Where can I buy Panasonic HIT N250 Slim solar panels here in the U.S.?

MTVR

Well-known member
The HIT panels are supposed to be more efficient and run cooler- I learned that here. ;)

The N250 panel dimensions would allow us to put 2,000 watts (8 of them) on the roof, and still leave room for a skylight roof vent fan thing.

But I can't find them here in the U.S....
 

shade

Well-known member

They carry a good selection of high efficiency panels, along some of the other components you'll need. If you arrange for local pickup, you can take in the views just north of Flagstaff, too.
 

MTVR

Well-known member
So is my math right on these?

If I parallel eight of these panels, I've got a max of about 2,000 watts possible.

If I divide 2,000 watts by 48 volts, I get 42 amps of current.

So a single 50-amp MPPT solar charge controller would work for this?
 

Rando

Explorer
Just add up the short circuit currents 8 x 6.03 = 48.2A. So yes a 50A MPPT would work with 8 of these.

Edit to add - this also depends on your system voltage, which I assume is 48V based on your post above? The MPPT spec sheet should provide both a maximum Isc for the panel input and a maximum I output to the battery. They are often the same, but not always. I think most Victron's you can 'over panel' by a 20 - 30%.
 
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dreadlocks

Well-known member
they are 60v as far as your solar charger is concerned, 53v max @ 25C, but that number will go up as those temps go down.. so lets say 60V just so you dont feed your Solar Charger too high voltage.. it needs to be able to take that on the input...

A Solar Charger's Amp output is not calculated on the Solar Input, but the battery output.. Dont matter how much amps you feed it, it will be less than the amps going out because the voltage out is always lower.. so if you output 50A, the input is always less than 50A, dont worry about calculating amps in.. the question is how many amps out do you want? probably alot more than 50A right?

edit:
For example, my Panasonic HIT 325W are 70V Max @ 25C, but Ive seen voltages higher than that in winter.. so I'd buffer that up to at least 80v, at full output my Solar charger normally sees about 5A coming into it from a single panel, but its outputting 25A @ ~13V.. so I got a Victron SmartSolar 100/30, it takes 100v on the input side, and outputs 30A on the output side, I can actually hook up 2 panels in parallel to this charger and its fine, output maxes out at about ~430W combined @ 30A, but I cannot wire my 2 panels in a series because that would exceed the 100v input rating by a long shot and fry my charger, so parallel only unless I got a higher voltage victron.
 
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dreadlocks

Well-known member
this is again where we need to know your house battery voltage and capacity to be nailed down before hammering out the solar charger needs..

400AH @ 12VDC * 0.4C = 160A (1920W) Charge Rate, To Obtain this you could run 4x50A SmartSolars, each with 2 panels at 500W (~40A)
200AH @ 24VDC * 0.4C = 80A (1920W) Charge Rate, To Obtain this you could run 2x50A SmartSolars, each with 4 panels at 1000W (~40A)

This is one of the things you gain on going to 24v, your dumping half the amps in for the same wattage, so you could have half the chargers.
Screen Shot 2020-07-18 at 12.38.29 PM.png

Notice how the "Nominal PV Power" doubles when going from 12v to 24v, the controller supports both voltages but way more panels in 24v.

They do make chargers bigger than that, but prices reflect that.. and since you have stuff mounted on roof that could shade some panels I'd advise against trying to wire all that solar into a singular charge controller, put all the panels likely to be shaded by a roof vent or something on one controller and the rest on the other.. more controllers with less panels would cope with varying shade on roof better than less controllers
 
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MTVR

Well-known member
Okay, I think I got it- MPPT solar charge controllers are rated for the amps out, so the lower my house battery bank voltage, the higher the amps, and thus the more money I would be spending on solar charge controllers.

I'm sketching some other systems out today- right now I'm working on a 24-volt system with an "orphan" 12V AGM battery stashed in a cabinet near the winches, and a small charger to keep it topped up.
 

dreadlocks

Well-known member
you also got a system capable of producing enough power to burn things down and since you cant really turn off the sun on demand you should fuse the hot solar side of the system and make it so you can disconnect them to work on stuff without those wires being hot..

most of us with much smaller systems dont bother, its easy enough to overkill the wiring that even full short at the solar wouldn't cause a fire.. but ours look tiny in comparison to what your building, your at a full house scale so pay attention to safety.
 

MTVR

Well-known member
If I put the "electronic warfare room" outside, I can fuse the solar panel positive side in that outside cabinet, just inches after coming off the roof, before it connects to my solar charge controller inside the cabinet...
 

MTVR

Well-known member
this is again where we need to know your house battery voltage and capacity to be nailed down before hammering out the solar charger needs..

400AH @ 12VDC * 0.4C = 160A (1920W) Charge Rate, To Obtain this you could run 4x50A SmartSolars, each with 2 panels at 500W (~40A)
200AH @ 24VDC * 0.4C = 80A (1920W) Charge Rate, To Obtain this you could run 2x50A SmartSolars, each with 4 panels at 1000W (~40A)

This is one of the things you gain on going to 24v, your dumping half the amps in for the same wattage, so you could have half the chargers.
View attachment 599299

Notice how the "Nominal PV Power" doubles when going from 12v to 24v, the controller supports both voltages but way more panels in 24v.

They do make chargers bigger than that, but prices reflect that.. and since you have stuff mounted on roof that could shade some panels I'd advise against trying to wire all that solar into a singular charge controller, put all the panels likely to be shaded by a roof vent or something on one controller and the rest on the other.. more controllers with less panels would cope with varying shade on roof better than less controllers

I like that.

The only other thing we're gonna have on the roof, is a 14"x14" low-profile roof vent with a reversible multi-speed fan in it. It would be positioned within the footprint of where the "9th" panel would have gone, so in order to shade anything, the vent lid will have to be up AND the vehicle (and the sun) will have to be oriented just right (just wrong?). If it shades one panel and I see the 4th controller go to zero, I'll know that I need to drop the vent lid if I want to regain that power.
 

dreadlocks

Well-known member
it wont drop to zero it'll just bypass that panel, in northern latitudes in the winter months those shadows get bigger than you'd think, especially when its not noon, even if vent is closed it may cast shade if it sticks up at all.. you'd see one controller outputting about 50% or 25% less than the other if one got shaded out but otherwise were in identical conditions.. this is one of the downsides of wiring panels up in parallel, the lower voltage panel will get bypassed entirely due to built in diodes.. wired in a series one just adds voltage to the next so they dont need to match, 4 internal diodes in the panel will keep it from losing all voltage when shaded and the unshaded series of cells can still contribute, depending on how the shade is cast.. still possible to cast shade across all 4 diodes and take the panel out with most of it in the sun.

controller per panel lets each panel contribute the most it can w/out being bypassed simply for not keeping up with its neighbors, this and thats why house systems now often have AC inverters installed on every panel so each one has its own lil controller and converter.. but for a DC system your size and in personal budget, likely way overkill.. probably moot for most part, especially since we convinced you to get a genset for your aircon and we dont needa squeeze every watt we can get outta it.
 
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