Solar PV Hints, Tips & Troubleshooting

sphinxicus wrote: »

Thats the job. So when you're in UPS mode, I'm assuming that means that the subset of sockets/circuits are the only ones that receive power? Or is it whole house? And if its whole house, what happens if demand outstrips what solar generation + battery output can provide? Sorry for all the questions.

If you have a daisy chane of hybrids and enough power from your batteries, or you could go with a high powered inverter, 10kw solis hybrid or other, even an off grid setup will do. You just need to calculate your loads over time, to save on the amps you could just get a gas bottle cooker, your shower doesn't necessarily have to be electric, 8kw of power is alot for an electric shower, you can use the 3kw element in your hot water tank.
Alot of options.
You will trip your inverter if its overloaded

sphinxicus wrote: »

And if its whole house, what happens if demand outstrips what solar generation + battery output can provide? Sorry for all the questions.

Yes its whole house

daughy wrote: »

You will trip your inverter if its overloaded

It is one advantage of the switch being manual, as that will allow me time to ensure any possible high power items are off - cooker/dryer/washer etc before switching into UPS mode.

sphinxicus

daughy wrote: »

You just need to calculate your loads over time,

this is where I'm at right now. Only at the start of my "Solar PV journey" and trying to get my head around everything. The more i read, the more options that seem to open up!

daughy wrote: »

to save on the amps you could just get a gas bottle cooker, your shower doesn't necessarily have to be electric, 8kw of power is alot for an electric shower, you can use the 3kw element in your hot water tank.
Alot of options.

Got a small gas camping stove to use indoors and gas BBQ for outdoors so cooking is covered when we lose power which seems to happen when the wind changes direction.

We have solar thermal collectors to heat water, (i think they have glycol in them - they were on the house when it was built) and they do a great job from May - Oct. We dont actually have an immersion element in the tank. Water is heated up from the pannels or gas boiler. No dependency on electric shower but i have no idea how much the pump on that system needs to run.

daughy wrote: »

You will trip your inverter if its overloaded

Good to know. So thats another item to add to the list. Figure out how much each applience uses so that i can make sure the appliances classed as "necessities" can be powered within the limits of said inverter.

Thanks

KCross wrote: »

You either have a very high “no battery” quote or something else is wrong in your figures.

The extra grant doesn’t cover the extra costs involved so something is up if you say there is only €40 in the difference.

I disagree. 1240 is about the cost of a 2.4kWh battery and hybrid over non-hybrid inverter to an installer. DrPhilG got an extra Pylontech for 700 over his original quote. 540 is definitely ballpark what a hybrid inverter costs more than the non-hybrid equivalent.

sphinxicus wrote: »

this is where I'm at right now. Only at the start of my "Solar PV journey" and trying to get my head around everything. The more i read, the more options that seem to open up!

Got a small gas camping stove to use indoors and gas BBQ for outdoors so cooking is covered when we lose power which seems to happen when the wind changes direction.

We have solar thermal collectors to heat water, (i think they have glycol in them - they were on the house when it was built) and they do a great job from May - Oct. We dont actually have an immersion element in the tank. Water is heated up from the pannels or gas boiler. No dependency on electric shower but i have no idea how much the pump on that system needs to run.

Good to know. So thats another item to add to the list. Figure out how much each applience uses so that i can make sure the appliances classed as "necessities" can be powered within the limits of said inverter.

Thanks

Instead of going all out right now and getting a full monitoring kit, you can just easily purchase a watt meter, plug it in to your fridge for 24 hours and it will give your overall usage, fridges are normally around 1kwh used for 24 hours.
Washing machines only ramp up when they spin.
I wouldn't touch a dryer in a grid down unless you have more than enough solar to cover the export of the battery during the day.
Combi boilers are bad for grid down,plus there is no hot water stored, just mains runs through them.
Go with a 48 volt system as your wire diameter is smaller.
Led lights, no desktops as they can use up to 3 to 400 watts an hour, laptops are not that efficient either 150 watts , try a tablet.
Amazon is good for dc circuit breakers. Anything else just ask.
YouTube is great for learning about off grid, on grid is the easy part.

KCross

garo wrote: »

I disagree. 1240 is about the cost of a 2.4kWh battery and hybrid over non-hybrid inverter to an installer. DrPhilG got an extra Pylontech for 700 over his original quote. 540 is definitely ballpark what a hybrid inverter costs more than the non-hybrid equivalent.

Thats the key point there garo.

No point in looking at retail prices for batteries. You need to compare quotes from SEAI registered installers and there sure aint €40 in the difference between a battery and non-battery install unless the installer is massaging the quotes.

I've got enough quotes of my own at this stage to know the price difference unless something has radically changed in the last few months.

battery, hybrid inverter, odds 'n ends and labour minus the grant does not get you to €40.

As a few of us have said before, better keep the money in your pocket, get the €1800 grant and pay a few extra quid to get it to 3-4kWp (which doesnt cost much extra as the installer is already on site) and then utilise FiT when it comes in.

No issues with a much more expensive hybrid inverter packing up or batteries degrading in the lifetime of you trying to break even, not to mind be up money, and FiT will "make you money" as an "infinitely" sized battery without any capital expenditure or degrading parts. I know we need to wait for that to come in but I'd rather wait a few years for that than pay for Li-ion batteries now that wont break even for 10-15 years, at least.

But peoples opinions differ here so each to their own. At least the readers are getting both opinions on it!

sphinxicus

daughy wrote: »

Instead of going all out right now and getting a full monitoring kit, you can just easily purchase a watt meter, plug it in to your fridge for 24 hours and it will give your overall usage, fridges are normally around 1kwh used for 24 hours.

I used to config/maintain network monitoring software so what can i say, i love a good graph :P but you make a good point, a watt meter would give me a ball park for certain appliances alright to get started with.

daughy wrote: »

Washing machines only ramp up when they spin.
I wouldn't touch a dryer in a grid down unless you have more than enough solar to cover the export of the battery during the day.
Combi boilers are bad for grid down,plus there is no hot water stored, just mains runs through them.

Washing machine wouldnt be a priority for me and can be done in the sink at a push if we have "storm ophelia" length outages. The missus may disagree there

The gas boiler heats water in the same tank as the thermal panels we have. If we know of a storm coming and the tank isnt already warm from the pannels i usually give it a 60min boost just to make sure we have a full hot tank. Have to admit, i've never thought about how much power a boiler would consume until now.

daughy wrote: »

Go with a 48 volt system as your wire diameter is smaller.
Led lights, no desktops as they can use up to 3 to 400 watts an hour, laptops are not that efficient either 150 watts , try a tablet.
Amazon is good for dc circuit breakers. Anything else just ask.
YouTube is great for learning about off grid, on grid is the easy part.

All LED lights here. Unfortunately massively offset by 2 servers running 24x7 plus now 2 laptops from us working from home. Your advice is much appreciated. Given me lots more to think about and research!

slave1 wrote: »

I don’t know why such negativity around batteries

Because I measure their system performance and find them uncompetitive with conventional power prices.

KCross wrote: »

Thats the key point there garo.

No point in looking at retail prices for batteries.

But who is looking at retail? BTW, slave1 shared the quote via PM and the original battery-less quote was not at all expensive.

sphinxicus wrote: »

I used to config/maintain network monitoring software so what can i say, i love a good graph :P but you make a good point, a watt meter would give me a ball park for certain appliances alright to get started with.

Washing machine wouldnt be a priority for me and can be done in the sink at a push if we have "storm ophelia" length outages. The missus may disagree there
The gas boiler heats water in the same tank as the thermal panels we have. If we know of a storm coming and the tank isnt already warm from the pannels i usually give it a 60min boost just to make sure we have a full hot tank. Have to admit, i've never thought about how much power a boiler would consume until now.

All LED lights here. Unfortunately massively offset by 2 servers running 24x7 plus now 2 laptops from us working from home. Your advice is much appreciated. Given me lots more to think about and research!

Don't forget to learn how to calculate your power.
Your amps, watts, volts calculations, after you have that down you can sail through your off grid setup.
Not all solar panels are the same, the voltages may differ, as an example, you can't have let's say 20 panels at 40 volts each, 20x40= 800 volts, and your inverter can only handle 600 volts, it's over voltage.
Your batteries are the same, a 48 volt battery setup at 200 amp hours is 48x200= 9600 watt hours.
If your going with agm or lead acid that above number is halved as lead acid and agms can safely only discharge to 50%, so you only have 4800 watt hours, that's the beauty of lithium, can really discharge to 20% and still be fine.
I know you can go to 0% but not advisable.
So your 4800 watt hours is 4.8kwh..
Just get used to your calculations..
You need to understand circuit breakers also.
If I have 5kw of solar coming in to a 48 volt battery I need a dc breaker, 5000 watts divided by 48 = 104 amps, 104x1.25= 130 amp breaker.
Hope this helps

KCross

garo wrote: »

But who is looking at retail?

Because the prices mentioned for batteries dont include the installers profit and labour.

As I said, the only figures that matter, if you are using the grant, is the bottom line of the quote. Figures you see online dont matter.

garo wrote: »

BTW, slave1 shared the quote via PM and the original battery-less quote was not at all expensive.

You can get a 4.2kWp system with no battery for just shy of €4500 after the €1800 grant and thats for a slate roof, so its possible to get it even lower than that.

Are you telling me you can get a with battery quote for the same money? I very much doubt it.

My point is that using a hybrid instead of non-hybrid inverter and adding a battery doesn't require that much extra labour. And an installer may be willing to do it at cost of parts to seal the deal with a customer who may not do an install otherwise. We already know that margins are pretty generous in this game as FUD abounds and more knowledgable punters definitely are able to haggle for better deals.

daughy wrote: »

that's the beauty of lithium, can really discharge to 20% and still be fine.

So if I spend 4 times more on an alternative chemistry I can extract 30% extra?! Bargain!

I'm testing a hybrid at the moment (two actually) and I know I've said before the efficiency is dire compared to a batteryless system. What I've just discovered is I'm also getting a power factor penalty on top because I can't just obfuscate the problem and give it to the power supplier...that's me.
Derate another ~20% energy.

Sir Liamalot wrote: »

So if I spend 4 times more on an alternative chemistry I can extract 30% extra?! Bargain!

Your not considering the life cycle Of lithium and the dod, for instance the pylontech has a cycle. Life of 6000 cycles at 80% dod,

A normal lead acid will be 3000 cycles at most. Likely 50% dod

Lithium can handle faster charge rates.

You have to consider the storage also, have you ever picked up a sealed lead acid.. Nobody likes to move these things around.
The only issue you might have with lithium vs agm or lead acid is the temperature.
Lithium doesn't like the cold.
I don't like the prices of lithium but they can last if cycled properly a very long time, lead acid is going to cost you more in the long run..
I thought you where all about payback?

https://youtu.be/Yf9N9zBgyB8

Let's say for instance you just charge your fridge for the lifespan of the lithium 2.4kwh pylontech.
How much is a pylontech after tax?
Let's say 1100 euro.

So for instance a fridge uses approx 1kw for 24hrs,
That 1kwh in todays electric cost after vat, standing charge, carbon tax works out at approx 25 cent a kW.
So 365 days of the year at. 25 cent = 91.25 euro.
If the charge cycle lasts 6000 cycles, and it doesn't finish at 6000 cycles, it will degrade but still work, so 6000 cycles divided by 365 days is
16.4 years
16.4 years times 91.25 euro = 1,499 euro..
If anyone can verify these figures I would appreciate it, plus the lifespan of the lithium will last longer as your not going to 80% dod..
Your looking at about 30 years for the lifespan of that battery..

For the off grid guys here this guys videos are worth watching, also for the on grid guys.

But here is the facts about lithium

So my Eddie arrived dismorning, but unfortunately I have to get an electrician out to wire up the live and neutral from the hot water tank to the main board,the hot water tank element still works as its getting continuity, the people that lived here before me disconnected that line for gods no why.
I have the harvi and hub, is it possible just for now to connect up the harvi and hub and use one of the clamps for the live solar just to monitor the incoming feed from solar, or does the Eddie need to be involved

unkel

Sir Liamalot wrote: »

So if I spend 4 times more on an alternative chemistry I can extract 30% extra?! Bargain!

It's not 4 times, it's about 2-3 times the price per usable kWh comparing LiFePo4 prismatic cells brand new from China including all taxes and shipping costs versus used good quality lead acid over here, like the 92Ah AGMs I recently sold on adverts.ie for €62.50 each (after bulk discount). Compare new with new and lithium is less than twice as expensive

And the life cycle is more than 2-3 times

So the cost per cycle is less for lithium than for lead acid. Also you can get away with a much smaller (thus cheaper) battery if you want to put a typical charge / discharge of say 3kW through it

And the elephant in the room with lead acid is that it has to be fully charged at least once a week. If your PV setup can't handle that or if you don't set it up like that, or don't manually charge them regularly, your lead acid batteries will be as good as dead after one winter

Because of these reasons I recently switched from lead acid to LiFePo4

daughy wrote: »

So my Eddie arrived dismorning, but unfortunately I have to get an electrician out to wire up the live and neutral from the hot water tank to the main board,the hot water tank element still works as its getting continuity, the people that lived here before me disconnected that line for gods no why.
I have the harvi and hub, is it possible just for now to connect up the harvi and hub and use one of the clamps for the live solar just to monitor the incoming feed from solar, or does the Eddie need to be involved

For anyone trying my solution, it needs a registration code from the Eddie when it's powered to the hub. So unfortunately will have to wait

All this talk of batteries is really confusing? Surely the point of the battery is to improve your consumption of any electricity you generate?

For most users the highest electricity usage would in general the evening when cooking dinner ??. outside of that would be when ever people use washer / dryer / dishwasher or shorter bursts of high use for toaster/microwave/kettle? Yes there will be exceptions to this.

If i had no battery i would export most of what i generate on my SE and SW facing roofs during the morning and afternoon. At this time of year by time we start dinner solar generation has dropped considerably. But with the battery aim to be full by mid afternoon and then that covers part of cooking requirements and so far (I know I'm only a week in) usually powers the house between 12 to 4am (longer if we have a takeaway

)

Once a feed in system comes along it still will depend on the price you get vs what you you pay for electricity to determine when to use battery vs when to sell? also expect if along with smart metering new time based charges come in then it could also be worth having a battery to discharge when the cost of electricity is highest and PV generation is not able to sustain your needs ?

Also when people are calculated pay back do you consider prices rising over time? EI just increased there prices.

I also don't get why we have a PSO levy for electricity but for gas there is a carbon tax. With the tax the more you use the more you pay. with electricity it makes no difference as everyone pays the same levy value irrespective.

graememk

idc wrote: »

All this talk of batteries is really confusing? Surely the point of the battery is to improve your consumption of any electricity you generate?

For most users the highest electricity usage would in general the evening when cooking dinner ??. outside of that would be when ever people use washer / dryer / dishwasher or shorter bursts of high use for toaster/microwave/kettle? Yes there will be exceptions to this.

If i had no battery i would export most of what i generate on my SE and SW facing roofs during the morning and afternoon. At this time of year by time we start dinner solar generation has dropped considerably. But with the battery aim to be full by mid afternoon and then that covers part of cooking requirements and so far (I know I'm only a week in) usually powers the house between 12 to 4am (longer if we have a takeaway )

Once a feed in system comes along it still will depend on the price you get vs what you you pay for electricity to determine when to use battery vs when to sell? also expect if along with smart metering new time based charges come in then it could also be worth having a battery to discharge when the cost of electricity is highest and PV generation is not able to sustain your needs ?

Also when people are calculated pay back do you consider prices rising over time? EI just increased there prices.

I also don't get why we have a PSO levy for electricity but for gas there is a carbon tax. With the tax the more you use the more you pay. with electricity it makes no difference as everyone pays the same levy value irrespective.

On a purely financial basis its hard to make a battery pay its way, even with the extra grant. Even with no feed in tariff. Do you know how much you get out of the battery every day, in Kwh, multiply that by your day rate and that would get you what you are "saving" by using the battery.

once a feed in tarriff comes in that would skew the figures even worse.

Now that you have solar in, I would really recommend getting a day/night meter in as most of your daytime use will be covered by solar and then you get the night time rate, at night for 9 hrs.

I love the idea of the battery and being able to use what you generate, and if you get it as a fun project, or for the feel good factor, go off grid, then go ahead, but to save money with it, is a false economy at todays prices and todays price of electricity. I still might get an AC connected battery But I'll be getting it knowing it might just pay for itself over its lifetime.. if I'm lucky!

The rise in electricity prices doesn't concern me, as I switch every year and go for the one that costs me the least amount of money.

Currently Im paying about 15.6c for day and 7.4c for night, (only have a 36% discount instead of the 41 that you can get now!)

graememk wrote: »

Do you know how much you get out of the battery every day, in Kwh, multiply that by your day rate and that would get you what you are "saving" by using the battery.

As still on single rate with EI thats 18.21c/kWh so per day so about a euro a day! Won't know how well works in dec/jan! night rate would modify that too i expect.

graememk wrote: »

I love the idea of the battery and being able to use what you generate, and if you get it as a fun project, or for the feel good factor, go off grid

I've always wanted to get solar since i first stayed in off grid houses in australia, so there is an element of this being an experiment/feel good factor. I'm still on lookout for some kind of complimentary urban wind system even its just 1-2kW to power house during the night and thus make the battery more of a backup/top up supply when PV/wind insufficient. (if such a wind turbine system is possible!!!!)

Lads yer regurgitating promotional marketing at me. Please stick to claims yee can prove yourselves.

idc wrote: »

All this talk of batteries is really confusing? Surely the point of the battery is to improve your consumption of any electricity you generate?

It disimproves it. It's a gimic to make manufacturers, installers and funding bodies money at end user expense. Try measuring it...I don't believe any of the proponents document their findings.

The purpose of a battery is wireless power.

unkel wrote: »

And the elephant in the room with lead acid is that it has to be fully charged at least once a week. If your PV setup can't handle that or if you don't set it up like that, or don't manually charge them regularly, your lead acid batteries will be as good as dead after one winter

Doing it wrong Unkel.
The elephant in the room is Li-ion has a BMS and Lead doesn't.

C/10 :eek:

unkel

Sir Liamalot wrote: »

Doing it wrong Unkel.
The elephant in the room is Li-ion has a BMS and Lead doesn't.

Mine doesn't

unkel

garo wrote: »

C/10 :eek:

That's no problem as long as you install at least 40kWh of it :pac:

Sir Liamalot wrote: »

It disimproves it. It's a gimic to make manufacturers, installers and funding bodies money at end user expense. Try measuring it...I don't believe any of the proponents document their findings

Are batteries only a gimic due to their current cost?

Or are you saying they will always be a gimic when used in a grid connected system?

Does the presence or not of FIT make any difference. ie at the moment there is none, hence at least the battery i have will save me day to day running costs. (then again as others pointed out high price of battery may mean i don't recover the cost of it over its lifetime)