Domestic solar PV quotes 2018

unkel wrote: »

You can under size your inverter as you will never see the full 4.5kw from an EW setup, but there is not much point as modern inverters are already very efficient with a very small load (like 20%). Under sizing means if you want to add a few panels later, you might have to upgrade your inverter, adding unnecessarily to the costs. As a 5kW inverter costs only a tiny bit more than a 3.6kW inverter.

I agree with unkel here.
If you look at price difference for very common Solis inverter 3.6kW to 5kW only adds ~50 euro.

unkel wrote: »

You can under size your inverter as you will never see the full 4.5kw from an EW setup, but there is not much point as modern inverters are already very efficient with a very small load (like 20%). Under sizing means if you want to add a few panels later, you might have to upgrade your inverter, adding unnecessarily to the costs. As a 5kW inverter costs only a tiny bit more than a 3.6kW inverter.

Thanks. I was purely looking at if the inverter would be more efficient if operating closer to its limit more of the time but haven’t seen any actual in use data comparing similar set ups

spose wrote: »

Thanks. I was purely looking at if the inverter would be more efficient if operating closer to its limit more of the time but haven’t seen any actual in use data comparing similar set ups

What make / model inverter are you getting? The old motto that undersizing your inverter gives better efficiency must stem from the olden days of PV. These days inverters reach near max efficiency at about 20% load. In fact at full load they are slightly less efficient than at half load:

Since this is now a general PV thread, I will ask here. Since the install 5 days ago I have noticed that my inverter does not fully direct electricity it is producing to household consumption. When I start an appliance the meter whirrs faster for a few minutes before it stops or slows to a crawl. It is a 4.8kW E/W system with a Growatt 3600 inverter. Initially I thought that the CT clamps must have been done incorrectly and not capturing usage right but it seems that after anything from 1-5 minutes the inverter does direct energy to the appliance. This is when the production is more than sufficient to cover the appliance and also when power should be drawn from the battery.
Also the app seems to have weird numbers on it. It is meant to be a snapshot every five minutes but there seems to be a small import or export number all the time. 20W or so.
Finally the battery doesn't seem to get used fully. Last night the battery only went down to 40% SOC while my meter showed 2 units imported from the grid. It's a Pylontech 2000 so I know that it can only draw 1.3kW max but the app never showed consumption going to that level. Is this a setup issue?

Thanks for the reply. It is definitely not the case that I am consuming more than what is being produced. For instance yesterday at 12:30 the system was producing ~3450W. My consumption was ~200W with nothing big on and the app and inverter panel showed close to 3000W being exported. I turned on my 3kW immersion and the meter started whirring fast. After about 5 minutes the meter stopped and the app now showed all the production being directed to the element. There was no cloud cover in those 5 mins. But I had imported and been metered for a good 0.25 units in those 5 mins despite having a surplus.
Will get in touch with installer.

What's the capacity of your Pylontech battery? The standard US2000 model can only handle 25A, so charging and discharging of the battery is limited to about 1.25kW

garo wrote: »

Also the numbers from the app are all over the place. Right now they show me exporting 15W

Yeah, that is impossible. Sunset was an hour before your post

Time to ring the installers methinks...

Keep us updated!

My system only went in 6 months ago and I'm already well over 2MWh. Most of it gone to the grid, that's my contribution

4KW system with 5KW inverter and 5.7KW battery €10k including Vat
Grant back €3800
Cost to house €6200
Hot water diverter €300
PM me and ill get you company, 30yr on panels (85% efficient after 25yr), Alpha Smile 5 battery and inverter

Shefwedfan wrote: »

Is this good or bad?

I paid almost identical figure for for 4.2kw, (14*300w on E/W array) 5kw inverter and 4.8kwh battery

2950 watts produced in 11 months. Should easily be about 3300 watts produced in 12 months. This is in line with expectations for my E/W array.

air wrote: »

In my opinion it's madness not to include at least a small PV system in any new build nowadays.
The installation cost should be much lower since scaffolding is in place and trades are on site anyway.
You also have the option of an in roof system which saves on slates/tiles and will look very neat and tidy.

The cost of say a 3kW system without a battery should provide an acceptable payback even without a FIT. If you could split it East/West all the better as it will increase self consumption and improve payback.

Yeah thinking about it again I will look into it. My mantra was to keep things simple build an air tight well insulated house with an air-to-water and HRV and I shouldn't need much heating and complications after that. But I think we will all be moving to EV's soon and was thinking myself of getting one in the next year or two anyway and having PV could help in charging this. If the FIT is any good then its a no brainer.