Solar powered pond - part 1

Well, this is more of a starter-kit experiment....and a venture into figuring out how solar panels, controllers, inverters and batteries all come together.

I initially bought some kit as mentioned HERE.

However as time has moved on I've been learning a thing or two.

 

One thing I've learnt is that I'm a bit of an idiot :-D (no surprise there for my missus).  I now have lots of "spares" in the kitchen as I have go along the journey.  BTW - this is not a cost-saving exercise, unless the price of electricity really goes through the roof by the end of 2022 and all of 2023/2024/2025.  I've spent a lot more than I'll probably ever save, however, this is more about the exploration and knowledge experience, something you cannot put a price on.  I'll keep telling myself that.

So, what did I have and how did it "grow"?

Well, I originally had 2x100W solar panels, an eco-worthy PWM controller and a 12v 110ah leisure battery.  They were setup, as previously mentioned and we're ticking over in the kitchen.  Then the battery hit about 3years and dropped down into the dangerous 10v range.  I thought it was dead.

I then purchased a new battery.  I re-setup the environment outside the kitchen in the garden area.  I already had a 1500w inverter (or inveater as it amusingly says on it) and I had a 2000w pure sine-wave inverter too.  I plugged everything in, I connected up the new battery and I hooked up the 2000w inverter and I then plugged in the pond UV light, as I thought it wasn't going to take much power what with it being 20 or 40watt bulb.  I noticed the inverter was always showing 0amps output so I assumed it was broken, I swapped the 1500w one back into place and carried on.  Then the voltage kept dropping to 11.8v and then down to 10.0v and the inverter starts screaming/beeping LOUDLY!  So, I assumed that there was something wrong and ordered another newer 2000w inverter.  It was BIG.  It looked like it could handle the job.  I re-connected everything and it also showed 0amps being drawn from it when plugged in.  Again, same thing happened, about an hour after plugging in, the inverter powered itself off and we're back down to 10.0v.  I was a little puzzled here.  So I did some sleuthing.  Well, some YouTube-ing and some internet duck-duck-go-ing.

Turns out I was toasting my batteries!  I knew that you only used 50% of the lead battery, but I foolishly assumed that meant I could go from 12v to 6v...silly me.  No, after checking and reviewing, if I get to 11.8v, my battery is considered to be dead.  oops.

I now had two 100/110ah leisure batteries, one only a week old that I had taken down into dangerous territory.  Could they be revived?  I left them plugged into the solar panels for a week or so and then followed the same procedure as before.  Same result, within an hour the inverter was down to 11.8v and time to stop.  I then did some more research and it turns out I should not really be using the 2000w inverter with less then 3 batteries! ah ha.  okay, so I switched back to the little 1500w inverter.  I also now only plugged in some xmas twinkly LED lights, they are mains plugged but they would be a very low power consumption, so I thought I would test to see how long they would last.  They lasted about 2 hours and then no more.

I then wondered if it was the eco-worthy PWM controller that was the "problem" - so I then purchased an MPPT controller as I'd heard they were much better and I could get access and have more visibility to more data, and we all know more data means more insights to what is going on.  Plugged that in..same thing. 

I was not liking this solar stuff, I thought it was better than this.  I had watched YouTube videos of people claiming they had run their home office equipment all day from their setup - also, people have motorhomes (like me!), who run off-grid for 3-4days at a time from their solar panels and batteries, how can I be so bad, what am I doing wrong?

I then thought I'd plug in the C-Tek battery trickle charger that I use for my classic car batteries - after 1 day it brought up the "new" battery back to 12.5v.  It also has a 'recon' mode that aims to do some deep-cycle magic that can recondition the battery - I thought I'd leave that on for a day...oh yes! it brought the battery up to a steady 13.9v.  I repeated the exercise on the "old" battery ad it did the same.  Although I didn't really have much faith that would last, we'll see.

I bit the bullet and whilst driving to a car show, I swung into Halfords and picked up this leisure battery (I had a £20 off voucher, so why not).  Then, when I got home I thought to myself, I'll connect all 3 batteries up in parallel, so still just having 12v, but a lot more capacity and being 300ah.  I connected it all up, I plugged in a new Maxcio adaptor to show me the actual usage of power output - this was VERY helpful to see exactly what the levels the UV light was pulling in wattage/amps.

I then left it all running for just under 2 hours.  The batteries were showing 12.6v at the start.  They showed 12.5v after 2 hours usage.  This was the sort of progress I was looking for originally!

 

As the new Halfords battery allegedly was charged, I did volt meter test it and it did read high, but I thought I'd leave the solar panel setup for the next few days to top-up the batteries slowly to their max. capacity before I then do a full test to see how long it takes to discharge them down before the inverter starts screaming again - although the new MPPT controller should stop that from happening - in theory.

I also picked up from the many YouTube videos that I really should fit some fuses / circuit breakers in the equation.  This is not shown anywhere from any of the manufacturer info. or from any of the solar panel kits that you can buy, so I didn't think it was needed - however, thinking about it, it does make sense.  I've ordered a couple so that I can also disconnect the MPPT controller in isolation and the batteries to the inverter - I'll fit them when they arrive in a few days time.

I was also umming and arrrring about batteries.  I maybe foolishly and a little bit too quickly decided to buy a LiFePO4 50amp lithium battery - which would have been £270 on its own - in a kit that comes with another solar panel, another PWM controller and another 600w inverter.  Yes, yes, yes... that's a lot more duplicate stuff - however, I actually want to have 2 setups, one for the house/pond area and one for the end of the garden relating to the greenhouse and the automated systems I want to build and put into place down there - therefore, I might take the Lithium battery and swap it into the current setup (and change the MPPT settings for this) and use the lead batteries for the greenhouse setup.  Also, the entire kit was £400... so working out the pricing for the extra components, I was getting a little bit more for my money than had I bought then items individually.

As you can see (?) those solar panels need to go up in the air and onto that pagoda - where they were originally - you can also see that once I've trimmed the jungle down a bit and removed the dead wysteria branches, I can line up a lot more panels, this design goes further around to the right also, even double the depth, so potentially can get about 24 more panels if I really want - also that top window on the right is the "home/office" so very easy to feed some cabling up there.

What is it I want to be doing with all of this?  

Well, initially I was going to just purchase a solar panel a month, as I do have room for about 12 on the pagoda behind the kitchen! and then extend the cabling to then run up the kitchen roof into my "home/office" (drill hole in wall under window for wiring to go through) and then have a board that has the MPPT controller, the inverter and a Raspberry Pi (with a USB / 485 serial converter) connected to the MPPT controller to log the data, connected to the Lithium battery(ies) under my desk in the home/office and then I can run my laptop(s), monitor(s) and work stuff from the solar energy - I may still do that.

 

However, the main purpose is actually to make it so that the POND equipment can run totally off-grid.  There are currently 2-3 large pumps and a smaller pump that feeds the UV light and an air/bubble maker thingy.  1 of the larger pumps is not used all that often as it feeds the waterfall / river flow system that I only use once every 2 months or so, same with the air/bubble maker, that's mainly for when it's really hot and we need the oxygen.

Also, there is a hot-tub/spa.  That does have a peak/surge when it needs to kick in the giant kettle to heat the water up, but that is usually for 5 minutes or so every few days, mostly it just ticks along.

So, the aim is really to see if the 2xsolar panels can charge the batteries/battery enough for the 24/7 power drain for the pond equipment and the hot-tub.  As mentioned I assume I'll need a lot more solar panels in reality, we have the space and I'll make slow purchases, also you can connect them up to their own controllers, so I can re-use.

For now though, I can currently stand in my kitchen and look out and see the MPPT remote controller telling me the stat data  - until I can get an RPi setup to collect & transmit the data for me to use it in a smarter way.

The view if I look out the window:

and if I squint hard enough I can see the data being presented:

 

Looks like I'll be learning a lot more about sizes of power cable thickness for the current being pulled through them

As a side note - I only have about 3-4 more weeks to finish the Arduino / Servo project to make an automated fish-feeder - that was how I wandered off into this realm of solar panel stuff, I wanted to make sure I could power the 5V Arduino and servo for a 3 week period of time, whilst I was away in the motorhome.  I just got a little side-tracked!

I'll make a list of all the kit I have acquired, with links to all of it in another article, once I've cleaned everything up and made it all 100% safe and above board.  It does the job okay at the moment, but those messy cables and the usage of really-useful-container-boxes for waterproof protection makes me roll my eyes.