diy solar

diy solar

High charge rate batteries

Would lead acid be a better choice for this use case? I think they can take extra current for a duration and simply boil off some (so requires some maintenance but maybe not a huge deal to check/top off water regularly).

Just thinking out loud here. I'm not an expert by any stretch.
 
Seems to me if your load is constant the issue of having too much charging current available to the battery is not going to be a problem. A variable load condition would be.
 
plund said:
Sure bigger batteries is the easy solution, but space is limited and also don't want to spend more then necessary on batteries as well.
Click to expand...

So, you're adding new constraints to the solution. Be specific, and don't hide information.
 
jgh said:
So, you're adding new constraints to the solution. Be specific, and don't hide information.
Click to expand...
If bigger batteries was a good option i wouldnt have any problems from the beginning right? Coz that would solve the problem
 
Mattb4 said:
Seems to me if your load is constant the issue of having too much charging current available to the battery is not going to be a problem. A variable load condition would be.
Click to expand...
Every load is constant, but there is multiple of them. Plan is to turn them on/off depending on the output from the solar charger. Too much charging current to the battery would fry it in the long run no?
 
plund said:
Every load is constant, but there is multiple of them. Plan is to turn them on/off depending on the output from the solar charger. Too much charging current to the battery would fry it in the long run no?
Click to expand...
Is there a minimum of load you intend to have always on? You need to understand that loads drive supply so if your SCC/panels can not service them your battery must or things shut down. The SCC outputs base on load and the ability of the panels to supply the load.
 
Mattb4 said:
Is there a minimum of load you intend to have always on? You need to understand that loads drive supply so if your SCC/panels can not service them your battery must or things shut down. The SCC outputs base on load and the ability of the panels to supply the load.
Click to expand...
No. If there is 0A from the solar charger, the load should turn off as well. It should only operate during sunlight. Let say there is 10 loads, where all 10 will only operate during noon in june/july. Early mornings and late afternoons there would only be 1 load in operation. I know that load drive supply and thats why I will have the functionality to turn off loads as SCC power decreases.

Sure there is some minimal power required to keep controllers and stuff alive during the night from the battery, but that's very low power compared to the load in this case.
 
plund said:
No. If there is 0A from the solar charger, the load should turn off as well. It should only operate during sunlight. Let say there is 10 loads, where all 10 will only operate during noon in june/july. Early mornings and late afternoons there would only be 1 load in operation. I know that load drive supply and thats why I will have the functionality to turn off loads as SCC power decreases
Click to expand...
SCC power decreases due to load decreasing. If the panels are unable to supply the SCC/load you can not operate. The purpose of the battery is to do this. It would be quite the trick to turn off the load with no power to do it.

Turning off loads due to PV output not being there is likely to prove very frustrating to manage.
 
Mattb4 said:
SCC power decreases due to load decreasing. If the panels are unable to supply the SCC/load you can not operate. The purpose of the battery is to do this. It would be quite the trick to turn off the load with no power to do it.

Turning off loads due to PV output not being there is likely to prove very frustrating to manage.
Click to expand...

Suppose the battery is in between the SCC and the load. If the battery is kept running around lets say 60-80%, then there will always be a demand to the SCC from the battery?
 
plund said:
Suppose the battery is in between the SCC and the load. If the battery is kept running around lets say 60-80%, then there will always be a demand to the SCC from the battery?
Click to expand...
Battery is not in between. It is in parallel on the common DC bus consisting of SCC output, battery, DC loads (inverter may be here as well).

However a lot of setups rely on the battery sitting at float voltage (neither charging nor discharging) so that the PV supply can be used for loads instead of the SCC shutting off once reaching battery full charge condition.
 
plund said:
Fair point. Its electrodes for electrolysis. And I have no idea about the minimum on-time at the moment
Click to expand...
Well, that's a critical constraint, no? If there's no minimum off-time then maybe all you need is a big capacitor, the size of which would depend on the responsiveness of your control system.

But now I see that you want power all the time for control, so you need _some_ battery?

Is it possible your electrolysis system draws current depending on the applied voltage, so maybe something as simple as hooking the solar panels up to the electrolyzer will automatically generate (hydrogen?) according to the available power, and you don't need to jump through all these hoops. There are, for instance, solar pump controllers that'll optimize panels and loads automatically...

If there's no NDA, can you share the manufacturer, model, specs, etc for this electrolyzer?
 
wpns said:
Well, that's a critical constraint, no? If there's no minimum off-time then maybe all you need is a big capacitor, the size of which would depend on the responsiveness of your control system.

But now I see that you want power all the time for control, so you need _some_ battery?

Is it possible your electrolysis system draws current depending on the applied voltage, so maybe something as simple as hooking the solar panels up to the electrolyzer will automatically generate (hydrogen?) according to the available power, and you don't need to jump through all these hoops. There are, for instance, solar pump controllers that'll optimize panels and loads automatically...

If there's no NDA, can you share the manufacturer, model, specs, etc for this electrolyzer?
Click to expand...
Yeah well if i could run it without a battery I wouldn't be here in the first place :)

At the moment I don't know what voltage and current I want to run the electrodes at, and I also don't know the minimum off-time. I just know that if I have 120A, I want to use 120A. But if it's 5 or 20 in parallel I don't know. This I will learn from experiments. So I'm vague coz I don't have the information myself, I need to build this at a first stage to get the information to optimize the power system later.

Please elaborate on solar pump controllers that optimize panels and loads automatically?

Can't share that, sorry
 
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