Living On Solar Panels...

[doodlebug]

Hi there,

I'm a newcomer to solar panels really, i've used them small scale but want to use them on a large scale basis, let me explain my situation.

My girlfriend and I live on a smallish narrowboat, just outside of london. We go to uni almost every day, and we go home at weekends, we just use the boat as a place to stay during the week.

Our heating is a wood stove, and a gas boiler, so no electricity used there. Our only electrical usage is our laptops for uni work, and lighting. (We use our unis laundrette, watch TV on laptops, and figure we don't need a fridge (any fresh food we use we will pick up on our way back from uni)

Currently, if we wanted to use a hook up to use mains electrics, it will cost us 1000 pounds a year. Which is extortionate for the few things we use. The roof of our boat has about 10m2 space on it.

Our laptops are rated at 5amps, although on average I work out that it usually uses more like 2-3, so lets say 4 to be on the safe side.

Lighting in total comes to 3amps.

I would estimate that at the most, we would use our laptops for max 5 hours a night, for uni work. And on average would have the lights on for 6 hours a night.

So that makes 55 amp hours a day, that we would use.

I used this calculator, and put in all that data, to work out what wattage solar panel's we will need.

http://www.thesolarcentre.co.uk/pages/solar_panel_calculator.html

It says that at the most we need 417w solar panels, in the darkest months of the year.

I have found these solar panels on ebay:

http://www.ebay.co.uk/itm/100W-200W-300W-500W-1000W-Semi-Flexible-mono-solar-panel-12V-solar-modules-/221016713590?pt=LH_DefaultDomain_3&var=&hash=item33759f6976#ht_4120wt_905

If I was to have 5 of those, it would cost

[russ]

Some thing you should also have a serious look at is wind turbines. There is a lot of info out there on them and it can get confusing as to what is right and who to believe. Depending on where the property is located will determine whether a turbine is suitable, turbines can be a great way to suplement solar energy, indeed in some locations turbines will out strip panles for performance.

That post is 100% nonsense with the exception being that proper siting of a turbine is essential.

[Sunking]

OK so you are using roughly 700 watt hours/day.

That will require:

450 Watt Solar panel
40 Amp MPPT Charger
400 AH 12 volt battery.

Keep in mind the battery needs replaced every 1 to 5 years depending on the quality and care you give it. Get a cheap battery and abuse it, you will replace it every year.

[Roil]

Exiting project

I would tripplecheck the PC' powerconsumption. My experience is that by fare the biggest consumers we got in our of grid cabin is Laptop's. That goes for my own Dell, or the kids Macbook's. In addition you will probably charge smartphones etc, and this all adds up.

A new LED Samsung TV 29" an the other side is only 1,6A, and might help you save power.

Wish you good luck.

[PNjunction]

To conserve laptop power, remember that if you are running it from an AC inverter, the laptop will be running full-bore not knowing it isn't connected to the grid. You may want to purposely force your power-savings options into "laptop" or some other power saving mode when using an inverter.

The other consideration is that you might be using nearly double the normal power just to charge your laptop's internal batteries at the sime time you are using it. I went from 60watts down to 30watts once my internal li-ion battery was charged from the inverter. A plan here might be to make sure your internal battery is charged fully at the university, use it as much as you can on the internal batteries when you get home, and then pull it out when you run from your own system so you aren't charging it. Of course you'll be flat in the morning having to hunt down some ac to charge it again during the day...

[inetdog]

use it as much as you can on the internal batteries when you get home, and then pull it out when you run from your own system so you aren't charging it.

Be sure to turn the system off or hibernate it (not sleep!) before removing the battery or you run a high risk of losing your work in progress. Also save often in case your inverter cuts off unexpectedly. I am not sure that the gain is worth the risk, depending on what you use the computer for.
Having a second battery which you keep fully charged just for use when you are running from your inverter might make sense and also give you more reserve capacity if you ever really need it.

[John J.]

doodlebug; I don't know how/if amazon ships to UK but do a search for "car adapter [your laptop brand & model]" or "car charger [your laptop brand & model]"
You can save a little power by not having to need an inverter to run the laptop. Not to mention a little less wires & clutter this way.

"doodlebug" that sounds sooo British.

[geebus]

[edit] Dang - it's an old thread.
Do you need flexible panels? Might be a bit harder to mount rigid ones, but a fair bit cheaper.

I've just got a second hand 230w poly panel for my lorry for £95.
I'm running lights (not much) and a quite chunky laptop from it, as well as phone charger, torch battery chargers etc. However, just one of me.
Since I bought it, it's always got the batteries up to full charge every day - no doubt that will change as we get to winter and get some traditional British weather back. Am hoping to get some more and a MPPT.
(Though I'm in West Yorks at the moment, so you'll get a bit more useful Sun than me anyway I believe.)

At the moment mine is just going through a £12 20a PWM controller from ebay.

There's plenty of deals on panels around - somewhere in Harlow on ebay selling new 195w mono panels for £142 or so I think it was. 240w poly panels from bimble solar were £123 + £30 p&p for the first one and £3 for each one on top (or 290w mono for £160 + P&P).

I'd definitely recommend toning down your laptop settings - mine has a 150w charger, but if I don't let the i7 have it's full performance, it doesn't seem too bad.

On some computers you can set the battery to not charge without removing it - that way you don't need to worry about knocking the lead out, but may save power.

Incidentally, so far I've just got 2x100ah numax 'leisure' batteries in series as my vehicle is 24v, but want to get a better battery system (be it more of them or some decent batteries).
I've also got a 4kva generator; not that cheap to run as it's a bit overspecced for this sort of use - however, you may want to consider a smaller one and a decent charger for nastier winter weeks.