Homebrew Solar in the UK

[OuttaSight]

I've been a lurker here for a while and usually post over at a thread I hog at:

My thread at Mr. Sharkey's homepage

Here's where I'm at today after almost exactly one year of playing with some solar panels in my back garden.

From the top left there's:

1x BP 3160S 160Wp (35.1Vmp)

2x Sharp NE-80 80Wp (17.3Vmp)in a pair

From the bottom left there's:

6x TopRay 15Wp amorphous (17.5Vmp) grouped in 3 parallel pairs

8x TopRay 12Wp amorphous (17.5Vmp) grouped in 4 parallel pairs

There's more on the garage too...

From the near end there's:

2x Kyocera KC40 40Wp (16.9Vmp) in a pair

2x Sharp ND170E1F 170Wp (23.2Vmp) in a pair

6x TopRay 15Wp amorphous (17.5Vmp) grouped in 3 parallel pairs

The big 170Wp Sharps are on one Morningstar 15A MPPT controller and the rest are on a second identical controller that parallel charge 4x 110Ah 12V leisure batteries (yeah, I know, but they were really cheap) wired for 220Ah at 24V.

I've got some DVMs that read battery charge Amps on embedded shunts (made by just sticking pins into the 8AWG feed wires at measured distances) and a SmartGauge to accurately read the bank state of charge in %.

I've got a couple of 12V LED lights in the room with the solar gubbins but the rest of the house runs off a Cotek SK1000 24V 1kW pure sine inverter with a remote control and load / battery monitor in the livingroom.  I also have a home-made wireless remote (fashioned from a cheap wireless doorbell!) upstairs so we can turn the power (and so the lights) on without having to stumble downstairs to the inverter controls.

Another embedded shunt on the inverter provides info about net battery charge / drain with a little mental arithmetic from the other two meters.

Finally, a pair of cheap plug-in kWh meters measure yield and Winter charge from a grid charger to stop the batteries rotting.  It's only a 3A 24V electric bike charger that I bought at a car boot sale for £2, but it does the job and I haven't had to use it since February .

My system is still pure off-grid but with the house lighting circuits switchable between grid and solar by a change-over socket.  The rest of my solar appliances run on a completely separate "ring main" that consists of some semi-permanent trailing sockets round my livingroom, into the kitchen for some low watt appliances and upstairs to the computer room.

Last month I broke 100kWh offset from the grid and this week I broke 5% lifetime offset as a percentage of all electricity I've used since starting measurements on December 8th.  In June/July my weekly offset averages were 9.9% of all electricity consumed (solar plus grid).  On a daily basis I might get up to about 15% or 2kWh.

My goal is to be able to run the computer room 24x7 off-grid.  I work at home so the internet router, wireless, and mail/firewall/browser/file&print PC is a challenge.

[SparWeb]

I can tell when someone is really enthusiastic and having a fun time.

Thanks for posting.  The tinyurl links didn't work correctly, though.

Are those your wires, or the utility company's wires spanning between buildings?

[super windy]

Hi outtasight

have you got room for a wind turbine, I have 2 wind turbines and 3 solar panels and even now in the ""summer"" the wind is strong and I am able to keep the batteries topped up and use the router and laptop for a good 8 hours a day, plus enough for lightning in my house.

Super Windy

www.windchasers.eu

[OuttaSight]

Thanks.  Weird about the tinyURL links... The images display properly in-line in the posting as I'm looking at them now (Firefox 3.0.13).

It's quite fun and it's really a form of a "collecting hobby".  My wife collects 1950's crockery from car boot sales and I collect solar panels and batteries (to her increasing despair of a pretty garden)

Those overhead wires are the DC feeds from the solar panels.  There is an AC grid feed to the garage but that's an underground armoured cable.

The 340W Sharp pair use proper 4mm UV resistant solar flex.  The 90W amorphous bunch of panels feed via a separate 1.3mm UV resistant cable (common outdoor DC lighting flex).  The 80W Kyocera pair feed separately (but to the same controller as the amorphous array) by some ~2.5mm loudspeaker flex (I picked a 50m reel of the stuff for like £5 at a car boot sale).

The Sharps flex goes all the way back to their dedicated controller but all the others meet at a waterproof junction box on the garden wall before being piped indoors by a 6mm feeder to their controller.

The stuff on the garden wall and ground feed by more of the 1.3mm DC lighting flex or left-over bits of 6mm flex to the junction box.

The controllers are connected via 20A DC fuses and DC disconnects to the battery by 10mm car audio cables and the inverter and battery links are 35mm jump start cables. The inverter is connected via 3x 30A DC fuse (in addition to the internal ones it has)

I decided to mount the BP and small Sharps on the wall near the controller to keep the cable runs short as they are older panels that use 36 or 72 cells. They only make about 35Vmp in series so DC line voltage drops are more of a problem (with battery EQ needing almost 30V).  The Sharps on the garage roof are new and use a higher voltage (46.4 Vmp in series) so they can be used on longer wire runs but you have to use a MPPT controller and proper wire (as Voc runs to something like 58V - quite dangerous).  Having said that, even the pairs of amorphous panels have very high Voc ratings that put them at 50V when open in series (even though their Vmp is 17.5).

[OuttaSight]

Hi, Super Windy!

I saw your post and your site the other week.

I'm not planning any wind generators for my system as it's likely to annoy the neighbours more (a spinning thing high in the air and potential complaints about noise).

Also, we're situated in a square of houses (so all the back gardens face each other).  This has the effect of creating a 10m high "castle wall" around the gardens which combined with all the tall trees surrounding the outside of the houses means that the gardens are very sheltered from wind...  Makes it safe for my panels as they will never be exposed to direct gale force winds but no good for wind turbines.

I did build an exercise bike generator from junk I bought at car boot sales  The bike cost me £5. The generator was a scrap 240V DC 16 pole motor from a washing machine I got for 50p. It doesn't have any magnets in it but just about manages to self-excite and produce power (with the field windings in series with the rotor windings).  A tiny residual field in the laminated steel rotor is enough for it to positive feedback and then it gets going.

To get it going, I have a momentary button that I press to connect the generator to a 4 Ohm load and that gets a few mA going which starts the thing and then a diode between the battery and the generator means it starts charging a spare 12V battery once the generator is making 12.8V.  Then I can release the button and the generator will keep going but now charge the battery.  If you pedal too slow, the volts drop below the battery voltage and the diode cuts in and that causes the series field current to stop so the whole thing stops and you have to start again with the button.

I've got a thread on the building of that at Sharkey's as well.