Red Rubber Gloves Posted March 28, 2022 Posted March 28, 2022 (edited) Hello again. Admittedly, this is a very easy topic to obsess over. So many numbers. So much kit. Such magic. I have some designs and ideas in the pipeline but it did occur to me to throw out a request for ideas to the forum, before I lay out my scheme with specs and lunacy attached. Now, we have small needs and reasons for not investing in a major installation. So imagine this setup: A little shed. Roofs in variable shade. One has good sun 10am to sundown. Another decent 8am to midday. We need 1.3-1.8kWh per day...(laptop/wifi/modem/fridge) And we'll need it for days on end, ie this is off-grid. At present my idea, roughly, is to approach it like this... 24V system 1 x LBSA battery (5.2kWh) 1 x Victron Phoenix inverter (1200w) 1 x Victron Smart Solar MPPT 100|50 2 x Canadian Solar 380W panels, in series. (with the option of adding 2 more "2 x Canadian Solar 380W later, in series but in parallel with 1st two attached to same MPPT) (I also have the idea to add a battery charger to the mix, in case my solar setup goes squiffy) Does it seem I'm overdoing it? I've calculated for days autonomy and catastrophe as well as room for growth. Still, it's not a cheap exercise. Anything anybody would alter? Thanks. RRG Edited March 28, 2022 by Red Rubber Gloves Quote
Scorp007 Posted April 1, 2022 Posted April 1, 2022 On 2022/03/28 at 3:18 PM, Red Rubber Gloves said: Hello again. Admittedly, this is a very easy topic to obsess over. So many numbers. So much kit. Such magic. I have some designs and ideas in the pipeline but it did occur to me to throw out a request for ideas to the forum, before I lay out my scheme with specs and lunacy attached. Now, we have small needs and reasons for not investing in a major installation. So imagine this setup: A little shed. Roofs in variable shade. One has good sun 10am to sundown. Another decent 8am to midday. We need 1.3-1.8kWh per day...(laptop/wifi/modem/fridge) And we'll need it for days on end, ie this is off-grid. At present my idea, roughly, is to approach it like this... 24V system 1 x LBSA battery (5.2kWh) 1 x Victron Phoenix inverter (1200w) 1 x Victron Smart Solar MPPT 100|50 2 x Canadian Solar 380W panels, in series. (with the option of adding 2 more "2 x Canadian Solar 380W later, in series but in parallel with 1st two attached to same MPPT) (I also have the idea to add a battery charger to the mix, in case my solar setup goes squiffy) Does it seem I'm overdoing it? I've calculated for days autonomy and catastrophe as well as room for growth. Still, it's not a cheap exercise. Anything anybody would alter? Thanks. RRG I will use the roof with good sun from 10h. As you will have may be 10 days in the rainy season where PV power will be less than the 1.8kwh use per day you have a nice big battery for 2 days not much sun. Do you have a genny to charge the battery if the system does fail as you mention of getting an AC charger. Might also be needed a few times in the rainy season. Also important is which area as some areas have low PV in winter. Quote
P1000 Posted April 2, 2022 Posted April 2, 2022 For off-grid, I would go with the 4 panel option at least. Go here: https://re.jrc.ec.europa.eu/pvg_tools/en/tools.html#SA And try to get the days with battery empty to 0%. You can also add your horizon data to study the effect of the shadows. (Azimuth should be 180° for North) Quote
Red Rubber Gloves Posted April 2, 2022 Author Posted April 2, 2022 5 hours ago, P1000 said: For off-grid, I would go with the 4 panel option at least. Go here: https://re.jrc.ec.europa.eu/pvg_tools/en/tools.html#SA And try to get the days with battery empty to 0%. You can also add your horizon data to study the effect of the shadows. (Azimuth should be 180° for North) That is so nifty, thanks!!! Quote
Scorp007 Posted April 2, 2022 Posted April 2, 2022 (edited) 22 hours ago, Red Rubber Gloves said: That is so nifty, thanks!!! Looking at my most recent 2 years full use of PV one could expect 3.85kwh/kw of panels(Gauteng). This would border on the maximum as I don't have batteries that can be fully charged or not enough load connected. This then gives a 2.96kwh on average for the year for 2 x 380W panels. Using my worst days of which there are a few I got as low as 0.75kwh/kw of PV. This then works out at 570wh for these worst days. The large battery will help but there will be times like during January where we get 4 days in a row with low PV. Even using 4 x 380W will only give 1140wh for these bad days. See graph below for January and the 27-30 Jan was a bad patch. This is where one would need a genny even if only for a few hours that can also charge the battery to reduce running time. The last few days we saw some resources for PV. I have compared their forecast as well as their actual for Jhb and found some days their actually lower than the actual I got. An examples 25-03 was a lot worse than 24-03 and 26-03 yet their actual value point to be about the same. Today 03 Apr is one of those days that a 1kW PV setup seems to only provide 0.8kwh for the whole day working full time. Edited April 3, 2022 by Scorp007 Added PV power for 03 Apr. Quote
Red Rubber Gloves Posted April 4, 2022 Author Posted April 4, 2022 Thanks @Scorp007 This is quite instructive, actual results. Seeing as I'm in my "planning/research" phase - which has been enlightening, absorbing and at times highly irritating - most of what I have to go on are calculations, which for all their beauty are still largely abstract, excellent tutorial YouTube goggles and lastly, sales blabber and hidden details. So this graph shows something. And I'm in G'teng too. It has dawned on me that if you're to kiss the grid goodbye you in effect become a little grid yourself with all it's little managements and engineerings going on. If only I could milk the state for funds I'd be set. Regards RRG Quote
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