Batteries not accumulating power for night

Re: Batteries not accumulating power for night

abdoudiaw wrote: »

Hi,
I just bought a solar system that includes:
-2 solar panels of 230W each, mounted in parallel

What brand/model/Vmp/Imp 230 watt solar panels do you have?

Most of these type of panels need a MPPT type charge controller to use "all of their avaiable power"... PWM controllers can be horribly inefficient when Vmp>>Vbatt-charging.

-one charge controller 30 Amps with WellSee Solar software. I have not been able to verify that the charge controller is an MPPT type.

From this thread, it appears the Wellsee is not a MPPT type charge controller but PWM instead.

-2 Solite CMF200 200AH mounted in parallel (could not find what type)

Assume this is 400 AH * 12 volt battery bank?

-one freezer 12/24volts, 72W, connected to the ‘Load’ of the controller

You do need to know, over time, how long the loads are on and off during the day... Assuming that the Freezer runs 50% on, then the energy consumed during the a 24 hour period would be:

• 72 watts * 0.50 duty cycle * 24 hours = 864 Watt*Hour per day
• 864 WH per day / 12 volt battery bank = 72 AH per day

I don't believe you are in the US/Europe, so it is probably too expensive to get--But a Battery Monitor (or this battery monitor) or DC Amp*Hour meter would be handy to figure out what is going one with your system.

-one inverter 12v/24v input, 220V output, 1500W, connected directly to one of the batteries. I often leave it OFF.

What Brand/model is this inverter? I have not seen a commercial 12/24 volt input inverter before.

In daytime everything seems to be working fine but when comes night time the batteries last no more than 2 hours, obviously not having accumulated enough battery.

As others have said, automotive batteries are not good for deep cycling... They will not last very long if cycled more than 15% from 100% full (weeks/couple of months).

And the broken solar panel, if working now at 1/2 power, will quickly fail. There is nothing you can do that will "save" the panel.

The max reading of ‘charge’ on the controller has been 12ah while the freezer was taking around 8ah (‘load’ reading), the difference (12ah – 8 ah = 4 ah) supposedly being accumulated into the batteries.

• 12 Amps from controller * 14.5 volts charging = 174 Watts

What you should be getting:

• 2x230 watts * 0.77 system derating * 1/14.5 volts = 24.4 amps typical maximum current charging discharged battery bank

Actually, I am kind of surprised you are getting even 12 amps with the panels and controller you have... Are these Vmp=17.5 volt panels?

I’m thinking of mounting the 2 batteries in series to have 24volts (and maybe also the panels). Is that a good idea ?

Really need to know more about the solar panels (Vmp/Imp ratings at least).

You may have to choose another charge controller (that supports 24 volts). And if you cannot make the Vmp-Array ~ 35 VDC (i.e., Vmp-Array is >> 35 volts), then you will need a "real" MPPT charge controller (~$300-$600+ USD).

For testing I have only a voltmeter and batteries always read ‘very good’

We need to know:

1. Battery Voltage when charging
2. Battery voltage next morning (and if running load or not)
3. Battery Resting Voltage (gives estimated state of battery charge)

• 12.7 volts ~ 100% state of charge (no charge/load for several hours--resting voltage)
• 11.6 volts ~ 20% state of charge, battery nearly dead
• 14.5 volts ~ battery charging maximum voltage (battery getting nearly fully charged, charging current will slowly drop over several powers to 2 amps or less, then full charged).

You can read about batteries here:

Deep Cycle Battery FAQ
www.batteryfaq.org

One panel has the protective glass broken: does this severely affect electric performance? I have left the thousand glass pieces but maybe, while waiting to have the glass replace I should remove these pieces and expose the cells to direct sun.

Nothing you can really do other than cry... Covering with glass or plastic may extend the life a little bit (weeks/months?). But it is not long for this world.

-Bill

Re: Batteries not accumulating power for night

The website redirects over to this one...

And perhaps these are the specifications for your panels (PDF download).

Vmp=29.23 V
Imp=7.53 A
Voc=36.35 V
Isc=8.00 A

Vmp=29 volts is too high of voltage (~17.6 volts required) to efficiently charge a 12 volt battery bank with a PWM controller... And too low (~35 volts required) for charging a 24 volt battery bank with PWM.

Regarding at least this one model of WellSee controller--That one was not MPPT (sorry, forgot to put link in earlier post--also fixed):

Wellsee (60 amp?) MPPT



-Bill

Re: Batteries not accumulating power for night

That model is a PWM controller, not MPPT.

So, the efficiency with a Vmp=29.23 volatt panel on PWM controller charging a 12 volt battery bank is:

• 17.6 volt recommended /29.23 volt = 0.60 or 60% vs standard "12 volt" panel

So, your 220 watt panel is only ~132 watts of useful power in this system configuration... (there are other losses--this is just the difference between the "right Vmp" vs the "wrong Vmp" panel for your setup).

-Bill