Generator vs. BIG solar?

PNW_Steve · 08-25-2017, 12:21 PM

Good Morning Everyone!!

I started my electrical plan with a clear vision of including shore power, generator, solar and engine/alternator charging.

In my last bus I installed an 8kw Kubota water cooled diesel generator and loved it. I had the same planned for my latest bus but a bit smaller. With the mini-split air's that I am planning I have been searching (& searching...) for a 3-5kw water cooled diesel generator.

I have yet to find anything that fits my "want list" for less than $3k used. I really do not want a gas generator in my diesel bus.

I have started wondering how much additional solar, battery, inverter etc I can buy for $2-$3k??

If, instead of spending $2k on a solar system and $3k on a generator, I spend $4k-$5k on my solar system will I be able to live comfortably without a generator?

I will be running propane for heating water & cooking. I will have a 110v "apartment" fridge.

I would certainly include a 100+ Amp 24v alternator on the bus engine as backup/supplement for house battery charging.

Perhaps:

2kw Solar
2x Outback MPPT
24v/600A/H AGM battery bank (7.2 Kwh usable)
PSW Inverter sized for the fridge
PSW Inverter sized for TV, laptop & misc small loads
PSW Inverter for air conditioning. (1-12k Btu & 1-9k Btu mini splits)

Anyone out there living this way?

Note: We plan on living in the bus 4-6 months at a stretch with plenty of boondocking in sunny, moderate climates. Southwest in the Winter and PNW in the summer.

Thanks.

S.

PNW_Steve · 08-25-2017, 12:34 PM

Yes, I have done an "energy budget". Unfortunately the air conditioning is a BIG variable.

I have figured that the system above is about double my need without air conditioning.

brokedown · 08-25-2017, 01:03 PM

I don't have the roof space to install enough panels to run an electric air conditioner. Using solar for heat or cooling is going to dictate your system, and you're going to have a ton of waste capacity when you don't need them.

PNW_Steve · 08-25-2017, 01:11 PM

Quote:

Originally Posted by brokedown

I don't have the roof space to install enough panels to run an electric air conditioner. Using solar for heat or cooling is going to dictate your system, and you're going to have a ton of waste capacity when you don't need them.

I do have enough room. It will have the added benefit of shading my roof.

Yes, I will have a ton of excess generating capacity when I am not using the A/C. Kind of like having a 5kw diesel generator and not running A/C.

I would love to hear from anyone who has experience with trying to go full solar instead of running a generator.

Thanks.

S.

Iceni John · 08-25-2017, 01:52 PM

I certainly plan on being 100% solar when everything's up and running. I'm still in the construction phase now, so it will be a while until all my appliances are running off solar. I have a small Champion 3500W gasoline generator for emergencies only, and I converted it to run off propane to avoid the problem of a gummed-up carburetor and stale gasoline due to lack of use. Like you explained in another thread, I have sized my system for a worst-case scenario of a cloudy winter day - if I can still harvest a few hundred watts at times like that I'll be happy. During the summer I may have more power than I need, unless I have an A/C running all the time. There's absolutely no reason that I cannot run a 12K inverter-type minisplit A/C off solar. And as for needing more A/C than that, I do not plan on being anywhere so hot that I need a roof-full of A/Cs to stay comfortable - isn't that why buses have those round rubbery things at each corner, so we can drive to where it's not too hot or too cold?

If I'm parked somewhere nice off-grid, I definitely don't want to have to listen to a generator. That's the main reason I have solar.

John

PNW_Steve · 08-25-2017, 03:52 PM

Quote:

Originally Posted by Iceni John

isn't that why buses have those round rubbery things at each corner, so we can drive to where it's not too hot or too cold?

If I'm parked somewhere nice off-grid, I definitely don't want to have to listen to a generator. That's the main reason I have solar.

John

Is that what those are for?? I thought they were dog urinals.......

When I set out in my first bus (25 years ago.....) I had the same "Go where the weather suits my clothes" mentality.

Unfortunately I had to work a job while traveling and the job dictated Minneapolis in February and Las Vegas in August.

This time work will take a back seat to climate.

I agree regarding boondocking in a nice spot. Who wants to listen to a generator??

I also like the idea of converting the (emergency) genny to propane. I will be carrying propane anyway. Is yours straight propane or dual fuel?

brokedown · 08-25-2017, 04:39 PM

That's basically my plan, I'm following sprig time or as close to that as possible.

I agree that running a generator sucks. My AC is a engine driven, so if it gets too hot I need to run the bus. I can also cover or uncover widows as necessary open or close the, run fans, etc. Overall I think I'm still ahead compared to buying/maintaining/operating a generator and electric air conditioner, but I did have to replace a compressor a little while back and it just stopped working again (undiagnosed, maybe just electrical?)

I try pretty hard to reduce my consumption as much as possible. I save a good amount of power by running as many things as possible from DC rather than using an inverter. Anything that plugs in that has a power brick or wall wart should be run from DC power directly instead!

I just installed soe power meters to my system and my fridge is gulping a lot more juice than my kill-a-watt meter showed before i put it in the bus. Inverters aren't particularly efficient to start with, and I"m not using a PSW. Generally speaking I don't turn my fridge on until my battery is back to full, and I don't need to run it very long when I do (chest freezer being used as a refrigerator).

Defjr333 · 08-25-2017, 05:49 PM

I will be doing a hybrid of the 2. 1.2kw of panels 820ah batteries and 3k/6kw inverter/ charger with a 3kw generator as backup. I have this set up in my garage with panels on a rack outside. It will allow the 5500btu ac unit to run for aprox 3 hours before battery bank is at 60%. That is a night time run with no solar input to compensate. During day hours I can run it for nearly 5 and a half. I plan to start my genny when running AC most the time to conserve my bank. If you want to see what is required to go FULL solar, here is a guy I met on TNTTT.com His build blog is

2013 CarMate 100% Solar Heated and Cooled Over The Top Cargo Trailer

Dont even want to think of the $ he has invested in that setup. Granted it is in a cargo trailer (my original plan...now changed to bus), but man is it sweet and he knows his stuff. I am an ex aviation electronics tech from US Navy, and he spits out of memory more than i have forgotten. Hope that helps u on your question.
Doug

Iceni John · 08-25-2017, 11:12 PM

Quote:

Originally Posted by PNW_Steve

I also like the idea of converting the (emergency) genny to propane. I will be carrying propane anyway. Is yours straight propane or dual fuel?

I used one of the kits that feeds propane through a metering block that bolts between the air filter and carb. The carb's jet is not altered at all, unlike some kits that require the jet to be drilled out. This way I can switch back to gasoline if I want, but there's no reason to ever do so. One change that I did do from the instructions was to make a 90-degree adapter for the air filter so it still fits within the generator's frame tubes - the instructions wanted the frame tube to be cut to make space for the air filter!

The generator now starts on the third pull every time, unlike on gasoline when it would start on the first pull every time. This is because it has to suck the propane through from the Garretson demand regulator to the metering block - no big deal. It runs quieter than before, and I haven't noticed any difference in power output. So far, so good.

John

JDOnTheGo · 08-26-2017, 08:10 AM

Quote:

Originally Posted by PNW_Steve

Anyone out there living this way?

Howdy Steve,

I am not. However; I'm close to it. I like your way of thinking.

I'm not even sure where to start and don't have lots of time at the moment. In short...

The thing I have missed so far is not having air conditioning (and a generator to power it) while traveling. My situation is different than yours but I am starting to feel that this is an important consideration.

I have even considered adding more panels to my roof just for the shade!

Probably more later...

PNW_Steve · 08-26-2017, 10:12 AM

Quote:

Originally Posted by JDOnTheGo

Howdy Steve,

I am not. However; I'm close to it. I like your way of thinking.

I'm not even sure where to start and don't have lots of time at the moment. In short...

The thing I have missed so far is not having air conditioning (and a generator to power it) while traveling. My situation is different than yours but I am starting to feel that this is an important consideration.

I have even considered adding more panels to my roof just for the shade!

Probably more later...

I look forward to it!

I have figured that the 1.9Kw in panels would cover about 24'-25' of my roof. I could bump that up to 2.4Kw, add a 10' deck and have my whole roof shaded.

With panels available at $0.33 to $0.50 a watt adding more is cheap. It is the batteries and associated electronics that get expensive.....

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