CadilacKid, Solar storage vs solar capacity

[Brewerbob]

This says I have the roof space for 3500 w. I tried to be accurate with hatches and spacing without anything more than panel dimensions.

[Brewerbob]

Originally Posted by jofred99

Several good 48v inverters from Outback, Schneider, Magnum. Most can be purchased with an option of 120v output or split phase 120v/240v.

Ideally I would want a 2 way 48 V inverter. 55mph for 10 hrs down the interstate is a whole lot of charge time from the engine that otherwise lost. I know there are 24 volt bolt on alternators. I doubt there are 48 volt ones.

[Brewerbob]

Originally Posted by Brewerbob

Ideally I would want a 2 way 48 V inverter. 55mph for 10 hrs down the interstate is a whole lot of charge time from the engine that otherwise lost. I know there are 24 volt bolt on alternators. I doubt there are 48 volt ones.

Question: is inverter the right name for the widget that would step up 12/24 V to 48 V? Old school that's just a simple 2:1 step up transformer.

[PNW_Steve]

Originally Posted by rffffffff

The only thing I’d disagree with is 12v. I would highly recommend 24 at minimum. 48 may limit choices on peripherals or require dc-dc converters but I regret my 12v decision.

Too many people are "stuck in the 12v box"

I have suggested to a number of folks to consider 24 or 48 volts for larger systems. I cringe when I see someone install a 12v 800a/h battery bank and a 3000 watt 12v inverter.

[Brewerbob]

Originally Posted by PNW_Steve

Too many people are "stuck in the 12v box"

I have suggested to a number of folks to consider 24 or 48 volts for larger systems. I cringe when I see someone install a 12v 800a/h battery bank and a 3000 watt 12v inverter.

Reduces the heating requirements.

[john61ct]

DC-DC converter is the proper term for dumb power supply devices.

DC-DC Charger when capable of that function as well, variable setpoints, de-rating current, intelligence for float stage etc.

Obviously efficiency losses just as with inverters, usually much higher than claimed by spec sheets.

The cost of heavy gauge wiring is a once off.

Gadgets & battery banks are consumables need regular replacement.

But a mixed 12/24V system is not too bad extra costs.

[john61ct]

What do you mean by "2-way inverter"?

[Brewerbob]

Originally Posted by john61ct

What do you mean by "2-way inverter"?

Maybe just two converters. If I wire bank batteries to alternator, I need to go from 12 V (24 V) alt to 48 V bank while driving down the road. But I also need to go from 48 V bank back down to 12 V outlets/lights both driving and parked.

[jofred99]

Originally Posted by Brewerbob

Maybe just two converters. If I wire bank batteries to alternator, I need to go from 12 V (24 V) alt to 48 V bank while driving down the road. But I also need to go from 48 V bank back down to 12 V outlets/lights both driving and parked.

If you have small, short term loads for the converters to handle, they make a lot of sense to use. The downside is that there is a power loss during conversion (see device efficiency specs).



Consider that most of our buses have modest battery storage and need to be conservative with usage, especially if we are charging via the PV panels on our roofs. A day or two of clouds and we are having to fire up a generator. Yuck!

[john61ct]

Originally Posted by Brewerbob

Maybe just two converters.

Yes, such a two-way device does indeed not exist.

Inverter means from DC to mains-style AC.

What you are talking about is DC Converters.

For charging 48V, you need 52 - 59V output, ideally adjustable both voltage and current

This complexity leads to much higher costs, lowers reliability and greatly reduces energy efficiency.

Stick to one system voltage is best.

[magnakansas]

Ive always like the idea of sending power to heating element in hot water tank.

solar/ wind power ignorant, but learning

william

[magnakansas]

I have a mental image of a box of electronics the out put of the alternator goes to box of electronics, the out put of the box has a positive and negative lead going to each battery. the electronics can see the voltage of each battery and can adjust charge rate to each battery.

What would a commercial device that does this be called?

So I have a 200 amp bosch alternator for the 54 ford with 5.9 12v cummins and I have a 160 amp with neece leville external regulator for the 58 international bd282 inline six gas motor

william

[john61ct]

Completely unnecessary complexity.

[musigenesis]

I like the idea of running everything off diesel. Too bad I just bought a propane stove/oven.

[Drew Bru]

Originally Posted by Brewerbob

As a full timer, I'm glad you chimed in. How gray is your gray water? I'm all for Leave no trace but how bad is the water?

Dump it away from a stream and it shouldn't be all that bad especially if you dig a cat hole. Depending on soil it could take awhile for 45 gallons to seep in but if you aren't moving for a week, then you've got all week.

P.S. Thx for the numbers!!

We just go to a dump station. The gray water is pretty stinky and we don't use biodegradable soap. It takes 10-12 days to fill the gray tank so it's not a big deal.

[Doktari]

For myself there’s no such thing as too much panels. I’m overpaneled and under batteried so I simply heat up more water during the day and take longer hot showers if I want to . Then I turn off the water heater in the evening. There’s so many ways to do solar. For example; turn on a A/C unit during the day.
Also when the cloudy weather comes then I may have just the adequate amount of panels.
It’s the weight of the panels that bugs me. A big array of framed panels is some serious weight. 12 panels at 50 lbs each is 600 lbs. Add maybe 100 lbs for a rack brings it to 700 lbs. I’ve noticed my rig sway more after I added a big solar array. That’s like having three big people on the roof while driving.
Is it true the semi flexible panels have not been out long enough for long term testing? Are there 20 years reviews of any semi flexible panels. Or any particular brands that have a track record?
Thanks

[john61ct]

Nah, they're shite, hard to install properly, even then might only last 3 years if you're lucky.

Stick to rigid and be glad you haven't got a dinky little van

[Doktari]

Originally Posted by john61ct

Nah, they're shite, hard to install properly, even then might only last 3 years if you're lucky.

Stick to rigid and be glad you haven't got a dinky little van

Thanks, I suspected as much regarding shoddy semi flexible panels.
I should have mentioned the weight of batteries but that doesn’t bother me as much as they can be located low and near the frame.
Good tires and suspension go a long way to solving the weight issues. Air bags sound good but can have leaky lines in my limited experience.
Hope you got the answer to your panel vs battery capacity question. My crumby Evergreen panels don’t produce anywhere near their already crumby 13% efficiency rating. So getting a definitive answer is tricky. They wouldn’t overcharge my battery even if directly shunted to the batteries without a charge controller. With a 2400 watt array I think I saw 1700 watt output once.
I should check to see if one string of panels is not working. That’s a whole other subject and thread.