how to size your solar power system if money doesn't matter

[John61CT]

Thanks for the advice. Yeah it seems that my thoughts do not float well here. Darn. And great point about starting a forum. Will probably have to do that next.

It's a **lot** of work.

Your thoughts are very sound, just need to perhaps look at very specific context examples to avoid over-generalizing.

This comms format is great for helping get the truth out, like the men feeling an elephant in the dark, each of us bring our own filters and paradigms to bear on the big picture.

Disagreement and debate help us all learn and grow, ideally following facts and evidence where they lead, rather than sticking with our limited preconceptions.

Soon as we stop learning new stuff, that's when we become old.

 

[John61CT]

AWG 3-2 wires are fine for a 2000W inverter, as long as your round-trip distance is under 10 ft, you don't bundle wires in a conduit, and that current level isn't for very long periods of time.

Get up to 30ft or run continuously, then 0 gauge is not enough, 3/0 gauge ("000") is needed to keep voltage drop to 3%.

I highly recommend the Blue Sea Circuit Wizard app for calculating minimum wire gauges. Gets very expensive paying for bigger than you need.

 

[willprowse]

0 gauge 3 feet wires are cheap and stay cold. They work best for 2000 watt inverter. 2-3 gauge are fine if its for short term use. If you push 1500+ watts, which I had to do for hours, you want larger than necessary. If you feel the wires and they are getting hot, its best to make them bigger.

And yeah but 30 feet?? why would anyone ever do that? You have to be joking me. You are supposed to keep the inverter next to the battery, then run 110 ac lines for long distance. Have you ever seen anyone in your life use 30 foot 3/0 gauge wire? Seriously?

And sure it gets expensive. But why in the world would you be running dc 12 volts for 30 feet? I am so confused that you would even consider that as an option. Please elaborate.

 

[cyndi]

Folks, this is just a friendly reminder that many of us have limited bandwidth so we ask that you carefully trim any quotes you include to the bare minimum. When you are reading on a phone, and you have to read the same post twice to get a new comment, it can be frustrating--especially if there are pictures!

Be kind and trim!!

 

[willprowse]

It's a **lot** of work.

Your thoughts are very sound, just need to perhaps look at very specific context examples to avoid over-generalizing.

This comms format is great for helping get the truth out, like the men feeling an elephant in the dark, each of us bring our own filters and paradigms to bear on the big picture.

Disagreement and debate help us all learn and grow, ideally following facts and evidence where they lead, rather than sticking with our limited preconceptions.

Soon as we stop learning new stuff,  that's when we become old.

Yes very true. I always wonder how much information in my brain is completely false. But that implies there is an objective reality. Which is... questionable... haha

 

[lenny flank]

100 watts?? What are you powering?? That is so tiny. I would die if I had to live off a single 100 watt panel. Unless I had a big alternator and high charge rate lithium battery. Is there any reason you choose to have such a small system?

It suits my needs just fine. And that is all it needs to do.

I see zero point in wasting my money on a big-ass expensive system that I simply don't need.

EDIT: That is precisely why a "one-size-fits-all !!" solution is not a good solution.

 

[John61CT]

does depend on the inverter. My last zantrex was 2000 watts and it used .3 amps at 12 volts during standby. Very small.

8AH per day is not small for many systems already pushing their limits.

On cool days, that can be the total consumed by an efficient 12V compressor fridge.

As you agreed above, a small inverter per device that needs one lets you powere the inverter switch on/off as needed.

If any inverter is actually needed at all, which is rare in my experience. Many people just buy one after watching some YouTube videos, never realizing there are more efficient alternatives.

 

[John61CT]

100 watts?? What are you powering?? That is so tiny. I would die if I had to live off a single 100 watt panel.

Do you have a high consumption medical device required for your survival?

Or was that just hyperbole?

Realize many people live on $500-1000 a month, all up including vehicle expenses. Very few over $2000, around here that's considered a luxurious income.

Why would you buy more than you actually need?

 

[lenny flank]

the first step in designing your solar system is determining how much power you are going to need

Double yes to this.

My needs are pretty minimalist. I simply don't NEED a big expensive system.

 

[John61CT]

No thats not true at all. Buy the largest one possible because the discharge rate is high and most large loads are not powered for that long at all. Tell the newbies to get the largest inverter possible, and watch the voltage of their system. Easy as pie. And inverters have low voltage warning/shut off system. So what you said does not matter at all.

Crazy logic there.

Again, few people actually need any device that requires an inverter.

The money for extra panels and batteries required to power heavy loads like that is usually better spent elsewhere.

Minimalism is the key ethos to sustainability, just throwing money at problems when you don't have clarity on the specific situation is a fool's errand.

 

[tx2sturgis]

If any inverter is actually needed at all, which is rare in my experience. Many people just buy one after watching some YouTube videos, never realizing there are more efficient alternatives.

In some states, to get a cargo trailer, van, truck, bus, whatever, certified or re-certified as a motorhome or RV, one of the things it must have is a 120 v electrical system. I know...crazy huh?

A working inverter that's bolted down somewhere can actually meet this requirement...so there is that....

 

[VanDwellerMod]

How do I change the title of this thread?

What title do you want and a mod will change it for you.

 

[willprowse]

What title do you want and a mod will change it for you.

Thank you!! The other admin is not responding. Here it is: [font=Verdana, Arial, sans-serif]"how to size your solar power system if money doesn't matter"[/font]

 

[John61CT]

A $20 throwaway attached to an AC powered thrift shop clock radio for the inspection.

 

[John61CT]

But that implies there is an objective reality. Which is... questionable.

A fundamental problem for those who let themselves get gaslighted by modern propaganda.

"O, that way madness lies; let me shun that"

 

[Suanne]

I'm glad this thread is still active. Personally, I like hearing about this lifestyle from a different perspective Will. It challenges my assumptions, which I like.

Let me challenge yours too. I live out of a Prius, typically camping in remote areas, in nature. I specifically purchased devices that are 12v with the lowest possible energy consumption. I have no need for an inverter. I enjoy being a minimalist. On sunny days, even in winter, I can easily charge my electrical devices with my 35W of portable panels. Although I'm online a lot, my electrical needs are minimal (small 2n1 laptop, smartphone, fan, hotspot, backup lithium batteries). I don't have a fridge, cooling by evaporation when necessary. On days without much sun, I charge my devices by running my Prius which is, in effect, a very efficient/quiet generator on wheels.

If/when I get a larger, non-hybrid vehicle, I will likely follow almost all of your 5 steps. I won't, however, get a large inverter. The power savings I get by sticking with 12v items makes more sense to me ... unless, of course, I decide to get a microwave.

Carry on.

 

[kllcbosmetris]

40 amps is how much current the solar charge controller can handle. Each solar charge controller is quite different in design and some 40 amp solar charge controllers can handle a lot more power (total wattage of solar panels going through it) by having a larger input voltage. This will require putting the panels in series/parallel arrangement until they reach the ideal voltage required by the solar charge controller. Follow the manufacturer recommendation for how many solar panels to connect to the solar charge controller. 

Yes absolutely! Almost any size lithium will work with any size of solar panels. Lithium *typically* have a higher charge rate than lead acids. That means that you should buy as large of a lithium battery as you can afford, and as many solar panels as you can fit on the roof of your vehicle. Unless your solar system is being used for a very specific application. 

Charge Controller: 

So, the charge controller's 40 amp is the capacity that the controller allow the energy coming from solar panels (which I am guessing producing 0 to X amp, depending on the sun exposure). 

- What is the maximum charge (in amp) you can get from a solar panel (say for an individual 100w panel or for a combination 400w or 600w system, wired in parallel or in series)? Could it ever be more than 40 amp at any given time? 

- What is the best (with max capacity) charge controller you can get, if you want to make sure everything can go through the controller (and into your battery storage/pack), without much loss due to controller capacity? Is 40 amp the max for charge controllers in general (since you only mentioned 20 and 40)?

- I've recently researched fuel-powered 'inverter generators' and found out the top two manufacturers (especially for 2000w range) are Yamaha and Honda. Do you have a similar 'top manufacturers' for charge controllers? 

Yes absolutely! Almost any size lithium will work with any size of solar panels. Lithium *typically* have a higher charge rate than lead acids. That means that you should buy as large of a lithium battery as you can afford, and as many solar panels as you can fit on the roof of your vehicle. Unless your solar system is being used for a very specific application. 

Lithium Battery: 

- Are the Battle Born and GBS top lithium batteries? Anything else I should look at?

- If you are trying to minimize the space the lithium bank takes in your van, is GBS the only (and the most compact) option?

Induction loads, such as large motors and microwaves, require a large amount of electricity just to get started. So typically, it is best to double the size of your largest induction load, when sizing your inverter. If you have a 1800 watt load, buy a 3600 watt inverter. Even if you do not plan to run a large load, you should buy as large as possible. I have seen so many inverters turn themselves off when powering loads they were rated for. The biggest cause for this is using inverter cables that are too thin. Especially with large inverters. You need cables as thick as quarters if you are powering large loads with inverters (0 gauge at least for 2000 watt inverters). This is because we are working with 12 volts. If you had a 48 volt system, the inverter cables would be much smaller. But then you would have to buy a specialty inverter which would cost much more. So typically you are fine to use common, large 12 volt inverters, just be sure the wires are bigger than needed. 

Inverter:

I was under the impression "just give another 300w allowance (to your appliance watt power) for the initial surge" was the way to go. I don't know the initial surge of the oven or whether it will use 1800w at all times, regardless of the heat temperature you use it with (toasting or reheating vs. baking at 450 degrees).

- What are the top manufacturers for pure sine inverters? I heard Magnum and Xantrex. 

- If you are going with more than 2000w inverter, what is the gauge you recommend? Say for a 3000w inverter. Still 0 or is there a thicker cable.

[P.S. I do not know the difference between 12v vs 48v systems. I am assuming all this is based on 12v?]

 

[kllcbosmetris]

AWG 3-2 wires are fine for a 2000W inverter, as long as your round-trip distance is under 10 ft, you don't bundle wires in a conduit,  and that current level isn't for very long periods of time.

Get up to 30ft or run continuously, then 0 gauge is not enough, 3/0 gauge ("000") is needed to keep voltage drop to 3%.

I highly recommend the Blue Sea Circuit Wizard app for calculating minimum wire gauges. Gets very expensive paying for bigger than you need.

Conduit:

You mentioned "if you don't bundle wires in a conduit." I am guessing that is for the heat radiance reasons? I've seen a lot of van built videos with conduit use and it seemed like a great idea at the time (i.e. less mess, protection from other elements of construction) but with this new information, I am not sure. When you are building these systems, how do you position your wires (i.e. long ones going from solar panels to controllers as well as the short wires needed for the inside battery box set up. I was thinking wires would be somewhat tidy and hidden besides the wall-carpet-panel or cover/cabinet or insulation. When you do insulations for the van walls, do you leave the wires out? Is it better to leave them out in the open for some air so they don't heat up?

 

[John61CT]

No, just with conduit (like thicker insulation or lots of heated up wires bundled together), you need to go to a thicker gauge to compensate.

But voltage drop prevention usually requires upsizing well past the overheating issue.

Such safety issues only appear with large current loads, most normal vanners no need to worry too much.

Poor crimps and missing circuit protection more of an real life problem.

A cheap infrared temp gun can show hot spots, very useful.

 

[tx2sturgis]

I was under the impression "just give another 300w allowance (to your appliance watt power) for the initial surge" was the way to go. I don't know the initial surge of the oven or whether it will use 1800w at all times, regardless of the heat temperature you use it with (toasting or reheating vs. baking at 450 degrees).

Ovens like this are resistive, and not inductive, so there is virtually no 'surge'...although there can be what is called 'in-rush current', but it is not enough to change the rating of the oven. 

1800 watts is what it will pull at MAXIMUM. 

It will use that much power when it is pre-heating, but then it will cycle on and off when maintaining the oven temperature. It will also use that much when it is broiling, since the top elements are normally constantly on. 

So, if the inverter is rated at 2000 w continuous, with a 3000 w surge, you would be fine. But a 1000 w inverter with a 2000 w peak will not do the job.

Keep in mind the 2000 watt inverter will be very near its top capacity, so it will run warm, and lose some efficiency, and possibly, not last as long.