Using the lite 200 with DC input Voltage derived from rectified AC grig voltage

[ulisse10000]

Hello from Rome 

I am building a mixed off the grid / grid system and some time in winter when there is no sun I need to re-charge the batteries during the night using the grid power.

My question is:

It is possible to supply the Calissic Lite (I have  lite 200) using a rectified and filtered voltage of 50 volts at 30 amps derived from the grid AC voltage?

In principle should be possible provided that I do not exceed the maxim input power of my lite 200 and that classic SW will not do strange thinks.

In this case I could use the classic as a normal batteries charger during the night (when is needed) using as input voltage instead of the solar panels voltage,  the DC voltage derived from the grid that will be switched with a rele' to the Classic input.
If  this will work I can avoid to buy another battery charger for the nigth use.

My battery voltage is 24 volts

Can some one help me?

Many many thank
Fabio

[Vic]

Hi ulisse...

Have done this,  using the OB MX-60 CC,  in the past.  Works great.

Suggest that you use a full-wave rectifier,  and a fairly LARGE capacitor bank to filter the output DC.  You will want a circuit breaker on the output,  and perhaps a diode to protect the Classic from a shorted capacitor causing damage to the Classic.

Assume that you are getting that 50 volts by using a transformer connected to the mains.  Although,  guess that the source of your filtered DC could be a switching power supply.

More later,  Vic

[vtmaps]

It is possible to supply the Classic Lite (I have lite 200) using a rectified and filtered voltage of 50 volts at 30 amps derived from the grid AC voltage?

Yes, but I seem to remember boB writing somewhere on this forum that it doesn't always have a happy ending.  For one thing, the classic may not like trying to find the Max Power Point of a power supply.

--vtMaps

[ulisse10000]

Thank  for your help Vic,

my intention is to use a transformator 230 Vac to 36 volts ac and than to rectify the voltage with a full wave rectifier, (as you suggests) , after that a bank of capacitors to filter I was thinking around 4700 UF plus a 100 nf plus 100 Pf plus protection (breaker and diode).
So I will not use a switching power supply but just a trasformer plus rectifier and capacitors.

Do You experience strange behaviours of the classic due to the fact that is trying to found the MPP of a fixed DC voltage?

Thanks again
Fabio

[Vic]

Hi Fabio,

First,  I have not used a Classic CC in such a battery charger application.  Have only used the Outback MX-60.

A Classic in Legacy P&O mode may work OK.  I just have not tried the Classic.

Your capacitor bank should be 20 or 40 times larger than your proposed 4,700 uF -- something on the order of 100,000 - 200,000 uF.  This will reduce the ripple voltage that the Classic experiences.

It has been pointed out that a DC power supply such as you propose has a fairly low output impedance,  and as such will not behave very much like a PV module.  This COULD make it difficult for any MPPT CC to find an input voltage that satisfies its view of how PV modules behave.

Since I have not used a Classic,  it is quite possible that Hydro mode would be much more suitable,  I have no experience.

This setup is probably in the "not exactly recommended" category for MPPT CCs.

Sorry,  but this is about all that I have on the subject.  Good Luck.   Vic

[boB]

Whatever you do, do not use "SOLAR" mode.  Legacy or maybe even Hydro and starting with Manual MPP V at
a voltage near the Voc (open circuit voltage) of the rectified AC.

It is also good that a step down transformer is being used and also that the secondary voltage is
nice and close to the battery voltage.  This is probably the best if you do need to do something like
this  (rectifying AC).

Running a high AC voltage rectified into an MPPT charge controller is probably not a good idea
because it is harder for the CC to regulate and protect things.

No, we do not advocate doing this, but if you must, using that step-down transformer as
you are suggesting is a fairly safe way of doing this.

boB

[phonetic]

I modified a 48 volt 50 amp Telco battery charger to output unregulated 90 volts, forced SCR/diode bridge rectifier of battery charger on full cycle. feeding Classic 150 PV input.
It Max's out my 2.4kVA Genset, Classic 150 output 80 amps @ 28 volts.
Its  a quick way to charge my battery bank

[ulisse10000]

Hello Gentelman

Thak Yuo to Vic and to Bob for their reccomendations and help
Ciao
Fabio