solar panel charger

[RockingDad]

Evening,

I'm starting a solar panel project as a starter project for off grid power. I've got a 12v 20 watt panel that I'm going use to charge a 12v battery connected to a purpose made charging point for phones etc and also power led lighting from. Also I'll use it to keep the Jeep battery topped up when on the trail.

Quick question, do I need to have a charge controller amp rated close to its rating or can I use a ten amp controller without any adverse effect?

Thanks

RockingDad

[Yorkshire Andy]

My 60w panel is fitted with a 10a controller yet only pushes about 4a...

Double check but I think the 10a is more to do with the load via the regulator

[Yorkshire Andy]

Looks like both in and outputs check the spec before buying

This looks the same as mine which came factory fitted

http://www.dx.com/p/12v-24v-10a-solar-c ... 6C_zOBwYm8

[RockingDad]

Thanks...I'll check. Just didn't want to find it needs a 10amp supply to ensure correct switching for load or something crazy.

[Hamradioop]

Hi Rockingdad my understanding is that a 4 amp charge controller will give a maximum charge rate of 4 amps. It is also capable of switching a load of 4 amps. You can off course draw a higher load by connecting to the battery direct with an appropriate rated fuse.

[Hamradioop]

MPPT Charge Controllers

These charge controllers give approx 30% more power than a PWM charger and you can connect high voltage panels to lower voltage battery banks.

In a normal charger the battery acts as a resistor reducing the amount of power you can get out of the panels, these chargers use Multi Power Point Tracking (MPPT) which keeps 2 separate circuits for the panels and batteries allowing upto 30% more power to be collected from the panels.

By using higher voltage on the panel side will also benifit by less volt drop and can use thinner cables. On large arrays we run everything at 100V - 150V.

We did a side by side test between MPPT & PWM controllers, read the results here http://www.bimblesolar.com/beginnersguide#mpptpwm

To work out what size controller you need calculate by
(Peak Solar Panel Watts) / (Battery Voltage) = MPPT Amps (ie 240W/12V = 20A)

PWM Charge Controllers

These are PWM (Pulse Width Modulation) charge controllers which take panels with an Open Circuit Voltage of upto 48V, so they work with our panels.

We would highly recommend using our MPPT charge controllers rather than these, but offer these as they are a cheaper alternative if your on a tight budget. You will get less power per panel from these chargers than the MPPT ones.

We did a side by side test between MPPT & PWM controllers

see http://www.bimblesolar.com/ for more info of which this is an extract.

[Yorkshire Andy]

going from my tests i get close to the panels rating with the supplied PWM regulator...




full sun (ratings are based on 1000w lighting over 1sq m )




when overcast





this is what i have

http://www.photonicuniverse.com/en/cata ... ystem.html