Off grid solar system design

[Diallodjeri]

So all that data does not determine how many watt hours you will consume each day.

Try to remember that going off grid means you are relying totally on your batteries because the sun will not be shining every day. So your battery system will have to provide the entire amount of watt hours you plan on using.

So my question is what loads will you use each day and for how many watt hours. Once you total that amount you will come close to sizing your battery system. Once you have that determined you size your panel wattage.

Thanks a lot,
The house is not going to be 100% off-grid because I will still have access to a grid whenever I need to, but it's just not anything like a grid-connected system in the States. I would just have to unplug my loads from the solar and plug into the grid. The bottom line is that I need to harvest from my system a minimum of 5KW/h. I just need the right information to make that happen. I can always arrange and adjust my consumption accordingly.

[SunEagle]

Thanks a lot,
The house is not going to be 100% off-grid because I will still have access to a grid whenever I need to, but it's just not anything like a grid-connected system in the States. I would just have to unplug my loads from the solar and plug into the grid. The bottom line is that I need to harvest from my system a minimum of 5KW/h. I just need the right information to make that happen. I can always arrange and adjust my consumption accordingly.

Makes sense. I would look into having your bigger loads connected to the grid because they will just greatly increase your battery needs. Try to keep the "off grid" loads as minimal as possible. That will help keep your costs down as you build your solar/battery system.

Based on some recent prices a solar/battery system can cost between $1500 and $2000 for each kWh it can safely deliver each day. So for a 5kWh system you may be looking at a cost of $7500 to $10,000 USD.

[Mike90250]

Get a spreadsheet and put some numbers into it. don't do half the math in your head and half on paper !!

Power estimator load requirements.jpg

[Huru-ukko]

Hi Dialloljeri

I have been using wictron energy products for two summers now. I have 6 x285w panels , 150/70 mppt, 3000/24/70 multiplus. I dont have a possibility of grid. I hve 4 200ah ( c20?) cheap agm batteries . My daily consumpion when the sun is shining is between 1,5-4 kwh with no problems. When cloudy I dont use logging machine cook water etc. Normally the system goes to float at about 11-12 am. So When the aun is shining I can use the energy from the panels and the batteries are not ”used” but the mppt just raises the wattage used and still keeps floating.

So I’d say just go for it put more panels if u can and use the energy when its shining for example cooling the house.

But as said i have only been using the system for second summer now

[Huru-ukko]

And you should be able to connect your grid to your inverter and use it to charge batteries when you get grid electicity, but ask that from your dealer , at least multiplus has generatorsupport built in.

[Huru-ukko]

And totally agree with mike, make calculations properly and add50% extra - you will use it anyway...

[Kalintosh]

Your power consumption is too high for offgrid application. Either you make some changes to your lifestyle or you, simply, spend waaay lots of money on a very huge solar system

[Fisherus]

I'm surprised by your assumptions and comments, when you're here seeking advice on your project. The responses you've been given from these folks, who have been kind enough to help and advise you, have been spot on. My advice to you is to be smart enough to understand and use what you have been told, do some do diligence in research but, don't be argumentative with those who know far more than you. If you are sure of your design ( you must be to be so argumentative about what you were told) what is your reason for asking your questions?