What to do with the power

[Capt Slog]

I have two 80w PV panels and a small wind turbine (about 5 foot, actually 2 square meters which rarely sees any wind) which charge a couple of 85Ah batteries.  This system runs a few of my house lights, mainly LEDs and has one of Ghurds nice controllers to dump the excess power.

This time of year I'm generating far more power than I need.  The nights are short, not using much lighting, and the days are long and sunny.  This means that by 9am I'm seeing the dump light come on and I'm effectively heating my shed!

I'm wondering now if I should get a small (read: cheap) grid-tie inverter?  This means that my power is at least going somewhere (pond pump etc).  But the inverters I've looked at are for connection directly to the generating source, and I think they would fry if I put them onto a battery bank, basically they are controlled by the input rather than the load.

The problem is that I like the storage aspect of my system, the thought that I will have some power for a time if the mains goes off appeals to me.

So.....


Is there a way that I can hybridise my system to work a cheap grid tie inverter and batteries or is it case off splitting some of the generating input?

[Rover]

I think with the small size of your system, the cost of grid tying such a small output is really not worth it. (And stay away from the recepticle plug in inverters)

Until you move into  a larger system, I'd suggest stayiing off grid, finding more ways to use the power. Increase pond pump size, maybe some more lights. I have a similar system, too small to grid yet producing plenty of usable power. Powers my stream etc, I do things like extending the run time on the stream, trying to balance out the usage.

With te same dilemna in summer time, I wish there was a viable no heat producing dump load, something that actually cooled ...alas I've not found one.

[Rover]

Another thing a I have is small inexpensive 400W inverter, that i use to charge up my rechargeable tools (trimmer, etc) , removing that small load from my house supply.

[Rover]

I'm playing hookey today, hence multiple replies to my own posts  . Another thing to look at is what G's controller is set to. You may be going in to dump too early. I like Ghurs's controller, but a think I'd have a pwm (mppt if you want to spend the money) solar controller for the solar panels, it should charge them better, with a proper float charge.

With the solar controller you shouldn't go into dump unless your turbine revs up and your battery bank gets above the set point.

[wooferhound]

What voltage is your system ?
Are you using an inverter now ?

You need more loads for your Summer use, I suggest Fans , stereo music system, TVs or other entertainment devices.
Do you play an instrument, maybe an amplification system.
Be creative . . .

[Capt Slog]

Just thought I'd add an update to this.

I bought a small gridtie inverter, it's G83 compliant and I was able to plug it in to my house electrics without any problems (or permissions, to the best of my knowledge).  This cost me £90 including the postage.

My initial question on this was to have some sort of circuit that could switch the 12v into this inverter or to the batteries depending on conditions. In practice I found that I was usually using around the full output of my solar panels ALL THE TIME!.  Ok, I know this is not good, but there is always something on in the house, the biggest load being the pump which moves the water around in my fish pond. Others include modems/routers, mains clocks, and very low standby TV (0.3W)

I ended up making a large switch, single pole double throw, which I use to route the power from the solar panels to either batteries or to the gridtie inverter.  At the moment, this takes place once a week.  On a Sunday morning I move the switch to start charging the batteries instead of running the gridtie, and around Sunday lunch (2pm) I move it back again.  This isn't ideal, but it's working well.  The batteries get charge from just the wind turbine the rest of the time, on the odd occasions when it actually kicks out some power.

I'll be watching my electric bill for any difference this will make, and will celebrate regardless of how small the victory.

[wooferhound]

My small solar power system saves me about $25 a year and my system cost me about $550 and a lot of my time. Sure I celebrate the $2 I save on my power bill every month, but I have lights and TV when the power grid goes off and that is priceless.

Glad to hear that you system is working good for you too . . .

[snake21]

in fact friends,what ihave learnt here,in this forum is that maybe we wont be able to recover the amount of money,or even to break even,or time but the importance is to helpin saving the world.it is the action that counts.

anyways,i have a similar question as the titleof the posting.i will be placing 300watts of solar panels in some weeks.i have a 12v,100amps battery and i power some led bulbs with it at night.producing 300w per hour is  bit more for the battery coz i use about 300 watts in my battery per day but th panels will continue producing power even if the battery is full and excess power will be dumped.

i was thinking to place a small 400w grid tie inverter which will send excess power to grid.some small grid tie inverter on eby seem reliable

wht do you advise friends.

thanks

[snake21]

hi,ghurd can help you with such circuitthat you need

[Bruce S]

in fact friends,what ihave learnt here,in this forum is that maybe we wont be able to recover the amount of money,or even to break even,or time but the importance is to helpin saving the world.it is the action that counts.

anyways,i have a similar question as the titleof the posting.i will be placing 300watts of solar panels in some weeks.i have a 12v,100amps battery and i power some led bulbs with it at night.producing 300w per hour is  bit more for the battery coz i use about 300 watts in my battery per day but th panels will continue producing power even if the battery is full and excess power will be dumped.

i was thinking to place a small 400w grid tie inverter which will send excess power to grid.some small grid tie inverter on eby seem reliable

wht do you advise friends.

thanks

Snake21;
 Like <woofer> says be creative Instead of a 400w grid tie that will be expensive, grab a MSW that is big enough to say brew a pot of coffee, tea, hot cocoa or even make toast.

Like <Woofer> my little system will probably never pay for itself unless those EMPs go up and the grid is toast  .
BUT the cool factor was off the charts when last time the entire block -2 houses were without power. LED light was turned on and 4-cup Mr Coffee makes was turned on and we walked out side with hot coffee in hand while everyone else was doing the "huh" look.

THAT"S when it pays for itself 

So rather than look at grid tie, look at what can be powered by much Cheaper MSW inverters. ALL my appliances that use resistive heat are wired this way. Then sit back and enjoy 

Cheers
Bruce S

[TomW]

I agree with Bruce and Woofer Find a creative use for it and you will enjoy that more than pennies off the bill for big dollars invested.

But that is just me.

Tom

[DamonHD]

Agreed on the creative bit.  I can't tell you how good it is to go in to a technical interview/meeting and tell people how I walk the talk, with a solar-powered Internet server for example!

You'll never "stick it to the man" with savings on your bills (though you *might* with a decent feed-in-tariff and low interest rates), that's why the grid exists!

Rgds

Damon

[Capt Slog]

Whilst I understand the sentiment behind the "be creative" line, it does take quite a lot of effort to use the power as 12v/24v and the costs of routimg DC around can mount up.

For me, the simplest long-term solution was the small gridtie inverter, I've been able to just plug it in and forget about it.  It required very little wiring to install, and it happily sits there helping out.

@Snake21.  The inverter I bought was 300w, and compared to the outlay* in panels, it didn't cost too much.  If like you I had 300+W in panels, I would split the output, sending some to the batteries to keep them topped up in case of power cuts, and have the rest going to the inverter.





(*Outlay:-  I work out most things these days by "Tanks full of petrol".  To fill my car with 50 litres of fuel costs around £56 and this lasts for two weeks if I'm lucky, so costs such as going out for a meal in a reasonable restaurant at around the same price don't seem as harsh.  As I pointed out to Mrs Slog in a restaurant last weekend "the bloody car eats better than we do!" )

[DamonHD]

CaptSlog: pls check your PMs or email me!

Rgds

Damon

[Capt Slog]

In response to being asked about this inverter, below is some of the original Ebay listing.

...

The ONE NATION Ultimate 300 Watt Wind & Solar Grid Tie Inverter
 
All units tested and certified for G83/1 in the UK
RRP £ 100
 
14V-28V DC / 220V/50Hz AC
 
Features :
1.    The ON300W grid tie inverter is designed for the small solar pv panel & wind energy markets. Suitable for family renewable energy systems.
2.    This inverter can be used with solar panels and wind turbines to feed power directly in to the domestic mains grid.
3.    Easy to install, just needing solar panel/s or wind turbine, this grid tie inverter, then plugs directly in to any mains socket and feeds power into the domestic mains.
 
Please note : This inverter only has grid tie inverter function and does not have the traditional inverter function, please do not connect batteries for a 12v dc source. Any further questions, please e-mail : info@onruk.com
 
1.     Ease of use
The ON300GTI can be simply plugged in to any mains socket in the home. The inverter IC (integrated control) monitors the volume, frequency and phase of the mains power on the national grid, then produces a pure sine wave to match the prevailing grid power, when power from the Renewable Energy Generator is sufficient to export on to the grid, the Inverter's uses current controlled Pulse Width Modulation (PWM), to control output power exported to the grid. The inverter will only export power when there is mains supply present (according to G83/1).
 
2.     Why use the ON300GTI ?
When solar panel/s or wind turbines are used through this grid tie inverter, the homes electricity meter counter will reduce in the accumulation of chargeable kilowatt hours (when using other electric appliances), if not stop or even reverse (when no appliances in use).
 
3.     Unique Properties of the ON300WGTI
Traditional grid tie inverters have renewable energy generators connected to them in series, so if one solar panel/turbine doesn't work or is inefficient, the whole system can be effected, but the ON300WGTI, can be used in parallel, such that, with each inverter having its own maximum power point tracker (MPPT), every renewable energy generator / solar panel functions at its maximum potential.
 
4.     Anti-islanding protection
ONWGTI has 3 green led's. When the export function is normal, the 3 lights are lit, but if there are no dc sources (as for example during the night, when no sunshine or on a rainy day), the red led will light and the inverter stops working. In these circumstances, the inverter switches off the connection to the grid and grid power cannot be fed back into the inverter.
 
Brand
ONE NATION
Model No.     ONW300GTI
Continuous Output Power    300W
Output Wave Form    PURE SINE WAVE
DC Input Voltage      DC 14 Volt – 28Volt
AC Output Voltage    AC  190v-250v
Frequency    50Hz
Efficiency    90%
No Load current Usage    0.7A
Distortion     2 %
Temperature Protection   55 Deg.C ± 5
Net Weight   2.0 kg
Assembled and tested in  UK


...

It looks like any of the other Chinese inverters on Ebay pages, but this one isn't listed at the moment or I would post up a link.






 
 

[kurt]

ya the UK has totally different rules about those little inverters than on this side of the Atlantic i wish this board had a place that said were people was from like some boards do that way you would get area specific answers.