Utilising Solar Power at the maximum. But how?

[Neha007]

Hai Everyone. I have 4 solar pannels of 12 volts 40 watt each, and a 12 volt battery of 150Ah. I am new to the basics of utilising the solar power. Please guide me about what more i require, or how can make the maximum of the available resources.
My basic questions are, should i use independent solar charge controllers for each pannels? How are the controllers connected? How the inverter should be connected? I am in the process of making my house self sufficient with solar power for alteast Fan and lighting loads for 24 hours a day-365 days. Please guide me with your valuable responses sugessions, and experiences in the matter.
Neha

 

[srizbf]

from solar panel --> charge controller --> battery.

individual controllers is easy for maintanence . but add up cost .

srizbf
15thmay2010

 

[karesz]

Hallo Neha!
Nice Idea!
As srizbf said, + use pls by the parallel connecting of your PV-panels pro panel a serial Schottky diode to separate the individual panels from others, so you will have the best charging if their will became nonuniformity...
Is your battery not a little underdimensioned pls?
K.

 

[Neha007]

Thanks karez.
Do you mean to say use a Schottky diode in series to every pannel, make a single output and use a single controller? So what rating should be the controller be? Actually i am thinking of eliminating the Inverter which is the maiin source for draining the batteries. Is there any way it can be done? I think i 'll have to use direct 12 volts and use 12 volt appliances. Regarding the battery, it is the one i am now using with my regular Inverter.

 

[karesz]

Hi,
Yes, these is idea.
Your controller must can the maximal possible solar power
I think, the inverter less modus isnt good idea_your battery must be loaded for possibly full level because evry changing/decharging will limit the usability years :-(
Dont forget pls, a 12V battery to charge means: to have voltages from PV of minimum (I remember)at 14V!
K.

 

[FvM]

Optimized operation of the solar panels should be distinguished from optimized energy distribution respectively efficient utilization.
If we assume an existing storage battery, the first problem is about achieving highest effciency of the solar panels. Generally, it
requires maximum power point tracking (MPPT) operation, in other words an additional DC/DC converter that interfaces the solar
panel to the DC load (the battery). This is because for each irradition value, a solar panel has an optimal output voltage, usually
different from the battery voltage. Step-up as well step-down operation may be necessary to meet the MPP.

If the irradition of individual panels can be expected considerably different (due to the mounting conditions), you would need individual
MPPT converters for each panel. If the operation conditions are almost identical, parallel circuit with schottky diodes, as suggested,
or possibly series circuit would be sufficient. Most low voltage solar supply systems don't use MPPT however, they simply connect
the panels to the battery (operating as current sources) and have a charge controller, that cuts the solar supply, if the battery is
fully charged (e.g. at 14.4 V).

If you know the expectable daily course of solar irradiation at your place and the exact solar panel characteristic, you should be able
to estimate the benefit from using a MPPT converter.

For the energy consuming side, the best solution mainly depends on the existing loads. But I'm rather sure, that 4x40 W solar panel
can be only a small contribution to "self-sufficient" energy supply.

 

[srizbf]

while the avoidanvce of inverter looks good at first , it carries lot of problems in distribution of power to loads.

remember you have to place a "thick" or "heavy" wires for your(DC) main lines .
apart from cost(which will be very high if you claculate for wires) , u dont have flexibility and line drops or contact drops will have a say on
your proposed inverterless scheme.

better to use an inverter of good quality .

as karesz said use schottky diode with one controller ,
u may reduce cost to certain extent.

with regards

srizbf
16thmay2010

 

[Neha007]

At present, i am using a traditional inverter built with Lm741 oscillator + pulse transformer+ Driver transformer +Output Transformer driving 8 Nos 2N3773 transistors. I have noted that this inverter when swicthed on without load, consumes about 8-10 Amps which is not a good idea when i swicth on to solar. Along with all my present ideas, i am looking about which inverter will suit my appplication the best? Wether the sine wave or the PWM inverters in respect to the No load consumption? (Naturally all the new inverters come with Mosfet based final stages.) Thanks every one for the valuable guidance given.

 

[srizbf]

a sinewave inverter is a pwm one.
you will get marginal reduction in noload consumption.

but comparison of what is available in your place for the pwm inverters , then only ,
it can be decided which is best .

No load current is definetly a factor considered for efficient solar applications.

srizbf
17thmay2010

 

[FvM]

I've seen inverters with a sense circuit at the output, that switch on/off automatically, if a load is connected/disconnected.

 

[Neha007]

a sinewave inverter is a pwm one.

Thanks for the guidance. Sorry...But could you explain me your words quoted above?

I've seen inverters with a sense circuit at the output, that switch on/off automatically, if a load is connected/disconnected.

Thanks Frank for the nice word. Yes...there are such inverters available, but shall i go for Sine or PWM wave?

 

[srizbf]

basically the inverter is pwm inverter.
in the output of pwm a filter is employed to get 50/60 hz output.
as pwm frequency is veryhigh compared to 50hz(pwm freq isusually in 25 to 100khz range).

pwm makes switching of driver transistors(IGFETs) easier.
this also reduces the standby loseses.


srizbf
17thmay2010

Added after 9 minutes:

please add :
basically sinewave inverter is a pwm inverter.

 

[karesz]

Hallo,
What about the both, relative simple, solutions pls?
K.
P.S.:
Ideal Blocking Diode Circuit (only60mV)for Photovoltaic Solar Panels

 

[srizbf]

the ideal blocking diode soltion is a news and it is good.

the controllers can be made if the thread poster is ready to make one by himself.

srizbf
17thmay2010

 

[richmon74]

I think you should change that your inverter. It's really taking a lot of your power.

There are a lot of good inverter projects in these forum you could build for your self.
Maybe I could post one that looks good to me for you to try.

Added after 6 minutes:

This project was posted somewhere in this forum but i can't seem to find it so I'm posting it for you to see if it interest you.

It's a 12v to 220v 300w inverter

 

[richmon74]

The circuit is more visible here

 

[richmon74]

there is an organized introduction to renewable energy on this link:

www.totalgreenenergy.net

 

[energy2greenreview]

You can add connectors to your panels and connect to your charge controller. Your charge controller may have a built in feature that stops energy from flowing back into your panels.

 

[mechatron28]

i amnew in solar field.
i had made 2 solar pannels of 40watt each.
the problem is i am not using charge controller.when i connect solar pannel with battery tge amperes sent to battery is low.
should i do

 

[karesz]

Hi Mecha,
Chek it first with only one of your both solar panels pls.
You must know, that the delivered voltage of a solar panel is depending not only from sunlight, but from the load_i.e. a battery too.
Your solar panel voltage must be every time higher as the battery, but its not so a simple subject to say how many current will it deliver if you dont used a charger....
You can build yourself a solar charger, I belive that its the only one good way to have a reliable solar system at home.
See i.e. the from me linked "Solar Charge Controller / Blocking Diode" publications from 17 May 2010 11:00. I think you needs both...
K.