a much more effective communication tool than simply voicing a negativite opinion. Just sayin.

[john61ct]

I don't recall a single post saying it can't be done.

And without the specific technical details and examples of **how** to make it happen, lots of people would waste time and money on ineffective systems.

Assuming having aircon available is the real goal, as opposed to chasing idealistic windmills.

The average van dweller learning what he wants will cost many thousands is likely to call that impractical.

Accepting the factors I outlined in post #3 is what begins to make it at least possible.

[Twigg]

Originally Posted by Flowstatebus

It’s really frustrating to read so many people automatically stating “it can’t be done” or anything along those lines. If we said that every time someone tried something new we would still live in the Stone Age.

Constructive conversation is a much more effective communication tool than simply voicing a negativite opinion. Just sayin.

They're not saying "it can't be done".

They are saying that as an engineering project it can be done, but the cost and complexity make it unviable for all but the most determined.

That said, I like seeing people push the boundaries if they feel it appropriate to spend many thousands of dollars where a few hundred gets it done with a generator.

[Flowstatebus]

As skoolies get more popular, you’re already seeing people with expendable incomes dipping their toes in (Our bus included). The amount of solar budgets in the $15-20k+ range are showing up more and more just like they have been for years in the RV world. There’s folks rolling around with $40k+ powerplants under their rigs, and to them it’s not impractical or frivolous. Being able to afford it is only half the battle though. Many people are coming to this forum to figure out HOW to do it, not IF it’s possible.

I also recommend checking out some of Brian Boone’s RV SOLAR groups on Facebook. He does high end mobile installs while fulltiming in his RV. Lot s of helpful information there for builds of this expected size.

[Twigg]

Originally Posted by Flowstatebus

Many people are coming to this forum to figure out HOW to do it, not IF it’s possible.

Believe me, I'm on your side. I love seeing people push the boundaries.

However, on this site the solar ambitions of the past have tended to run to systems in the 300W to 1kW, to increase the boon-docking potential but without running AC as a regular thing. Folk still buy gennys for that.

Just recently we have seen threads springing up converting EV batteries to school bus use, and with that level of power comes the requirement to add sufficient solar to charge it unless you just want to extend the days from hook-up much further out.

What we need to see, and what would help many others is seeing detailed build threads of the type you are discussing ... Off grid systems in the 3kW to 4kW range and the storage capacity to benefit.

That would help the collective wisdom enormously. It will still be out of my price range, but I'd cheer on your build all the way.

What I think I'm saying here is that you have arrived at the start of a growing technology, not in the middle of a mature one, wrt buses anyway.

[JDOnTheGo]

Originally Posted by Twigg

Believe me, I'm on your side. I love seeing people push the boundaries.

Amen!!

Originally Posted by Twigg

What I think I'm saying here is that you have arrived at the start of a growing technology, not in the middle of a mature one, wrt buses anyway.

Yep, totally agree Steve.

I would say that the technology (the components, hardware) is readily available (not that it is totally mature) and its costs are already falling/within "reasonable" pricing range (arguable because that is subjective - as Flowstatebus stated). I believe this is especially true when true costs are factored out over a period of time. The fact that using this technology is "new" to the RV/bus world can be quite frustrating when talking to others. It is the whole generational thing where the guy that has always used cash says he will NEVER have a checkbook... then he will never have a credit card... and so on. Getting those people to look past previous experiences and what they "know" is usually a waste of time. The trick is being able to see their position/attitude for what it is. Not that it is irrelevant but maybe not accurate either.

There are also some very "personal" issues at play that not everyone agrees on. These types of things are often impossible for some folks to understand and sometimes lead to debates. A prime example is noise. What is noise to me is not noise to the next person.

I think most everyone agrees and has said (repeatedly) that the specifics of the equipment, location, situation are going to dictate how 'capable' this type of system will be.

[nanoplane]

My budge for Solar is well under 10K and that includes Batteries and Inverter, most of which I would have had to have in any case. My needs are not overly extravagant, I'm mostly in moderate climates so I don't expect heating / cooling to be a problem..

Observations so far on my build (the whole 2 days :
- In hazy sun, I'm getting 1600 W most of the day and can fully charge the batteries while under a 500W load.
- on a cloudy day, I only get about 800W most of the day and the batteries won't fully charge...

I don't have the Trimetric battery monitor hooked up yet.. I'll get more objective results then.

I am using the solar for all the power needed on the bus for the build right now..

Bottom Line is that I expect to be absolutely successful in sunny weather.. in the Winter time, I'm not so confident... I will have a generator.. (I like the Champion dual fuel, but that means I'll have to carry gas or propane...)

[john61ct]

Is there any DC powered aircon involved in your setup?

[nanoplane]

Originally Posted by john61ct

Is there any DC powered aircon involved in your setup?

No, the mini-split is 120V AC

[kazetsukai]

I don't know why you'd need a $40k budget for solar. Perhaps it really has just gotten that much cheaper, or maybe that's the do-it-for-me-contractor price.

Between panels, batteries, charge controllers and inverters, I'm going to spend around $10k. And I'll have what I already consider to be a ridiculously overbuilt system with 3000W panels and 20kWh real storage capacity.

I have a 600W, 2.4kWh system already, and it has overperformed for my purposes in far from optimal conditions (perpendicular to the ground, in the shade most of the day). It covers 80% of my needs, since I'm going the DC route with appliances wherever possible.

And contrary to what some people seem to be hinting, it isn't rocket science. If you know nothing, go to Harbor Freight and pick up one of their 100W kits, a battery, a multimeter and start experimenting. Understand Amps x Volts = Watts, understand Amps|Watts x Time, and what it means for your capabilities.

If you're building a bus there's no excuse to not learn a thing or two about DC electrical. NONE.