Grid Tie inverter.

[Sounduser]

Hi. Ive got a fish tank that uses about 500watts during the day.

If I got a grid tie inverter and some solar panels that add up to more than 600 watts. That would power my fish tank without batteries and anything else?

The panels connect to the inverter. I plug the inverter into the house and thats it?

Cheers.

[XeonPony]

Only when the sun was shining, but to hook it into your house safely you'd need a real grid tie and not the garbage being sold on ebay.

Keep reading the forums here and you'll get a good understanding of it.

500w is a rather useless rating for sizing a system efficiently, what is its (K)watt hours?

[madlabs]

Depends on what your goal is. If the idea is to offset your aquarium's power usage, then the scheme you outline will more or less work. But you are going to need a real legit grid tie inverter and proper and legal installation. Not cheap.

If the idea is to have a backup or independent system then you will need batteries and such. If this is the case, start by getting xomething like a kill-a-watt and find out how many kWh you are using a day and how many days you would like the system to be able to support the aquarium. Then you can start sizing components.

Jonathan

[Sounduser]

Hahaha I was totally looking at the ones on ebay. Have you got any links to proper ones?

[dnix71]

The lives of your fish and your financial and time investment in them should not be left to an ad-hoc solar grid-tie arrangement. If the electrical cost of the aquarium bothers you, then talk with Damon here. He has a legit grid-tie solar setup and lives in the UK as do you. He can tell you what you need to do to cut your bill by adding solar grid-tie.

[DamonHD]

Yo!  Who woke me from my coffin by calling my name?  B^>

Yes, I have a big old solar PV system on my roof that basically zeroes out my energy imports and bills round the year, but measuring and reducing consumption was more significant in footprint/money-saving terms than the PV.  (Plus I filled a friend's roof and my kids' school roof and I'm working on others!)

Give us an estimate of your yearly kWh consumption for your whole house (should be on your latest electricity bill) and your tank (a £10-ish Maplin plug-in meter will give you a reasonable kWh/day estimate after a day or more) and what sort of space you have for PV, and I can do some simple sums for you.

PM me a Google map URL for your house and I can make a better estimate of what you might be able to achieve.

Rgds

Damon

PS. Possible power monitor to plug your fish tank in to (though there are smarter ones): http://www.maplin.co.uk/plug-in-electricity-cost-and-usage-calculator-223573

[Sounduser]

Wow. This is getting complicated fast.

I'm really just wondering if it would be worth offsetting the power used by my aquarium.

The leds draw about 180, T5 florescents about 90, main pump 65, + 30 for circulation and maybe 45 watts for the protein skimmer.

So call it 500 watts. I was just wondering what how much it would cost to have some kind of set up that could offset this. And maybe a touch more.

Ive got a part of the roof which is south facing. But also a shed. (Not sure if you can do that) But the shed gets baked all day.

[DamonHD]

Depends what you mean by "worth" and "would that power"?

If you mean in cash terms, it won't be cheaper than grid electricity (yet) unless you get the feed-in-tariff and that will have to be done with MCS-approved panels and inverter and installed by an MCS-approved engineer and might possibly cost you a little under £1000 for 500W+ of panels.  But that 500W of panels will only power your equipment in full bright sunlight or the equivalent of maybe 2.5h/day in the UK.  No power at night, and only partial power most of the time.

Note that if you leave all that 500W of equipment running 24x7 then you use as much power (upwards of £500 at retail prices) as my entire 5kW PV system generates year round which covers my family of four for all heat and light etc, and trimming that or your other loads would be cheaper than putting up PV in money terms and carbon-saving too.

A 4kW system (ie a little smaller) gets you the maximum feed-in tariff, cannot usually be refused by the electricity people (the DNO, technically), and will cost you about £6000.

Rgds

Damon

PS. Shed roof may be usable.  Your roof-space does not need to point due south unless steeply pitched; my strings face east and west.

[XeonPony]

Every watt you shave off your current load is equivalent to a couple watts generating, in short making power is expensive, saving it is free, so start by reducing the power you use via timers or better units or what have you. After that then start to think of generating, to go grid tie is not cheap no matter how you cut it. 

As for the ebay garbage, it may set your house on fire it might not! (Do you enjoy russion roulette and gambling?) It may electrocute you it may not,  There are more entertaining ways to tempt fate for an adrenaline thrill then using those POS's

As stated, you need to figure out what it is really using befor any thing can be don.

For example here in the prairies of Canada (Sask, Regina area) I have a solar array with a label power of 540w, on average I see it making 300-480 real world watts, on a given sunny day I make up to 2.5 to 3KwH a day, to hold that power I use 4 series parallel golf cart batteries

Batteries = 1,600 dollars
Charge controller = 900 dollars
Panels 2 years ago = 2,600 dollars (Yes I got raped for them, that's BC for you!)
Inverter = Free, I found it in the rubbish tip and sort of hacked it (Noma UPS 1800w)

Now this is a pretty basic set up, not including the wire! you can see the ruff cost of it. This is after 3 years of monitoring power usage and shaving loads where ever I could! and I do really need another 250w panel (400 dollars!)

But keep in mind I am 100% off grid, but I run some things 24/7 and have a micro wave and all that jazz so if you are just looking to shave off the current bill then you can get away with a bit less solar but the mother of expenses will be the GTI and the contractor to install it!

The concept is simple, the application of concept how ever can get very complicated when regulation and safety come to play, that and making a system worth having!

[dnix71]

500 watts all day long is 12kwh a day. That's a lot of consumption. The US household average is 30 a day for a single family home with central a/c and heat. A new full-sized refrigerator only uses about 1 a day. Either learn to live with the cost or get a cheaper hobby.

My apartment monthly grid consumption averages 4kwh (.133 a day). That's just over 1/100 of what your fish get.

[OperaHouse]

A constant load like that is ideal for a solar application if you are using smart technology in a stand alone system.  A small processor board like a UNO could add and shed loads throught the day with nothing more than a small SLA battery to smooooooooth out momentary fluxuations in solar generation.  Making things operate directly on DC also buys extra performance. You likely want something dumb as a stump and that will cost you dearly.  The reality is if you actually have to ask how to do something, you can't.