Going solar

[turf]

Nice score JB!!

ya, i answered some ads on craiglist for some solar like that... i had to meet the guy at a certain time and place... it just sketched me out... and i like the bigger wattage avail at the new place.

dessert... i misunderstood... parallel. ok ... that makes sense. i was thinkking series @`150 volts


so im looking at a 150v 60a charger?

in parallel, i'd be around 55v max input and the total of my panels plus safety buffer is 52A@28.8v

[desrtdog]

Panels in series => voltage is additive; parallel => current is additive

So yeah, I think the 150/60 charger would work, but check the VictronConnect site to ensure it can handle the total watts of your array. I have a 100/50 controller which is good for up to 700w but have a total of 800w on the roof…

[jayb]

My panels are 24v. I have 4 in banks of 2 @ 48v. Sometimes the voltage goes up as high as the mid 70's. My controllers are Victron 100/30 which means that if it gets to 100v it will disconnect or if it is over 30 amps will limit to 30 amps. so I have 2 banks with 2 chargers. (actually 3 chargers as I have a 48v charger connected to a third victron 100/30)

[Iceni John]

Originally Posted by nikitis

The only exception to this rule is if you are separating the banks So if one side is a bank and the other side of your bus is another bank, then one bank won't affect the other, but in that scenario you still have one bank that's more absorbant than the other and you suffer a little loss compared to those who have the whole bank at the same exact angle.

Why not have two entirely separate battery banks, each with its own charge controller, and if each bank's output feeds through a Schottky diode it will still be electrically isolated from its neighbour. This is essentially what I have, with each array of panels having its own MPPT charge controller that charges its own bank of batteries. In aircraft-speak this is called "redundancy"! If one bank or CC ever goes tits-up, I'll still have at least 50% of my power available.

John

[Tejon7]

Originally Posted by jayb

My panels are 24v. I have 4 in banks of 2 @ 48v. Sometimes the voltage goes up as high as the mid 70's. My controllers are Victron 100/30 which means that if it gets to 100v it will disconnect or if it is over 30 amps will limit to 30 amps. so I have 2 banks with 2 chargers. (actually 3 chargers as I have a 48v charger connected to a third victron 100/30)

You probably know this and I'm going to sound like a know-it-all nerd, but I'll say it anyway in case it keeps someone from turning their Victron MPPT into a pretty blue paper weight:

The first number (100 in your case) is maximum open circuit voltage and exceeding it will permanently damage your charge controller. "24 volt" solar panels often have an open circuit voltage of around 45v according to the Internet. Your 2s2p panel configuration should theoretically never go above 90v, so no worries. Future solar installers - read your equipment manuals and know your exact panel specs before installing.

Edit: actually @jayb, you might want to check your panel specs using the Victron charge controller calculator. Depending where you travel and what temps you see, you might still fry your controller. I put in some assumed and dummy figures and found that the cutoff for a setup like yours is just a bit below freezing. And that 100v is a hard limit by all accounts.
100v =
101v =

[nikitis]

Originally Posted by Iceni John

Why not have two entirely separate battery banks, each with its own charge controller, and if each bank's output feeds through a Schottky diode it will still be electrically isolated from its neighbour. This is essentially what I have, with each array of panels having its own MPPT charge controller that charges its own bank of batteries. In aircraft-speak this is called "redundancy"! If one bank or CC ever goes tits-up, I'll still have at least 50% of my power available.

John

Costs. I don't wanna buy two charge controllers. But you can certainly do it that way.

[nikitis]

Originally Posted by Tejon7

You probably know this and I'm going to sound like a know-it-all nerd, but I'll say it anyway in case it keeps someone from turning their Victron MPPT into a pretty blue paper weight:

The first number (100 in your case) is maximum open circuit voltage and exceeding it will permanently damage your charge controller. "24 volt" solar panels often have an open circuit voltage of around 45v according to the Internet. Your 2s2p panel configuration should theoretically never go above 90v, so no worries. Future solar installers - read your equipment manuals and know your exact panel specs before installing.

Edit: actually @jayb, you might want to check your panel specs using the Victron charge controller calculator. Depending where you travel and what temps you see, you might still fry your controller. I put in some assumed and dummy figures and found that the cutoff for a setup like yours is just a bit below freezing. And that 100v is a hard limit by all accounts.
100v =
101v =

My max solar voltage is rated at 145v on my chinese no name branded one, 60 Amp limited. So it's designed for higher voltage panels to reach a lower amperage.

[Tejon7]

Originally Posted by nikitis

My max solar voltage is rated at 145v on my chinese no name branded one, 60 Amp limited. So it's designed for higher voltage panels to reach a lower amperage.

Sorry if I muddled up this thread... I was responding to jayb's comment ("...if it gets to 100v it will disconnect...") and what I said is only true for Victron charge controllers and their naming scheme. I've heard of several people who assumed the first number is a soft limit and have bricked their expensive kit.

[nikitis]

Originally Posted by Tejon7

Sorry if I muddled up this thread... I was responding to jayb's comment ("...if it gets to 100v it will disconnect...") and what I said is only true for Victron charge controllers and their naming scheme. I've heard of several people who assumed the first number is a soft limit and have bricked their expensive kit.

No problem, thanks. The warning is welcome and good to note. I hadn't even considered that myself. I was only looking at not going over the max amperage, not voltage.

And calculating mine if I run all 6 as one bank 33v operating, would make it 60Amps exactly on my 320 watt panels. She's gonna charge real quick and will max out the charge controller.

[turf]

thanks Tejon!

i was curious about the 100v limit and when it was mentioned that it just cuts you off. well i stopped worrying..... i dont want to damage anything.

last night after purchasing al these bit for solar, i decided it was time to put pen to paper and make a plan.

well i didnt get to far cause im dumb.

the switch to 24 volts is hurting my brain. so the dilemma i found quickly is ..... i was planning this electric conversion over time. ive had battery for a while, now i want to charge with solar, and the next step is inverting the whole bus.

i have a 12v 1000 watt inverter i use now, for my tv, computer. so i wasnt planning on buying another inverter to hardxwire yet. the little one is fine for its use.
hardwiring an inverter will let me use it for AC. right now, i cant,
AC is only on gen.

the rub is my old inverter is 12v. the next invert will be 24.

so this charge controller.... sizing it for 24v is wrong for my 12v need.

im going to need to sit down, and figure what my output is in both situations and go from there....

confused

[nikitis]

Originally Posted by turf

thanks Tejon!

i was curious about the 100v limit and when it was mentioned that it just cuts you off. well i stopped worrying..... i dont want to damage anything.

last night after purchasing al these bit for solar, i decided it was time to put pen to paper and make a plan.

well i didnt get to far cause im dumb.

the switch to 24 volts is hurting my brain. so the dilemma i found quickly is ..... i was planning this electric conversion over time. ive had battery for a while, now i want to charge with solar, and the next step is inverting the whole bus.

i have a 12v 1000 watt inverter i use now, for my tv, computer. so i wasnt planning on buying another inverter to hardxwire yet. the little one is fine for its use.
hardwiring an inverter will let me use it for AC. right now, i cant,
AC is only on gen.

the rub is my old inverter is 12v. the next invert will be 24.

so this charge controller.... sizing it for 24v is wrong for my 12v need.

im going to need to sit down, and figure what my output is in both situations and go from there....

confused

Correct, if your inverter is 12v, you'll need a new 24v inverter, and you'll want to arrange the batteries in a 24v configuration as well.

Also remember it's much easier to step down than step up in Voltage for the DC Side of things. Going to an AC inverter it's not safe to step down, so by going 24v, you'll be able to charge faster than with 12v, but not with the inverter. A step down transformer is used for all 12v DC devices like lighting etc.

Everything from Solar Panels to your inverter input is DC, but the inverter converts to 120v AC, which then you connect the inverter to a breaker box like in your house, and then wire AC outlets to, to run your microwaves, laptops etc.

USB outlets use DC, and typically only 5v DC. The reason it's difficult for most wall outlets in a home to have USB ports is because they have to have a mini inverter built into the outlet, or you run separate DC lines as well as AC lines to the same outlet, and the DC needs to only carry 5v which is a step down from 12v DC, or 24v DC in your case.

Every transition from DC stepping down requires a step down transformer. And for each transformer you want to connect the transformer to it's own individual Bus Bar, and network of devices in that voltage class. So by going 24v, you're going to have 4 networks. 24v network for 24v devices. 12v network, 5v network, 120v AC network.

So you have:
Solar Panels in 24v configuration
|_PV Combiner / Charge Controller (sometimes one in the same, not always)
---|_Batteries (in 24v configuration)
-------|_24v Inverter
----------|_House Circuit Breaker panel (120v AC)
-------------|_Wall outlets throughout bus for home appliances
-------|_24v DC Bus Bar with fuses
----------|_24v devices/outlets (Maybe a 24v fridge.)
---|_Step down Transformer (24v to 12v)
-------|_12v DC Bus Bar with fuses
----------|_12v devices (Ceiling lights, fridges, etc)
---|_Step down Transformer (24v to 5v)
-------|_5v Bus bar
----------|_ Wires to 5v USB outlets throughout bus

[turf]

hmmmmm

yes.

those issues.

more too

the 12v wiring vs the 24, and the charge controllers specs were different in both circumstance.
so if i stick with my original 24v battery... what device do hook up my 12v invert to?

the only thing hooked up to the battery is the charge controller and the future 24v inverter. what bit will give me 12v for my inverter and what bit will feed 12v to all my existing 12v - fridge, lights, heater, starlink.....???


my battery bank is 2 - 280AH lifepo12v batteries. 560AH total

[nikitis]

Originally Posted by turf

hmmmmm

yes.

those issues.

more too

the 12v wiring vs the 24, and the charge controllers specs were different in both circumstance.
so if i stick with my original 24v battery... what device do hook up my 12v invert to?

the only thing hooked up to the battery is the charge controller and the future 24v inverter. what bit will give me 12v for my inverter and what bit will feed 12v to all my existing 12v - fridge, lights, heater, starlink.....???


my battery bank is 2 - 280AH lifepo12v batteries. 560AH total

You don't, you sell your 12v inverter or save it for another project.

The 24v inverter will plug into your 120VAC breaker for all home appliances. the 12v inverter would be redundant. The inverter is only for AC Device network. i.e. home fridges, microwaves, laptops, tv's. the 24v inverter will handle this, and handle it better than your 12v inverter would. You'd have less loss in electricity in the conversion.

If you want to use your 12v Fridge, that's a DC fridge, not an AC Fridge. A regular fridge you'd use in your home is an AC Fridge and you'd plug it into a home wall outlet which is connected to your 24v inverter ultimately.

Your DC 12v fridge will plug into your 12v Bus bar, and the 12v Bus bar is connected to the 24v to 12v step down transformer.

[nikitis]

Here's a graphic of your layout in your bus.

I didn't include fuses and fuse locations, but everything else is there.

This may be how you want to layout your bus.

You could double the MPPT Charge controllers if you have a ton of wattage from solar panels and need to. Then split your battery bank which makes it a tad more complex but this is the simple version assuming your single charge controller can handle your solar array.

[turf]

yeah... i have a finished working setup now.

change is tough

so let me tell you what house loads i have.

12v - fridge, heater, lights, water pump. 120 inverter

120v - computer, tv, phone charger, 12v converter, 2x rooftop AC,

240v - electric range, electric heat

i have 50A shore hook up and a 12K diesel generator to run everything boondocking.

the gen is loud and the more i can do on battery is best, so im trying to reduce the gen time to just cooking with the range. theoretcily i may try the range if i do twin inverters.

so i have the battery now. im spending a bit on solar to keep it charged. the when i financially recover from this ... will go in to twin inverters.
or that was the plan... but 24v conversion confuses me.

doing it for 12v now and redoing in a year for 24v.....um no

[turf]

here is a rough diagram of how im hooked up now.

i see that when i get a new inverter the problem of the old boondocking 120v disappears but the lack of 12v to run all the existing gear is still missing.

[nikitis]

If you don't already have solar, and want to tie into your existing system as you've drawn out you could do this. Just leave everything already in place as is and that will be your 12v network.

You'd just need an extra panel space for the new Victron CC, and new battery space, and new 24v inverter space, and you can keep your 12v inverter. This only works this way because you're using a battery charger from the electric panel to maintain your 12v Battery System.

If you can chock the space for the above you could do it.


Now if you want to use your current 12v batteries in the 24v system, you'll need to rip out the battery charger, and instead connect your 12v system via a 24v-12v Step transformer, which hooks into a 12v bus bar, and from the bus bar hook up all of your 12v items. This frees up space cause you don't need the 12v inverter anymore, and batter charger anymore, but requires more re-wiring.

Choices. You have to make one.

[turf]

i made the trek to Denver today and got my solar parts. i have 95% of what i need to get the stuff up on the roof. the warehouse was short the angle brackets that attach the roof to the rail. so... except for starting... i have everything panel wise.

i agree with your pic nikitis.

after pondering the diagram for a day.....
i believe my 12v charger will suffice as a 12v converter.

i think i'll just go ahead and bite the bullet and get the 24v inverter now and simplify my choice.
a 12v temp work around is the wrong thing todo.

[NovaTRON]

Originally Posted by nikitis

This is why most of us fabricate our rail system.

3 large panels at most will give you 960 watts with today's technology. They are about 320 watts per panel for the most expensive ones. And they need to be mono crystalline, which is one silicate pour per square. Poly crystalline will be crumbled pieces of silicone pressed into one square and they aren't as good at absorbing the sun.

600+ watt panels are becoming standard now, heck, the ones i bought 4 years ago are 400watt bi-facials and they were very affordable @ under $200 each. So let me rewrite that - "3 large panels can give you 2000+ watts with today's technology."

SOURCE: https://www.solarfeeds.com/product-watt/650/

670 watt panels >>https://www.pv-magazine.com/2021/03/...w-solar-panel/

[nikitis]

Originally Posted by NovaTRON

600+ watt panels are becoming standard now, heck, the ones i bought 4 years ago are 400watt bi-facials and they were very affordable @ under $200 each. So let me rewrite that - "3 large panels can give you 2000+ watts with today's technology."

SOURCE: https://www.solarfeeds.com/product-watt/650/

670 watt panels >>https://www.pv-magazine.com/2021/03/...w-solar-panel/

Bifacial ones you aren't gonna get nearly that many watts though on a Bus application. Maybe in a lab setting with a mirrored back. I may be a little behind on what's available but realistically I've looked into bifacial and it's difficult to get light bouncing under your panels unless you have a reflective setup behind the panels that can redirect side light to the back of the panels. And they do help with coverup.

You can realistically get 420 though, 320 was best when I purchased mine 6 years ago.