Recent content by 3 Acre

Perfect, thank you. I'll update when it comes together if anyone is interested.

Thank you - a matter of volts - it's starting to click. I'd been thrown by internet guides suggesting to match panel wattage to load wattage in direct connection. Provisional setups: 100W PV --------- 24-12v DC-DC --------- 12v DC Pump 35W (3 amps) 100W PV ----------24-12v DC-DC -----------12v...

That's helpful thankyou - I think I'm almost there on the rudimentals of this. With the buck converter in place, is it the case that the pump motor (or other load) will only draw the current it needs (at 12v) and no more? I think this is still the big gap in my knowledge here - can I use a...

I spotted this - it's attractive as a complete system and would be useful for other (bigger) applications on our small farm - but I was a little unnerved by some of the feedback. Thanks, I'll check out your thread.

Thank you that's great! I think I'll try a pump like this. Cheap enough to experiment with and likely enough head for this little system. I'm struggling to fully understand the buck converter element (still learning my fundamentals). Presumably 24v-12v because the 'open voltage' of a 12v...

Something like below? Would that cure the issue of excess from the 100w panel burning out the 35w pump on very sunny days? I lack some basic watt/volt knowledge here!

As a real world example over a period of years, that's worth a lot, thankyou. This is the direct connection pump I found - but not cheap. Very low start up current draw. https://www.motralec.com/public/fichiers/docs/Lowara_ECOCIRC_D5_VARIO.pdf

It might work - if I understand correctly this should limit volts/watts - but an expensive* unit to experiment with (*for this project at least - an adequate pump is only $25) I wonder if the variable load of a motor (startup 'spike') might destroy it eventually.

That could give me a watt-matching panel, but I'm really after a larger panel (to compensate for low light conditions) with some sort of simple limiter to avoid burning out the pump when the sun really shines. There are direct solar pump controllers for this task - or specialised pumps but...

That does seems the standard way. Concern is underpowering during low sunlight. Hoping for a way to link a larger panel to avoid that and limit the output somehow.

The more I think, the more it seems a variable resistor would not work as a current limiter for a variable supply!! There must be some sort of solution to limit the supply current to 35 watts (without also resisting the current when it is below 35watts)?

Hi, I'm working on a offgrid system of direct to PV components. In this case, a 35W water pump to circulate nutrients to tomato plants in our greenhouse. The project does not justify the cost of batteries, expensive controllers etc. and I'm allergic to unnecessary complexity! Most 'redneck'...