Quote from: Trillium on September 28, 2014, 01:43:45 AM

You need to consider that for most battery types you cannot take the Ah rating and assume you can use 100% of this, because, cycling most kinds of batteries that deeply will permanently damage them. Be sure to carefully review the manufacturers tech sheet and find the max discharge depth, THEN calculate the "real" Ah rating from there. You can use this to calculate watt-hours or joules stored, which is a more meaningful piece of information for sizing your solar setup.

Also the 6 hour charging time above is unrealistic for a full charge for most battery types. Again you need to see the manufacturers spec sheets.

Cycling batteries between deep discharge states and back to their full capacity on a daily basis will also reduce their lifespan a lot more than usual as this is not considered standard operation. Arbitrary example: Most lead acid car batteries are discharged only less than 3% of their total capacity when starting a car, this will get them 3-5 years. Now take the same battery and discharge it 25-50% every 24 hours (if it's even possible to recharge it within spec limits that quick). Suddenly it lasts 6 months to 12 months tops.

A lot of people "make" battery storage systems for solar without researching how much they can drain their batteries, and how low of a voltage they can be taken. There are newer types which can take more punishment but there are always limits. I know a handful of people who've purchased various setups on ebay and of their own design only to wipe out $5k of batteries in half a year.

Your points are very mush valid.
In my system I finally dropped using battery backups for the rest of the sun time and is using grid.
Battery back up will just act when in an emergency.

Normally in professionally installed battery systems they will only discharge upto 20% of the capacity.
So, the battery bank(s) will last for 10+ years even if they are not looking for breakeven.
They get ROI from their business by account these costs to customers.

Regarding Charging Time, atleast 10hrs is recommended for C10 batteries but we only get 6hrs.
So we are forced to charge in 2 days or in a single days with more current. The second one will shorten the battery more.

Here in the case of home miner or even home farms, the Solar + 24hrs Battery will never ROI.
But a Solar + Grid can breakeven in the long run, if and only if we can use the maximum power the panels generate.
Again, no mining device is available at this point in time to mine for ROI.

Inshort, just forget about "any" Solar setup for atleast this time.