small off grid solar setup

[bigbrovar]

Hi guys. I have been lurking around this forum for a long time now but this is my first post. Going through past threads has contributed immensely to my solar setup knowledge.

I am trying to setup a small off grid system with a 12v 200AH batteries, 1050VA Interter (With battery charging capabilities), a 30A Epsolar Mppt charge controller.

As to the panels, I have access to 2 240watt 24v poly panels and 1 220w 24v poly panel.

The panel config are:
PMAX = 240w
VMP= 30.5v
Imp= 7.78
VOC=37.7
ICS=8.42

I was initially going for a 24v system until I read here that the VMP at 30 would be inaquate for a 24v setup once heat and wiring loses are subtracted. I come from Nigeria where it can get real hot (31-38c) all year round. So decided to use a 12v system with an Mppt charger.

However my Mppt charge is 30A and has a Max. PV open circuit voltage of 150V and Max. PV input power of 520W.

Question is how best do I use my panels to get the most optimal results from the panel.

My plan initially is to connect 3 panels in parallel .. Or do I connect them in series of 2 as 3 might take it over the Max PV rating of the controller.

Also what is the expected current I could get using whatever setup is recommended.

Also my country Latitude is 10º00´ North of the Equator in this case, which direction is best to point the panel towards? I hear people in northern hemisphere generally direct towards the south. Will same apply to me.

I am a newbie never done a solar project before, however I have tried to do lots of learning and catching up. Due to the shortage of professional solar installers in my country I will be heavily involved in my setup to ensure things are done right (especially with the panel setup side of things)

I would also appreciate advise on the size of breakers both dc and AC I would need between panel and controller, controller and battery, battery and inverters, and Inverters and house, grid to
inverter.

Lastly, I read somewhere that the charge controller (the Epsolar Tracer 3215BN) has the capability to backoff once it detect the battery is being charged from another source (i.e Inverter) is this a general feature of MPPT controllers or just a feature of this particular controller.

Am sorry if my questions are stupid or I should have researched more. I have been on Google and on this portal for most of the past couple of weeks.

Also apologies for my English.

Thanks in advance

Well I lost one of the

EDIT:
Unfortunately I lost one of the panels (The 220W panel) had an accident while transporting to my premise so right now I have 2 240watt panels with following specifications.
PMAX = 240w
VMP= 30.5v
Imp= 7.78
VOC=37.7
ICS=8.42

I have (for now) One 12 volt battery for the setup with the hope of increasing it to 2 in the near future. I had plans of going for a 24 volt system with a larger charge controller but that would go over my finances (which is already over the budget as it is) so I intend to move slowly.

With the 2 240w panels, if I connect them in series I could expect potentially around 40amps from them for my 12v setup. (kindly correct me if am wrong) which would be over the limit of my charge controller which has the following limitations
Rated battery current 30A
Rated load current 20A

does this mean I can not use a setup which would potentially push out 20A?

Also if I connect this panels in parallel what would be my estimated amount of charge current all things considered.

Thanks once again

[bigbrovar]

Most be something I said :/

[Sunking]

Question is how best do I use my panels to get the most optimal results from the panel.

My plan initially is to connect 3 panels in parallel .. Or do I connect them in series of 2 as 3 might take it over the Max PV rating of the controller.

You cannot wire them in parallel unless you run at 12 volt battery. You panels are not high enough to operate on a 24 volt battery if wired in parallel. You can only wire them in series. When wired in series you can run 12 or 24 volts. However if you use 12 volts you can only use 1 of your panels because your controller is not large enough to operate with 700 watts input. At 12 volts you are limited to around 350 watts.

I have no clue what would prevent you from running 24 volt battery. Just wire all the panels in series, problem solved.

[QUOTE=bigbrovar;n298370]Also what is the expected current I could get using whatever setup is recommended. With MPPT OUTPUT CURRENT = PANEL WATTAGE / BATTERY VOLTAGE

Also my country Latitude is 10º00´ North of the Equator in this case, which direction is best to point the panel towards? I hear people in northern hemisphere generally direct towards the south. Will same apply to me.

Straight up

[QUOTE=bigbrovar;n298370]Lastly, I read somewhere that the charge controller (the Epsolar Tracer 3215BN) has the capability to backoff once it detect the battery is being charged from another source (i.e Inverter) is this a general feature of MPPT controllers or just a feature of this particular controller.

Normal operation for anything. The source with the highest energy state will do the work. Think of sloar as a very lazy person. It will not do anything if there is anyone else around to do the work.

[bigbrovar]

I have no clue what would prevent you from running 24 volt battery. Just wire all the panels in series problem solved

I was actually going for a 24v system when I noticed the panel was 24v. I wanted to use it with a offgrid hybrid system which came with an inverter with built in CC. However after reading here that my panel was inadequate to power a 24v system. And in other not to go over my financial limits.. I decided to go with a 12v but with an Mppt controller ( already got the solar panels for free, 1 12v battery instead of 2 and a cheaper inverter) if the panels had been adequate for 24v would not be required to get a CC since the 24v inverter I planned on getting came with one (pwm)
Anyway cost limitation kept me to a 12v system.

I have just 2 panels now meaning I could setup in series and get Max 40amp out of them. Which would give me enough room to take losses from heat and wire connection.

I have learned so so much from you guys just listening to the conversations. Just want to say Thankyou. I already got the Inverter (and off the shelve Indian brand called su-kam plus went for it because it has a temperature sensor which can be handy for a tropical region such as mine) I got SMF batteries from same company .. Was going to get AGM batt but was not sure if the su-kam inverters could charge it without damage (maybe I should of asked ).

The controller is the Epsolar 30A MPPT controller. The BN series. Most reviews says it is a decent affordable controller. Just waiting for it to be delivered.

The panel themselves look grade B to me. I intend on getting a multimeter and test out their out put. I know whatever the case it should be adequate for my 12v setup.

All am looking for now are DC breakers. Which I intend to put between PV and CC, between CC snd Batt and between batt and Inverter. And between Inverter and mains and grid and Inverter.

Would let you guys know how it all went.

[Sunking]

You misinterpreted everything you read. There is no reason you cannot use 24 volts.

[bigbrovar]

You misinterpreted everything you read. There is no reason you cannot use 24 volts.

My choices where use my 24v panels with 30.5v VMP with a 24v hybrid solar inverter with a built in PWM charge controller. From what I read on here.. This won't work.. The panel's VMP is too low to power 24v batteries.. If I connect the panels in series to say 48v the PWM CC won't take advantage. I can't afford new panels. Hence I decided to get a 12v Inverter and an Mppt CC with a 200AH 1 battery. My needs are quite modest as is my pocket.. A couple of 8watt energy efficient light bulbs, led TV , and satellite receiver are all I need.

[Sunking]

Hence I decided to get a 12v Inverter and an Mppt CC with a 200AH 1 battery. My needs are quite modest as is my pocket.. A couple of 8watt energy efficient light bulbs, led TV , and satellite receiver are all I need.

How many times do I have to say there is no reason you cannot operate at 24 volts with a MPPT controller? What part do you not understand? Or what am I missing?

[bigbrovar]

How many times do I have to say there is no reason you cannot operate at 24 volts with a MPPT controller? What part do you not understand? Or what am I missing?

The part where 24v system requires 2 12v batteries connected in series? My setup is a reflection of what I could afford. The money for the extra battery in my initial plan for a 24v setup was what I used in getting a Mppt controller.

You don't want a 24v setup as much as I do. I spent time racking my brain juggling figures to see if I could afford one. Here is my calc

24v hybrid Inverter with inbuilt PWM CC = N45k
2 12v Deep cycle batt = N110k
2 24v Panels got those for free

Second option

Mppt CC =N55k
12v Inverter = N33k
1 12v Deep cycle battery = 55

24v system with MPPT would mean extra cost of Inverter around 45k and extra battery 55k which would blow my budget when u add cabling, roof rack, breakers and fuses.

[Amy@altE]

Not that it matters much now, but those panels are not 24V, they are 20V. 24V panels would have a Vmp of around 36V and the Voc of 44V. You have 60 cell 20V panels. Helps avoid confusion to use the right terms. Either way, you are right that you needed an MPPT charge controller to get them to work well with a 12V system.