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Different voltage for Pannels / Battery?

VeritasC&E

New Member
Joined
Jun 27, 2021
Messages
23
Hello,

I've bought the following items:

9x Solar Pannels: A model called EcoDelta ECO-330M-60D *

and I'm considering to buy:

3x 12V 300Ah LiFePo Batteries

I'll also need to buy the other components (on a very tight budget) to make up an off-grid system.

I have a few questions on how to proceed:

1) I read the following on internet: "For correct solar system sizing, your solar panels, inverter, and battery bank all need to use the same voltage. i.e system voltage." and then elsewhere that this no longer was true with MPPT controllers. Each pannel is rated as 33.8V at Maximum Power (Vmpp) which is not a multiple of 12V. How do I deal with the fact that this is not a multiple of the battery voltage nor coresponds to the ratings of solar controller and inverters when I look at them? Can I for instance use a 36V charge controller even though there's only 33.8V input?

2) Can the solar pannels and battery be wired to run at different voltages? If yes, can the solar pannels be wired to run at a lower voltage than the batteries or only a higher voltage (with an MPPT Charge Controller)? i.e Can I have pannels wired for 33.8V and batteries for 12V and can I have pannels wired at 33.8V and batteries at 36V?

3) I understand that the pannel voltage should be as high as possible to decrease transport loss, however can it be said that the efficiency difference is negligeable between the ways batteries are wired together if (unlike the pannels) they are very close to the charge controller and inverter? or is there still a significant efficiency difference due to the equipment?

4) In order to use my system as early as possible can I wait until I have more money to add the batteries and use electricity only during the day (having the same charge controller and solar inverter I will use with the batteries and just adding the batteries later on)?

*https://www.enfsolar.com/pv/panel-datasheet/crystalline/43529
 
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