I just upgraded the solar system at my family's off-grid cabin. It's incredible how much battery technology has improved over the last 10 years.
Everyone is getting tired of me checking the panel to see how many watts we're bringing in.
Next project, install a shunt and get a Raspberry Pi talking to it over USB. And then I'll be able to build a Grafana dashboard. :)
I have a similar project, I'm so overpaneled I bought an electric heater so I could actually see how many watts I brought in during a nice summer day. The victron UIs have an excellent graph history.
The next step for people like you and things like nations: what do we do with this extra electricity we have laying around so often?
What people figure out to do with actually free energy will be exciting. There are a lot of extremely "inefficient" things that might suddenly become commonplace.
Proto-replicator technology where you dump your garbage into a barrel and it gets decomposed and recomposed into something similar to crude oil, blocks of metal, pure gasses, etc? Hydrocarbon fuel from air? Flying cars? You name it.
Generating hydrocarbons at home from their air with excess electricity is like the ultimate endgame in my opinion. It’d be so sick and enable a million new possibilities, essentially getting us into a net-zero emissions state without needing to use batteries for everything.
I doubt that it ends up being actually better due to efficiency losses but it’d be really cool!!
I often daydream about electrolysing water to generate oxygen and hydrogen and store them to use for heating and like welding torches and stuff.
To make electric energy I would have to make a small steam plant to run a turbine.
>To make electric energy I would have to make a small steam plant to run a turbine.
Or a hydrogen fuel cell: https://en.wikipedia.org/wiki/Fuel_cell
The round-trip efficiency is of course abysmal compared to batteries, but if the input energy is "free", the increased density could pay off.
For most purposes, I would avoid the shunt and use a current transformer (for AC) or a DC current sensor (conceptually the same thing but with a Hall effect sensor or other mechanism that works for DC). This way you don’t need anything to touch the potentially rather large voltages on a solar array.
The OP mentioned modern battery technologies - generally the shunt sits between an LFP battery negative and the main circuit negative/ground, and the solar panels connect to MPPTs. So the voltage at the shunt is a nice consistent nominal 12.8V (~13.3V in practice) or a multiple thereof (for series battery setups).
I just upgraded our hybrid caravan to 24V LFP (2x 300Ah 12V), roof solar + extra MPPT for external solar, shunt, inverter-charger, 24V->12V converter for existing circuity (lights, pump, etc), DCDC charger from car, battery balancer, a little touchscreen interface inside (all victron gear with renogy batteries). It was as a lot of fun and it's amazing how much power we have off grid now! The system would work excellent for a little cabin exactly how it is (minus DCDC).
Or an esp32 to not run Linux and whatnot off of an sd card. Should be more reliable in the long run
Really curious about the difficulty of doing a self install with Solar. I'm moderately handy (built a Sauna from no plans) and confident with electrical. Any gotchas?
I just did an install to add solar and batteries to my shed to power lights and an AC. It was pretty easy. Hardest part was flattening the ground since I did a ground mount system. 5kw panels and 5kwh of batteries. $1000 for the panels, and $1,400 for the battery and inverter. $250 for the ground mount. Plus a bunch of miscellaneous expenses (tools, wires, permits, etc). It would be cheaper if I did it again since batteries and inverters seem to get cheaper every 6 months.
Check out https://m.youtube.com/c/WillProwse and https://diysolarforum.com/
I'm just getting into Solar myself and while it seems like a lot there are some things that you have to do math for. If you've got 10 panels you'll want to find out how to get all that energy to the inverter/mppt without going over the volt/amp limit on the device. This is probably the most difficult part and for everything else there's a huge solar community of people starting exactly where you are. I myself just bought an Anker solar battery and 2 panels that I bring out during the day to charge the battery and it runs my laptop and monitor for the evening after I get home from work. I want to do more but I'm renting so I'm just trying to find ways to do so. When my state legalizes balcony solar you bet I'm going to play with that too.
Its not difficult, you just have to change the configuration of your panels between in series and parallel.
Ideally you dont buy the all in one batteries as they usually have anemic solar inputs.
> without going over the volt/amp limit on the device.
It’s not clear what device you’re referring to in this context.
The MPPT solar controller.
MidNite has a sizing tool for this: https://www.midnitesolar.com/sizingTool/
So the most difficult part is using a calculator to determine the charge controller capacity.
No, you also need to calculate the voltage drop over your distance to show to minimum wire sizing, and the voltage and power levels at the ASHRAE minimum temperature, the current level at 156.25% over the wiring at the ASHRAE max temperature to compute the temperature adjusted resistance and show that your wiring meets minimum spec, etc.
It’s not too hard to actually do the computations. But there is a ton to learn. I installed my own 14.85 kW system last year, with batteries, and I spent hundreds of hours just researching everything. I know I went overkill, but the hardest part of the project was just getting up to speed on all the requirements to meet code.
Someday I’ll write up my entire experience and share my site plan I used for permitting in the hopes it will help someone else. But doing solar right is a nontrivial investment for a newbie (like me).
So the most difficult part is using domain specific online calculators to determine the wiring requirements and charge controller capacity.
The most difficult part is acquiring the necessary domain specific knowledge, including what your AHJ changed from the national codes. But yes, once you know everything it’s all pretty straightforward stuff.
No, just figure out how much solar you want and buy and accordingly sized charge controller/MPPT.
They will all tell you maximum input volts and amperage. You can calculate watts by multiplying those two and just need to wire your panels in a way that doesn't exceed either value.
It's fairly easy and there are a lot of forums around with knowledgeable people.
My main issue was ensuring wire gauges were correct. One's intuition about dealing with house wiring @15A changes when you're dealing with 50A circuits. Also you need to pay attention to things like equal cable lengths between battery banks so you don't overcharge one battery in a series.
However, I'm dealing with an off-grid cabin so I don't need to deal with any grid-tie circuitry, which would make it much more difficult and I'd definitely get an electrician for that.
Modern off-road/off-grid inverter chargers make wiring to the network pretty easy. I'd still recommend an electrician, but most they'd likely need to do is wire the grid into the inverter-charger input, and your cabin to the output, and check whatever protection (like RCDs) your cabin has is sufficient/up-to-date.
Very cool. Thanks for the tips!
Where is the cabin? Roughly speaking of course
The "Sunshine" Coast of BC.
Right now we're limited by the charging capacity of the inverter/charger. It can only do 50A in from an external solar controller. In hindsight I should have gone with a 48V inverter/charger to get twice the power going in. On a sunny day we're maxing it out at 1200W for several hours at a time.
Hi, from the other coast. I wish I had solar maybe someday. Do you ever watch Artisan Electric from the UK? He tried to run his shop on 100% solar+battery. He ran into a problem where sunny day batteries full shop using power but the panels themselves were throttling. They had no where to send the extra power. He bought a bitcoin floor heater (lol), charged EVs, and some other stuff. https://www.youtube.com/watch?v=evkdqTcMbWM
Yeah that's the point. Most systems are over producing on peak hours of peak days so they can average out to enough power on lower light days. You can buy more batteries, but if you don't have batteries it's waste.