New solar installation - optimization and tips for improvements

Re: New solar installation - optimization and tips for improvements

The diagonal one with the two vertical jumpers (new.jpg). It is easier to check for equal current flow with a clamp meter (two center jumpers).

And, personally, I like the one with two vertical jumpers because it is easier to monitor battery bank voltage. When you measure each 12 volt (or 6 volt) battery block, they will have different voltages (if there is a problem). If you connect each individual block in parallel, then you force the same voltage across each battery pair and it is much more difficult to use a volt meter to see if there is a battery problem.

If everything is working right, you don't need to parallel the sub batteries together because they should all be at the same voltage. If they are different voltages, then you want to know that.

Also, if you do have an electrical problem, it is possible for two batteries in parallel and one battery in the second set--You will kill the second single battery (50% discharge on two parallel, 100% discharge on one below).

Interesting idea about the connections--You did meet (from what I can tell) the requirement for equal cable length for all electrical paths (assuming all jumpers are the same length). The new.jpg drawing is just my preference.

-Bill

Re: New solar installation - optimization and tips for improvements

I, personally, do not like to connect secondary current paths for series/parallel batteries.

If everything is working well--There will be no current flow through the 6mm wire. If you have an open cell/connection in the 50mm wiring, then a bunch of current will flow through the 6mm wire and start a fire.

And, the extra wire will hide problems. If you have a cell/battery/poor wiring connection. The extra wiring puts another battery in parallel with the failing component and makes it difficult to see the problem (I suggest using a volt meter to measure each cell/battery voltage once a month to look for problems (high or low voltage compared to others in the bank). You can also get a DC Current Clamp type DMM to measure shared current flow. With "extra cross connections", it makes it very difficult to see these difference.

So--I would just remove the 6mm cable and call it a day.

Also, with paralleled batteries, in theory, each string should have its own fuse/breaker for electrical safety (wrench falls on battery bank, cell fails shorted, etc.). The extra fuse/breaker per parallel battery string is expensive and a bit of a pain to install. Many people (probably most) do not do the extra fuses/breakers--But electrically and for safety reasons is is a good idea.

-Bill