Solar PV for shed/office & garage

[OtleySpark]

For the last year I've been powering my PC in my shed/office from a single 250watt solar panel.
The panel is hooked up to a MPPT solar charger to 2 x 110amp hr batteries.
I have a 3000w pure sine wave inverter to convert the battery voltage up to 240 for the pc.
Here's the current setup:

The wires heading out top right are to the panel (there's an isolation switch just off the picture).
Having ‘proved’ it for myself I'm now expanding it. Tomorrow I should get 6 x 170w panels (that 1020w) delivered and using the same charger and inverter should be able to power the 2 freezers in the garage, the outside lights and my shed computer/printer/lights too.
The first 250w panel was £357 - I got the 6 170w for a total of £470 - so prices have really dropped in the last year.
I'll be taking down the single panel and running the 6 as 2 sets in parallel. Each set will have 3 panels in series.
When I’ve got the 6 on the car port roof I’ll post a picture.
Later in the year I hope to get more batteries to give me more storage in the darker months.

 

[fmck]

Really interesting in how to power a shed got me thinking about my project building.

One thing though. Why would you want to take your pc down the garden into the shed ?

 

[kbdiy]

One thing though. Why would you want to take your pc down the garden into the shed ?

You should see some of the web sites .......

Incidentally, anyone got a view on all those flammable liquids in such close proximity to a device (inverter) that produces 240v and a heap of heat into the bargain? In a wooden structure ....hhmmmm

 

[leeco]

Really interesting in how to power a shed got me thinking about my project building.

One thing though. Why would you want to take your pc down the garden into the shed ?

How much did that MPPT cost?

I have a crappy PWM on my set up

 

[mattylad]

Is that real creosote? Or just the replacement stuff....

 

[ToolbeltDandy]

Why are you removing the 250 W panel? Can they not all be used in series?

 

[Peter1919]

Why are you removing the 250 W panel? Can they not all be used in series?

Because different panels will produce different voltages and currents

 

[ToolbeltDandy]

Why are you removing the 250 W panel? Can they not all be used in series?

Because different panels will produce different voltages and currents

I understand that the different voltages precludes connecting them in parallel but why not in series? What would the voltage be then? Does it exceed the capacity of the battery charger?

 

[Peter1919]

In order to maximise the efficiency of the system you need to only connect the same type of panels in series as generally the smaller inverters (which this would be) only have one MPPT (i.e. can only set themselves up for the peak efficiency of one string of panels in series). If you put two different panels in series then the inverter could end up at the wrong point on the MPPT peak curve to produce the best results out of either panel in the series so overall you could well end up with a worse overall performance despite including one larger output panel in the system.

 

[OtleySpark]

Really interesting in how to power a shed got me thinking about my project building.

One thing though. Why would you want to take your pc down the garden into the shed ?

It's my office - I write books and build websites. Just for info here's a website advertising my book www.yearofthecelt.co.uk

 

[OtleySpark]

Really interesting in how to power a shed got me thinking about my project building.

One thing though. Why would you want to take your pc down the garden into the shed ?

How much did that MPPT cost?

I have a crappy PWM on my set up

Here it is:
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=320787349951&ssPageName=ADME:L:OU:GB:1123

It was £188.00 (inc postage) when I got it November 2011. The support has been good too (i've asked them lots of questions and they answered them quickly and patiently).

 

[OtleySpark]

In order to maximise the efficiency of the system you need to only connect the same type of panels in series as generally the smaller inverters (which this would be) only have one MPPT (i.e. can only set themselves up for the peak efficiency of one string of panels in series). If you put two different panels in series then the inverter could end up at the wrong point on the MPPT peak curve to produce the best results out of either panel in the series so overall you could well end up with a worse overall performance despite including one larger output panel in the system.

That's more or less what I was told.

 

[OtleySpark]

An update and another question.
The 6 170 panels have been installed for 4 months now and all seems to be well.

Except I have the original 250w panel sat in the shed doing nothing. Given the problems of mixing different panels already stated is there some way round this?
The 250w panel has Vsc 60.5 (Vmp 50.6). The 170w 44.0 and 35.0
Each string of 3 170w is actually running in daylight at 118-120v.
Is it possible to get another 250w and pair it up in series with the original to give me a third string?
Would/could the use of a voltage regulator (or something simpler) be used to make the new string match the other 2?

 

[chalkywhite]

For the last year I've been powering my PC in my shed/office from a single 250watt solar panel.
The panel is hooked up to a MPPT solar charger to 2 x 110amp hr batteries.
I have a 3000w pure sine wave inverter to convert the battery voltage up to 240 for the pc.
Here's the current setup:

The wires heading out top right are to the panel (there's an isolation switch just off the picture).
Having ‘proved’ it for myself I'm now expanding it. Tomorrow I should get 6 x 170w panels (that 1020w) delivered and using the same charger and inverter should be able to power the 2 freezers in the garage, the outside lights and my shed computer/printer/lights too.
The first 250w panel was £357 - I got the 6 170w for a total of £470 - so prices have really dropped in the last year.
I'll be taking down the single panel and running the 6 as 2 sets in parallel. Each set will have 3 panels in series.
When I’ve got the 6 on the car port roof I’ll post a picture.
Later in the year I hope to get more batteries to give me more storage in the darker months.

May I ask what make of panels you use, and to share the setup image again please? Thanks