Domestic solar PV quotes 2018

And since the solar tube coil is at the bottom of the cylinder, the whole tank will heat if I get 30 tubes..

Tradnuts wrote: »

Yes, the same setup as me so!
I was thinking of the PV's because i didn't want the expense of the servicing of the tube liquid every 18-24 months and cost of the pump replacement at some stage in the future. (plus the running costs).
At least with the PV's i get some reduction in electricity bill and a fair amount of hot water, especially in the summer when the oil heating is not on and we are only using the immersion. I would imagine i would need the immersion very little for the 4 months of the summer with PV's.

Whats the likelihood of legionnaires?
Where did you get the hot water sensors?
Thanks

Im in the same mind as yourself more or less.

There is talk on here before about Thermomax Tubes that dont need a dump or have the glycol replaced as often as 24 months, more like 3-4 years depending on how hot the summers were preceding them.

For us, we dont use that much electricity. No one in the house all day and efficient appliances so the main cost we'd have is hot water.
The cost of PV would be about double that of the tubes for equivalent hot water generation. And to make use of PV in the evenings means a decent battery and thats 1000s more. Payback would be 15-20 years for us I think.

But with FIT and the cost going down, it is still temping to start small and see from there.

Don't know too much about the legionaries, just know that they can take hold at the bottom of the tank as the water is cooler and possibly stagnant.
Copper cylinders prevents it naturally. Stainless steel doesn't.

The sensors are just cheap Aliexpress ones
I taped them up a little to make sure that the ends done come off and used a wire from a coat hanger to slide the end in to the sensor cavity in the cylinder.
Works perfect for what I want for the moment. I will get proper ones one I know which way I am going to go.

Tradnuts wrote: »

System i'm quoting for is a 2KW system with a diverter for the immersion.

Don't get an immersion diverter for such a small PV system. It will never pay for itself. Cheaper to just let the overproduction go back to the grid for free (it's also likely we'll get a FIT some time in the near future)

AidenL wrote: »

I still haven't pulled the trigger. Looking for some opinions, even though its probably the wrong time of the year to install PV now.

Most recent electricity bill, 19th July till 11th December, 67 days.

Used 807 day units, 12 per day, 339 night units,5 per night. Total cost of the electric, after discount, including VAT, but excluding standing charges and PSO was 170 euros. So that's the amount to play for.

So, I guess my base load and night load would be right for PV and a 5kw battery which would probably take me through the night, at least at this time of year.

Any thoughts?

I would think a 5kWh battery wouldn't make economic sense for you. You should get a smaller battery just to tide you over until night rate kicks in. In almost all instances, using a battery instead of night rate electricity doesn't make any sense financially.

What is the cost of the 5kWh battery? Divide this by your night rate unit cost and then work out how many battery cycles are needed before it pays for itself.

Alkers wrote: »

I would think a 5kWh battery wouldn't make economic sense for you. You should get a smaller battery just to tide you over until night rate kicks in. In almost all instances, using a battery instead of night rate electricity doesn't make any sense financially.

What is the cost of the 5kWh battery? Divide this by your night rate unit cost and then work out how many battery cycles are needed before it pays for itself.

garo wrote: »

AidenL, I agree with Alkers here. A 4.8kW Pylontech battery setup is about €2000-2400. I have a very similar usage profile to yours and was consuming about 15 units a day in the summer. Mind you in the winter you would be consuming 18-20 due to longer nights and more use of the clothes dryer. I went for a 4.8kW system and in the summer it definitely produces more than I can use. But on the flip side I get more production in the evenings and on cloudy days. I have an EW orientation.
Battery costs are coming down at ~10% per year and if we get a Fit it will render the additional battery useless. According to my calculations it costs anything from 6-10 cents to cycle one KWh through a battery. So you don’t save a huge amount over night rate electricity.

The battery seems to be around 3000 including VAT, less the grant? Hard to see exactly how much it is in the quote, I got a lump sum price. So that would be 2k nett, divided by 0.08 - so 25,000 cycles? Is that correct?

Or am I doing the calls wrong?

Would the battery not cover say, from 8pm these days till midnight, with a saving on day rate if it was fully charged on a bright sunny day like this? And then night rate overnight at 8 cents? And back to recharging the battery tomorrow?

What am I missing? Im not sure what the saving would be on a smaller battery.

And in winter, is it not sensible to charge the battery overnight at night rate and expend it during the dull winter mornings?

Most batteries are rated for 6-10,000 cycles. You may get 25,000 cycles are greatly reduced capacity but I think it is safer to assume 10k cycles at 90% discharge. Do you know the make of the battery you are going for?
So a Pylontech 2.4kWh will give 2.2kWh per cycle at ~90% DoD. Times 10k cycles gives you 22MWh. At a cost of 1300 off eBay shipped you are talking 6c per unit just to use the battery. Charging at a night rate of 8c you basically save about 2c max. Not worth it IMO.
Yes these days you will get a 5 KWh battery to last until midnight. But for 3-4 months in winter you probably won’t be able to get them fully charged. It’s about whether to go for a small 2.4kWh battery or a larger 5kWh one. I went for a smaller battery and am willing to wait for a FIT or 25% cheaper batteries in 2-3 years. You may decide otherwise.

Yes agreed. I find the 2000 with a max discharge of 1240W is not enough when the oven is on. On eBay the 3000 was almost 50% more expensive so return on cost is pretty linear. And I would rather spend that 500 euro on the bigger battery than an Eddi as I use Nat gas for HW.
So unkel you are not going for a 2 ton lead acid bank then?

garo wrote: »

So unkel you are not going for a 2 ton lead acid bank then?

About half a ton (16 batteries of nearly 30kg each), but yes, lead acid!

20kWh :cool:

Waiting for a waterproof cabinet that was supposed to come my way, before I can build the battery and have the other components all hooked up.

Winterman1234 wrote: »

Total novice question but what is the difference between dual inverter and hybrid, should i not have been quoted for a hybrid inverter to use with the 2.4kw array and polytech battery or can the solis dual 2000 inverter be used to charge battery.

Dual means the inverter can handle 2 strings of solar panels. You need this if you have 2 different arrays in different orientations, say x panels east facing and y panels west facing

For use with a battery, your inverter needs to be a hybrid, so yes you should have been quoted for that

Also, if you are going for the grant scheme, I would go for a 4kW array as the extra panels over a 2.4kW array will cost about the same net to you (or even be cheaper) as you get an extra €1100 subsidy for this

The aim is about €6-€7k for a 4kW system with hybrid inverter and a lithium battery (net after the full €3,800 subsidy)

Thank you unkel for explaining this, the information from many of the registered SEAI installers is vague and more a sales pitch, when questioned about detail you get the feeling some don't fully understand.

The quote for 2.4KW JA array, solis 2000 tl inverter, eddi and 2.4KW polytech was €4500, I will question them on the inverter and try to get a more bespoke quote for the larger array. The same company for a 2.1KW JA array, solis 2000 tl inverter and eddi was €3300.

Winterman1234 wrote: »

Thank you unkel for explaining this, the information from many of the registered SEAI installers is vague and more a sales pitch, when questioned about detail you get the feeling some don't fully understand.

The quote for 2.4KW JA array, solis 2000 tl inverter, eddi and 2.4KW polytech was €4500, I will question them on the inverter and try to get a more bespoke quote for the larger array. The same company for a 2.1KW JA array, solis 2000 tl inverter and eddi was €3300.

I take it that those prices are after a grant rebate, on a tiled roof and single roof direction?.

Bungalow should be a cheaper install as scaffolding may not be required. Read through the thread for actual quotes and I would agree with Unkel. Aim for 6-7k for a 4kW system with a battery. Eddi is not strictly necessary as if you heat your water with Nat gas you won’t make your money back for a long time. PM me for info on a couple of installers.

Not much gas here in rural donegal, we are using oil grant vortex. It was more for convenient during summer when oil is not in use. But yes you have a valid point.

Any boiler is likely to last a long longer if not used at all for 6 months of the year as well.
Many boilers (especially oil) don't modulate and their nominal output is going to be a lot higher than the achievable heat transfer rate into the hot tank.
This will lead to short cycling which means more wear and tear and likely further reduced efficiency.

A low cost alternative to a diverter would be to install a lower wattage immersion element and run it on a timer for a few hours during the summer. Should provide most of the benefits at a fraction of the cost, especially if the house is unoccupied during the day, like many are.

Another option is to pick up a cheaper diverter. I got one for a buddy for <€100 from eBay (2nd hand) and he is delighted with it.
They are easily retrofitted post installation.

unkel wrote: »

Dual means the inverter can handle 2 strings of solar panels. You need this if you have 2 different arrays in different orientations, say x panels east facing and y panels west facing

For use with a battery, your inverter needs to be a hybrid, so yes you should have been quoted for that

Also, if you are going for the grant scheme, I would go for a 4kW array as the extra panels over a 2.4kW array will cost about the same net to you (or even be cheaper) as you get an extra €1100 subsidy for this

The aim is about €6-€7k for a 4kW system with hybrid inverter and a lithium battery (net after the full €3,800 subsidy)

To update quoted €6700 for 4.2KW array, solis 3.6KW hybrid inverter (had asked for 5KW though), 2.4KW polytec battery and hotwater diverter.