I have a device that pulls about 10 amps and is typically powered with a car battery. It runs fine with less amperage but needs 9 to 14 volts. I want to power my device directly from a solar panel but haven't accomplished anything if the solar charger requires a bulky battery.
It works with a DC DC buck converter but inefficiently, pulling ~70 watts from a 120 watt panel. I want something more efficient.
I found a mppt solar charger that powers my device efficiently when connected to a 5 amp-hour battery, but again I don't want the bulky battery.
Can you suggest a way to power a solar charger with a very small battery and not have it discharge when clouds block the sun?
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Is there an MPPT out there that doesn't require a battery?
edit:
Many of you asked "what is the load?"…… I have four titanium electrodes, spaced about 1/4 inch apart, and place them in salt water, to produce bleach. The bleach is used for sanitation or disinfecting water in developing countries.
If I had 12 volts and 10 amps the batch of bleach would be done in an hour. I don't need to run at night and it doesn't bother it to stop when a cloud covers the sun.
As far as the buck converters…..The ones I purchased don't have any adjustment….. Someone asked for the circuit diagram for the buck converter. I just hooked the input to the solar panel and the output to the bleach making unit.
The unit will operate fine with less than 10 amps, it just takes longer to make a optimum strength of bleach. It likes 12 volts but will work fine at 9 to 14 volts.
I have been told that the problem is similar to powering a water pump directly from a solar panel.
I didn't know there was a MPPT "controller" that would not need a battery. That's why i tried the "solar charger". I'll look for one or maybe you could point me in the right direction.
Best Answer
If you don't want a battery, why did you look for a charger?!
First, when a battery powers something it discharges. That's how it works. Second, most likely there is a way to hack charger schematics to keep it "operational", i.e. powered up without the sun. But what would be the point of that if there is no sun to get power from and no battery to charge?
I believe they called "Direct-coupling photovoltaic systems". You have to research those yourself. The MPPT controllers (not MPPT chargers!) are commonly used for loads that do not have strict power requirements, for example water pumps, water heaters etc.
However the fact is, most loads cannot operate in the wild output power range of the solar panels. Using them without battery basically negates the efficiency gains of the MPPT, because they will shut down in low light when just a little extra juice from the battery could have kept them working. At the same time in very bright light the extra available power is wasted when it could have been used to top up the battery.
So if your device (you haven't given us enough details) is the kind that can operate intermittently and you want it to draw as much power as available but don't mind shutting down in low light, then MPPT controller is what you need.
If you want your device to have stable operation in variable light conditions then what you really need is a bigger battery and MPPT charger. Then you can limit power available to your device at say, stable 100W 10V and use the remaining 20W (when they available) to charge the battery.