Steve said:
Vs. losing your batteries early because you listened to a poser on the
net who thinks he's a solar consultant because he can weld. Shut up
george, you are embarrasing yourself and damaging the credibility of
real consultants everywhere.
Taken from alt.solar.photovoltaic. Same question - 50% vs 70% DOD.
Well steve, does this look familiar:
1. Enter your daily amp-hour requirement. (From the Load Sizing
Worksheet, line 10)
2. Enter the maximum number of consecutive cloudy weather days expected
in your area, or the number of days of autonomy you would like your
system to support.
3. Multiply the amp-hour requirement by the number of days. This is the
amount of amp-hours your system will need to store.
4. Enter the depth of discharge for the battery you have chosen. This
provides a safety factor so that you can avoid over-draining your
battery bank (Example: If the discharge limit is 20%, use 0.2) This
number should not exceed 0.8
Yes, it's straight off your web site. Interesting thing is that 0.8 is
an eighty percent DOD.
How do you explain this?
Misinformation is the hall mark of many people in these groups.
Do you use 50% of your battery capacity every day?
Do you propose that other people should use 50% of their batty capacity
every day?
Are you really so willing to spread any misinformation in your quest to
prove me wrong?
This following is the full quote from my post. Steve felt that it would
not serve his purpose to use the full quote. Again. Despite the fact
that he is quite happy to advise that a DOD of up to 80% is acceptable
on his site
Tim this is a complete and utter fabrication. You can use as much as 80%
max DOD. I prefer 70% myself. What it comes down to is how often you
discharge your batteries to this level and how long they stay in the low
state of discharge.
During normal operating conditions your daily DOD should be in line with
your chosen days of autonomy and your daily load.
If for example you have a daily load of 2kWh and five days autonomy you
would need a battery bank of around 1400Ah. This would provide 2kWh a
day leaving your batteries ~70% discharged after five days. Your daily
DOD would be 13.5%
Now if you reduce the max DOD to 50% you would need to increase the
battery bank to nearly 2000 Ah.
On the other hand if you are working at a 50% daily DOD you will have
only one and a bit days autonomy, no matter what size your battery bank
The credibility in question is yours Steve.
If you were to use 20% as the max DOD the size of the battery bank would
be nearly 4900 Ah in the above example. So who's a poser, Steve?