Solar Panels

ghogie91

Hi all

Looking to see if someone could explain use of solar pannels to me?

I get the idea of the panels taking in sun light, being linked in someway to a battery set up and then a power inverter is then used to power stuff

What I don't get is how the power is used, as in how long stuff can run, or how much of my solar energy is used to charge a phone for example or an iPad and maybe running a tv and a DVD player or everyday stuff like that

The reason I ask is I am living at home in an extension off the side of the house and would really like both my bedroom and sitting room to run off solar power

The only power consumption would be a tv, charging a phone and iPad, a lamp and a DVD player, I just don't know how to go about calculating what sore of power would need to be stores to run the likes of these things daily, as you can see I am totally clueless regarding this

Thanks,
Gary

hexosan

First off its a PV panel you need not a solar panel to generate electricity.

ghogie91

See I haven't a clue would need a quick brief run through

rockabaloo

A solar PV panel is a solar panel too.

fclauson

Ok google pv

Then look at esb for micro generation

Batteries are just not cost effective - it's best to have pv grid connected and then to push to grid when not needed and pull when needed - the esb will set this up for you

For each unit pushed you get 9c and for each pulled its 8c at night and about 18c daytime (rates subject to your provider)

hexosan

rockabaloo wrote: »

A solar PV panel is a solar panel too.

While you are correct, in order to help the OP along its more correct to point out to him/her that they need to look up PV panels as opposed to solar to get the info they're looking for.

rockabaloo

I wouldn't have thought solar panels were synonymous with solar thermal is all I'm saying. I didn't think the OP had said anything wrong.

freddyuk

Solar thermal collectors heat water from sunlight to heat water which is pumped into a hot water cylinder.
Solar photovoltaic modules collect light and convert this to DC electricity which can either be connected to an inverter connected to the grid supply and used in house or exported back to ESB or fed via a solar controller into a battery to recharge the battery. You can then use the battery power as DC current to run 12 volt devices (or higher voltages with more batteries) or via an inverter connected to the battery which outputs 240volts AC household power.
I think the OP is living at home with their own extension living space and wants to run low power devices off solar battery power. This is simple to achieve based on the loads suggested. If you are not heating water or heating the rooms then it is possible to do. No kettles or toasters!
Check each devices label which will tell you the watts each uses. Then work out the time each device will be used per day on average. This will give you a watt/hours number. Let us know what this total comes to.

hexosan

rockabaloo wrote: »

I wouldn't have thought solar panels were synonymous with solar thermal is all I'm saying. I didn't think the OP had said anything wrong.

Wasn't trying to imply the op was wrong just stating people normally associate solar with heating & PV with electricity.

ghogie91

freddyuk wrote: »

Solar thermal collectors heat water from sunlight to heat water which is pumped into a hot water cylinder.
Solar photovoltaic modules collect light and convert this to DC electricity which can either be connected to an inverter connected to the grid supply and used in house or exported back to ESB or fed via a solar controller into a battery to recharge the battery. You can then use the battery power as DC current to run 12 volt devices (or higher voltages with more batteries) or via an inverter connected to the battery which outputs 240volts AC household power.
I think the OP is living at home with their own extension living space and wants to run low power devices off solar battery power. This is simple to achieve based on the loads suggested. If you are not heating water or heating the rooms then it is possible to do. No kettles or toasters!
Check each devices label which will tell you the watts each uses. Then work out the time each device will be used per day on average. This will give you a watt/hours number. Let us know what this total comes to.

Ok I had a general look and it's roughly 240 watts daily I would use, not talking about heating or cooking or anything like just smaller things like iPad charging, lamp, phone charging, tv for a couple of hours etc

Keeping it small to get the hang of the system first

freddyuk

You can probably re charge your Ipad/Iphone etc from a 12 volt car adapter? By using 12volts you are not adding to losses via an inverter so check this as 12volt cigar sockets cost pennies so get a double one.
The TV will need a small inverter to run it but really you need an LED model to cut the power usage by about 60% against standard LCD/Plasma.
The lamp can have an LED bulb which will cut the power usage by up to 80%. If you can convert this to 12v then even better.You can get standard fitting bulbs in 12v.
You say your load is 240 watt hours? A small TV will use about 100watts so for 2 hours that is 200watts already used. A lamp at 60 watts for 4 hours is 240 watt hours. There are about 20% losses in a battery system and an inverter adds another 15% or more.
So what will be mains 240v? Just lamp and TV?
If so I suggest 2 x 100wp solar panels, 20amp charge controller, 3-500 watt pure sine wave inverter, 100-110ah battery (deep cycle). This ensures the battery will not be deeply discharged which will shorten it's life and you have a little capacity for expansion. If you get a simple multi meter you can check the battery voltage to monitor it's status.
Once you see how this works you can decide how to progress. If you have a few dark days on the trot you may need to recharge the battery via the mains which is a cheat but for a starter kit it makes sense.To make the kit cheaper you can replace a solar module with using the mains charger.Then monitor and design up from there. In winter 2 x 100wp (12v) is a minimum in my opinion. You can add to the kit but remember adding old batteries to new ones is a bad idea.
Turn everything off when not in use including the inverter.

ghogie91

freddyuk wrote: »

You can probably re charge your Ipad/Iphone etc from a 12 volt car adapter? By using 12volts you are not adding to losses via an inverter so check this as 12volt cigar sockets cost pennies so get a double one.
The TV will need a small inverter to run it but really you need an LED model to cut the power usage by about 60% against standard LCD/Plasma.
The lamp can have an LED bulb which will cut the power usage by up to 80%. If you can convert this to 12v then even better.You can get standard fitting bulbs in 12v.
You say your load is 240 watt hours? A small TV will use about 100watts so for 2 hours that is 200watts already used. A lamp at 60 watts for 4 hours is 240 watt hours. There are about 20% losses in a battery system and an inverter adds another 15% or more.
So what will be mains 240v? Just lamp and TV?
If so I suggest 2 x 100wp solar panels, 20amp charge controller, 3-500 watt pure sine wave inverter, 100-110ah battery (deep cycle). This ensures the battery will not be deeply discharged which will shorten it's life and you have a little capacity for expansion. If you get a simple multi meter you can check the battery voltage to monitor it's status.
Once you see how this works you can decide how to progress. If you have a few dark days on the trot you may need to recharge the battery via the mains which is a cheat but for a starter kit it makes sense.To make the kit cheaper you can replace a solar module with using the mains charger.Then monitor and design up from there. In winter 2 x 100wp (12v) is a minimum in my opinion. You can add to the kit but remember adding old batteries to new ones is a bad idea.
Turn everything off when not in use including the inverter.

Hi Freddie

I done a lot of research in the last 12 hours or so

I have come up with:

4 x 130w 12v PV panels
battery charge controller (microprocessor version)
Battery level indicator
1200w pure inverter
2 x 100ah batteries connected parallel to keep 12v all around

I was looking around and I have an 80w smart led TV, Xbox one on the way so that's only 30 according to MS, 15w lamp, 15w alarm clock, 35w iPad charger (guesstimate), 35 watt free to air box, 35w phone charger= 235w load

235/12v = 20A... 200AH/20A= 10hrs x 0.5 (%)= 5 Hours actual run time

Am I correct here?

freddyuk

Impressed with your due diligence. You have gone straight for the working version! You need to allow 20% losses for the 12 volt battery feed and another 15% if using the inverter hence the reason to use direct 12v feed wherever possible. If you can keep the battery discharge well above 50% your investment in decent batteries will pay off. Don't be tempted by cheap leisure batteries.
Anything that is running all day is going to give you problems so turn it off if you can. Routers can be run off 12v and need to be turned off at night as they are doing nothing then except drain power. Check the length of your lamp cable and size accordingly to run off 12v LED. Dump the clock?
I think you are talking about a MPPT controller? These can be bought with a display screen which will allow you to monitor the battery SOC. No need for a separate battery monitor unless the system supply becomes critical.If you get a remote version you can disconnect the display thus saving more power whereas an in built display is using extra power. If you are using an MPPT controller you can use cheaper 2 x 250wp modules which will run at higher voltage and be converted by the MPPT controller into more useful amps. I assume you have a decent south facing roof- shade free.
Keep researching you are on the correct track but will need a decent budget so make sure you get the correct quality kit.

ghogie91

freddyuk wrote: »

Impressed with your due diligence. You have gone straight for the working version! You need to allow 20% losses for the 12 volt battery feed and another 15% if using the inverter hence the reason to use direct 12v feed wherever possible. If you can keep the battery discharge well above 50% your investment in decent batteries will pay off. Don't be tempted by cheap leisure batteries.
Anything that is running all day is going to give you problems so turn it off if you can. Routers can be run off 12v and need to be turned off at night as they are doing nothing then except drain power. Check the length of your lamp cable and size accordingly to run off 12v LED. Dump the clock?
I think you are talking about a MPPT controller? These can be bought with a display screen which will allow you to monitor the battery SOC. No need for a separate battery monitor unless the system supply becomes critical.If you get a remote version you can disconnect the display thus saving more power whereas an in built display is using extra power. If you are using an MPPT controller you can use cheaper 2 x 250wp modules which will run at higher voltage and be converted by the MPPT controller into more useful amps. I assume you have a decent south facing roof- shade free.
Keep researching you are on the correct track but will need a decent budget so make sure you get the correct quality kit.

Cheers freddie

yes I was looking at the 24v panels and i seen people saying that they were more efficient and the mppt would convert with no loss in watts

I was allowing for batteries to to 60% minimum but if 50 is ok they I will factor that in.

I didnt know about the 35% total loss between the battery and inverter.

I am basically drumming up a kind of 'whatever the cost' budget so I have been looking at basically the best of the best in terms of equipment. Everything I plan to run off this system can be switched off and dont need to run all the time

I totally forgot to factor in the router for net so that will have to be added to the overall total

Batteries wise, would it be smarted to link parallel or in a series? Im pretty unclear on the series I know putting 2 x 12v in a series would make 24v with no increase in Amp Hours?

quentingargan

ghogie91 wrote: »

Batteries wise, would it be smarted to link parallel or in a series? Im pretty unclear on the series I know putting 2 x 12v in a series would make 24v with no increase in Amp Hours?

Yes - better to work on 24V provided you can use this voltage to run appliances. The power (watts) = Volts X current (amps)

So if you have a 100W load, this can either be 24V at 4.2A or 12V at 8.4A. Similarly putting batteries in series or parallel changes the voltage or amps, but the Watt-Hours or power stored remains the same.

It is better to run at lower currents - the wire size for larger currents is higher, and more importantly, voltage losses are higher.

You can also use a range of DC DC converters to convert from 24V down the voltage used by your router, or computer etc., without using the grid, whereas DC DC converters to raise voltage from 12V to say 19V are harder to come by.

Capt'n Midnight

You should invest in a power meter for €10-20

this will give you your peak output too - for sizing an inverter / UPS

But look at the numbers

240W * 24 = 5.76KWh per day
= 12V * 480Ah which is 10 car batteries in size (and they'd have to be deep discharge and even then draining them that low shortens their life so realistically you'd need more)

Don't forget we get a lot more sun in summer than winter so you'd need massive batteries to ride over dull days.

Much cheaper to keep the grid connected for now.

DC-DC from 12v to 19v easy enough , Aldi/Lidl do them every so often

24V is handier for fridges and stuff.

Don't forget that 12v from a battery is anything from 11.3V to 14.4V so stuff like hard drives which are expecting 12.1V (+/- 5%) might not like a direct connection. - rule of thumb if it's got a heavy wall wart transformer (DC 12V) or a car cigarette lighter connector then it'll take a direct connection to a battery, but if it's not 12V or it's a lightweight adapter then it won't - but always double check

freddyuk

Capt'n Midnight wrote: »

You should invest in a power meter for €10-20

this will give you your peak output too - for sizing an inverter / UPS

But look at the numbers

240W * 24 = 5.76KWh per day
= 12V * 480Ah which is 10 car batteries in size (and they'd have to be deep discharge and even then draining them that low shortens their life so realistically you'd need more)

Don't forget we get a lot more sun in summer than winter so you'd need massive batteries to ride over dull days.

Much cheaper to keep the grid connected for now.

DC-DC from 12v to 19v easy enough , Aldi/Lidl do them every so often

24V is handier for fridges and stuff.

Don't forget that 12v from a battery is anything from 11.3V to 14.4V so stuff like hard drives which are expecting 12.1V (+/- 5%) might not like a direct connection. - rule of thumb if it's got a heavy wall wart transformer (DC 12V) or a car cigarette lighter connector then it'll take a direct connection to a battery, but if it's not 12V or it's a lightweight adapter then it won't - but always double check

OP has done the calculations and is estimating running time is 5 hours per day not 24 hours. This makes a massive difference especially if some run time is in daylight. Also I am sure the chargers do not take 5 hours to recharge Ipods, phones etc. so the actual loads will be lower than the estimate however he needs to include the losses and cover the dark days.
Most decent LED lamps will run 24 volts.
However on a small system with short cable runs I think 12 volt will be more effective simply because much of the kit can be directly connected. Adding converters will add to the losses and expense.

Capt'n Midnight

freddyuk wrote: »

OP has done the calculations and is estimating running time is 5 hours per day not 24 hours. This makes a massive difference especially if some run time is in daylight. Also I am sure the chargers do not take 5 hours to recharge Ipods, phones etc. so the actual loads will be lower than the estimate however he needs to include the losses and cover the dark days.

Ah

The phone chargers are only 3W so more like 150W load (but measure with a plug, they are a lot cheaper than overspecing the system )

4*130W , 1.2KWatt hour storage - sounds about right, - But check local sunlight hours Wexford gets a LOT more sunshine in winter than Donegal

but that would pay for a many years of ESB standing charge




http://www.solarbook.ie/solar-insolation.html - sunlight Dublin Airport 2005


http://www.met.ie/climate/monthly-data.asp?Num=1575 - check local data at Malin head the worst month is just 7% of the best one :eek:

Mackerdave

Hi all.
I installed a solar water heating system a few years back, and am now looking into PV as the price of panels drops. While I will not become self sufficient, I am looking to reduce my consumption from the grid, hence getting a return on my investment. This would be a grid connected system. Can anyone recommend a good supplier for PV panels and associated bits? I know when I had the solar heating installed you could only get the SEI grant if you used an approved installer. As far as I could see this was a license to charge you higher installation fees to grab some of the potential grant. What's the position in getting an installation signed off? Could you do a self install and get this signed off by an electrician (if they would)?
Thanks

ravendude

This may be of interest to some, - if its a success it will be only a matter of time before they are selling here also!
http://www.reuters.com/article/2013/09/29/ikea-britain-solar-idUSL5N0HN27U20130929

You'll find that all your appliance ratings are lying to you the power consumption figures listed, on almost every device you have is a maximum value for peak output. While it's helpful to use these figures to calculate system requirements if you use an ammeter you'll find discrepancies of up to 80% over-ratings on nominal consumption.

Making mirco PV off-grid work requires a lot of energy frugality, and adequate cable is the best investment you can make.

There's ~21" LED tvs on the market today as low as 20watts, some of them take a regulated 12volt supply.
The auto industry is a great source for cheap buck/boost regulators and power supplies as the auto market will require the same voltage tolerances as 12v PV.
Because a DVD player has a motor spinning a disc it's got a higher consumption than say a computer hard disk (especially if it's a flash hard disk).

On a system as small as you are contemplating I wouldn't consider MPPT, you'll more than likely find a greater return of investment on a top PWM temperature compensating solar regulator and spend the change on more solar modules. A system < 600W PV is not worth it as far as I've researched.

Batteries; if you're serious and you want them for 15 years then get full traction 6v or 2v.
If you're experimenting then 6v flooded deep cycle semi-traction. 12v leisure batteries are aimed at holiday makers; campers/marine/barges etc. They can live up to their warranty by lack of use.
If you want good batteries in use everyday then put 6v in series. These are for golf carts, forklifts, scissor lifts and mobility equipment...industry standard; tried and tested.

A good price for solar modules is ~€1.20 per watt. If you're handy you can make an array from cells at ~ €0.40 per watt.
Monocrystalline are king in Ireland's average diffused light conditions.

Inappropriate cable gauge and overly long runs is the most common waste of energy DC systems suffer from. Often €50 of cable instead of €15 will save you the same power loss that will be offset by €150 of solar modules. Check your voltage drop charts; cable gauge vs distance then overspec. everything by 2 grades or use an inverter where voltage drop is negligible.

You need a master 12volt buck/boost regulator for a 12 volt system, or a 24 volt buck regulator for 12v on a 24v system, or individual regulators for everything you run that requires a stable voltage, or a pure sine wave inverter. If you don't get one of these you will end up spending that saving on replacing electronics. Although many devices are rated 12v, a 12 volt battery can be anywhere between 10.5v and 16v, this will hugely reduce the lifespan of electronics.

Modulated inverters are a waste of time unless you want to make an energy saving on self consumption.
Inverters are inefficient. Larger inverters have a larger self-consumption. So a small and a medium inverter makes a better power saving than one large one that runs everything.
In the first scenario I would have a 150watt pure sine inverter for electronics and a 1.2kW modulated inverter for some power tools (brushed motors), resistance loads and other devices.
Modern electronics, microwaves, desktop computers, induction motors are some of the many devices that go apesh1te on MSWs.

Voltage drop due to too thin cable manifests as heat and therefore pointless energy loss.

Put the solar controller right beside the batteries on serious cable.
Put the main regulator closest the sockets and furthest the batteries on serious cable.
If you are using an inverter then serious cable to the inverter, and regular amp ratings will do after.
Remember cable is rated for max. allowable temperate not min. allowable voltage drop. On PV any transmission heat is a waste.
AC electrons vibrate, DC electron travel the conductor so often listening to a trade electrician will lead you astray. In DC conductivity is key.

Certain things like DC car laptop chargers will have their own buck/boost regulation. Do not use these on the regulated feed. Have a separate unregulated feed for stuff like this as two regulators will compound inefficiencies.

Pure sine inverters are the easiest and most expensive way to run devices.
12volt regulation is the cheapest and most efficient (but not by much).

If you're going to cheap out on cable get an inverter because 12v then becomes the least efficient.
If cable's costing you more than a pure sine wave inverter get the inverter.

The most important thing of all to get is a real shunted additive ammeter battery monitor that tells you voltage, amperage, % charge and % used. Don't get a solar controller remote with an SOC reading, these are highly misleading glorified voltmeters. Voltmeters have their place as quick references only, measuring state of charge off a voltmeter without idling the system 24hours is grossly inaccurate. If you can't monitor the system you will harm the batteries/devices. Also if using power during the day you do not suffer the 20% loss of lead acid charging because you are using the current directly and you can adjust your consumption by reference to an ammeter to charge portable devices etc from this surplus.
Best of all it's a diagnostic tool. It will tell you if a module is down for the count, or a fuse is blown, solar controller needs a reset, you left something on you forgot about etc.

Don't forget to water the batteries every now and again, and stick a hydrometer in them while you're at it to verify their status.

Sulphation (death of batteries) starts around < 12.4v if you can't keep the batteries above 12.2v then you need more batteries/generators.

I can PM links for quality kit I've referenced, and links to successful systems.