PowerBudgetTraining 3

so station design ideas for solar powered monitoring stations part C Reserve time let's talk about how we should um determine the size of our our Reserve that we want in our system okay so um you want to think about things yeah yeah okay so when we're in our station we want to think about how bad weather is going to affect your site you know if you're trying to make the people aware of the weather conditions during a hurricane you don't want your system to go dead halfway through the storm right you want it to survive

the storm um some places um uh one country in South America for example they they won't put up solar panels anymore because 40 percent of the population doesn't have access to electricity and they see a solar panel and they think wow I can use one of those things to charge my cell phone or charge an LED light so I can go check on my animals at night my kids can stay up a little later and do homework I don't have to buy candles or things like that so um if you have a situation where there

might be vandalism you gotta you gotta think about how much time do I want to survive after the vandalism of the solar panel or something so that I can have time to get up there and fix the situation how would alarm conditions affect your loads if you're setting up a station maybe you've got a couple stations maybe one's up in a drainage up above a city or something and you're putting some rain gauges up there and averaging the rainfall in those different areas to calculate the potential flooding that will happen later you could send a

message down Downstream over the radio to another Data Logger that could turn on some warning lights or something and so how long do you want those warning lights to be able to run so you've got to think about how long you want those those kind of situations to survive um will limited Peak sign hours also limit my battery charging so this is a case in Northern uh Iceland in northern Alaska Northern Canada probably in the Nordic countries in Europe uh those in Antarctica they're having a situation where you get beyond the Arctic Circle and you

have complete days or weeks or months without sunlight so excuse me you'll need to uh you'll need to plan out for those long periods without Sun and uh let's say you've got a station that's running and it's doing fine everything's great but then your supervisor comes and says uh um the the Mayors or the the head of the institution is saying we want to see the data fight every five minutes real time instead of uh once a day to see the accumulation of all the five minute data values well in that case you may have

to turn on a cell modem or a radio all the time and that will direct dramatically and drastically reduce the reserve time that you have so you might need to re-analyze your power system in those kind of cases so um also uh yeah those more frequent Communications for example can can be devastating to your design so you your your decisions can completely undo your hard work of calculating what you want in the system okay um but in general terms uh based upon your your latitude you uh you may want to have at least a week

if you're around the tropics maybe a couple weeks in the mid-latitudes and a little bit farther extremes you might need to have three weeks or more and if you're near the polar regions you might need 90 days or 180 days or even 160 days and you might have to bury your batteries and then some kind of insulated enclosure under the snow so that so that you can avoid the extreme temperature um cold spells that could uh slow down the chemistry in your batteries for example here's a graph of three a little over three years of

data and I um I took this data and uh and he did a calculation to figure out the Peaks on hours per day uh and you kind of see a a little pattern here right you can see that uh there's a line right here for winter and then for summer and then back down to Winter it's just a sine wave right or a cosine wave I guess depending by you look at it but um why can't we just use this bottom line right here as our estimated solar well it turns out that we're not living

in a place where there's just sunlight and night time we're living in a place where there's uh weather where there's other things and they create these dots below the line now notice in this one from Logan Utah there's a particular times in the winter where we have fog or snow storms and so you kind of have to um measure the the sun that's available that are that may be blocked by dust vegetation Hills aerosols maybe salt spray from the ocean waves or clouds or thunderstorms and things like that so if you have a pyranometer measuring

the sun you could kind of predict what it should be based upon this sine wave but if you have less than that then you know that there was weather on those days or or dust or things like that so when you're doing a pyranometer you're kind of measuring the missing Sun rather than the the Sun but we have to average these these bad days into it and find out the worst 30 days or the worst couple weeks to find out what sun is available for us in those times of the year so how do we

do that well uh we need to plan a long enough Reserve time to outlast that bad weather and uh and dust and pollutions and stuff like that in the worst part of the year so we will need a longer Reserve time um we may need to protect it for periods when the snow or on the solar panels may take some time to melt off hurricanes or tropical storms may park right over your location that could be a problem clouds on mountaintops can reduce the solar panel production at higher elevations um adding flashing lights or Sirens

to their station May alter um for a learning Personnel of danger might use more power than normal here's a some graphs that I got from customers up in Canada and they didn't quite size their system either they needed a little bit more Sun or a little bit bigger battery because it worked fine on the first year but the second year it went down and they lost data the third year they lost months worth of data and then they re-changed the battery and then they were back into the first year problem where they lost part of

their data again so they need a little bit bigger system there and here's another side that same kind of thing it did partially okay the first year or the second year it started really dropping so those are signs that you need a bigger system all right that's the end of part C