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hardcore asked

Small setup advice please (Smartsolar 75-15)

Hello,

I have been dabbling in solar since 2005 (Back when a 80w panel was nearly £300!) & still not really moved past the basic user level, but keen to save on my electric & improve my setup, despite my limitations.


I am not allowed Solar on my roof, as my home faces a heritage site, so as an alternative i want to create a off grid setup which will be based at the end of my garden. The panel(s) will lie horizontally between my fence & the shed roof, which leans towards towards the fence. I will make a wooden frame to mount the panels for extra support & this will act like a roof between the fence and the shed.

(At the moment i have a 80w panel, mounted directly onto my fence which still gets plenty of sun, although not directly. The panel is now around 10 years old, but still looks great. This connects to my controller (Victron B/S 10-75) & inverter (Sinergex Puresine 1000) All in the shed (Less than 2m cable run) This allows for Mains & 12v lights in the shed)


Anyway I now wish to run an extension lead from the inverter, to the front of the house & power my TV (40" samsung LED (5-10 hrs per day max) & a few other low drain items like 8W LED Rope light & occasionally nintendo switch (10 hrs per week) Which all plug into a Surge protected mains tower outlet in the house.

I have just upgraded to the 15-75 Smartsolar controller (Saw a good deal so i went for it) & now wondering..

- As my panel(s) will be facing upwards, rather than directly towards the sun, would it be beneficial to have an oversized rig to compensate & allow better harvest on cloudy days? Would this potentially damage the controller or can it handle / block off excessive current should it be super sunny?

-If i go for 24V do i need two 12V panels & wire in series to achieve this or can i get a 440W 24V single panel? The panels im seeing for sale are not advertised as either 12 or 24V, so im a bit confused on that tbh & need clarification on how to tell please.

- If im feeding in 24V to my controller, will it be best that i run two 12v batteries in parallel or series to benefit?

-My Sinergex Puresine 1000 inverter is quite old now (Purchased in 2012 for £150 second hand) but a solid old beast & never lets me down. If i just wanted it to be active from say 7am to Midnight, how would this be achieved? Or would i need a more modern inverter that has a built in auto standby feature or remote control..)

-I am considering my options battery wise & likely to opt for either one or two AGM Leisure batteries.

Sorry if it sounds like i haven't done my research.. I have spent time on this but it seems more interesting and fun to hear from you guys now & sadly ive forgotten some of what i read back in 2005 when the only resource i had was a book called "electronics afloat"


Thanks & i appreciate your helpful replies :)



offgrid
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1 Answer
Alexandra avatar image
Alexandra answered ·

@hardcore

Victron have tools now for sizing mppt arrays. It gives a neat graph at the bottom if you enter your general location to give an idea of projected yeilds throughout the year.

What voltage battery bank are you aiming at?

12v x15A give a yeild of 180w

24v x15A will give 360W

You can over panel about 30%. There is a downloadable spreadsheet if you want to tinker with a few panels and ideas.

But rule of thumb is, the 75 is the max VOC of the input of panels (hard limit). And adding more strings to max of short circuit ability of the mppt. The manuals all have a technical section where you can get the information. The voltage whether 12v or 24v is not an issue with an mppt except for the max input voltage.

There is some online training (for free) if you want to brush up or expand your knowlege. Or a youtube chanel with some short videos for basic knowlege.

Battery bank voltage and capacity are based on your energy needs and Depth of Discharge you want to keep. And inverter sized for peak loads.

I have a 360W single panel on my 75/15 for a small 12v system (200AH lithium) with a 800VA pheonix inverter. Does tv all day and a few lights all night. DOD about 50% everynight. So the system produces about 0.9 to 1.1 kWh a day. Never connects to grid.

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