Newbie attempting to plan a solar rig

A5c11 · January 2016

Hello, this is my first point on this forum - so hi everybody

So, I've been reading about solar panels, and related technology for a few weeks now - but I'm still very much a novice. I have never attempted to generate electricity using any of the methods I explore so even the things I do 'know' can be considered theory at best and nonsense at worst.

What I would like to do is describe what I intend to build, so that people more knowledgeable than me (you) can advise me on whether this proposal is feasible - and where the stumbling blocks may be.

To begin with, I live in a town house and the model will be built over 3 levels - the roof, the 2nd floor and the 1st floor. Access to the roof is via the 3rd floor (you can think of the roof as the 3rd floor if it makes it easier to visualise.

First of all I will list the equipment I intend to use, as well as a link to where I intend to buy it from-

- Maplin 600w modified sine wave inverter (I know that pure sine is the better option but for my purposes and from what I have read I consider that this type of device would be okay - unless I am told differently)
http://www.maplin.co.uk/p/maplin-12v-modified-sinewave-600w-inverter-a18fg?gclid=CNim5s2j1MoCFcSRGwodeb4A6g

- ABS 110ah 12v leisure battery (perhaps a bit small but for the budget I have and the solar panels its about the most I can hope for, I think)
https://advancedbatterysupplies.co.uk/product/abs-lp110/?gclid=CIqyt4yk1MoCFScXwwodG6cFXg

- 175W 12V Monocrystalline Solar Panel (x 3)
http://www.bimblesolar.com/solar/individual/shanghai175w

- Solar 60 60a Charge Controller
http://www.bimblesolar.com/offgrid/chargers/solar60

As you can see, I haven't included in my plan anything to do with wire or fuses, and this is basically because I have no idea of what kind of fuse I should use or where - and what kind of wire would be suitable for my rig?

Some of the many questions I am trying to find answers to are-

1) Some of my cable runs are long, the longest is probably 30ft('ish) how much of a problem is this for transferring my harvested electricity?

2) Are my batteries best kept out on the roof, or inside the house (locked away in a cupboard). I always intended to keep them inside the house but now I'm wondering what is safest for us, and best for the batteries?

3) So I've read bits and pieces over time and some of it makes this stuff sound a bit dodgy. Is having a rig like this to power indoor electrical items dangerous? Should I be considering doing this as a novice?

This post is getting pretty long so I may leave it there for the moment.

Many thanks in advanced for any advice.

Blindowl1234 · January 2016

I'm pretty new at this too but are you in the U.S or the U.K? Reason I asked is your battery and inverter I guess are coming from the U.K. Just me but as I slowly build my system I'm going to try and get what I need in the U.S. I've got stuff from China etc...it always takes longer than I thought and gets stuck in customs. Just my two cents worth and I'll let the others answer your other questions

A5c11 · January 2016

Hi Blindowl1234, I live in the UK.

This post sounds a little bit weird when I read it back because it almost comes across, why did I even bother mentioning my house without properly detailing the rig - this is because I intended to write alot more than I actually did but I had to run off and deal with one of the kids, story of my life!

Continuing on from above....

* I would like to have the solar panels (3 of them to begin with) on the 3rd floor - or - roof.

* The battery (1 to begin with) will be on the second floor secured inside a lockable cupboard (out of childrens way!) along with the charge controller.

* The cable carrying the electricity will feed from the battery down to the 1st floor (our bedroom floor) where it will come into our bedroom and through the inverter to my computer (the first hardware I'm trying to move to solar power).

* I'm going to add a UPS to my computer to plug any gaps between switching from solar/battery to grid. I would like to have a switch to flick from solar to grid. The idea is when the juice stops flowing from my internal rig, the UPS keeps the PC alive for 5 minutes - enough time for me to flick the switch to the grid, and the UPS goes to standby again.

vtmaps · January 2016

A5c11 said:

The cable carrying the electricity will feed from the battery down to the 1st floor (our bedroom floor) where it will come into our bedroom and through the inverter to my computer (the first hardware I'm trying to move to solar power).

Not feasible. The cables between the battery and the load (inverter) need to be very fat and very short.

--vtMaps

A5c11 · January 2016

Hey vtmaps, thanks for your response.
Can a normal electric cable (13amp) run from the 240v side of the inverter? In other words can I curb the problem by keeping the inverter with the battery and the charge controller, and running the mains cable to the bedroom?

Also, when you say the cable needs to be thick, how thick does it need to be? Could you recommend something, I really have no idea what type of cable I'm looking for.

South Africa · January 2016

A5c11. Welcome.

I 'hear' what you are trying to do. Cables are easy, once the rest is in place.

You are starting out small, which is wise, but trust me, when you see it working, you are going to expand. Been there, done that.

If I was you, I would start with a pure sine wave inverter with a MPPT charge controller. Why? You are going to connect your fridge one day, and before that, your lights ... and some bulbs do not like modified sine wave, they may flicker a bit.

MPPT will allow longer cable runs from panels to batts and you are going to add more panels in the next year or two.

Cable between batts and inverter, normally are included with inverter, or the manual will tell you what is required.
Cable from inverter AC output to your equipment, is normal regulation (for where you live) AC wire.

vtmaps · January 2016

A5c11 said:

In other words can I curb the problem by keeping the inverter with the battery and the charge controller, and running the mains cable to the bedroom?

That is the conventional and preferred way to do it. By the way, charge controllers and inverters can be noisy... While you are lying in bed, trying to go to sleep, ask not for whom the inverter hums, it hums for thee.

A5c11 said:

Also, when you say the cable needs to be thick, how thick does it need to be? Could you recommend something, I really have no idea what type of cable I'm looking for.

Your inverter installation manual will specify the cable size and length, and also the circuit breaker size. Most inverter manuals are available on line.

--vtMaps

westbranch · January 2016

If you can not use the (2 too short) cables that come with the inverter, come back here and give us all the info as longer cables may need to be of a larger size (length dependent) and that size needs to be calculated...

A5c11 · January 2016

Will do - thanks. Wasn't aware that the inverter would come with cables at all.
I've been watching some tech video's on youtube and I figure for a 600w inverter I will need 60amp cables.
If I want to be double safe and go with 100amp cables, is that a good idea?
Something I'm a little bit unsure of -

Do I just connect the battery, solar panels, and inverter/load to the charge controller - or am I missing a component in that model?

vtmaps · January 2016

A5c11 said:
Do I just connect the battery, solar panels, and inverter/load to the charge controller - or am I missing a component in that model?

You are missing circuit breakers. Anything and everything that is connected to a battery needs circuit breakers.

--vtMaps

westbranch · February 2016

A5c11, please consider this 'little' project as grade 1 or kindergarten.... in solar schooling... we want you to succeed AND be SAFE!
VTmaps brought up a very important point and that is the need for circuit breakers on ALL connections to the positive battery post. There are a lot of types to select from, the choice is yours please go here and look at the range and types
http://www.solar-electric.com/installation-parts-and-equipment/midnite.html
and here
http://www.solar-electric.com/solar-information-faq-learning-section.html/

happy reading

Raj174 · February 2016

A5c11,

It is good you have come here first, before buying anything. The biggest mistake that newcomers to solar make is that they spend money on equipment that they do not need before they understand how it all works.

If you take your time and learn what is available and how to put it together then you will be better able to determine what will meet your needs, and how to go about it. It took me 2 or 3 months before I learned enough about solar power to design a system to meet my needs, and that was with help This forum is a resource, so are equipment manufacturers. Take your time and use them to your advantage.

South Africa · February 2016

And the golden rule before you start: The cost of solar installation is directly like to Needs vs Wants.

Needs are quite a bit cheaper than Wants.

)

First reduce Wants to Needs, then solarize.

It is a very rewarding and enlightening journey for Electricity, she is a very dangerous and wickedly expensive mistress, and she does not let you go once you have stared into her eyes.

A5c11 · February 2016

Thanks for all your help guys

I'm just exploring circuit breakers this morning.
Do I need to have a separate circuit breaker for each of my solar panels?
I could have a 20A circuit breaker for each solar panel. Or should I just get a 60A circuit break and run all of them through it?
Sorry if these questions sound a little dumb - circuits are not really my forte.
I'm guessing I need a breaker between my charge controller and the battery too - I don't have much idea of what size breaker that needs to be - would be that be relational to the wattage of the device?

Thanks.

South Africa · February 2016

It depends.

A5c11, all your questions can be answered by the fundi's here, but to do that, you need to give panels, inverter, controller, battery bank specs.

So you cannot get a 20A breaker / fuse and use it everywhere. You may have your house burn down, with the breakers still perfectly happy, because the wires melted.

The wire thickness used dictates the amps of the breakers.
And wire sizes differ between panels to controller and between controller and batts to inverter ... and then from inverter AC to your equipment.

Or you may decide to go fuses.

vtmaps · February 2016

A5c11 said:
Do I need to have a separate circuit breaker for each of my solar panels?
I could have a 20A circuit breaker for each solar panel. Or should I just get a 60A circuit break and run all of them through it?

If you have three or more panels in parallel, then you must have a combiner box with fuses or circuit breakers. This is because if one panel shorts out, the combined current from the other panels could cause a fire in the shorted panel or its wiring. The combiner box should be weatherproof and near the panels.

The combined output of the panels runs through a cable to the charge controller (but going through a circuit breaker that is near the controller). This circuit breaker serves as a switch to turn on/off the PV input to the controller.

A5c11 said:
I'm guessing I need a breaker between my charge controller and the battery too - I don't have much idea of what size breaker that needs to be - would be that be relational to the wattage of the device?

Anything and everything that is connected to the battery needs a fuse or circuit breaker. The purpose of the breaker is to protect the wiring from overcurrent. Therefore, the size of the breaker depends on the size of the wire. The size of the wire depends on how much current the controller can produce. (and also on the distance between controller and battery, because if the distance is too long you may need thicker wire to reduce the resistance).

Your charge controller should come with recommendations for cable size and length, and size of circuit breaker. If not, I can calculate it if I know the output rating of your controller, the distance to your battery, and the voltage of the battery.

--vtMaps

Raj174 · February 2016

Also you must use DC rated breakers for DC circuits. AC breakers in DC circuits could easily burn up and cause a fire.

A5c11 · February 2016

Hey guys,

Thanks for all the feedback on this thread.
There are a couple of things I wondered, and I'm not sure how well you will know the answer to one of them since it is quite region specific but perhaps even an insight into the situation in your region would provide some idea..

So two things are bugging me most about my rig - I'm anxious to get started but I'm also anxious about the implications of getting it wrong - I don't intend on getting it wrong which is why I'm doing much research first.

1) My original idea for this thing, was to have it inside my house. I wanted to store the battery, inverter and charge controller in my top level bathroom - this has a lockable cupboard with a doorway onto the lower roof so is idea for the rig to live. I'm somewhat unsure whether this is a good idea or not. The top level of my house is where my children sleep - in other words the last place I would want a fire to occur. I hear fire being talked about alot in relation to solar rigs, and I wonder how real the danger is. What do you guys think about this? Is having vital components of your rig on the same level as your children's bedrooms a bad idea? Should it even be indoors at all? I have an out housing made of brick and cement which I intend to use to "test the water". If the system runs fine in there for a month or so with no problems can I consider it safe, or is that a bad assumption?

2) As with the large majority of people in this country - the UK - I rent my home from a private land lord. This is very common here, few people can afford to buy homes. Is it a bad idea to have a solar rig in a rented home? Would you imagine that a land lord be opposed to such things?

Thanks as always,

littleharbor2 · February 2016

The "so called 12 volt" solar panels you have shown aren't 12 volt nominal and quite frankly are in a very uncommon voltage range. the listing specs are 23 volt vmp and 29.3 voc. This isn't a deal killer if you use a MPPT charge controller. Someone at "Bimble Solar" needs to be flogged for claiming these are 12 volt panels though.

Raj174 · February 2016

If it is done correctly with the proper wiring and safety devices then the risk of fire will be minimized. However as with anything electrical, a fire is of course, still a possibility. The idea of a test setup is a good one. It will allow you time to gain knowledge and experience which can help prevent mistakes in more critical situations later on. As far as the landlord goes he might not mind a hobby setup, but running wire floor to floor might be something to run by him first.
I agree with littleharbor2 about those panels. You get might 300 watts total out of them with a PWM controller.

BB. · February 2016

Wiring solar is very much like wiring a boat... If done correctly, the chances of fire are pretty low.

However, if wired wrong, or if something goes wrong (such as battery over charges, vents electrolyte, potential fire/explosion in a wooden cabinet)--Then it can be a tragedy for you and your family no matter how rare the event.

Personally, I would suggest that you install the battery/charge controller/inverter outside the house--And just run the 220 VAC into your home as needed. Especially if you are not really comfortable with wiring up DC power systems at this time (even a single "car sized" lead acid battery can get a typical home size wire glowing red hot if there is a dead short).

Flooded Cell Lead Acid batteries are pretty safe--But they do vent gases (hydrogen and oxygen) and a little electrolyte mist (water+sulfuric acid). They are relatively safe--But the electrolyte fumes can smell like rotten eggs and corrode/ruin nearby metal and other stuff.

Sealed Lead Acid Batteries (typically AGM type used for solar) are very nice in that they don't normally gas/vent fumes. And, in some ways are better than flooded cell (battery charging/discharging current support).

However, either battery type can vent if over charged and/or the electrolyte "boiled out". So, I would suggest that Sealed batteries are vented somehow--And that you prepare for "end of life" events (batteries vent/out-gas as they get towards end of life) or other failures (charge controller fails and over charges battery).

-Bill

A5c11 · February 2016

Hey guys,

Thanks for some interesting information. I think I'll be taking your advice and having my rig outside in my out-house, certainly at first if not for the duration. I guess I'll run an electric cable into the house (weather proof, ofcourse) I think I'm probably perfectly safe with that type of a setup as long as my house feed mains cable is correctly fused so as not to over-heat and catch fire.

Bill - Something I wasn't sure about - you say that if the Charge Controller fails the battery over charges and causes problems for me. Is there something I can do to prevent this happening? A fuse between the charge controller and the battery perhaps?

Thanks again, sorry to be a pain

BB. · February 2016

We rule of thumb 5% to 13% of a battery's 20 Hour discharge rate (100 AH battery, 5 to 13 amps charging current).

Once a battery is fully charged, even a 2.5 to 5% rate of charge is enough to boil a battery dry/overheat/possibly cause a fire. One company that makes equipment/services large commercial battery banks said that if they see a continuous current of 2% or more (float charging), that they replace the battery bank immediately--In their experience, overheating/fire sometime in the near future is a strong possibility.

All it takes is a transistor (or diode) to short in a charge controller, and you now have current directly from the solar panel to the battery bank. Does it happen often, no... But it can happen so it is not a bad idea to ensure there is no flammable material nearby/under the battery/charge controller/etc.). Having a non-flammable wall--we use gypsum board in the US--And a non-flammable floor under the system--even use cheap floor tile--Will help prevent failures from becoming worse.

There are ways around the failing charge controller--You can put a second "dump" controller on the battery bank--If the battery over charges, the dump controller turns on and feeds a resistor bank. But nobody would ever do that. Just monitoring your battery bank (voltage, electrolyte levels, temperature, physical inspection, etc.) is usually good enough.

One of the problems with trying to make something "fail safe" (2nd charge controller in case the first fails)--Makes things more complex and creates more possible points of failure. Good quality and keeping things simple is a really good start. And sizing wire correctly and correct value fuse/breakers should do well for you.

Not to scare you--Just want you to make educated decisions and be careful.

-Bill

A5c11 · February 2016

Hey Bill,

Not at all - if I'm making a situation dangerous I'd rather you tell me, nothing wrong with a bit of education

Frankly if somebody on here with a wealth of experience told me that this was a terrible idea, chances are good I wouldn't even bother.

My out house is brick wall and concrete floor - short of an explosion taking a wall out a fire isn't going to make much of a problem.
The wall doesn't even join the house, it joins another empty brick out house

I would want to have my mains feed from the inverter into the house on a permanent basis though - I hope that won't cause a problem. Once the voltage is 240v A/C through a standard fused 13a mains cable (UK) I'm hoping the danger element is somewhat reduced.

BB. · February 2016

You should be fine... Placing the battery bank outside the living area, in my opinion, is a good idea if you have the option.

Many folks will put them in a basement or garage--And with a little ventilation, they will work fine. A few folks are sensitive to the sulfur smell.

-Bill

simmtron · February 2016

And don't install the inverter and charge controller in a closed cupboard with the batteries. Inverter and CC should be separate but close to the batteries.

zoneblue · February 2016

You are right to exercise care in the DC side placement, and general circuit protection, to many enthusiatic folk treat battery systems like an arduino project. Other things to consider:

- try to use quality components from companys who have something to lose from failures
- UL listing is a good reassurance that products have been adequately tested for the intended application
- be mindful about the impact on your house insurance, as dodgy non code installations may give nasty surprises
- checking the code where you are is always educational, and complying with it usually mandatory.
- When in doubt involve an electrician.
- Be especially wary when doing any DIY wiring on voltages over 50V. Your liabity in the event of electric shock etc.

BB. · February 2016

Note, many electricians have no knowledge of DC power systems.

Educate yourself so you can double check the work of others.

-Bill

Newbie attempting to plan a solar rig

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