Did I Do This Right?

[john61ct]

And if you can't figure out my meaning with a bit of google-fu, just ask specific questions and I (or someone else) may well be willing to clarify things.

[CMORGANSKOOL]

How about 1600 square ft house uses 35,000 watts a day in the summer!!!
Puts my solar rig to shame.

[firebuild]

Originally Posted by JDOnTheGo

I wasn't sure what this meant until I saw your reply to John. I now believe it means that I presented too much technical info.

Sorry, I should have been more clear. No, I wasn't saying your response was too technical; I was referring to this:

Originally Posted by firebuild

If you posted exact instructions for me, someone else would come along and insist some part of what you said was wrong and add some other step to confuse the whole thing. Then, most likely, a third person would weigh in on how what the first two proposed was flawed. Then I'd see some YouTube video throwing even more confusion into the mix.

It's very hard to be on the novice end of a discussion where it's impossible to determine who the authority figure is, because whatever someone says, someone else contradicts it, rightly or wrongly. The 60-watt-bulb-isn't -really- 60-watts part if the post is also an illustration of this.

[firebuild]

Originally Posted by john61ct

Of course not everyone wants to learn enough to get optimal value.

Please don't mistake my current ability to comprehend for unwillingness to learn. My head isn't in the sand.

Learning is cumulative and follows steps. There's a reason we don't teach calculus to first graders.

When I'm ready, I'll be tossing around data like the rest of you.

[firebuild]

sorry, duplicate post!

[TheHubbardBus]

Originally Posted by CMORGANSKOOL

Yes the bones of that system
1 panel $115 1 controller $20 1 battery $170 and 1 inverter $150 and about 25” of cable and 10 connectors $25 will get you started and power a fridge or lights and a tv or power tools while building. It will run 30 amp continuous for 20 hours and 200 amp surge. It runs my 5000 btu Ac for about 45 minutes and recharges in about 4 hours. And is fully expandable when you get around to it.

Sorry, but I fail to see how this - or any other 'build it up as you go' solar system - is fully expandable. Or even close to it.

Cheap / small solar panels are both less efficient and more costly per watt than grid-ties. So if you were ultimately going to upgrade to a significant system, you'd either be behind the curve buying a bunch more small panels (and all the complication of wiring them all in), or be starting all over going w/ grid-ties.

As for batteries, the popular notion that you can just add batteries as you go is fraught with complication. If you were keeping the same system voltage, that would imply adding one or more parallel strings (generally a bad plan, becoming a worse plan, exponentially, with every parallel string you add), in addition to adding new batteries to old, both of which will present substantial difficulties balancing your bank. The best case result: significantly shortened battery life. The worst-case: flames and loud noises.

If you were going from 12 to 24, then you'd very likely find it impossible to use the old batteries you already had even if you wanted to (which you don't). For example, you could put together a nice reliable high-capacity 12V bank using six 2V batteries in a single string. In order to go to 24, you'd have to get 6 more 2V, all in series, for a total of 12 in a string (think of all the cabling, all the connections, all the points of failure). Then, if you wanted additional amp-hour capacity, you'd have to run another string... 12 more 2V batteries on top of the 12 you've already got, when fewer 4 or 6V (maybe even 12V) batteries would likely do the trick.

Your 600W inverter would be useless in a larger system pulling much more than that peak, so that's going on Craigslist. Same goes for your charge controllers, which would likely need to either be replaced or paralleled with new units to support your increased panel wattage.

Your wiring / cabling / fusing / overcurrent protection would all have to be replaced, unless you oversized them from the get-go. You might get away with the same wiring from you panel combiner to your controller(s) with some creative wiring (which likely means a less-than-ideal panel configuration), but that's about it from what I can tell.

Am I wrong?

[john61ct]

Not completely.

But proper prior planning certainly can allow for such expandability.

May not be as optimal as, getting everything right the first time, but the compromises involved aren't fatal, and over time will get corrected.

Starting off from the beginning with larger, rigid, high Voc panels is good advice (not necessarily "grid tie"), since ideally they will last well over a decade even in mobile use.

[CMORGANSKOOL]

My system is expandable up to 30 amps or about 400 watts in series. I can add a second controller to add more panels or a bigger one. They’re $16 or under $100 for a decent mppt. Batteries in parallel strings balance themselves. One valid concern is putting a new battery on an old bank which has depleted capacity but mostly once they reach that point it’s time to upgrade. Wires get sun rot and need to be replaced fairly regularly so upgrading those is not a big issue. And I suggest a 600-800 watt inverter for one battery assuming this is a shorty or van build and they’re concerned with weight over functionality. 600 watts will run a small fridge or any electronics you may have. Not a microwave obviously or a vacuum but all the important stuff like cameras and tv and phone and lights. I don’t see any reason to recommend someone buy an all in one over a modular system for mobile solar based solely on cost and repair ability

[CMORGANSKOOL]

Here’s my latest monster.
4s 16p 128ah LiFePo4 5c chargeable and 25c discharging.
47lbs total. $700 total build cost including inverter and parts.

On my bus I have multiple battery banks on a switch at the controller. Charge one, switch charge another switch. And you can switch banks on the inverter.

[TheHubbardBus]

Originally Posted by john61ct

Not completely.

But proper prior planning certainly can allow for such expandability.

May not be as optimal as, getting everything right the first time, but the compromises involved aren't fatal, and over time will get corrected.

Starting off from the beginning with larger, rigid, high Voc panels is good advice (not necessarily "grid tie"), since ideally they will last well over a decade even in mobile use.

Right. Proper planning. Meaning you know where you intend to go before you get there. That's the polar opposite of starting out with a random battery, cc, and panel and adding more stuff every time you need another electric accessory. Which is the implication I was responding to.

"over time will be corrected"... not sure what that even means. I guess if you have unlimited time and money you can afford to be so nonchalant. I was working under the assumption that most normal folk would hope to limit the number of mistakes they make in the process of getting from point A to B.

[john61ct]

Battery banks get replaced, cheap controllers get upgraded, improper crimps get re-done

etc etc, over the decades things improve

Of course do it right the first time is better, but not an option for everyone

[TheHubbardBus]

Originally Posted by john61ct

Battery banks get replaced, cheap controllers get upgraded, improper crimps get re-done

etc etc, over the decades things improve

Of course do it right the first time is better, but not an option for everyone

Decades...

"Welcome to ABC solar! We've got two popular plans to choose from. Plan A) you spend a weekend working out a comprehensive energy use evaluation, then we determine the best way to meet both your immediate needs, as well as your long-term goals, in the most time and cost-effective manner possible."

"Plan B) We play pin-the-tail-on-the-donkey to pick out your system components. Then, over the next 20-30 years, we replace sh*t till we get it right".

"We recommend plan B., because... Lulz".

[john61ct]

You are arguing against a straw man, not what I am actually saying.

Plenty of people start out with a very limited budget.

If they have perfect expert level knowledge, they can avoid wasting money and start out small, then expand later on with few compromises.

With a low level of understanding, a greater proportion of their overall spending building up their system - quantity and quality - over the years may be wasted it is true.

But probably not as much as taking advice from people motivated by selling them stuff.

[TheHubbardBus]

Originally Posted by john61ct

With a low level of understanding, a greater proportion of their overall spending building up their system - quantity and quality - over the years may be wasted it is true.

But probably not as much as taking advice from people motivated by selling them stuff.

As someone not selling anything to anyone, much less anything in the solar arena, I don't believe this to be a factual statement. Are you suggesting that people who don't have a clue what they're doing with solar/electric are better off on their own than (at least) consulting with a company that specializes in such endeavors? This is, after all, electricity we're dealing with here.There's more than just economic considerations at stake.

Granted, all business entities are not created equal. But with little homework it shouldn't be difficult to find a reputable operation ran by educated & experienced folks who probably wouldn't charge you one red cent to piece together a system for you - if they don't already have an off-the-shelf solution worked out - that would get you started off on the right foot depending on your specific needs. All for what... a 5% markup over amazon? You'd save whatever money you spent paying retail on your first (inevitable) day-one mistake. A mistake which - depending on the circumstances - actually could be fatal.

Which kind of brings us back full circle to the OP, who even while doing everything short of screaming "I don't know what I'm doing", keeps getting told how to 'design and build' his own system (just keep the colors the same. How hard could it be?), even while he insists he's not comfortable doing so. Maybe it's just me, but I feel this sentiment to be irresponsible. Fortunately he's well aware of his current limitations (I was hoping to get one pun in. Yay).

[john61ct]

Of course if the prospect is unwilling to learn themselves, they are at the mercy of salespeople.

However if motivated to learn, they can educate themselves with the help of resources online, including advice from forums like these.

It may seem daunting at first, many start out inconfident, but it ain't rocket science.

[TheHubbardBus]

Originally Posted by john61ct

it ain't rocket science.

Often said just prior to, "hold my beer".

[roach711]

I've gotta agree with John. I started our bus conversion adventure already familiar with residential AC electricity and vehicle DC electricity but my big learning experience was learning how to make the two work together. My bus wiring plan changed several times as I learned the ropes and the original install has worked out fine for us.

I could have cobbled up something cheap that may or may not have been ultimately useful but I took the time and learned how to do it right the first time.

I can very well understand how someone who's not versed in things electrical could look at the AC/DC/solar interaction and want to run screaming but I learned how from books and The Net and so can others. If someone is motivated and patient they will succeed.

[firebuild]

[QUOTE=john61ct;342303]Why are batteries expressed in Amp hours instead of Watt hours?

By specifying voltage separately, the unit of 'Amp hours' allows convenient recalculation for different series/parallel combinations of batteries, as well as easier calculation of battery lifespan (measuring load current is easier than load power).

Amp hours relate to the basic chemical reaction of the battery whereas Watt hours are much more affected by state of charge when charging and discharging and by rate of charge and discharge./QUOTE]

OK, just reread this whole thread, and the above answers all the questions I came in with. I should have stopped reading there. It was all the other stuff that overwhelmed me. Thank you.

Originally Posted by TheHubbardBus

with little homework it shouldn't be difficult to find a reputable operation ran by educated & experienced folks who probably wouldn't charge you one red cent to piece together a system for you - if they don't already have an off-the-shelf solution worked out - that would get you started off on the right foot depending on your specific needs. All for what... a 5% markup over amazon?

Have you by any chance had any conversations with any solar companies? The idea that anyone out there is gonna help put together a system for a 5% markup over Amazon is... well, send me some contact info if you've found that company. The last quote I got - and mind you, my needs are minimal - was approximately 6 grand. More than double the cost of my bus, and about equal to the cost of my entire build thus far. I don't have that kind of scratch.

Originally Posted by TheHubbardBus

Which kind of brings us back full circle to the OP, who even while doing everything short of screaming "I don't know what I'm doing", keeps getting told how to 'design and build' his own system (just keep the colors the same. How hard could it be?), even while he insists he's not comfortable doing so. Maybe it's just me, but I feel this sentiment to be irresponsible. Fortunately he's well aware of his current limitations (I was hoping to get one pun in. Yay).

Yeah, it is irresponsible to keep telling someone who has clearly stated they don't feel comfortable building their own system how to build it. Thank you. I know WATT I don't know (you're not the only one with puns in their arsenal)! I didn't ask for anything but the answer to a basic question. I run into this with mechanical work all the time - people insisting I take on projects I know I'm not ready for - and anyone who knows me from this group probably knows I've come a long way in a year.

Oh, and by the way "he" is a "she." Guess that accounts for how much "mansplaining" you all need to do, right? LOL

[firebuild]

Originally Posted by john61ct

With lead, a high Peukert value means a bank hold many more Ah if discharging at a lower C-rate.

What is c-rate?I googled; no luck in this context.

[john61ct]

current rate proportional to bank capacity

given a 100Ah bank, 100A is 1.0C

200A is 2C

50A is 0.5C