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Tim from Eat Sleep Van avatar image
Tim from Eat Sleep Van asked

Feature Request: MPPT Streetlight but on during the day

After experimenting with the streetlight feature of the smaller MPPT controllers, it's doing exactly the opposite of what we need. We want the load to be on during the day, but not at night. Despite the slightly confusing configuration options which almost seem like it can work, it can't.

My particular use case, I'm controlling daytime only cameras. I can imagine it would be very handy for a lot of remote solar projects.

My request is to add some extra options to the firmware. Something like:
At Sunrise: "Switch on" or "Switch on before sunrise and keep on"
At Sunset: "Switch off" or "Switch off after sunset and keep off"

This would be ideal. Then we can switch on the load an hour before sunrise and turn off an hour after sunset for example.

Previous questions asking how to do it with some answers is here, but none of the answers actually work.
https://community.victronenergy.com/questions/96657/how-to-keep-load-on-during-the-day-and-switch-off.html
Using the battery voltage isn't an option, because it would be off on non sunny days when the battery isn't full. And the suggested streetlight settings do not work.

Edit: thinking more, one extra option to NOT turn off the load at sunrise would mean the existing 'Switch on before sunrise' and 'Switch on for a fixed time' options combined would do what I want. The only problem is at the moment 'switch on before sunrise' always switches off the load at sunrise. i.e. it is actually 'switch on before sunrise and turn off at sunrise'. I'd like the extra option 'switch on before sunrise and stay on all day'!

MPPT ControllersStreetlight
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4 Answers
Matthias Lange - DE avatar image
Matthias Lange - DE answered ·

You can invert the function by just adding a relay.

But how should the MPPT know "it is now 1 hour until sunrise or sunset"? For that you would need your location and a real time clock to calculate time of sunrise/sunset.

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Tim from Eat Sleep Van avatar image Tim from Eat Sleep Van commented ·

Hi, it already has the ability to switch on the load x minutes before sunrise, but the problem is it then turns it off at sunrise! (for an early morning streetlight) I want it to stay on after sunrise.

I think the way it does this is it learns the sunrise and sunset times from previous days.

Actually thinking about it, if it just had a 'don't switch off at sunrise' option, it would do what I want! I could use the existing 'Switch on before sunrise' e.g. by 1 hour, then tick the 'don't switch off at sunrise' option, it would stay on all day, then at sunset I could set the existing 'Switch on for a fixed time' for it to stay on 1 hour after sunset.

So @victronstaff, one extra option would do it :)

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Tim from Eat Sleep Van avatar image Tim from Eat Sleep Van commented ·
A relay to invert it might be the best option in the meantime, but it won't be able to start an hour before sunrise and stop an hour after sunset which would be ideal. But I could make it turn on for all time except x hours before sunrise. Or x hours after sunset. Actually one of those would probably be fine in my case. It just means even as the days get longer into summer, it will always be off for x hours no matter how long the day is. So I could choose to have it on early or late by a number of hours, but not both. At least I think that's right... who doesn't love a good lump of logic.
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Tim from Eat Sleep Van avatar image Tim from Eat Sleep Van Tim from Eat Sleep Van commented ·

I just realised inverting the output with a relay means we won't be able to use the battery saving features of the MPPT controller... . In our case that's one of the main advantages of the Victron MPPT controllers, it'll protect the LiFePO4 battery if it gets too low and there's no sun for too many days. And no, I don't think there's room in our boxes for a battery protect as well!

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Alexandra avatar image
Alexandra answered ·

@Tim from Eat Sleep Van

A cheap product already exists for that purpose. It is an mcb timer control switch.

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Tim from Eat Sleep Van avatar image Tim from Eat Sleep Van commented ·

Hi, an MCB timer doesn't know about sunset/sunrise without some sort of voltage detection on the solar input, or it's own light sensor, and the brains to do stuff with that information. I certainly considered a dedicated timer, but that's extra bulk and residual draw. Might be the best option though. Cheers

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nickdb avatar image nickdb ♦♦ Tim from Eat Sleep Van commented ·

Plenty of smart (wifi) timers that do exactly that and can also be interfaced via node red.

Tuya, ewelink etc..

I have several installed for this purpose.

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Tim from Eat Sleep Van avatar image Tim from Eat Sleep Van nickdb ♦♦ commented ·

These are remote solar powered boxes, and although the pi style device we are powering has a 4g connection, we need the power management to be completely separate and reliable (thus the Victron MPPT controller). Occasionally the computer locks up, or the 4g fails, that's one advantage of turning them off and on again each night, it'll reset each day it even if it fails. We need them bullet proof as some of these things need a 3 hour drive and a digger on a construction site to retrieve them... so wifi or smart home gear isn't an option sadly.

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nickdb avatar image nickdb ♦♦ Tim from Eat Sleep Van commented ·
Ah ok. Understand. Unfortunately all these smart devices rely on internet access for the timer/smart automation to work. They rollover and play dead without comms.

Pity, as they are a cheap and easy solution.

I use sunset/sunrise for several automations (mainly for lighting) with some added delay, it does work well.

Works great for sequencing also - like turning off a geyser when it senses current has dropped to 0 and then activating the next device.

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zeron avatar image zeron Tim from Eat Sleep Van commented ·
Cerbo GX can run Node Red as well (on release candidate atm and "soon" on stable firmware), would that solve the reliability problem?


I haven't put it in service yet (waiting for stable) but from what I saw of the Victron nodes on my regular node red instance, they don't to use IP network to communicate so it must be done directly through the VE.Bus?


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Vlade Mališ avatar image Vlade Mališ Tim from Eat Sleep Van commented ·
Hey Tim, I was also looking for a way to achieve this in order to save the battery during the night, when the load is not used. Did you manage to make any progress on this?

Or perhaps you found some external of the shelf way to control the load. Thanks!

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bigbadbob76 avatar image
bigbadbob76 answered ·

My smartsolar MPPT 150/45 has a programmable relay that can be set to do that.

not to be confused with the programmable load output that the 75/15, 100/20 etc mppt's have.

It's the bigger version of 150/45 with the optional display. the smaller version doesn't have it.

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wjf avatar image wjf commented ·
@Bigbadbob76 can you please give more details? We want to turn on a load at sunrise and turn off again at sunset. Can this be done, and if so, can you walk me through it please?
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bigbadbob76 avatar image bigbadbob76 wjf commented ·

6117e4a9-94cc-43ad-adee-18a91afa04da.pnge1519c85-8636-41a7-8025-4d55d9a5e652.png

As above, set the relay settings to turn it on during daylight.

I then connect the common terminal of the relay to battery positive, n/o terminal of the relay to the positive terminal of a solid state relay. And negative of the ssr to negative of the battery.

Ssr output can then be used to switch your load.

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wjf avatar image
wjf answered ·

Thanks a lot, @Bigbadbob76 , appreciate it....

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