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

[willprowse]

Inverter LVDs are typically set battery-destroyingly low. I have no idea what "the discharge rate is high" means.  What will be high is the purchase price and the parasitic draw.  "Get the largest inverter possible" may be the worst advice I've seen on this forum, other than stuff that can get one hurt, killed, or jailed.

If you think newbs don't get confused by big inverters look at the number of posts that fantasize about a 100W panel, wally world "deep cycle" battery and 2000w inverter.  
As sternwake said:

oops yeah I should have made it more clear. I meant that when people use a large inverter, the discharge rate is high for a short time, which is why its great to have a large inverter. In case you need it. Because most large loads are only powered for a short duration. Sorry I didnt elaborate on that. 

And yeah totally, the parasitic draw is crazy on some of them. Not the xantrex. 

And I am still sticking with "buy largest inverter possible". Turn it off if its not in use. and dont buy a cheap one so the parasitic draw is low. its not bad. if you need to power a tiny ac appliances, buy a 20 dollar one to do so. problem solved.

and the system you mentioned, though horrible for most things, still could safely run some appliances just fine. yes, horrible for most applications, but it depends on what you want to do. having a large inverter kicks butt! not saying that people can use it for long, but its great to have.

 

[willprowse]

Yes, huge cultural difference,  YouTube where money is made establishing a personal Brand, being young and cute carries weight but little fact-checking is going on,

While here in forums, more traditional internet values dominate,  no one knows you're a dog, everyone starts off on an equal footing and "tall poppies" with hubris but don't really know your stuff,  quickly get cut down to size.

what did I say that was incorrect? bring it on. I have been doing this stuff for years. Tell me how I was wrong.

 

[willprowse]

Yeah I just deleted the large comment I wrote. It doesnt help anyone. And yeah guys, if you are not powering much, get a tiny inverter. If you have different sizes of ac loads, get different inverters or use a dc dc buck converter. I personally LOVE having a huge inverter in case I need to power some seriously large power tools. Its great!! Especially when you are far away from the city. Its GREAT. But yeah, if you are just powering a dinky little laptop or something, use a tiny inverter haha! Of course. I thought that was a given. I guess I need to be super specific on this forum. Sorry guys. Looks like people talked a whole lot about this. Oops. My fault.

 

[John61CT]

OK Will, sorry to make you so defensive, please don't take it personal. But here you go, couple more examples.

No laptop needs any inverter.

Much more efficient using a DC-DC converter.

Pretty sure even makers of big power-hungry ones designed for gaming provide a "car adapter", and if not you just need to match the requirements from the AC power brick.

Same with monitors, printer/scanners, many even available in 12V native, and if not just convert to their 19V DC or whatever.

And if you really need to carry (and have the space for) a bunch of power tools, the cordless ones are usually more appropriate. Most makes include a 12V charger in their line up.

If you need something corded, you may fing carrying a small generator may be more generally useful than an inverter that will only use to run the tool for a few minutes.

I'm just trying to be helpful for most use cases here, I'm sure there are some scenarios where a big inverter is totally worth it.

Some people with full-on RVs find their partner just won't come along without the rig carrying a full-sized microwave or an induction cooker, for example.

I'd still recommend the little genny though, but as Will states for short time usage a big enough bank can carry the load.

Getting the power used back in every day becomes a bigger challenge of course, and the genny solution can be very helpful for that, even with lots of panels in suboptimal solar conditions.

 

[Weight]

My lap top needs an inverter. I would not trust my investment to an off-the-shelf dc to dc converter. If I could get a my-laptop-brand dc/dc then I would use it. but that does not exist. My little inverter was pricey, but I trust it with a lot of hard work and expensive equipment. I doubt it is very much less efficient than converting 12 volts up to 19 volts.

 

[Weight]

My coffee pot, toaster, and microwave need my 2000W inverter. I think that is large. Getting the power back in every day depends on the power used every day. No relation to using a small inverter to charge lap top, or large inverter for microwave. Use less power, easier to recharge, but I have no problem recharging with 400W solar. I do use a generator occasionally, and/or mains power, but only to equalize while I have time to observe the process.

 

[willprowse]

OK Will, sorry to make you so defensive,  please don't take it personal. But here you go,  couple more examples.

No laptop needs any inverter.

Much more efficient using a DC-DC converter.

Pretty sure even makers of big power-hungry ones designed for gaming provide a "car adapter", and if not you just need to match the requirements from the AC power brick.

Same with monitors,  printer/scanners,  many even available in 12V native,  and if not just convert to their 19V DC or whatever.

And if you really need to carry (and have the space for) a bunch of power tools, the cordless ones are usually more appropriate. Most makes include a 12V charger in their line up.

If you need something corded, you may fing carrying a small generator may be more generally useful than an inverter that will only use to run the tool for a few minutes.

I'm just trying to be helpful for most use cases here, I'm sure there are some scenarios where a big inverter is totally worth it.

Some people with full-on RVs find their partner just won't come along without the rig carrying a full-sized microwave or an induction cooker, for example.

I'd still recommend the little genny though,  but as Will states for short time usage a big enough bank can carry the load.

Getting the power used back in every day becomes a bigger challenge of course,  and the genny solution can be very helpful for that,  even with lots of panels in suboptimal solar conditions.

I already said that. I literally just said that. I have a full 20  minute video on youtube teaching people how to use them, how to connect them and calibrate them, that I posted over a year ago. Thats why I said it two seconds ago. This entire post is redundant. 

A generator for short duration large loads? When you have a battery  bank with high discharge capabilities? Why? Why not get a large inverter?

 

[willprowse]

My lap top needs an inverter. I would not trust my investment to an off-the-shelf dc to dc converter. If I could get a my-laptop-brand dc/dc then I would use it. but that does not exist. My little inverter was pricey, but I trust it with a lot of hard work and expensive equipment. I doubt it is very much less efficient than converting 12 volts up to 19 volts.

Just get a laptop charger that works with a cigarette lighter. Which brand is your laptop? I bet I can find a "ready made" plug n play solution. And yeah, tiny inverter is probably fine for you because its such a small load. The losses are probably less than 15-20%

 

[Almost There]

A generator for short duration large loads? When you have a battery  bank with high discharge capabilities? Why? Why not get a large inverter?

Because for probably the vast majority of us out here full-timing on the road, 99% of the time we don't need a large inverter nor that large of a battery bank.

It's only for that miniscule occasional odd use that the vast majority of  us need THAT much 120 V power. At that point, a generator that most of us carry/have on board anyways since most of us aren't a) living in the sunbelt all year round (we do like to travel!) and b) realize that cloudy days are going to happen, makes more sense than the installation of a very large battery bank to cover the draw of a large inverter.

There is no one size fits all here. Trying to fit all of us into *your* perception of what works, well it won't!

 

[John61CT]

Obviously inverters only discharge from the bank, no help in recharging.

Generators can be used with your high-amp shore charger to get your lead bank refilled quickly (if a high-CAR chemistry) up to 80-85% in the morning.

Then solar, even few panels or cloudy conditions, will get them to 100% Full (defined by endAmps) over the next 3-5 hours.

If you're doing other things that use a lot of power at the same time, without discharging the bank, even better.

 

[John61CT]

With LFP and a little genny, no solar is needed at all, since there's no need to get the bank full.

 

[John61CT]

My lap top needs an inverter. I would not trust my investment to an off-the-shelf dc to dc converter. If I could get a my-laptop-brand dc/dc then I would use it. but that does not exist. My little inverter was pricey, but I trust it with a lot of hard work and expensive equipment. I doubt it is very much less efficient than converting 12 volts up to 19 volts.

Another way to go is to run off the output

 

[John61CT]

Sorry kids

Another way to go is to run off the output

of a lithium jumpstarter powerpack with a laptop output, while it remains fully charged plugged into the 12V.

Remember, your laptop is actually running input power through its internal batt anyway, trust is not really an issue, they're designed to take a very wide range of inputs with no problem, some down to 16V seen others as high as 23V NP.

 

[willprowse]

I dont know why any of these points need to be discussed. Sure there is exceptions to the rules, and more efficient ways to do everything, but seriously guys? I am looking through these forums and I am realizing that you guys just argue. Everyone is trying to say "you are wrong, my thoughts are better".

It doesnt seem constructive at all. And solar is so simple. It either works for its intended purpose or it doesnt. End of story. And yes I realize that everyones needs are different... but the points that are being argued here are silly. Thats whats great about electicity, there is no argument. It works, or it doesnt. No need to argue at all.

I have seen it in other threads on this forum. Someone will state something, and people will try to find that one instance in which said statment is wrong. Why? It makes for a massive waste of time honestly.

I also frequent some other battery building/solar forums and I have never experienced this kind of arguing before. It is so strange for me to see here. It is as if you need to explain every... single... point. Everytime. Very frustrating.

 

[willprowse]

Because for probably the vast majority of us out here full-timing on the road, 99% of the time we don't need a large inverter nor that large of a battery bank.

It's only for that miniscule occasional odd use that the vast majority of  us need THAT much 120 V power. At that point, a generator that most of us carry/have on board anyways since most of us aren't a) living in the sunbelt all year round (we do like to travel!) and b) realize that cloudy days are going to happen, makes more sense than the installation of a very large battery bank to cover the draw of a large inverter.

There is no one size fits all here. Trying to fit all of us into *your* perception of what works, well it won't!

Here is a prime example of what I mentioned a second ago. "almost there" is offended by me saying that a large inverter is not good, because in his life, it isnt. and then he makes a generalization saying that everyone here doesnt need a large inverter. who cares? why would "almost there" care so much to argue this point, then saying that I am trying to fit him into my "perception of what works"? Maybe he feels offended by how I am saying what works for me... But why would it? For me, and everyone around me, large inverters rock! I can find old tools in the trash, behind warehouses etc, and actually use them! I love having a nice 2000 watt inverter. So I tell people here "hey everyone, I like big inverters"... AND BOOM! I get this massive list of responses telling me that I am silly to think that? 

This forum is kinda crazy. These responses are so strange to see. Anyone else realize this? I havent seen this before.

 

[willprowse]

And I mean this with all due respect. I have only been offgrid and living on the streets for 8 years. Maybe some of you guys have been doing it for 40+ years. I dont know. I bought my first 120 watt panel when it was nearly 600 dollars directly from china, 8 years ago. Before that, I was building BEAM robotics when I was a teenager, and powered them with tiny solar cells. But of all things, solar is dead simple. Any electrical engineer could tell you that. The silicone wafers and the boron and phosphorus doping. Didnt we all learn that ages ago? But here on this forum, its like this massive argument. About solar?!?! Haha why?! What is so difficult about this that it requires arguing? Solar is super simple guys! No need to get offended or try to argue every single point. We can all get along and actually HELP each other.

 

[tx2sturgis]

Solar is super simple guys! No need to get offended or try to argue every single point. 

You, and I, and many others here have a grasp on the basic concepts and for us, it's pretty straight-forward. But it's not really 'simple'...and I don't mean to sound argumentative, but if that's how you see dissenting opinions, so be it.

You aren't the only one. 

Many good ways exist to do the same thing. What works for you is one way, but as I explained earlier, it might not work for someone else.

For many, solar power and the related technology involved is quite complex, confusing, and possibly scary, and if things aren't done right...then that can cause unforeseen problems that can be expensive or even dangerous. 

If you can learn some patience to go along with your knowledge, you might be a wonderful asset here. 

But...an impatient teacher, teaches little.

 

[frater secessus]

What is so difficult about this that it requires arguing? Solar is super simple guys! 

The panels themselves are the easy part, although there is some nuance in matching Vmp to PWM controllers.    Battery bank selection and charging is not so easy. Neither is Charge controller selection and configuation.

Making everything work well on a cheap rv living budget requires some amount of thought and effort.

No need to get offended or try to argue every single point. We can all get along and actually HELP each other.

There is more than one way to help;  some of us help by vetting information.  It might look like argument but it's not intended to be. 

Hopefully between both communication styles we will get newbies the info they need to make an informed judgement. 

Thanks for your feedback.

 

[highdesertranger]

Almost There is a she not a he. says so right under her screen name. now, am I ageing with you? highdesertranger

 

[Weight]

I can see will's point somewhat. Many on here try to tell me I should use a dc/dc china-doll-device to charge my lap top. The lap top manufacturer does not have or recommend a dc charging source. My small SW inverter and the brick that came with the lap top are my choice as they are my expenses and my investments at risk. I have tried to make my position clear, but still get static as i am "not doing it right".