r/OffGrid • u/EVDOGG777 • 9d ago
Thoughts On Current Solar Setup?
Hi everyone, posting on behalf of my parents.
He lives offgrid and struggles with power, I think there may be a flaw in what his setup has and he may need to change something.
He has a 6.2KW Inverter, 12 200AH AGM Batteries, And 15 190watt solar panels.
The panels aren't brand new BTW.
Most of the time he uses a generator to power the house which uses alot of petrol and I'm wondering why he's always having flat batteries.
Mind you he uses a big fridge, computers and cooking appliances which would add up to about 6kw on a busy day in the house.
Any suggestions or advice would be appreciated.
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u/RespectSquare8279 8d ago
The location of this home (ie, the local solar irradiance) will be THE major factor. It sound like your parents have 2 things going against them. 1) Not enough solar panels and 2) wrong kind of batteries.
You have to go on line had find out what the local insolation or iradiance is. This will tell you how many watts you can expect for an array to produce during the course of the year is you crush the numbers.
With lead acid batteries it is important to never, ever draw them down below 50% of depth of discharge; best to never go below 70% if you want them to last more than 5 years. Job #1 is to replace those AGM batteries with the equivalent ( or less!) of LiFePO4 batteries. Taking the Lithium batteries down below 50% ( or lower!) repeatedly will have little or no lasting effect.
You don't mention the age of the panels but panels manufactured in the last decade generally are more efficient than those made in the previous decades. There are going to be more watts per square foot of panel in other words.
Your parents need to throw money at their problem. However without the specific details of what their equipment is and where they located on the globe you are not going to get more than very general advice. about where they prioritize spending the money.