Solar PV with or without battery?

[chris101]

Greetings, everyone,

After dedicating over a month to researching Solar PV systems, I'm nearly ready to make a decision.

Currently, my inclination is towards a 7kWh optimized system. However, I'm grappling with the decision of whether to invest in a battery now or wait a few more years, as I have a budget of up to 3k for a battery.

My yearly energy consumption stands at 6000kWh, with daily averages of 12-13kWh in the summer and 20-25kWh in the winter.

My setup will include 16 panels, with 12 facing South (185 degrees) and 4 facing South West (247 degrees). Some of these panels will experience morning shading, but they're unobstructed from 10am to 6pm.

I'm curious about estimating my annual energy generation and export? During summer nights (midnight to 8am), our maximum grid import is 2.5kWh.

The bulk of our energy usage occurs on weekdays from 4pm to 9pm, and during weekends. I anticipate a significant increase in consumption during the winter due to our gas central heating and reluctantly using a tumble dryer from time to time.

Based on my understanding, if I export 75% of my generated power (likely via Octopus Flux), it might make more financial sense to delay the battery investment until I can afford a 13kWh+ battery.

One of the calculations shared with me suggests: "A 7kWh system should generate 7K kWh per annum conservatively. You will sell 75% of that for export at 22p via Flux = £1150 earned. Offset 25% of your consumption = £450 saved. Total = £1600 p.a."

Any suggestions and advice on this matter would be greatly appreciated.

[AGT]

Do you have an immersion heater and or electric car?

[nowty]

If your having it all installed (not DIY), then you get 0% VAT on the batteries if you have them installed at the same time as the panels. Adding them later will cost 20% VAT, so factor that in. £3k should get you at least 10kWh of Pylontech batteries at 0% VAT.

You estimations sound about right (without batteries), if you have batteries you will export a lot less and self use more.

Upgrading your tumble drier to a heatpump one will reduce energy use.

[NikoV6]

Left field! Go bigger battery first and fill up on the overnight rate, big enough and you should never have to pay day rate!

Do solar later.

[Fintray]

Welcome to the forum Chris.
If I was you I'd try to stretch my budget for the battery and go bigger from the outset and make the most of cheap night rates.

[greentangerine]

Battery +1

[Krill]

Octopus Flux requires a battery, otherwise the system is not eligible. It also requires the system have an MCS certificate (at the moment people on this site have been pushing Octopus on that).

In winter solar PV is essentially not going to do anything for you, so you will go no payback. A battery will at least let you get some benefit from a cheap rate.

If you are planning to have 4 panels in a separate string then you may want to consider having those 4 panels installed along side a major battery bank to get the vat reduction and then get the rest of the solar PV done at a later date (and this gives you a second opportunity for vat free batteries).

You could consider having the four panel string set up as direct dc battery charging as well, but you may have a problem with export limitation when you get the larger array built? I'd check with nowty on that one.