Off grid solar array. 1or 2 or 3 arrays

[Rollo]

Hi all first thanks for allowing to join. Have been reading a lot of posts on this forum and thumbs up to how questions have been asked and answered. OK this is my first post and I hope it is in the correct area or field . I am new to solar and have sort of started back wards in building a system. Meaning I bought a box of (50x75w fs-275) this film solar panels about a year half ago from the local mens shed. $250au. Could not pass it up. Now i am starting to buy items to make it work.. But before I do I would like some input into what would work best for the solar array or arrays. Total Max watt is 3750 worth of panels. I have decided to start out with a 24v system. My question is should I make up 3 panel arrays or 2 panel array or one. In live in country western Australia where sunny days for long periods are the norm. My battery bank is to start 8 x 200amp in series to make 24v. I have already bought a 24v pure sine inverter 3500/7000. But am stuck on what to do about mppt controller or controllers. It will depend on array or arrays. What array would be best.

[AzRoute66]

Welcome to the forum,

If you are building an off grid system, and if your mid-day and total power production is well covered I would suggest 'virtual tracking'. This involves pointing one array easterly and one westerly, and can be augmented with some pointed northerly. You won't increase total production, but you will increase the amount of time that you are generating meaningful production. This can be very useful in getting the batteries fully charged.

I'm am guessing that you mean that you have two strings of four 6v batteries for 24V. Not sure if you mean each battery is 200 Ah, or if you mean that the two strings make up the 200 Ah. That will be important to know prior to figuring out if virtual tracking makes sense for you.

You can never go wrong facing them all North at a tilt equal to your latitude. One other consideration would be shade, but since you didn't mention any I presume you don't have enough to mention.

[Rollo]

Each battery is 12v 200ah 10hr . Total of 8 batteries to start put in series to make 24v. . Panels would be in total sun no shade. If I made one array then i would use 2x 60amp mppt controllers and drop what panels to stay under the watts the controllers can handle. Sound OK

[Mike90250]

i wish you had asked us questions before you spent money. you now have a odd matchup of stuff. parallel batteries are not ideal. what is the voltage of the thin film panels?

[Rollo]

Have not set up yet. Batteries are on the way. Panels still in box. Sine wave on the way. Bought yes not set up... Joined here after searching the net for months for advice came across this one.

[Rollo]

Tried to upload label of the panel but will not allow me to. But says. Current at mpp 1.08amp. Open circuit voltage 92v. Does that help. More on there but no idea on what to look for

[sensij]

Each battery is 12v 200ah 10hr . Total of 8 batteries to start put in series to make 24v. . Panels would be in total sun no shade. If I made one array then i would use 2x 60amp mppt controllers and drop what panels to stay under the watts the controllers can handle. Sound OK

This makes no sense. When you put batteries in series by connecting the + terminal of one battery to the - terminal of the next, the voltage sums. For 12 V batteries, 8 in series would give you 96 V.

If you want a 24 V battery, you would put pairs of batteries in series, and then put those 4 pairs in parallel. That would give 800 Ah at 24 V, although it is more conventional to use the capacity at the 20 hr rate. What specific battery did you buy?

It is really important that you understand that if you proceed without improving your electrical knowledge, your system will probably fail and there are serious safety risks.

What size wire are you using between the battery and inverter, and how are you protecting it (circuit breakers, fuses)?

[Rollo]

Sensij was going to put in series to make 24v. As mentioned. I. E 2 banks of 4 batteries. Batteries are been picked up when I pick up other things in Perth next week. Cabling has not been organised as of yet as I have not yet decided where I am going to store them. All leads will be made by a shop. Properly crimped etc. Breakers fuses gauge wire size will be by what is recommended to match . No my knowledge is not that great on electrical engineering but I do have friends that are in the trade and people like yourself with good advice. All I have bought is panels. Sine inverter. Batteries . It will be done correctly.

[littleharbor]

You are going to need a big combiner box with all those high voltage panels. Unless you buy a 1200.00 USD 600 volt controller you will need at least 25 strings if you plan to use all 50 panels. Hope you saved a bunch of money on these panels as you are going to need it for all the cabling, fusing and controllers or combiners to make these panels work.

[Rollo]

Paid $250au ($189us )for all 50 panels. First solar model FS-275 panels

[littleharbor]

You did get a deal.

[Rollo]

You did get a deal.

Yes. Got too grab what you can when it costs not much.