Solar Panels Query

[River Song]

OK so I finally got my install.

12 x Solar Panels >>>> DC Isolator >>> Grid Tie Inverter >>> AC Isolator >>> Long cable from attic to garage >>>> AC Isolator >> Meter >>>> GRID

So Im giving some thought.....

[CharlesHarris]

Photovoltaics produce DC electricity from sunlight and are ideal for maintaining battery banks against self-discharge during extended periods of non-use. Properly designed solar arrays can provide sufficient current to run communications equipment directly or to maintain battery banks at operating capacity during periods of heavy load.

A photovoltaic panel producing a current of from 1% to 1-1/2% of battery capacity is recommended to compensate for self-discharge in storage batteries and can maintain them on "float" indefinitely. No charge controller is required because maximum current doesn't reach the threshold to evaporate electrolyte after full charge is reached. A Shotky diode is wired in series with the panel to prevent battery discharge at night when panel voltage drops below battery voltage. This method of float charging is recommended for storing vehicles or motorized equipment which are not used at least monthly.

Additional panels may be added to the system to replace energy consumed daily by the loads and to compensate for energy used by charge controllers, etc. To avoid overcharging batteries during periods of non-use, a charge controller is required to disconnect the panels from the batteries when they reach a fully charged state.

While voltage is nearly constant, the charging current produced is dependent upon incident light in watts per square meter under operating conditions. Under ideal conditions (full sun perpendicular to the panel in clear sky at 20 degs. C) this figure is about 800w/m2.. A 50w panel produce 1,500+watt /hours of energy weekly under full sun or more under ideal laboratory conditions, but only a fourth as much during a cloudy mid-Atlantic winter.

To properly size a photovoltaic system adequate to operate continuously, total all loads in watts, multiply by the average daily use in hours, plus a 30% allowance for DC line losses. Subtract the average daily energy produced by back-up generators and divide the total by the product of the module power rating times the “Area Factor” which compensates for local sun conditions (4 - in the US mid-Atlantic states) to yield the number of panels required.

[River Song]

Charles - Thank you for that. If you read the whole thread which I started, you'll find that this installation is a grid-tie installation put on the house by my employers which I occupy as part of my job.

The big question, which no-one has been able to answer due to the complexity, is how I can take the 400VDC and use it or get any SHTF Use from the panels. At the moment they are fixed to the grid and are unusable to charge batteries after Tango Uniform.

[Nix]

It's not complex, RS, it's simply dangerous if you are not familiar with high voltage.

You still haven't answered exactly what you want to do with this potential energy source, ie what are you wanting to power?

[Lightspeed]

An Idea RS:

I can understand completely that you do not want to start playing with the expensive installation that your landlord has installed. It could land you in trouble for damaging the property, or worse, killed if you start touching high voltage elements when they are live.

If I were you, I'd invest a deep cycle 12v accumulator, and a 240v to 12v smart charger ( the sort sold in Halfords to attach to garaged cars that are used infrequently.) Leave that plugged into your 240v PV assisted mains supply and you'll have as much back=up power as you want to invest in.

But you want to be able to use the PV array post TU, yes? So at the same time as setting up the 12v accumulator and charger, get yourself one of the Maplins 13w solar briefcases. They are about £50 and come with charge controller and various wire connectors. 13w isn't going to be much help after TU, but right now its a low power solar array that you can play with to understand how it works without risk to life and limb. It can also be used to solar trickle charge the 12v accumulator of course. The point is that you can learn from it how to rig up solar panels. This knowledge will allow you, when the time comes to have already kitted up in order to re-wire some of the high power panels on your roof the deliver the power you need.

[River Song]

LS

Now thats a sensible idea. I've already got one of those 13w brieftcase jobbies sitting around
so I'll experiment. What you are saying is "get educated".

Yeah I'll try that

[Lightspeed]

(25 September 2013, 11:41)River Song Wrote: LS

Now thats a sensible idea. I've already got one of those 13w brieftcase jobbies sitting around
so I'll experiment. What you are saying is "get educated".

Yeah I'll try that

Yep, get educated by hands on experimentation with materials that won't burn your arse too badly if you make a mistake.