Solar Install - best starting place for easy expasion later

Discussion in 'The Projects Forum' started by Upex, Sep 24, 2014.

  1. Upex

    Thread Starter Member

    Nov 10, 2013
    67
    3
    Hi All,

    Apologies if this has been covered in dribs and drabs across other posts, but having read a few pages of threads my head hurts and I'm no closer to an answer, so would apreaciate your input and guidance please:

    My garage has no electricity and will cost ££££'s to have installed - scrap that idea. So, I've just bought an 80 watt panel (12v) and bolted it to my garage door. Unfortunately, this points due North and is the only side I can put it on (far from idea) so is only ever going to be picking up ambient / indirect light.

    I want to be able to gradually build up the system to accomodate more and more as time goes by (as far as the light allows) so am wondering where to start so that expansion is as easy and releatively cost efficient as possible moving forward.

    My ideal (ultimate goal) is to have 5 x 80 watt panels (the most I can fit on the door) and have these charge 2 banks of batteries. 1 larger bank to power an inverter that will be used circa once every 2-3 weeks (i.e. hover the car out or a power tool) and a smaller bank that will power low current lighting in the garage and also provide a 12v charging facility for drill batteries etc.

    I'm stuck on what type of set up to start with so that expansion is easy. I have 1 panel and a 30amp charge controller at present, so I can link these up to a battery which is fine for now. But when I get a second panel, or want to start building up the second battery bank, will this mean a new controller (1 per bank of batteries) and if so does it have to be exactly the same as the current one?

    Also, is it possible that I can feed in 1, then 2 , then 3 etc panels into 2 controllers that then feed the 2 battery banks as I add new panels?

    I'm keen that I don't cook or neglect a bank of batteries by having a poor set up and also that I share the panels, so when one bank is full, those panels arent going to waste etc (there won't be enough sun to waste!).

    Hopefully this makes sense and is possible, as I don't want 1 panel, 1 cc and 1 battery bank set up twice, they need to share the power as it were!

    Many thanks,

    Upex
     
  2. wayneh

    Expert

    Sep 9, 2010
    12,151
    3,058
    For a given power rating, I find it hard to believe that a solar installation will be less expensive, especially with your poor exposure issue. If cost is really the driving force, I'd go back and look for options.
     
  3. Upex

    Thread Starter Member

    Nov 10, 2013
    67
    3
    circa £3,000+ for ele any to instal, maybe more if they dig up the path and hit any troubles, plus electriction costs to put in (or at least certify my instal) of a fuse board / breaker and such. Plus this would need to be paid in one go!

    Given that I can only fit a max of 5 panels on the garage door = at circa £50 each, thats £250, plus batteries and charge controllers - I think £600 - £800 wouldnt be far off. Plus I can buy a batter or panel at a time and spread the cost.

    I have a geni, but the fumes and noise make this not suitable for just powering a few lights and charging my drill etc.

    Open to other ideas, but the solar is winning hands down thus far, especially considering the infrequent powerful use (manily low - lights etc) and not too mention that I can take it with me when / if I ever move, which I can't to a mains feed.
     
  4. wayneh

    Expert

    Sep 9, 2010
    12,151
    3,058
    Are you completely free to install a system without the same certification required of a regular installation? This varies from location to location.

    I think you'll need to design the final, expanded system first and then ask how you can build it incrementally. It's just a change in perspective from starting with a small system and then looking how to expand it. But I think viewing that way, from the endpoint back to the start, will be easier in the long run than going the other way.

    Have you looked at the many sites out there devoted to alternative energy installations? I've seen some excellent resources.
     
  5. nsaspook

    AAC Fanatic!

    Aug 27, 2009
    2,912
    2,176
    Batteries are a consumable so I would have one bank driving two inverters with cells designed for RE cycling. A larger inverter for heavy loads of 300W or more and a smaller one for under that power level for things like LED lighting and small battery charging. I would also use a single battery string of at least 24vdc to reduce the current and wire size requirements for the DC side and use only AC power for all loads as this makes the power distribution simple (using standard wiring, panels, breakers and receptacles) and compatible with utility power or the generator if the solar is down with a simple transfer switch. I would use a MPPT controller that can take at least 150vdc input so you can wire the panels in serial strings to make it easier to relocate them to a location that optimizes the solar Insolation.
     
  6. wayneh

    Expert

    Sep 9, 2010
    12,151
    3,058
    My approach:
    83803-extension-cord.jpg
     
  7. Brownout

    Well-Known Member

    Jan 10, 2012
    2,375
    998
    I would use one battery bank and one inverter. What's the point of having two systems? Inverters are very efficient.
     
    Johann likes this.
  8. nsaspook

    AAC Fanatic!

    Aug 27, 2009
    2,912
    2,176
    The are very efficient at full power but a small inverter will usually have a much lower quiescent power draw and most have sleep modes that can reduce the power on to only a few watts with no load. So you would leave the large inverter with dedicated outlets for high power devices off until needed and leave the small one on at all times. For a system like this small 'vampire' loads can add up quickly.
     
  9. MrChips

    Moderator

    Oct 2, 2009
    12,449
    3,365
    Sensacell and wayneh like this.
  10. Upex

    Thread Starter Member

    Nov 10, 2013
    67
    3
    Thanks for all the input thus far folks, much appreciated.

    To answer a few, I've considered an extension, but the electrician said it's a no no really, as the cable run would need to be 120+ meters without making it tidy (ie going right across doorways etc) if wanted to run it properly, it be circa 150 meters, and I can't leave it out as crosses someone else land. He said the voltage drop means heavy cable, not easy handling to put in and out as needed and not cheap. Given in the large I only want some light, this isn't worth it in practice.

    My 'end design' would be that I have between 1-5 80w panels on the door (guess the number will be driven by how much light they pick up, so we'll see I guess). I'd have a battery bank of deep cycle leisure bats that power an inverter so I have a plug for a Hoover or drill etc. Infrequent use this, so if it takes 2 weeks to charge up, that's fine.

    I also want another 'branch' if you get my drift, that will charge another battery, smallish car type size or two, that will be the power some 12v low current led lights, little and often, and I also was hoping this would then give a little source for small 12v battery charging, like a have a twin 12v bike light, so can hook it up to that smaller set, even if the bigger bank is depleted from hovering etc. Doesn't need charging that often and is far less than the batteries would hold, so I think should be fine.

    Hope this makes sense.

    I think (definitely think as do not know, thus my request for your help) that all the panels need to feed into one (so all power is 'merged'), this would then need to feed into 2 separate charge controllers, 1 for the deep cycles inverter bank, and the other for the smaller batteries for much lighter, direct 12v use.

    I don't know if the above is true, or correct, but if it is, I'm unsure if the charge controllers have to be exactly the same, or how to merge the power from panels and then split off to the two charge controllers.

    Many thanks for your help folks and fingers crossed I'm not too far off.

    Cheers, Upex
     
  11. Upex

    Thread Starter Member

    Nov 10, 2013
    67
    3
    Wayneh , yeah I'm fine as long as it's standing alone, doesn't go near the mains and I keep to the places and sizes I've detailed. I'm not allowed to put on the south wall, as is someone else's wall, although would be ideally positioned, and would face the thoroughfare that's behind, so not good for people smashing it etc.

    So as long as I keep to the north facing door and it's temp instal, ie no buried cables etc I'll be fine.

    Having a darn wire put in has lots of red tape though, and the cost.

    I've been looking at various sites for the last couple of months and have got a little understanding, around sizing etc, which is blown right out as my exposure is an unknown, but can't seem to find much on having to banks linked but separate on the same panels. Severalmentions around boats with separate start and utility bats etc, but I can't seem to get it (either through understanding or them not being the same as I'm after). Sorry if this info is easily available, and I'd happy accept direction to it if someone can lead the way, not after wasting anyone's time, just a helping hand, in whatever shape that takes.

    Cheers, Upex
     
  12. wayneh

    Expert

    Sep 9, 2010
    12,151
    3,058
    I don't understand where there would be any benefit from parallel systems - more than one battery/controller/inverter. To me it sounds like having different gas cans for different engines, or keeping different dollars in different pockets. Every piece of equipment you add will have losses.
     
    Johann likes this.
  13. crutschow

    Expert

    Mar 14, 2008
    13,050
    3,244
    If the panels get no direct sunlight they will generate very little power. Have you measured the output of the panel you have?
     
  14. wayneh

    Expert

    Sep 9, 2010
    12,151
    3,058
    A mirror or white surface could add a lot. Can you put anything opposite the garage door?
     
  15. nsaspook

    AAC Fanatic!

    Aug 27, 2009
    2,912
    2,176
    Your current design is doomed to fail unless you optimize the solar power generation and power storage. You MUST move the panels to a location that will generate the most daily power or you will murder your batteries in short order. One charge controller with battery current monitor to track usage and one bank of batteries to handle all needs is the best way to do it. A CC like the KID should handle your needs easily. http://www.midnitesolar.com/pdfs/spec_sheet_kid_frontBack.pdf

    My firm suggestion is stay away from DC power from you bank for loads other than inverters unless you use a isolated DC-DC converter to stabilize the output voltage during charge cycles. I've never been a fan of DC power distribution for a project like this, if you need something buy the utility voltage version of it and plug it into a regular socket powered by the inverter.
     
    Last edited: Sep 24, 2014
  16. Upex

    Thread Starter Member

    Nov 10, 2013
    67
    3
    Ok, so if I have one bank, maybe I add another battery than otherwise would, can I run the lights and the inverter and charge my bike lights say, all from the same bank, without needing to unplug/wire each one as needed? Ie so the lights come on when I flick the switch and the inverter is already wired and ready to go etc.

    My conern is that I flatten the bank with the Hoover or drill and then have no lights for days till its charged enough again, as will be a trickle charge lol. Hense why I thought good to keep seperate.

    Regards putting something opposite, its very unlikely to be honest, not much there other than some parking spots.

    I measured the one panel the other day at 70milliamps, but it was foggy. Tried when it was nice and bright and think I got 4-5amps, but would rather check again before taking that as red, as maybe confusing myself, and will do when we get another bright day lol.
     
  17. NorthGuy

    Active Member

    Jun 28, 2014
    604
    121
    You're in South hemisphere, so facing North is towards the equator, right? Otherwise you have absolutely no chance.
     
  18. nsaspook

    AAC Fanatic!

    Aug 27, 2009
    2,912
    2,176
    If you have flatten (>50% SOC) the bank without sufficient capability to recharge them at a proper rate you will murder them quickly. You should never run the bank below 50% SOC except in a emergency so there should always be power for lights. So your battery bank Ah capacity should be about twice what you will use before the system has a chance to recharge.
     
  19. crutschow

    Expert

    Mar 14, 2008
    13,050
    3,244
    The op stated that the panel would "only ever going to be picking up ambient / indirect light" so I assume he's in the Northern hemisphere.
     
  20. Upex

    Thread Starter Member

    Nov 10, 2013
    67
    3
    Ac dc, I forget which is which.

    Northern hemi here.

    Ok, if I forget the inverter, can I simply run 1-5 panels (80-400w) into a battery bank that will provide lights, and some sort of charging ability for my bike lights and other small stuff, ie my 12v ele screwdriver or drill? Least it'd save me lugging those bits to the house whilst still giving me my light, even though no power for Hoover or big drill etc.

    I think Im fairly ok with that idea, panel (later panels) to charge controller. Controller to series of batteries, lights run off of charge controller load output, but how would I charge my bike lights, screwdriver etc, would I use wires from battery bank (like you would jump leads one from positive one to negative) or would I need to link to the charge controller load, ie take out the lights and put in the item to charge and then swapping back and forth etc?

    Can not move the panels to direct light, hense why I'm considering going up to 400w worth, to try and grab more ambient light.

    Cheers for all the help thus far. Getting somewhere I think, even though the Hoover dream died already lol.

    Thanks, Upex
     
Loading...