Solar PV (maybe with wind too) in London, UK

[DamonHD]

Hi Y'All,

First posting here: I've spent a large chunk of this evening reading this site since I stumbled across it.  Fab!

This is my fairly modest pilot solar PV project, initially just to power my study lighting 'off-grid': http://www.earth.org.uk/solar-PV-pilot-summer-2007.html

I'm also keeping my mobile phone charged exclusively by this 12V system right now, which gives me a warm feeling inside...  B^>

I have learnt so much in doing this project so far that a side-effect is probably to knock £1000 (ie USD2000) off our electricity bill (and 3 tonnes of CO2 production to make that electricity) in the next 12 months, so pretty good I think for a rank amateur!

I would be interested in your comments, but also on my hope that I have any hope of boosting power in winter when PV is poor, by using wind power.  I have a small house, in a dip, and cannot raise a turbine much beyond about 2m or more than a few meters from the house, and it must not be too noisy (ie annoy our neighbours).  I was thinking of VAWT for better low-wind-speed and high-turbulence tolerance, and I should ask again over in the right group, but I have to start somewhere!  Basically, do wind and solar PV play well together in town?

Rgds

Damon

[ghurd]

I'm not clear on you battery.  40AH SLA?

Being in a similar situation, I will say a small wind turbine certainly will help in the winter.  If there are trees, it will not do much except in the winter.

It won't need to be much of a turbine.  The small battery can only accept so much power, so fast.  Even a 1A windmill will make quite a difference.  

Here, in winter, there is no wind power for 4-7 days, then too much for 1-3 days.  The 1 to 3 days will bring the battery voltage up higher than it should be, even with a relatively small or tiny windmill.

I often bring my windmill in the house after the battery is full.  Really.  LOL.  Keeps kids from messing with it.

I would recommend a HAWT to start with.  There are not many successful low speed VAWTs.  A windmill close to the house has less turbulence than many people would think.  My best overall spot is 2 meters out from the corner of the house, so it can catch almost clean wind from most directions.

Might Google search the board (top right) for "box fan" to get started with some ideas.  And their blades work fairly OK, and they are quiet.

"Fungus" has chronicled a tiny simple stepper windmill making a 1/2A.  My luck isn't that good.  But a half amp will do quite a bit for a small system.

G-

[DamonHD]

Thanks for the feedback!

40Ahr SLA 'supergel' in fact, though one way or another I might increase that fairly soon...

I'd put my turbine on a charge controller so that it can't overcharge the battery.

Yes, 0.5A@12V would be wonderful, but how many hours per day in winter do you actually get that 0.5A?

Will go and check out "box fan" right now...

Thanks again,

Damon

[ghurd]

My "City Wind" at 2 meters high is either none at all, or too much at once.

It won't turn for days, then it gets the battery over-voltage in half a day.

A solar controller will not work with a wind turbine.

G-

[DamonHD]

Thanks again!

Yes, I understand that I'd need a separate wind controller, but I'm assuming that it will be quite safe to dump power via such as wind controller into the same battery as my solar controller does, providing each controller does its job right.

Really this is all about experimenting with what is possible and at least semi-practical without annoying the neighbours 5 yards away in urban London!

Rgds

Damon

[Bruce S]

Damon;

  Very nice read on your system. I like the thought process that went into deciding what this system is for and what your current and long term plans are. Knowing this isn't cheap and the pay-back is indeed long term, if ever, is a very good thing to understand.

Perhaps Ghurd will chime in here soon about his dump controller. It would be a very good addition to both your current setup and future additions, since it is independant of what type of controller you're using. It could also help make use of the extra power during the summer months to charge a seperate battery system.

Not that I'm pluggin his not for sale yet stuff ----- but I know the flexablity of it and how easy it is to add to an existing system--- plus I'm gently pushing him to tell more.

Perhaps as you go further into the design you could "zone" the system. Meaning the 40SLA for lighting and a different one for the DSL and WIFI systems.

I am curious about the always on needs though. Since both DSL and WiFi can be turned off during non-usage without fear of losing settings. This would help lower the overall power needs.

& WELCOME!! to the forum.

Cheers

Bruce S

[DamonHD]

Hi,

Glad you like the write up, and thanks for your kind words!

A few points in no particular order.

1. My current solar controller doesn't use a dump load (ie it's not a shunt regulator), which saves a bit of heat generation and is fine for solar.  I know that almost any non-trivial wind gen I add will need a shunt/dump regulator, but I'm really going to need someone to construct a low-power small turbine for me since my DIY skills are minimal!  Anyway, no hurry, since I'll only probably benefit from wind power in winter.
   
2. I am thinking of maxing out around the current controller to ~90W of solar panels, to have a chance of gathering enough power for decent lighting overnight, and to be able to have a chance to run some of the other kit, during even a fairly dull winter's day, and then probably bumping up the battery capacity to (say) ~200Ah to get one day's lighting-and-the-rest power at 50% discharge.
   
3. Beyond that I am definitely thinking of getting a separate set of kit for the higher-power loads, possibly even running at 24V to reduce current levels a little.  But if that was really going to run all the non-lighting kit all the time I'd need >500W of PV and >800Ah@12V (400Ah@24V) of battery for a few days' capacity and to avoid deep cycling.  If we get a loft extension done that we're thinking of then that's maybe were I could accommodate the panels since otherwise we'd have to cover half our tiny garden!
   
   

Rgds

Damon

[Bruce S]

Damon;

  You might want to contact fungus and claude. I believe they and a a few others are close " in relative terms":-) to you and would probably enjoy the gathering of minds.

Claude seems to be a wiz with visual things and so far and done a great jobs of "stuffing" many things into a small area and fungus already has some windies up on their place.

Just as a curoius question? which *nix are you using?

Cheers

Bruce S

 

[DamonHD]

For the new laptop?  The guy I'm buying it from (Adam of Xephi.co.uk) is still experimenting for me, but I think we'll probably end up with Ubuntu (ie a 'Debian' Linux).  It's important to have an up-to-date version of Linux with the 'laptop-tools' with lots of power-saving measures.

I'm aiming to boot the machine and run it most of the time off a memory card so that I need not even spin up the hard disc very often...  And the screen will be off.  And unless the sun is shining I'll do only the minimum processing necessary...

I'll get this all working as well as I can on mains power before lashing out on extra PV and batteries, since every W saved may knock the equivalent of as much as USD100 off the final PV system cost...

(Currently I use all Solaris at home, on third-hand machines, some 10Y+ old, and a mixture of Solaris and Linux hosted elsewhere in the world.)

Rgds

Damon

[ghurd]

Bruce et al interested in the controller,

The "free meter" morons screwed up. Again.  84% of the order this time. They do that a lot. Then they charge S&H, again.  Lesson learned.

Then 8AM, the FedEx truck hit the brakes hard, then kept going.  It's 11AM, so much for the 10:30 thing.

And that "work" thing is becoming a major inconvenience.

The controller is designed for people in just this situation.  Cheap and simple too.

Claude is in Romania. It's not near anything!

Damon,

A solar controller and a dump controller can be used on the same battery.

G-

[DamonHD]

Thanks for the confirmation about the using two controllers to charge one battery!

Rgds

Damon

[DamonHD]

Hmm, the addiction is settling in nicely now...

Just persuaded a supplier to give me a decent discount on a UniSolar ES62 amorphous panel which I'm going to stick on the roof of our garden shed when we refurb/replace it.  Then I'm at least in principle able to extend the project to powering the laptop in the summer... just.  That maxes out my current charge controller nicely.

I'm also talking to my local electricity supplier about getting the go-ahead to connect a mini grid-tie inverter to feed back any unused power when the sun is out and the batteries charged.  This masterplan may swing into action after/if I have installed enough PV capacity to run the laptop over the winter (eg assuming wind isn't going to be able to make a huge contribution) given the huge overcapacity that that implies for the summer.

And I've been discussing with my other half the possibility of covering most of our south-facing garden wall with PV.  Goodness.

Nurse!  Nurse!  Nurse!

Rgds

Damon

[DamonHD]

Hi,

Laptop is up and running and was briefly powered from the solar-charged battery this evening and was drawing ~21W from the battery running something near a real load (ie not completely idle), which is very respectable I think.  (My aim is to get to 20W or below unless there's lots of extra power available.)

I have an Ubuntu "Feity Fawn" release with laptop-mode and cpufreqd, with the kernel upgraded to the latest-available Gutsy version, which gets me the tickless clock and a few other power-saving features.

I'm keeping an eye on what might be wasting power with PowerTop.

(I'm not posting a link since my ISP managed to drop my DSL connection today, and it'll be tomorrow before it's fixed.)

Rgds

Damon