question

btv128 avatar image
btv128 asked

Feature Request - Load output based on available solar

I've got a BlueSolar MPPT 75

Could I request a feature where as well as the other load output methods there is also a load output of "If Solar Available" along with a minimum watts figure.

The load output will be ON if there is that amount of solar available at that time, and OFF if there isn't.

Use scenario is:

I've got a fridge that uses say 40W. Ideally I'd like to have cold drinks any time, so would like to leave the fridge on even when I'm not using the van. What currently happens would be the fridge runs and the solar charges the batteries all day. Then overnight, when there is no solar, the fridge continues to run and depletes the battery. Although I have minimum voltages and the load will turn off if the battery discharges below x%, the batteries do still deplete overnight to for example 75%. When morning comes, the solar kicks in and the batteries charge whilst the fridge runs on solar.

However, in the above scenario, that counts as a charge cycle on the battery, over a year it would be 365 charge cycles.

There is also the possibility the following day will be overcast, with no solar, and the battery could be depleted even further.

It would be far better if there was an option when the van was unattended to only put the load output on when there was enough solar to service the load, and avoid any discharge from the batteries completely. I'd be happy with a variable no of watts for a user to set manually as this threshold.

Is there any technical reason this couldn't be implemented, and if not, can it be implemented please.

I've tried bodging it with max/min voltage limits but just couldn't seem to get it to work, so think it would really need to be implemented properly as a feature.

Thanks

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2 Answers
Alexandra avatar image
Alexandra answered ·

@btv128

I haven't tried this myself, but you can use the streetlight function and invert the switching to switch the load output.

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btv128 avatar image
btv128 answered ·

Hi,

I did look at that, but as you say it works the other way around.

It is also has the issue that it only really works as a once per day switch i.e. night and day and would assume there was enough solar all day long, which often isn't actually the case depending on where you live and the season.

I tried a new custom voltage output profile but that didn't work either. Firstly the high/low voltages didn't seem to work, I think because they were voltages caused by solar input rather than the voltage from the batteries. And secondly, because it is possible to have a low wattage solar input on a dull day that will still show as a high voltage despite having nowhere near enough power to run a fridge.

I've played about quite a bit but I believe it would have to be implemented properly properly as a load output profile to get it to work.

That said, I don't believe it would be hugely difficult to do so.

Thanks



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