phil.g00 Posted November 22, 2018 Share Posted November 22, 2018 My goal is to switch certain loads (that are not time critical), on to take advantage of excess solar power. I want to go low-tech and off-the -shelf if I can, and I don't want to have to re-program anything after a power cut. What I want is a timer that will turn on for a certain time after it has been daylight for certain time. In other words, so I can switch on loads to use the most solar productive hours of the day. (I'll take the hit during poor weather, for the sake of simplicity). Say, turn on the pool pump after 4 hrs of daylight for a set time then turn off, rinse and repeat tomorrow. It should naturally fall in step the next dawn if the power went off during the day. Easy enough to build, but it would be really convenient if there was something off the shelf that could plug into a wall socket and handle 13 Amps. Has anyone come across such a switch? Quote Link to comment Share on other sites More sharing options...
___ Posted November 22, 2018 Share Posted November 22, 2018 1 hour ago, phil.g00 said: Has anyone come across such a switch? What I did once was take an off-the-shelf daylight switch, opened it up, found the voltage divider (with the LDR on the one side and another resistor on the other side), and reconfigured it. I made some calculations so I'd get a similar voltage output (bias voltage on the transistor not over 1V) and then I swapped the LDR to the other side so that daylight turns it on rather than off. It worked... but the daylight switch had other bugs (even when it was still a daylight switch) and in the end I abandoned the idea. Still... it worked :-) Quote Link to comment Share on other sites More sharing options...
Gabriel_2018 Posted November 22, 2018 Share Posted November 22, 2018 2 hours ago, phil.g00 said: My goal is to switch certain loads (that are not time critical), on to take advantage of excess solar power. I want to go low-tech and off-the -shelf if I can, and I don't want to have to re-program anything after a power cut. What I want is a timer that will turn on for a certain time after it has been daylight for certain time. In other words, so I can switch on loads to use the most solar productive hours of the day. (I'll take the hit during poor weather, for the sake of simplicity). Say, turn on the pool pump after 4 hrs of daylight for a set time then turn off, rinse and repeat tomorrow. It should naturally fall in step the next dawn if the power went off during the day. Easy enough to build, but it would be really convenient if there was something off the shelf that could plug into a wall socket and handle 13 Amps. Has anyone come across such a switch? It is easy. You can use a 5 w solar pannel, small. Its ISC use to be round 300 mA. Only an Arduino and a 10 Ohm resistor is needed. For example, if Voltage>2 V switch on and if Voltage <1.5 switch off Quote Link to comment Share on other sites More sharing options...
Chris Hobson Posted November 23, 2018 Share Posted November 23, 2018 A geyser timer can be set and had a battery that lasts weeks. ___ 1 Quote Link to comment Share on other sites More sharing options...
DeepBass9 Posted November 23, 2018 Share Posted November 23, 2018 I use one of these on my pool pump. Its has an internal battery so doesn't lose time. It also doesn't keep time very well though, I have to correct the time every few months. https://www.banggood.com/DANIU-AC-220V-16A-DIN-Rail-Digital-Programmable-Timer-Switch-p-1169520.html?gmcCountry=ZA&currency=ZAR&createTmp=1&utm_source=googleshopping&utm_medium=cpc_elc&utm_content=frank&utm_campaign=pla-mix-za-pc-0630&gclid=EAIaIQobChMI-u-IlI_q3gIVA853Ch3uZQ2JEAQYAiABEgLVM_D_BwE&cur_warehouse=CN I am also still trying to figure out a way to hook a cloudy weather switch into the system so the pool pump doesn't run when there is no solar. Quote Link to comment Share on other sites More sharing options...
Gabriel_2018 Posted November 23, 2018 Share Posted November 23, 2018 1 hour ago, DeepBass9 said: I use one of these on my pool pump. Its has an internal battery so doesn't lose time. It also doesn't keep time very well though, I have to correct the time every few months. https://www.banggood.com/DANIU-AC-220V-16A-DIN-Rail-Digital-Programmable-Timer-Switch-p-1169520.html?gmcCountry=ZA&currency=ZAR&createTmp=1&utm_source=googleshopping&utm_medium=cpc_elc&utm_content=frank&utm_campaign=pla-mix-za-pc-0630&gclid=EAIaIQobChMI-u-IlI_q3gIVA853Ch3uZQ2JEAQYAiABEgLVM_D_BwE&cur_warehouse=CN I am also still trying to figure out a way to hook a cloudy weather switch into the system so the pool pump doesn't run when there is no solar. Hi DeepBass9, after looking for expensive radiation sensor, for my solar pumps I use something like this: Quote Link to comment Share on other sites More sharing options...
Gabriel_2018 Posted November 23, 2018 Share Posted November 23, 2018 (edited) @DeepBass9Above is a cheap scheme and this is the price of a typical radition sensor: https://www.weatherhawk.com/product/signature-series-solar-radiation-sensor/ Edited November 23, 2018 by Javi Martínez Quote Link to comment Share on other sites More sharing options...
DeepBass9 Posted November 23, 2018 Share Posted November 23, 2018 Ja I see! I must get into arduino programming some time. then I'll be able to do all sorts of things. Chris Hobson 1 Quote Link to comment Share on other sites More sharing options...
phil.g00 Posted November 23, 2018 Author Share Posted November 23, 2018 I also don't know Arduino programming, but assume there is a timer that keeps things on while a cloud passes. Here is what I am going to try: http://www.gpslightlock.com/ It is a GPS based timer, which by default is set to sunrise and sunset. However you can specify other time windows as well relatively offset to sunrise and sunset when ordering. The loads wont know what supply they are being fed by, they will just switch on at the theoretical optimum times. But the more I think about it, because they are linked to one another via GPS they could be actually networked. I think these could really shine in off-grid usage, and even useful to downsize a grid supply. Multiple loads could be accurately staggered which would be very useful for someone to minimize maximum demand. I am going to have a good think about what I want before ordering. GPS_LightLock_Counter_Sheet_w_FAQ.pdf Quote Link to comment Share on other sites More sharing options...
Gabriel_2018 Posted November 23, 2018 Share Posted November 23, 2018 No, i use a small solar panel to know the radiation and switch off if It is cloudy... Quote Link to comment Share on other sites More sharing options...
seant Posted November 23, 2018 Share Posted November 23, 2018 Hobby stores usually sell a 12v day night switch kit . Often based on a 555 timer some of them have a light level adjustment which I guess you could use it to trigger a diffrent delay on timer circuit to switch whatever on if the sun was bright enough for a set duration. Very simplistic though. Quote Link to comment Share on other sites More sharing options...
___ Posted November 23, 2018 Share Posted November 23, 2018 (edited) 5 minutes ago, seant said: Often based on a 555 timer I was thinking of that solution too. You could even forego some components and just wire the light sensing LDR into a voltage divider and stick that on pin 4 (reset). At night it holds the reset pin low... then some time after sunrise the voltage on the reset pin rises high enough, and the chip wakes up. The downside: Long time periods with a simple RC timer usually requires a large cap, which usually means electrolytic, and with electrolytic comes high leakage so that you get to a point where the leakage is so high that the cap no longer charges to the required 0.67VCC and it never turns on... :-) Not to mention as the cap degrades over time... Edited November 23, 2018 by plonkster Quote Link to comment Share on other sites More sharing options...
Gabriel_2018 Posted November 23, 2018 Share Posted November 23, 2018 What I do using Arduino can be done with standard logic, Op AMP, latches, counters, 555...but is cheaper and easier to do with a microcontroller, in which is all integrated. ___ 1 Quote Link to comment Share on other sites More sharing options...
phil.g00 Posted November 23, 2018 Author Share Posted November 23, 2018 The radiation level really wont matter to me in a grid-tie situation. The borehole and other things will still need to turn on whether the sun is shining or not. This is not going to be used for load avoidance, but rather load timing. It's just that I want them to turn on when there is the best chance of sunshine. I made some more queries as to the flexibility of this off -the-shelf offering. 1. Could I use multiples of these timers to co-ordinate "ON"/"OFF" intervals between certain loads throughout the day, and be "OFF" at night.So I could manage my batteries and my maximum demand?2. Can they be programmed to absolute times, or relative to noon, or is it just offsets of sunrise and sunset? This was the reply: 1) Yes you can use multiple timers to control multiple loads, all being off at night if that's what you need.2) Yes we can switch at local time and we can also switch relative to Solar Noon when the sun is directly overhead as described in previous e-mail. I think these things have great potential. Quote Link to comment Share on other sites More sharing options...
Gabriel_2018 Posted November 23, 2018 Share Posted November 23, 2018 It seems like I al trying yo sell Arduinos, but with only one you can manage a lot of Relays, with Arduino+RTC. Quote Link to comment Share on other sites More sharing options...
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