Simple Solar Panel Help Please

Undervalued

Danno2k said:

So just a quick update

So every bulb in the house totals = 148 watts, but i would never ever have every bulb on, real would be more like 60 watts for around 5 hours a day, Less in summer 

All the are led, some are 5 watt, some are 7 watt.

So if say i had 2 of them solar panels i said 310 x 2 = 610 watts and say 3 battery's in parallel = 360AH, this should be enough for my lighting needs ? And with 2 panels it should charge fast 

Thanks

I assume you must be out a lot in the winter then? Weekends too?

pinnks

Just a thought but we use either 12W (uplighter) or 18W (ceiling light) in the living room.  Mid summer for 3 hours a day; winter for 9 hours a day, so probably 6 hours a day, 365 days a year.  The kitchen is also 18W, bedroom 3W, bathroom 9W.  Kitchen is probably on for about 2 hours per day over the year, the others perhaps 1 hour at, say 12W.  So, our lighting averages about 120Wh per day, or, at 15p per unit, about 1.8p per day.  That is less than £7 per year!

Danno2k

Undervalued said:

Danno2k said:

So just a quick update

So every bulb in the house totals = 148 watts, but i would never ever have every bulb on, real would be more like 60 watts for around 5 hours a day, Less in summer 

All the are led, some are 5 watt, some are 7 watt.

So if say i had 2 of them solar panels i said 310 x 2 = 610 watts and say 3 battery's in parallel = 360AH, this should be enough for my lighting needs ? And with 2 panels it should charge fast 

Thanks

I assume you must be out a lot in the winter then? Weekends too?

Not really, most of the time we are in the living room and we have a stand lamp on which is only 5 watts led b22 bulb

On the clamp watt meter on the lighting is averages around 7 watts at night, there is only myself and my wife in the home

Thanks

pinnks

So, if it's on for an average of 6 hours every day, then that lamp cost you about £2.30 per year to run.  Makes the maths for a PV lighting circuit set-up even less attractive from the RoI perspective

Danno2k

I know, just not worth it

I wonder why people buy like the full systems costing like 6k, is that because they get the 5.5p back per unit ?

Petriix

Danno2k said:

I know, just not worth it

I wonder why people buy like the full systems costing like 6k, is that because they get the 5.5p back per unit ?

A full grid-tied domestic solar PV system is a different paradigm entirely. The economics of doing it now are pretty marginal since the government withdrew the feed in tariff subsidy, which (depending on when they were installed) paid a lot more than the 5.5p you can get now. My £4k system is on course to break even after 9 years, then it might save/earn me another £5k over remaining 11 years it qualifies for the the FIT.

The fundamental point is that the vast majority of home electricity use is from a few large appliances: kettle, washing machine, dishwasher 3kW > oven 2kW > dryer, hoover, mower 1.5kW > computer, TV, stereo 100w > light 7w. You'd have to run that light for 14 hours to use as much power as boiling the kettle once.

Domestic energy storage is also problematic. Some people have a genuine use case where batteries make sense, but mostly exporting to the grid is better economically and environmentally. Batteries are expensive and deteriorate. 

Now, not every decision has to be based on the financial considerations alone. If you were wanting to ensure that you have working lights if the grid goes down then your idea might have some mileage. 

edgex

Danno2k said:

I know, just not worth it

I wonder why people buy like the full systems costing like 6k, is that because they get the 5.5p back per unit ?

because it's solarPV, & producing electricity, which anything electrical in the house can use.
There's a large amount of relatively small but constant/regular loads, that you could completely cover with solar when its generating; modem/router, fridge, freezer, computer etc. Even a slow cooker isn't very much load.

Danno2k

Hi, to be honest, i think i will still get a small setup and see how it goes 

2 x 310 Watt's mono panels
1 x Krieger 2000 Watts Power Inverter 
3 x 12V 120ah DEEP CYCLE LEISURE Battery's 

I was thinking of instead of doing the lighting as is so low, i thought i would power the Tv / Sky box / laptop and my lamp,
They are my main items, we don't use the kettle much, that would leave the fridge/freezer and at tea time the cooker

If i can run this, then to be honest this would and must save me loads over the year 

Must save me at least £1 a day, if not a lot more over 365 days it's paid back

joefizz

Danno2k said:

Hi, to be honest, i think i will still get a small setup and see how it goes 

2 x 310 Watt's mono panels
1 x Krieger 2000 Watts Power Inverter 
3 x 12V 120ah DEEP CYCLE LEISURE Battery's 

I was thinking of instead of doing the lighting as is so low, i thought i would power the Tv / Sky box / laptop and my lamp,
They are my main items, we don't use the kettle much, that would leave the fridge/freezer and at tea time the cooker

If i can run this, then to be honest this would and must save me loads over the year 

Must save me at least £1 a day, if not a lot more over 365 days it's paid back

You will need some other stuff, regulators for the panels along with blocking diodes and so on.
I did something similar a few years ago but and its a big but it was designed to be a 12v system for the house. I already had a couple of small 10w panels which were charging deep cycle leisure batteries I already had (kept them on the panels when not in use on the boat and camper).
These batteries havent usually lasted more than about 3 years, going by receipts for new ones so bear that in mind.

I kept my 12v feed completely separate to the 240v feed. I have a timber framed bungalow and was redeveloping/rewiring anyway so it was easy to feed the led lights with 12v as well as the 240v with transformers (I have a couple of electrical engineering degrees, hence why it was easy, easy, not straigthforward ;-)). Each of the led lights had a 240v component and I added in 12v strips to each to they would operate independently. If you wanted to do this 'easily' it might be better to have separate 12v only lights.

Running the 12v system in addition to the power usage (wasnt going to be used for anything other than lights in the event of a power failure) the length of runs of the 12v wiring was an issue. Not really a problem as I could put the batteries in the storage space room in the loft and each run to each light in the house was less than 3m from the battery.
Ive never used it (other than to test) as afterwards I bought a grid tied mains battery system although I still use the 12v system to run desk lights in the garage and workshop, 5v usb charging stations as well as lighting in the garden and running an old car stereo in the garage for music.

Ive just advised a similar backup system for a relative for an outbuilding but the kick in of fridges and freezers is usually a bit much for this type of system but YMMV. Certainly enough to run led lighting, usb power for phones, laptop power and a few other 12v designed things. I wouldnt be able to run my plasma off it for any length of time and the last time I had a sky box it ran 140w constant IIRC (they may have improved).

Would I do it myself as standalone  if I didnt already have the equipment? Probably not but Ive enough other sources of power (generator etc). Its a great electrical project for experimenting with but with the lead acid batteries etc it really wouldnt be worthwhile in monetary terms.

Petriix

Danno2k said:

Hi, to be honest, i think i will still get a small setup and see how it goes 

2 x 310 Watt's mono panels
1 x Krieger 2000 Watts Power Inverter 
3 x 12V 120ah DEEP CYCLE LEISURE Battery's 

I was thinking of instead of doing the lighting as is so low, i thought i would power the Tv / Sky box / laptop and my lamp,
They are my main items, we don't use the kettle much, that would leave the fridge/freezer and at tea time the cooker

If i can run this, then to be honest this would and must save me loads over the year 

Must save me at least £1 a day, if not a lot more over 365 days it's paid back

Don't just assume; actually do the sums. I have 3.42kWp of solar panels and save (on average) 4kWh per day from my previous usage. That's 50p worth of electricity. With 5kWh of batteries I could probably save another 3kWh for another 37p off my bills but that wouldn't break even in its usable lifetime.

The items you listed don't use much power so the potential savings are minimal. To save £1 per day you would need to generate *and use* around 8kWh every day. That's your 620w of panels generating at their peak power for 13 hours every single day. That might be possible if your house is in orbit, but otherwise unlikely.