How to Wire and what I need for my Off Grid

billa

Hi I am Billa from Tasmania Australia and would like some info I have been on a Pension for 30 years because of a back problem. I have slowly been putting together an Off Grid Solar System, so I have now got 24 x 250 Watts Solar Panels, and also picked up an as new, little use SMA Sunny Island S1 5048 Off Grid Inverter which is 48Volt and produce 240Volt plus 24 x VCI 740 2 volt batteries. Thanks for the help here I have got the batteries sorted. Can you please advise me as to what Controller I need to run my system also how to wire the panels and how many can I run for this system The Panels are ET-P66025250WWW Pmax: 250W Voc: 37.47V Isc: 8.76A Vmpp: 30.34V Impp: 8.24A Max Sys Voltage: DC1000V Thanking you for your help in advance billa

mcgivor

Your approach is unconventional, usually it is best to start with loads but as the items are aquired already you'll have to plan loads around capacity. For starters you will need MPPT charge controllers to work with the panels you have, so that would be a good starting point, once a decision is made then the current capacity, maximum voltage allowable etcetera, will determine the panel string arrangements. Quality charge controllers are the best choice Midnight, Outback, Morningstar, Victron, Schneider are examples, best to get one with local support, most are in the 60-80 amp, 150-200 volt input range, some 600V are useful if the distance from the array to CC is long. At least 2 or 3 will be required, best to research what's available and work with a specific models capabilities, once a choice is made.

billa

Hi and thanks mcgivor Yeah a bit back to front but what I am working on is setting up the best with what I have got and a Controller of coarse I am not relying on this alone I have grid connect as well but my intention is to set it up and run what ever I can off it comfortably and use less grid power

mcgivor

Being in the off grid category I assumed there was no grid, but based on the price of electricity in Tasmania, I can understand why you want to add solar, however using batteries solely  will still cost more than grid. A grid tied system would be the most cost effective, even with the rates you pay, batteries have to be replaced every x amount of years, so the replacement cost is what drives the cost per Kwh higher overall.

Estragon

Does your local utility have a policy on solar and grid connections? These policies can vary widely, ranging from places with very attractive rates at which solar power can be sold into the grid, to others where such connections are banned outright or prohibitively expensive. It would probably be worth finding out before deciding on charge controllers.

billa

With the situation at the moment I have a contract with the power company until 2019 with my grid connect system that I get $0.28 cent a k for return to grid power but if I add as much as 1 more panel to my system then they reduce my price down to $0.05 cents immediately so I am doing an off grid system so as not to upset that.

billa

Ok the batteries are sorted thanks to you and others in this Forum and I am about to order 2 x Outback FM80 (Lexmax80) MPPT Solar Charge Controllers 80Amp So what is the maximum comfortably that I can hook up to 1 of these FM80's and how is the best way to wire it up as I have read a little about using series and parallel or do I use 1 or the other I surely don't know what is better or what is the worse wiring I have now got 24 x 250 Watts Solar Panels, SMA Sunny Island S1 5048 Off Grid Inverter plus 24 x VCI 740 2 volt batteries. The Panels are ET-P66025250WWW Pmax: 250W Voc: 37.47V Isc: 8.76A Vmpp: 30.34V Impp: 8.24A Max Sys Voltage: DC1000V

mcgivor

Here is a link to the Outback string calculator, all you need to do is enter your information following the instructions, attached pdf. this will give the optimal string configuration for the charge controller.

http://www.outbackpower.com/outback-support/string-sizing-tool

Estragon

As Mcgivor says, check the string calculator with your local lowest temps etc. A typical wiring might be strings of three in series and four strings breakered and combined in parallel to each controller, so you'll need to order box(es) and breakers etc once you have the config sorted.