What Size Solar Cell is Needed to Recharge a 12V Battery Bank in 8 Hours?

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Discussion Overview

The discussion revolves around determining the size of a solar cell required to recharge a 12V battery bank rated at 1000Ah within an 8-hour period. Participants explore various calculations and assumptions related to solar energy generation and battery charging dynamics.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant asks for the size of a solar cell needed to recharge a 12V@1000Ah battery bank in 8 hours.
  • Another participant suggests calculating the total power stored in the battery and estimating the required solar generation, noting that charging rates vary and solar intensity fluctuates throughout the day.
  • A participant questions how many days a 1kW solar cell would take to charge the same battery, indicating uncertainty about the peak power output of the solar cell.
  • Some participants express a desire for maximum power output from the solar cell, while also acknowledging the cost implications.
  • One participant proposes wind energy as an alternative source, which is met with skepticism regarding its practicality in certain conditions.
  • A later reply provides a hypothetical calculation based on assumed efficiency and voltage output, estimating the time required to charge the batteries under specific conditions.

Areas of Agreement / Disagreement

Participants express varying levels of understanding and propose different methods for estimating solar cell size and charging time. There is no consensus on the exact calculations or the best approach to the problem.

Contextual Notes

Participants mention factors such as charging rates, solar intensity variations, and efficiency assumptions, which are not fully resolved in the discussion.

aussie101
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Hi all,
If I have a battery bank 12V@1000A-
what size solar cell (kW) will recharge this battery bank (from flat to full) over a 8 hour period?
 
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aussie101 said:
Hi all,
If I have a battery bank 12V@1000A-
what size solar cell (kW) will recharge this battery bank (from flat to full) over a 8 hour period?

You need to calculate the full power stored in your battery bank.
Then you will have to estimate the amount required to generate that power in 8 hour.
Batteries do not charge at constant rate, rate slows when it gets charged more and more.
Solar intensity is not the same for full day, consider this too. You need to add the amount of power generated in 8 hours,it will not be same for every time of day. Consider this and then calculate what kWp- kilo Watts peak solar cell array you require.
 
like most things these days I'm out of my depth of knowledge.
let me pose the question another way-
how many days would a 1kw solar cell take to charge a battery rated at 12 volt @ 1000Ah estimate
 
aussie101 said:
like most things these days I'm out of my depth of knowledge.
let me pose the question another way-
how many days would a 1kw solar cell take to charge a battery rated at 12 volt @ 1000Ah estimate
Is it 1kw peak solar cell. That is does it produce a maximum power of 1kw at highest intensity of sunlight?
 
what ever will produce the most power
 
aussie101 said:
what ever will produce the most power

The more power it produces, the more it costs.
Why not use wind as energy source?
 
because a wave will rip it off the boat
 
There isn't enough information to give a good estimate, but it is possible to make some assumptions.

Suppose the solar panel was giving 14 volts out and everything was 100 % efficient.

The solar panel maximum current would be 1000 watts / 14 volts or 71 amps.

If it was OK to to charge the batteries at 71 amps, then it would take 1000 amp-hours / 71 amps or 14 hours to charge the batteries.

If you had 5 hours a day of good sunlight, then this would be about 3 days.
 
thankyou vk6kro,
 

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