Help, Building my 1380W PV solar in Guatemala.!!

alexis1988

Ok, these are the systems that i want to buy. The panels is from Longi Solar, 24v. Rated, PMAX 345w. each. Im planning to buy 4. Voltage at Pmax (Vmp)37.35v. Imp. 9.237 Voc 45.74V. Maximum System Voltage 1000v, These are the specification of each module. so the problem is, should i wire them in Parallel or Series? And The Controller that i would like to buy is, Victron SmartSolar MPPT 150/85Tr. And on their website, stated, "Up to 1200 watts at 12 volts, 2400 watts at 24 volts, 4900 watts at 48 volts" And the Inverter, is  AIMS 2000 Watt Pure Sine Power Inverter 12 VDC. The Reason i will be using this, it's because of my budget, and I will only be able to get a 300ah battery bank wired to 12v. So i thought will run the Inverter, I will not be using it with heavy load continiously. Except that i want to run a Mini Fridge, and a 60' 4k TV. probably Samsung (maybe 4 to 5 hours each day, so I'm not sure which model yet or how many watts each electronics will be using, and I will be running probably 6 led light bulb, and maybe a 100w audio system, (4 hours or less) about 10w each. Do you think that's too much or so little? and will this system work with the mppt or and the battery bank or 3 battery of 105ah each. wired to parallel.

Ps. All I want is to have enought power, to use those electronics, and not staying without power. even on some rainy days. any recomendation? THank you!

mcgivor

The panels listed are 24V nominal panels, using them with a MPPT controller is often difficult because the voltage limits series arrangements, this would not be an issue with a 12V nominal system, but this leads to the next point, which is regards to the use of 12V. Using 24V nominal would be far better to reduce current allowing more array wattage the controller can manage and and reduce ballance of system costs.

However before buying anything an accurate load calculation should be conducted, this will determine what battery capacity is required, which in turn determine the PV required to change them. A quick glance at the list of loads and corresponding battery capacity, my guess is that it would be insufficient to support them, start with loads then build accordingly, don't put the cart in front of the horse, so to speak.

mike95490

On a rainy day, expect 10% of your normal harvest.  so your STC 1380 watts will be less than 138w

Your 2kw inverter is a problem, it's internal self-consumption is likely to be fairly high, better check the specs before you buy it.

westbranch

You are asking a lot of a 12V system, as others mentioned 24V is the superior option... You also need to tell us what is the most important item(s) in your list. I suspect it will be the fridge.... most fridges will run on at least 1.5 to 2.0 kWh per day...  the sad truth is that mini fridges us as much or more than a full size on... barring the Inverter models,  and I have read there are small models of these which are available in Mexico and south...

alexis1988

Yes, I was not sure what to do, but since then i was searching for the System., and Now I calculated the loads, which is 1900watts hours. And now, how many Amp Hours the battery should have to be able to satisfy this load? and what about solar panels? right now ima start over so i want to make sure i get the right battery size and modules. Thanks you! I only want to use 35% of the battery....thank u!

alexis1988

mcgivor said:

The panels listed are 24V nominal panels, using them with a MPPT controller is often difficult because the voltage limits series arrangements, this would not be an issue with a 12V nominal system, but this leads to the next point, which is regards to the use of 12V. Using 24V nominal would be far better to reduce current allowing more array wattage the controller can manage and and reduce balance of system costs.

You're right, The reasons of why i wanted to get those panels because of watts, which was 345, and i didn't look at the voltage, the guy that was going to sell  is only $190 each panels. but not anymore, ima stick with Renogy, 100W Mono...panels. so i already calculated the load, which is a 150w tv, and so on. in total. is 1850 Watt Hrs/day 420 Total Connected Watts. so how many battery bank should i have? I'm planning to go with 200ah battery, from Renogy, and How many of those should i need? to be able to use 1850w hours/day, and  is 200ah enough? without going under 50% or should i add another one? and how many panels should i need to charge 200ah in 6 hours or 5?

mike95490

for Rounding in solar, loads round up, charging rounds down.

I calculated the loads, which is 1900watts hours

So a 2kwh daily load (this per day right ?) would need about 5x that in storage, to allow for shallow daily discharge, and a cloudy day or two before you have to start the generator.  you need 10kwh of battery    That would be about 4, L-16 batteries or 8, golf cart batteries, built into a 24v bank..

You can make the bank smaller, with deeper cycles and replace it more often.  In that case, I'd go with 4 golf cart batteries in series for 24v

alexis1988

mike95490 said:

for Rounding in solar, loads round up, charging rounds down.

I calculated the loads, which is 1900watts hours

So a 2kwh daily load (this per day right ?) would need about 5x that in storage, to allow for shallow daily discharge, and a cloudy day or two before you have to start the generator.  you need 10kwh of battery    That would be about 4, L-16 batteries or 8, golf cart batteries, built into a 24v bank..

You can make the bank smaller, with deeper cycles and replace it more often.  In that case, I'd go with 4 golf cart batteries in series for 24v

Is There Any recomendation where to get those battery? how many ah will the 4 golf cart, produce? and how  many 100wats pannel should i need? do you think 800w enough to charge those batteries, panels wired in series?  just like the image below, 800w.

alexis1988

in my understanding, 1850 w, devided by 24v bank  is 77amps, of consumption daily, and now, to be able to charge those battery, as im trying to get 800 watts panel, -25% which is 600w which really will be producing, and 600/24 which is 25ah, x 6hours daily sun, 150ah right? so which means it will charge the amount of power that i will use on a 4 200ah conected in series, 2 wired in series to get 24, and another two, and then wired to parallel? am i doing it right? or should i add more panels? basically the 1850w, i know that when is cloudy, i will be reduce the amount of power i will consume oviously right? and do u think i should add more panels? 

mike95490

GC2 batteries (golf cart battery) are generally 6v, 190ah

4 in series to get 24V gives you 190ah which would experience a daily nearly 50% discharge, with less than 2 years expected life.

You would like to have at least 20A of charge current, which at 27V, & MPPT controller, 540watts harvested, which would roughly require a 700w well aimed array.  1Kw of PV would buy you margin in partly cloudy days.

MrM1

@alexis1988

Might i suggest a solar system calculator or 2.  This is a simple one for load calcs

https://www.altestore.com/store/calculators/load_calculator/

And this one for system calcs.  I used both, but this last one really helped me a lot in system design,  that and a lot of reading.

https://www.altestore.com/store/calculators/off_grid_calculator/