MPPT controller, BMS and inverter recommendations

There are many answers that can be "right". It just depends on many things. But if you have 600watt of panels to charge a 12v battery, that you can expect to get no more than 600/12 amps to the battery (50a). But you would only get 50a when the panels we perfect to the sun, the sky was clear, and the air could keep the panels cool enough. So if you had a 30a charger, it might be at 30 amps (maxed out) a good part of the day. If you have a 40 amp charger, it might be at 40 amps (maxed out) less of the time. It just depends on many solar and panel conditions.

Someday if you get a larger battery you might discover that even at 40 amps the charging takes way too long to make you smile. So you add another charger but that doesn't help much unless you go up to say 1000watt of panels. Then you could get 80 amps, but only part of the time.

For now I am going to go with the theory that two of the 30A controllers should do the trick. One for each panel. If I get really serious about going off-grid, then perhaps I get another panel and another controller and another bank of batteries. I could see just adding the lifepo4 280ah battery to a 2-panel setup with two of the 30A controllers. And a single additional panel running a 30A controller for the two lead-acid batteries.
So at this point I am just going to order two of the 30A controllers and call it a day

Now...still unanswered is about inverters. Any decent brands at a price that won't break the bank? Again, I am aware of Victron, but is there anything else somewhat reliable and efficient for a touch less cash?

Nikg736 said:

For now I am going to go with the theory that two of the 30A controllers should do the trick. One for each panel. If I get really serious about going off-grid, then perhaps I get another panel and another controller and another bank of batteries. I could see just adding the lifepo4 280ah battery to a 2-panel setup with two of the 30A controllers. And a single additional panel running a 30A controller for the two lead-acid batteries.
So at this point I am just going to order two of the 30A controllers and call it a day

Now...still unanswered is about inverters. Any decent brands at a price that won't break the bank? Again, I am aware of Victron, but is there anything else somewhat reliable and efficient for a touch less cash?

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I understand Giandel brand inverters are pretty solid. I have purchased 1500w 12v and 1200w 24v recently but I have not really used them yet.

After reading up a bit, it appears GoWise is a decent choice among the "lower level" brands. So I am going to order a 1500w GoWise pure sine off Amazon which seems to have the best price. Giandel also got decent ratings, so I think they are a toss up between the two. The GoWise is a touch cheaper. I don't mind paying a little more if I knew for sure that Giandel was better, but I'm not sure. Will Prowse seems to recommend the GoWise as a cheap option, so I think I will try it.

I am also going to take a chance on the Bestek brand on Amazon for a small 300W model. I am assuming that should be able to run my mini fridge. The mini fridge is the only thing that will constantly be running, anything else (microwave, coffee maker) would not run all that much. So I figure that huge 1500w model is apt to use a lot of idle power for the fridge. Therefore I am going to get the larger one for my occasional large device usage and make the little 300w model basically dedicated to the mini fridge.

Nikg736 said:

After reading up a bit, it appears GoWise is a decent choice among the "lower level" brands. So I am going to order a 1500w GoWise pure sine off Amazon which seems to have the best price. Giandel also got decent ratings, so I think they are a toss up between the two. The GoWise is a touch cheaper. I don't mind paying a little more if I knew for sure that Giandel was better, but I'm not sure. Will Prowse seems to recommend the GoWise as a cheap option, so I think I will try it.

I am also going to take a chance on the Bestek brand on Amazon for a small 300W model. I am assuming that should be able to run my mini fridge. The mini fridge is the only thing that will constantly be running, anything else (microwave, coffee maker) would not run all that much. So I figure that huge 1500w model is apt to use a lot of idle power for the fridge. Therefore I am going to get the larger one for my occasional large device usage and make the little 300w model basically dedicated to the mini fridge.

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I agree that small inverter for small loads is a good option. I had LED lights flickering on a 3000w pure sine wave inverter (until it was loaded to about 1200w) but the lights were fine in a $35 modified sine wave 500w inverter.

Yeah, I figured a dedicated little one for the fridge would be good because that is really the only thing that would be on just about all the time. Ironically, the higher wattage, more expensive unit is the one that will likely barely be used.
As for LEDs, I am probably just going to run those suckers right off the 12v from the batteries. No sense in converting DC 12v to AC and then converting the AC back to DC 12v. I have some 12v LED strips already, but I understand if you already have LEDs set up for AC

I went ahead and ordered the inverters.
So, now I have panels, inverters, batteries and solar charge controllers.
I also went ahead and bought some MC4 connectors, 10ga wire and 4ga wire.
From what I read and saw in numerous charts, the 10ga wire is plenty adequate to run from the panels to the controller. I am going to connect the batteries together in parallel with solid copper bus bars. I got 4ga to run from the batteries to the inverters. The inverters I got come with cables, but I was not sure of the size of cable and figured 4ga should be good especially for the larger one. Batteries to inverters length of wire will only be 2-4 feet at the most.

My final remaining question is what kind of fuses or breakers should I get and where to put them.
In my simple system we have wire runs of panel(s) to controller, controller to batteries, and batteries to inverter(s).
I am under the impression that a fuse, breaker or switch should be somewhere in between the panel(s) and the controller. Should I put breakers or fuses elsewhere? And if yes then what type or size? Forgive me...I know I just saw a thread with this the other night but now I can't seem to find it.

Any help on my previous post? I have been reading up a bunch in the forums and still confused, but I think I have the general idea.

Panel(s) to controller(s) - need a fuse or breaker, probably around the 15-20A range? If I run two panels then they will be in series, maximum amps from the panels are about 9A. Wiring is 10ga, so I figure even a 20A fuse/breaker is not out of the question. This fuse or breaker is typically more for being able to cut the power than protection, but does offer both.

Controller(s) to batteries - need a fuse or breaker, probably around 30-40A? I have two 30A MPPT controllers, so if using just one in the system then use a 30 - 40A fuse? And if two then a 60-80A? This fuse/breaker appears to be for protection, but I am not sure really what it is protecting? The controller? Guarding against fire if massive current from batteries tries to flow backward and overheats the wires?

Batteries to inverters- I am not sure about this, but assuming something needed. For the 1500w inverter I got it says input is 141A at 12.5Vdc. Does that mean I need a fuse in that range of 140A? This fuse/breaker again seems to be mostly for protection and not a switch.

After reading that cheap breakers can be unreliable and let much more current than they are rated for pass through them, I am leaning towards having all fuses. Maybe for the panel-to-controller line I would put a decent quality breaker or a combination of a fuse and a heavy-duty switch because as far as I can tell that is the only part of the circuit that anybody would want to turn off. The others are there for protection against fire.

Assuming I will use fuses, what kind should I get? Can I get away with just regular blade fuses for the 15-30A ones? And if I need a massive 100-150A fuse for batteries to inverter, then what kind should I get there? I went to Littelfuse's website and there are literally a zillion different types of fuses and I didnt bother trying to research it further.

Thanks

Keep to a 12v system, this is more practical until you get to use inverters over 2000 watts.

The fuses or breakers are to protect the cables (and what ever is on the end of the cables) from over current flowing from the battery in the event of a fault somewhere along the cable or in whatever is connected. The over current will start a fire.

Thus the fuses must be as close as practical to the battery positive

Nikg736 said:

Panel(s) to controller(s)

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will never fail, so the only use with one string of panels to to isolate the panels from the controller for commissioning or maintenance.

Nikg736 said:

Controller(s) to batteries

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At the battery end of the cables, a 40 amp in each positive feed to the 30A controller.

Nikg736 said:

Batteries to inverters

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A fuse for each inverter. Fuse at 130% , or near to, the expected current. So for the 1500 inverter use a 175 or 200 amp fuse.

Any fuse over 30 amps should be a link fuse ( Midi or Mega fuse) in a suitable fuse holder with crimped ring terminals on the cable.

A neat solution is to use a power distribution fuse unit,


Install this as near as practical to the battery positive.

If a longer cable is needed between this and the battery add a 'master' fuse at the battery,

select cables,

Mike

Excellent information. Very clear. One quick question...the low-amp from panels to controller is it OK to just use a regular automotive blade fuse? I am thinking yes because such a small current, but just wanted to check

Nikg736 said:

panels to controller is it OK to just use a regular automotive blade fuse?

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If fitting a fuse gives you confidence, yes in suitable holder. With just two panels in series, (or parallel) the panels can never produce a higher than the rated current so the fuse will never fail unless you get a lightening strike. However useful for a simple panel disconnect, use a 15a fuse if the panels are in series.

Mike

OK, thanks. Yes, this fuse from panels to controllers would essentially be used as a disconnect.

The reason I was asking is because it seems that blade fuses are not really recommended for higher amps, but 15-20 should be OK.
For instance, the ones listed below are 40A regular blade fuses. I'm not questioning the recommendation to use Midi or Mega link fuses for the lines from the controllers to the batteries, but I guess I just don't know enough about the different types of fuses to know why a regular blade fuse would not be used. Obviously the link fuses look more robust, but 40A is 40A right? I'm thinking it either has something to do with the quickness of how the fuse blows or maybe that folks don't want to take a chance on 40A blade fuses because the male ends of the fuse (and female ends of the holder for that matter) are not all that substantial and the connection is not nearly as good as a link fuse.

Maybe go to Amazon and search for "mc4 inline fuse"

So to answer your ques

Nikg736 said:

I am putting together a basic system for a Sprinter van conversion. I recently obtained two used 305w solar panels and two like-new 100ah deep cycle lead batteries.
For now, I am looking to use both batteries and probably one panel mounted to the top of the van, but want the option of adding the second panel either permanent on the roof at some point or just carry it along and plug into the system when parked. So, things would have to work off one or two panels. Also, I intend on upgrading to lifepo4 in the future and I will build my own batteries from cells. However, I have a trip planned soon and would not be able to get the cells, and build the battery in time, so I got the gently used deep cycle marine/RV wet lead batteries as a temporary solution. I will be running a regular 110v mini fridge, and maybe a microwave or coffee maker for 10-15 minutes a day. Not too heavy a load.

From what I have read, I should get an MPPT controller and a pure sine wave inverter. I have no clue about what kind of BMS to get. However, these components would need to be able to run off one or two solar panels, handle wet lead acid (200ah total) or lifepo4 (intend on doing 280ah), and be able to run some basic 110v appliances.

What brand and size of controller should I get? I am looking for reliable but not necessarily top of the line. I know Victron is very good but also expensive. I am under the impression that EPEVER is a decent brand maybe? Any thoughts on other brands? Renogy?

Same questions on brand and size for BMS and inverter. I am thinking 1000-1500w inverter should do it. I am clueless on the BMS to use.

Thanks
Nik

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tions..well some of them, I run 2 Epever at 40 amps each and at first was running just 1 with a 1000 watts solar so it was over paneled for just a bit each day BUT had more amps going to batteries most of day..it hit the 40 amps by 10 am every day now I have 500 watts in each controller so I am only getting 30 max or 60 for both which is 20 more for a few hours a day and more amps quicker in am and late pm..they run my LBF batteries better then my other 2 controllers that are not MPPT...I've been extremely happy with my Epever as recommended by a guy that designs and installs high end stuff mostly Victorn but it is much higher priced...Lithium is great BUT I am on my 7th year of leads for a total of 1100 amps..550 usable for a total cost of $650..got given 4 and bought 6 trojan T-105 new KEY is keep them watered! Hope that helps some!