Solar Energy and saving money

[Radioman]

First you can buy electricity at the low rate once you have a smart meter and agreed a tariff
Next you can store this energy and use it during the day
You need just two items to do this
A A storage battery
B An hybrid Inverter
Next and later if you wish to install solar panels it’s relatively a simple job to add these benefits are keep the batteries full and sell any surplus to grid
Finally to get the best elevation angle and compass direction ground mounting of solar panels makes the most sense if unshaded space available
Maintainence is simpler and potential roof damage avoided

 

[Marsupial]

A year ago today my PV solar system was installed. It's a west facing, roof mounted, 10 panel 4.15 Kw system with a 5Kw battery.

I received three quotes from well-reviewed installers in Munster (I live in West Cork) and as the two lowest were virtually identical, I went for the local man. Net of grants, it cost 9k to install, including the necessary BER survey.

The following two websites were consulted to calculate the estimated power generation for a year:-

https://pvwatts.nrel.gov/index.php ................. which predicted that I'd generate 2,990 kWh annually. and https://www.clare-energy.ie/calc_PV_production/ ...................... which predicted that I'd generate 3,450 kWh a year. My actual production was 3,365 kWh, which suggests that the second site [which uses one's Eircode] is more accurate.​

In the past 12 months I have sold 76% of the units produced to my energy supplier, generating an income of €540 and using the remaining 24%, thereby saving an estimated €250.

Further savings have been realised from charging my battery fully every night at the cheap night rate and using the stored power during the daytime. I estimate that this has saved me at least €380.

In summary, my outlay of €9K has resulted in savings in the region of €1,150, after tax but excluding depreciation.

I am very satisfied with this outcome and hope that the above may be of assistance to anyone contemplating a similar installation.

 

[_OkGo_]

Further savings have been realised from charging my battery fully every night at the cheap night rate and using the stored power during the daytime. I estimate that this has saved me at least €380.

Curious as to the breakdown on the costs of the battery were here?

Is your estimate based on 1825kwh (365 x 5kwh) moved from day to night rate? If so, how much was the battery to install with/without grants?

I've often wondered if the payback on a battery alone made sense or even if it is better than the solar

Or in your case, had you chosen not to install the battery, would you have been able to consume all or most of what was exported?

You exported 2555kWh so instead if you consumed an additional 1825kWh and only exported the remaining ~730 units you would have saved €815 from your day rate and generated €150 from export. You could be saving €965 with solar install only

 

[mugsymugsy]

Apologies if I am missing your point but the issue with not having a battery is consuming power at an expensive rate in the winter. By having a battery and charging it at night rate of say 8c then during the day if there is solar power generated then this can be consumed / refill battery so it can the be reused in the evening when no solar being generated.

If you don't have a battery you will then have days where you are taking from the grid at peak rates.

 

[Marsupial]

Is your estimate based on 1825kwh (365 x 5kwh) moved from day to night rate? If so, how much was the battery to install with/without grants?

It's not quite as simple as that. In the summer, the battery often retains a significant amount of charge at midnight, so it doesn't need to recharge fully overnight. Furthermore, in the daytime, particularly in the afternoon/evening (because it's west-facing) it is constantly being topped up by the panels, leading to a situation where, in the 153 day period between 1 April and 31 August, I drew down only 10 daytime rate units!

I've often wondered if the payback on a battery alone made sense or even if it is better than the solar

Me too! It's certainly becoming a lot more viable as the price of batteries keeps falling. .

Or in your case, had you chosen not to install the battery, would you have been able to consume all or most of what was exported?

Definitely not! In the last 12 months I have only used 355 day rate units.

Before PV, my day/night unit ratio was 45:55; since PV (and battery) this has changed to 10:90.

Incidentally, 78% of my total yearly PV energy was generated in the 6 months between 1 April and 30 September.