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

[John61CT]

kllcbosmetris

Solar controllers have max input specs to match with panels' max output specs so the latter doesn't damage the former.

For MPPT, based primarily on voltage (Voc) and current (Imp)

Even efficient models will usually produce far less than these maximums in average conditions.

Good brands in the US market include Victron, Morningstar, Midnight, Blue Sky and Outback.

Each model has its own specs, there is no one "best".

_____
Batts

A given chemistry will be the same space and weight per AH across makers. Claims of smaller and lighter for the same AH are a red flag, they are lying. Which is very common in thos market niche.

Post a new thread for a product you are considering to get specifoc feedback.

_____
Inverters

The extra power required for surge/startup varies with each type of load device, and is never a fixed margin over the continuous rating but a multiple or percentage.

Infortunately inexpensive current measurement devices can't capture these accurately, so best to post a tgread on a specific device see if you get recommendations.

Magnum is best, Xantrex service attitude sux. Vanner, Victron, MasterVolt, Sterling, Outback, ProMariner are excellent but pricey.

Samlex and Tripplite are solid middle ground.

_____
2/0, 3/0 etc are larger than 0, see the CW app I reference above.

_____
You see some 24V systems on bigger rigs, save some money on cabling but everything else is more expensive

48V and higher for specific devices using converters is best, otherwise for propulsion systems only.

 

[Motrukdriver]

And considering all the possible losses in a system

Cheap rv living implies frugality

Oh gosh why flooded?

If you size your wires correctly and keep the shortest length of wire run as possible between your panels and charge controller and then from your charge controller to your batteries your losses will be insignificant. There is beauty in efficiency.

Frugality yes.  You'll find that a lot of folks in here can get by quite nicely with one panel and one battery.  Adding more panels and weight for the sake of having a huge system adds weight and drag to your rig defeating the actual frugality you were trying to achieve in the first place.  Your approach of building a huge system and covering your roof is great for the snowbirders in the big Class A and Class C RV's.  They need that kind of power since the vast majority of them are trying to replicate what they have in their home when they go on the road for a few months.  This site caters to folks that might be living in a car or van or SUV or popup or what ever they can afford to keep the rain off their heads.  For this audience I think it's best to find the most affordable solution to having something to charge their phone and maybe tablet.. then lets go from there.

Flooded because I'm a stickler for proper maintenance.  Batteries are no exception.  If you use sealed batteries then human nature will eventually sneak in and you'll omit checking them out because why look at something you can't see anyway right?  When I'm using my little hydrometer to check each cell I'm also checking connection corrosion and anything else I can get my eyes and hands on.  Out of sight, out of mind is not something I want to make a habit of when it comes to producing my own electricity.  This is just my opinion of course and it also gives me something else to do instead of sitting around in a lawn chair soaking up the sunshine.  I'll also be checking on the wind turbines and tarp ropes and water levels in my tank, etc...

Please don't get my comments and replies wrong here.  I'm sure you know a crap ton more about solar than I do and your method is great for about 95% of RV'ers that want the biggest they can get to do stuff like run a washing machine and air conditioning and all the things they are accustomed to using.  I used to see those huge land barges traveling down to Florida or out to the Southwest when I drove a big truck and thought how cool is that.  Bob's group here is that other 5%.

 

[akrvbob]

My standard advice on how much solar to buy has never wavered:

LOOK IN YOUR WALLET, BUY ALL YOU CAN AFFORD*

*But, that must be tempered for the very few people who have chosen to be true miminalists and for them that's the wrong advice.

My advice on inverters is to buy 400-500 watt inverter with a low stand-by draw unless you have a very specific reason to need a larger one.

 

[Weight]

I have to adjust Bob's advice and say buy as much solar panel as you can fit. Then try to get as much battery as you can fit. The sun is free, but you have to capture and then store the energy when it is available. If you don't need much energy, by all means get one panel and a 12 volt marine battery. Some sunshine is better than none. Very true; is buy a quality inverter but only as many watts as you need. If your system expands later you can get a larger inverter and use both.

 

[jimindenver]

I would like to remind every one that no one is wrong unless their needs are not being met by their current system. Presenting as many concepts as possible gives those looking as many options as possible to be able to fill their needs. My system is certainly not typical nor do I think any should copy it. It does however show some of what is possible with solar, much of which I was told was not possible when I started in solar 5 years ago. One person not listening to the talking heads that know everything can change the way things are done.

 

[ValerieP]

I love all the perspectives with the explanations. I ask for advice all the time, and, since I am l am learning by leaps and bounds, I always need to find the reasoning through the why.
So, wire to connect a 2000 watt inverter/ charger to 2 100ah batteries- where do I look?
Thanks!

 

[John61CT]

How far is the wire run, round trip also rounded up?

2000w / 12v ~~ 160A, round up say 200A

Blue Sea Circuit Wizard app better than a lookup table

 

[ValerieP]

I think I’m going to try to put the batteries Under the Inverter, which will sit on a shelf above the batteries- is that the right way to do it?

 

[Weight]

My 2000 watt inverter recommends 2/0 cable at 10 feet. I have 2/0 cable at 24 inches. Electronics such as inverter and chargers should be separated from the batteries. The fume from any battery chemistry will cause corrosion within the device. The batteries should be protected with a cover, to avoid dropping the nuts and bolts causing a short. The electronics need open air cooling. If the question is where to buy cables. I use these guys by USPS; www.genuinedealz.com/
Or these guys on the west side.; https://baymarinesupply.com/

 

[John61CT]

Both excellent vendors.

Genuinedealz does custom lengths crimped to your specs. A sister website http://www.bestboatwire.com sells bulk wire and supplies.

If crimping yourself buy 3-4 sizes max in bulk and round up.

But good tools for big gauges cost a fortune, use GD for small jobs, under 50' and say 30 terminations.

 

[jimindenver]

I paid $28 for my 16 ton crimp tool.

 

[John61CT]

Which is 'good enough' for many, can last a while if not used too often.

But the dies that come with it are metric, not even close to AWG except a couple of sizes.

The real acid test for gas-tight fused-strand is a weighted pull test; MIL-T-7928G spec is best, at the bare minimum strive for UL-486A.

ABYC E-11 is a waste of time, much too lenient.

The crazy-accurate and much more durable ones that real pros need, the frame alone can cost $thousands, and good quality dies usually $250-400 each.

The main advantage of higher quality tools is knowing all your crimps are standard and repeatable, will meet your standard without needing to test each one individually.

Very savvy eBay watchers can sometimes pick up good used for 10-20¢ on the dollar, but even that's more than many here are able or willing to spend.

 

[jimindenver]

Too funny but you are right. There is always going to be something better out there. The trick is to understand the difference between better and acceptable. Have someone else do it for you and you end up with what they think is acceptable, not necessarily what you find is.

The dies are in metric on the TDK tool. It took me all of 30 seconds to work out that the 50mm was what I needed to do 1/0 crimps.

 

[John61CT]

And 53.3mm being larger than 50, likely NP.

Relying on genuinedealz is never a mistake, better job and rarely costlier than doing it (properly) yourself at $1 per crimp.

 

[frater secessus]

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.

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:

“One can only put so much inverter on so much battery… A lot of people will put a 2KW inverter, or larger, on a single 12v battery, but this can be compared to a 5 second drag car, which uses 5 gallons of gas to run the 1/4 mile, but then only having a 2 gallon gas tank.”

 

[frater secessus]

Full disclosere:  I am a subscriber to OP's YT channel.  

You guys can delete this thread if you guys do not seem to find it useful. Sorry that so many people here do not like it.

It's not that we don't like it.  It's that that undersupported claims are being made with way too much confidence.  It's an occupational hazard of doing YT monologs but can lead newbies into expensive  and counterproductive rabbitholes. 

BW, who calls their own site "the ultimate" anything?  That's the kind of tone deafness that is causing pushback here.

Bertrand Russell once said: 

“The whole problem with the world is that fools and fanatics are always so certain of themselves, but wiser people so full of doubts.”

It is a reminder to all of us, myself included, that humility and self-awareness expose our own biases and thereby encourages more rigorous thinking.

You are obviously bright and have years of experience.  I hope you stick it out with us.

 

[frater secessus]

Oh gosh why flooded? Why not sealed?

• half the price
• increased resilience to RV [ab]use
• greater energy density and therefore more capacity in a given form factor
• better suited to solar charging rates
• can be charged to higher voltages

AGM are fantastic for their original purpose:  extended periods of float in non-mobile applications without the electrolyte becoming stratified.  That's the opposite of how 'dwellers use their battery banks.

Compelling reasons for vandwellers to pay 2x for AGM:

• need increased charge/discharge throughput but don't want to spring for LiFePO4
• Cannot physically get to batteries to do maintenance
• chemical hypersensitivity
• (with carbon foam AGM)  tolerance to partial state of charge (psoc).

 

[tx2sturgis]

 "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.

Plus, buying a low quality but numerically large inverter at best means low performance and maybe a short service life. At worst, it could mean damaging the connected loads, or even worse, a fire or meltdown. There is a CRAPLOAD of current flowing thru a 2000 watt or 3000 watt cheapo inverter at full load. 

I believe in sizing a quality inverter just above the expected load, and that will help it keep it in it's most efficient range. In our OTR trucks, we had 2200 watt MSW inverters running the microwave and other cooking appliances the driver might want, and a 300 watt pure sine for the laptops, cpaps, etc. 

Trust me, with 4 group 31 truck sized batteries (heavy duty, commercial grade) in parallel and a 220 amp alternator, plus an APU with an additional 120 amps of DC available, we had PLENTY of hotel load power available. 

We STILL had inverter size and type matched to the expected loads.

Plus redundancy is a good thing if one or the other quits and you NEED to charge a laptop or phone and your DC charger just got stepped on....hey, stuff happens.

 

[John61CT]

undersupported claims are being made with way too much confidence.
...
BW, who calls their own site "the ultimate" anything?

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.

 

[Weight]

HEY! I'm not young, but I am still cute.