diy solar

diy solar

Have i drained my bank too far?

28 volts x 60 amps = 1680 watts. I think you're not overpaneled at the moment. Considering you can expect about 75-80% of nameplate rating of your panels I'd say you should be able to add more. MPPT controllers will throttle back when needed and you won't ever see more than 60 amp output regardless how much solar is connected. What is the highest wattage you have seen with your 1600 watt array?

You're correct about balancing issues. One remedy is using larger batteries. That being said lots of people have more than 2 strings. You need to wire your bank carefully. Study this from Smart Gauge. Example #3 is the most common strategy for wiring up 3+ strings of batteries. http://www.smartgauge.co.uk/batt_con.html

As to charging, AGM batteries will take up to 20% of their amp hour rating in charging amps. 15 % is a healthy charge so a 450 amp hour bank would be happy with 60 amps of current.
 
28 volts x 60 amps = 1680 watts. I think you're not overpaneled at the moment. Considering you can expect about 75-80% of nameplate rating of your panels I'd say you should be able to add more. MPPT controllers will throttle back when needed and you won't ever see more than 60 amp output regardless how much solar is connected. What is the highest wattage you have seen with your 1600 watt array?

You're correct about balancing issues. One remedy is using larger batteries. That being said lots of people have more than 2 strings. You need to wire your bank carefully. Study this from Smart Gauge. Example #3 is the most common strategy for wiring up 3+ strings of batteries. http://www.smartgauge.co.uk/batt_con.html

As to charging, AGM batteries will take up to 20% of their amp hour rating in charging amps. 15 % is a healthy charge so a 450 amp hour bank would be happy with 60 amps of current.
Ok thats good to know. I have about 900W spare from the old panels, but will need another 2 separate controllers to use them. They are 2 banks, 2 of them are 170W and another 3 at 180W.
The most I've seen coming out of the panels is about 800W or so. This was when I switched on a load. Will need to check again and see how it varies during different times of the day.
It's our winter right now and the angle of the roof is probably not the most ideal angle for this time of year, but they seem to be supplying close to max voltage for a good part of the day.

Regarding balancing, if I install a balancer, that should rectifiy that?
If I add another 270Ah of storage, how many watts of power should I typically need to keep this charged? I could get another 8-900w extra from the old panels providing they are still OK


That's good if the bank can handle more charge current, I was told it's closer to 10% but you can't change current with these controllers anyway, only the charge volts which would affect the current if you tweak that.
 
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