"Self-sufficiency does not mean 'going back' to the acceptance of a lower standard of living. On the contrary, it is the striving for a higher standard of living, for food that is organically grown and good, for the good life in pleasant surroundings... and for the satisfaction that comes from doing difficult and intricate jobs well and successfully." John Seymour ~ Self Sufficiency 2003

Saturday, 14 September 2013

Ramblings on our solar power

Firstly, welcome to my newest followers, Amy Lou from northern New Mexico. Amy Lou is a fellow off-gridder :)
On her blog Solar Rain BucketAmy Lou describes herself, and her blog, as follows:

 "We live off-grid in Northern New Mexico. Solar power. Rain catchment. Composting toilets. All that. Solarrainbucket is where we share what we’ve learned. And post pictures of dogs. And sometimes clouds."

Welcome, Amy Lou - thanks for hitting the followers button.

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Having just lived through our very first winter relying solely on our solar power setup, I thought I'd do a posting on the in's and out's of it.

We had a gradual slink into the winter weather - we got comfortable and thought "Ha! this is a breeze".  Then the overcast, and sometimes rainy days started.  Two or three days of overcast weather plays havoc with the state of the battery charge.
Our original 3 x 140watt
solar panels, secured to
a contraption on the front
patio whilst the building
work was in progress
2 of our original deep cycle
batteries.
Our system started 3-odd years ago, when we could least afford it.  So we opted then to go for 12 volt - panels, charge controller and inverter.  B-I-G mistake. In hindsight (it's always easier, isn't it :) ).
Our 6 X 1660Ah 2 volt battery bank
The most important part of living off grid - be that achieved through using only solar power, or that produced from a wind turbine, or both, is your storage capacity - your batteries.

Our first lot were 12 volt deep cycle batteries.  When we moved here, we changed them out for 6 X 2 volt batteries.  SIX!!!!???!?!?  Idiots, even though they were the major expense in our system, we should have gone for 12, strung the two sets of 6 in parallel (to increase their capacity but not their voltage) so that they retained their 12 volt capabilities, but were also usable in a (future) 24 volt system.  And, it's not as though we can buy another 6 now and add them. That would be a complete waste of time, as the newer ones would be affected by the older, more used ones - to the detriment of the new ones.  Also, buying 12 news ones is out of our budget at the moment...

Also, we should've purchased a charge controller and inverter which allowed for either 12 or 24 volt. They are available, but are, naturally, more expensive.  Sigh - it's all about affordability.  But, with that said, don't do what we did, rather scrimp on other things, and buy for the future of your power requirements, not just for the moment.
Seven 140watt solar panels mounted on the
roof of our garage.  Excellent north facing
45° 
angle to the roof, but the accessibility is
horrendous...
Our 7 X 140 watt panels are connected in series (i.e. + to - in order to increase the volts) and mounted at the 'ideal' 45° angle facing north (in the southern hemisphere), but, being mounted on our garage roof, they are also awkwardly inaccessible.  We figured 7 X 12 volt = 84 volts = well within our charge controllers capabilities.  But, we didn't know that solar panels are as cold as their surrounding temperature in winter, and due to this cold, you can have a situation where their voltage spikes in the early morning ( 8 - 9 a.m.) - which causes, in our case, their combined output to hit over 145 volts - and our maximum is 150. This causes the charge controller to shut down because it is receiving too high a voltage.  Shutting down means we are not charging our batteries when they need it most - after a long, dark night LOL  We have found that if we physically trip the fuse from the panels to the charge controller and allow the charge controller to "reboot" then the power surges into the batteries with little or no problem.  This action is not ideal though.  If we left the charge controller to "fix" itself, it will, but, in the meantime we are losing precious charge from entering the batteries during those long winter days of dramatically reduced solar input.
Our Outback charge controller
What we have also determined (through speaking to a very helpful gentleman called Lloyd from a ADSolar in KwaZulu Natal ) is that we can wire half (4) of the panels in series, and the other 4 panels in parallel - that way we will get the best of both - volts and amps. This, hopefully, will prevent the voltage from spiking next winter.

In summer, this will not be a problem.
Installing the 5 panels was a mission when we had
7 helpers (two are taking the slack off the rope
behind the garage). RMan, RSon and Wayne -
that's going to be interesting...
So, RMan and RSon and Wayne - guess what you will need to do this summer? Take the existing 7 X 140 watt panels down, add the soon-to-be-purchased 8th panel, and then rewire the 8 panels in series and parallel respectively, and re-install them...

Not a task they, (nor I - it's fraught work watching our solar panels being manhandled off and on the roof), am looking forward to... :)

On the positive side, we didn't run out of power this past winter, but some days it has been decidedly dicey.  And, to reduce the demand, we had to be very careful about what we switch on, and when.
The 600watt battery charger -
even though we only used it a few times, it
certainly was worth it's cost
We also purchased a 600watt battery charger, which is operated through switching on our petrol generator.  A very occasional (as in 6-7 times during the entire winter period) hour or two of charge happily gets us (the fridge) through the night... :)

So, although we discovered the con's of our system, we managed.  It was, through the monitoring of our remote control SoC apparatus in the house, careful use / prioritizing appliance use, and the assistance of the battery charger, all do-able.

Life was very comfortable, with all the important appliances fuctioning when required and the Rosie creating a wonderful, warm and cosy home - even with snow on the mountains...

30 comments:

  1. You are doing, with off-grid solar power, what I would aspire to do, if life had turned out slightly differently. We have the solar panel and deep cycle battery in the Land Rover (for the fridge)

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    1. Diana - Even with the limitations of our batteries you would not believe the feeling of freedom living off grid provides.

      You've made a start with your Landie fridge... :)

      Delete
  2. Oh, that darn "hindsight"!!
    I still think it's absolutely amazing that you guys are doing solar. It all sounds so hi-tech-I'd be intimidated. I admire what you're doing and hope that things improve for you.

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    1. Sue - Yeah, hindsight...!

      Nah, once you get into what you are doing, it becomes easy. Trust me, I am not handyman / techno savvy, but you can't help pick up a bit of info on the path of discovery... :)

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  3. Replies
    1. Shirley - Thanks for visiting and for taking the time to leave a comment.

      Sharing our experiences will, hopefully, assist someone else and prevent them from making the same mistake we did :)

      Delete
  4. Dani,that's a great, detailed post on something that a lot of people are very much interested in. I am going to link to it so people I know who are working on off grid can be benefit from your experience.

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    1. Harry - Thanks - appreciate it :)

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  5. Hello Dani. The solar systems can be a little tricky to get them just right. I agree totally on not scrimping on batteries too much too. I feel I lucked out pretty good with my system here, as it all works good here, in the summer time especially, but for me winter is coming on soon, and I don't care how many solar panels I have, I'm still gonna be running my small gas generator for an hour or 3 a day soon (in a month or so). I just accept the fact that where I am, I have 3 or 4 months period that I call generator season. If the sun were to shine bright each and every day in the winter, I would get maybe 3 or 4 hours of sunlight per day, and it is low. That's not really that much, and then to top it all off, the overcast skies, the snow on the panels etc., so my panels really don't see much sunshine in the winter. I have six 240 watt panels going to the same type charge controller that you have. Just so you can compare, I have them hooked in three strings of two panels. It would be safe for me to have 2 strings of 3 panels, but the way I have them is working good too. Each string is putting out about 72 volts at there peak. My batts and inverter are a 24 volt system. Just thought I would share some info with you. Something to me just don't sound quite right about the way you want to hook up your 8 panels. Now, I'm not totally sure about this, but I think what Lloyd is trying to say, is that you hook half your panels in series, and then the other half in series also, then you paralell those two sets of series(strings). That would give you two strings of 4 panels. Maybe this is what you meant to say, but to me something just didn't sound right. That's just the way I see it myself, but maybe I'm missing something.

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    1. FCD - Thanks for your detailed reply. I am going to check with Lloyd and will post a correction if I got his info wrong... ;)

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    2. Some clarity on solar panels strings. These are for battery based systems. On the back of a solar panel you have two values to take note of. The Voc or open circuit voltage and the Vmp or Pmax value.
      As panels do vary in voltage no blanket rule can be applied. A string is defined as the base electrical solar panel block and its panels are in series. The total combined Voc must be 15% or less than the maximum charger controller voltage but at the same time the combined Vmp must exceed the systems programmed equalization voltage by 15%. A 240W panel is normally called a 24V panel that has a Voc of 35-38 VDC and a Vmp voltage of 28-32 VDC. So we would have 2-3 panels as a sting on a 24VDC system. The project above are 140W Panels and they are called 12VDC panels which have a Voc of 18-21 VDC and a Vmp of 15-16 VDC so now a string on a 24VDC system must be 3-5 Panels. They have 8 so then a string must be 4, so 2 strings of 4 will be right. Lloyd Adsolar EPC

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    3. Lloyd - Many thanks for taking the time to read my post and comment - really appreciate it.

      One last question - did I misunderstand what RMan relayed to me after one of your many conversations - CAN we string 4 panels in series and 4 panels in parallel (retaining the 12volt configuration) and then connect both to our 80Amp Outback CC?

      Delete
    4. The charging amps of a system is the output of the CC and the comment on the strings is the input. On the MPPT ability of the Outback Flexmax 80 the input voltage needs not to be directly related to the system output. On the output the total watts of the panels must be divided by the system voltage and that must not exceed the max amps of the CC. So a 80A CC at a system voltage of 12VDC must not exceed 960 watts. At 24 VDC system voltage the limit of the total watts is around 2KW and @ a system voltage of 48 Volts its 4KW. I saying this, an Outback in the real world does a bit better with Max array size of 4800 watts at 48VDC system and 2400 Watts on a 24VDC system and 1200 Watts @ a 12VDC system. So now its about the total wattage, so you have 8 x 140watt panels so a total of 1120 watts on, and only on a Flexmax 80 will you be okay. Any other CC @ 80 amps you will have problem as you are over 80amps, so only 2 x strings of 4 at the 140w per panel. Your 8 panels are in figures over the limit of 80 amps but the Flexmax 80 will cope, but you need to adjust the maximum amps to 99% as the default is lower.

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    5. Lloyd - Thanks - I think... LOL

      The general gist of what you wrote seems to imply we are OK providing we make that 99% adjustment?!?!?!

      Delete
  6. Oh my. Seems like the 'simple life' requires an engineering/electrical degree these days. So much of our stuff requires electricity and we jump through hoops to get it. I doff my chapeau to you and Rman for taking on these challenges. When will the windmill go up? It doesn't need sunny days. *grin*

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    1. Kris - My brain hurts too.......! Every time I think I'm understanding it more, the more I find I R-E-A-L-L-Y don't know.

      Nope - the win here is too gusty, and one of our neighbour's previous (small 500watt) wind turbine was destroyed within 6 months. Plus we'd need to purchase a separate charge controller.

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  7. I really admire what y'all have done. Congrats for making it through your first winter off grid and I hope the upgrade goes well for you.

    When we transitioned to this life several years ago putting in solar panels was one of the things I intended to do. But I didn't make it a priority and now it's not in the budget.

    If we ever get it done, we'll put the panels on our barn, rather than the house, because the barn has a great Southern exposure and the house is shaded. So I was interested to see that yours are on your garage. But I hadn't considered how difficult it would be to access them there. Our barn roof is steep and pitched like your garage roof.

    Thanks for the great informative post.

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    1. Bill - You're very welcome :)

      Perhaps you should do what my son-in-law has done and that is to mount them at ground level in your sunniest spot. That way getting to the back of the panel is a breeze :)

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  8. Dani, Very impressive ! Tell me, we have very bad lightning here which took out our original whole house inverter which could power our house off an array of marine batteries. We now have lightning rods and multiple lightning arrestors which makes strikes less likely though not impossible. We still have a dead Outback inverter ! How is the lightning there ? Is this a problem at all in your area for homes, electrical systems, inverters or equipment ?

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    1. Jane - Lightning is not that great a problem here, but we do have our system wired to earth via a copper wire which is buried underground and runs for roughly 35 mtrs.

      Plus, we have a number of fuses on the system (from the panels to the Outback and from the Outback to the batteries).

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    2. That's very well grounded indeed, Dani. Thank you for your answer.

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    3. Jane : Does your system have lightning arrestors? That is, wired by the panels, and then perhaps another closer to the main equipment?

      Up here in Colorado, the lightning is intense. I gather the reason Tesla came out to do all his experiments.

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  9. Such an interesting post Dani. Indeed helpful. Our first winter here we had no sun for 2 or 3 months. It was terribly cold and I missed even the passive solar warmth through the windows! That experience really put a damper on solar plans for us. This summer has been the same. Lots of rain and very little sun.

    Real life experiences like yours are so much more valuable than a manufacturer's website or an "expert's" sales pitch. And your commitment makes it seem doable for the rest of us.

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    1. Leigh - A follower of mine posted a link to this posting, and he got a reply from an "anonymous" that all we are powering is one big room - and only a fridge.

      We are actually living on the solar power that is generated by our panels and stored by our batteries. Be that power for our fridge, TV, cable box, , internet connection, wi-fi, lights, chargers, PC, printer, laptop, water pump and washing machine.

      Only in the worst weather have we had to switch on our genny in order to charge our batteries for 1 - 2 hours. So we are pleased :)

      The more that people "out there" share their experiences and info, the less scary it will be, and hopefully, the more people will "take the plunge" LOL

      I have to admit, that without my Rosie winter could've been very miserable - thank goodness for Rosie! :)

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  10. Thank you for this information. We are still in the very early planning stages i.e. still looking for the perfect piece of ground in the Western Cape :) But I am trying to find out what we will need to live off grid, and how much it will cost. Scary stuff ...... we really can't afford to make mistakes at this stage so any information we can get is a bonus. I have spent a lot of time browsing your blog and will definitely be contacting you at a later stage about an oven and recipe books.

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    1. Rosemary - Welcome, and thank you for taking the time to leave a comment.

      Rosemary, there are various ins and outs regarding solar power - may I suggest that you read all the posts on my blog on that topic. It was only when we acually depended on solar power that we learnt what the suppliers didn't tell us... :)

      Please - also don't make the mistake we did - if you do install a solar power system, go for a minimum of 24 volt - not 12 volt as we did. That will give you better options for upgrading if, and when, you need to...

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  11. Fantastic article. Thank you. I am interested in going of the grid as well and ended up here. We have irregular power cuts scheduled here in sunny South Africa yet again due to lack of planning and maintenance and therefore the power demand being more than can be delivered. So we are getting 'load shedded' for the next 2 to 3 years in order for ESKOM to catch up with maintenance.
    I guess my biggest question is this:
    What is the benefit of having 6 or 12 2V batteries opposed to having 1 or 2 12V deep cycle batteries? I am really struggling to find 2V batteries.

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    1. JD Zeeman - Thanks for taking the time to leave a comment.

      JD, the difference between 12 volt 1060 Ah deep cycle batteries and 2 volt 1660 Ah batteries is that the 2 volt have a far greater storage ability and are more heavy duty. Far more suitable for an off-grid situation than the smaller 12 volt deep cycle batteries - irrespective of their Ah capacity. The batteries are from a company in Port Elizabeth - sorry, I can't remember their name. But, any reputable solar power company should be able to source you 2 volt heavy duty batteries.

      For the latest, and last, update on our solar power installation please go to: http://ecofootprintsa.blogspot.com/2014/06/powered-up.html

      We have finally got it right. Trial and errors recorded on this blog are finally complete and this set up is the final posting.

      Good luck with your move off-grid. Whatever it costs, you won't regret it. And who knows, perhaps one day when the "authorities" finally wake up, you may be selling your excess power back to the grid. If we had stayed on the grid, and continued using 15KwH / day as we were doing in town, by half way through the 7th year we would have spent more than our solar power system cost. Therefore, from year 7 on our off-grid smallholding, in our book, our solar power is free :)

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    2. Fantastic!
      Thank you for the quick reply.

      Delete

Thank you for taking the time to comment - it makes my day and removes the "loneliness' of sitting at my screen blogging supposedly to myself ;)