# ??? on building an expandable solar system



## Reblazed (Nov 11, 2010)

I have been researching expandable solar power systems and have a few questions for anyone who is familiar with them. If I'm understanding correctly the order the equipment goes is ... Panel to disconnect to charge controller to monitor to batteries to inverter to grid panel box or extension cord. If there are more steps I can't find them on line.

The questions are

1) Does the charge controller keep the batteries from overcharging or is that why there's a disconnect box? Or is it even possible for a battery to overcharge?
2) Each time I add an 80W - 100W panel do I also need to add 3 more 12v Deep Cycle batteries?
3) I'm thinking of having the batteries in a box on my enclosed (unheated) back porch, will freezing temps harm them?
4) How do you tell how charged the batteries are? The monitor?
5) If the system is hooked into the grid panel box would I loose all power when the grid goes down or could I still run on the batteries?
6) Are there any brands that you feel comfortable recommending?

I know these probably seem like stupid questions but just because I can picture how it's put together doesn't mean I have any idea whatsoever on how it works. :dunno: Help please.


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## NaeKid (Oct 17, 2008)

The simplest way to describe how solar to battery systems works is to compare it to the flow of water.

If you have a straw and you use it to fill a pool, it will take you forever to do so. To make things go faster, you would toss the straw away and take the garden-hose and turn it on. It would be faster, but, still would take a very long time to fill that olympic-sized pool. To really get that pool full fast, using a fire-hose will do the trick.

A small solar panel (13 watt) will be like the straw, it would do the job, but, take forever.

A medium solar panel (80 watt) will be like the garden hose.

A large solar panel (or array) would be more like the firehouse being used to fill the pool.

The pool is your battery-bank. Just as water finds its "level", batteries will do the same thing. It doesn't really matter how many batteries you have with regards to how many panels as they will all "fill" up equally. What you are trying to do is have enough batteries to handle the drain - the more batteries (water) you have, the longer it takes to drain.

The way that the charge-controller works is it senses how much power is on one side (source-power) and it allows the flow to the other side as required to keep them balanced. It is a one-way valve to make sure that the power will not drain during periods of darkness (night).

The disconnect is so that you don't shock yourself with the voltage from the solar-panels when doing work on the system.


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## Tirediron (Jul 12, 2010)

Batteries become much less efficient at colder temperatures
If I were setting up a solar system I would do it in stages, Xantrex builds decent controller/inverter units and there is a fair bit of info on their site.
If you start with a 2000 watt invertor and build to that capacity , you can add extra panels and batteries as you go , until you have enough to add another invertor. this way you get built in back up and it lets you build as you can afford it. 
Solar panel keep getting more efficient all the time so as time progresses ,unless SHTF, panels should keep getting better and cheaper
The other BIG thing is unless you want to spend a pile of $$ you need to "gentle down from grid power usage, I personally don't like grid intertie systems.


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## trkarl (Jun 16, 2010)

Reblazed said:


> I have been researching expandable solar power systems and have a few questions for anyone who is familiar with them. If I'm understanding correctly the order the equipment goes is ... Panel to disconnect to charge controller to monitor to batteries to inverter to grid panel box or extension cord. If there are more steps I can't find them on line.
> 
> The questions are
> 
> ...


The charge controller goes to the batteries. If there is a monitor it should be connected to a shunt that connects the cc to the batteries and inverter.

Here is a pic of mine:


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## Walker (Dec 5, 2010)

*Complete solar system description*

Over the past 25 years we've gone from a homemade 10-watt PV panel and the battery in our 1969 VW Bug to our current 1500-watt PV system with sealed gel cells. We also used single-phase and 3-phase wind machines, various PV trackers, and all sorts of charge control. This stuff is all modular and it can be as simple or complex as you like, based on your needs at the time. We often work to do neighborhood swaps of inverters, controllers, etc. for the various off-grid systems, though this is getting harder as more of our more affluent, power-hungry neighbors are switching to the grid, at least as a back-up power source.

If you'd like a peek at our solar system you can find photos and descriptions at GeoPathfinder .


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## jeanniesmart (Dec 25, 2010)

Solar Hydrogen is the best way.Unlimited storage unlike batteries and no replacement.This is the best system for heating and engine fuel.Biogas is another very good energy source when times are tough.Visit www.freeincome4u.biz to survive the tough economic times ahead.Thanks for your time,Ed


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## Nadja (Jan 12, 2011)

trkarl said:


> The charge controller goes to the batteries. If there is a monitor it should be connected to a shunt that connects the cc to the batteries and inverter.
> 
> Here is a pic of mine:


I am trying to insert a picture of one of my 4 xantrax c-60s for all to see. They are one of the best units as far a charge controllers go on the market. Very reliable to say the least. One of my is 15 years old (trace) and still going strong with never a glitch.


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