Solar power at nigh after sunny day

wprost1986

Hello,

Can someone explain me how is that working? Solars producing energy "live"...is that power stored any way or going streight to the grid? For example today I produced some energy, but used just 30% from it...whats happen with the rest of 70%? Is it going streight to the grid for a sell or what?:) In easier worlds: if You wanna use solar produced energy should you use application only when there is sun?:)

Hope someone will understand that:)

System

Your title is a little confusing!! My PV Solar produces no output at night.

Think of your PV Solar as a little power station. When it is producing power it is either being used by you or its exported to the National Grid. On a very sunny day you could be using some of what you generate with the rest being exported.

Let us assume that it is a dark and foggy day. Your PV Solar is 500 watts and you want to boil a kettle which is rated at 2.3kWs. The kettle doesn't care where it gets its power from so 500 watts will come from your PV Solar and 1.8kWs from the grid via your domestic meter. Conversely, if it is a very sunny day and your roof is producing 3.5kWs then the kettle will use 2.3 and 1.2 will be exported to the Grid.

wprost1986

So after sundown I always only will be using power from grid, even if I "sold" much of of power that day?

Andy_WSM

wprost1986 wrote: »

So after sundown I always only will be using power from grid, even if I "sold" much of of power that day?

Yes, assuming you are in the UK? - in the UK we get the FIT (the money you get for selling the power to the grid), which is more than you pay for grid power - so you effectively sell it in the day and buy it back at night.

wprost1986

Yeah, yeah, Im here:) And what about battery backup? Is anyone tried that...is it cost efective?

pinnks

I guess the simple way to view it is that when there is enough daylight to generate, you use as much of what you are generating as your appliances need and the rest is exported. When you are not generating, or using more than you are generating, you import from the grid. You pay for what you import.


You get 3 forms of monetary saving from solar PV. First, you don't pay your energy provider for anything self-consumed as you are not importing anything. Second, you get a payment, called the feed in tariff for what you generate. That is about 13p per kWh or unit generated. Third, you get a deemed export tariff equal to 50% of what you generate. That is currently 4.85p per unit. Neither the FiT, nor the export tariff are affected by what you use - they are based solely on what you generate.


So at night you simply import from your supplier as you have always done, unless you were to go in for battery storage but that is still way too expensive to generate any form of return over the average lifetime...

tunnel

You sound like you are trying to explain net metering, something that we don't have here in the UK(wish we did)

In effect, you generate and any that's exported can be used free of charge at times when you're not generating, taking back your export at no cost. But as you are paid for export net metering is not possible(cake and eating it springs to mind)

Hope that sort of explains it!!

Ectophile

wprost1986 wrote: »

Yeah, yeah, Im here:) And what about battery backup? Is anyone tried that...is it cost efective?

It is possible to buy a battery backup system to store the electricity that you generate. At today's prices, they are unlikely to ever repay the cost, as the batteries will need replacing every few years.

As batteries come down in price, that may change.

nigelpm

wprost1986 wrote: »

Yeah, yeah, Im here:) And what about battery backup? Is anyone tried that...is it cost efective?

No. In a word.

jimjames

wprost1986 wrote: »

Yeah, yeah, Im here:) And what about battery backup? Is anyone tried that...is it cost efective?

You can get UPS systems that will power decent amount of kit for a period of time, say 15 mins. They cost tens of thousands of pounds.

Then try to work that for say 8 hours of night time use and you'll see how viable it is.

If someone can develop a way of storing power overnight - probably not as electricity - then they'll be onto a winner!

EricMears

jimjames wrote: »

You can get UPS systems that will power decent amount of kit for a period of time, say 15 mins. They cost tens of thousands of pounds.

I guess it all depends on what you mean by "a decent amount" but a smallish UPS that would (say) keep a few lights working overnight would be in the 'hundreds of pounds' category rather than 'tens of thousands'.