We are 10/14 days in on the cooling off period. So would appreciate any advice on what we have chosen.
12 * 450 KW Panels
Currently using 2400kwh annually
2 * 5.18KW Batteries
5 KW hybrid Inverter
We have a perfect south facing roof, no shading.
I have estimated that we never use more than 7.8Kwh per day, so after lots of research and many quotes, signed on the dotted line.
We have now found this community, and as experience always counts, have we missed anything?
Also, we are told that we would be in a position to export.
As we will be shortly out of contract from our electric supplier, we are now looking for best partners for solar export. Any advice would be most welcome?
Have we done this correctly?
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Dave Foster
- Posts: 1407
- Joined: Thu Oct 13, 2022 7:21 pm
Hi, that sounds like a nicely balanced system and with enough battery to get you through the dark winter days (i.e. get a eco tariff that allows you to charge overnight at a low tariff).
Only a couple of small observations, you are going with a 5kW inverter which is more than capable of taking the 12 panels - however a 6kW inverter is the same size, only a few pounds more and would give you the ability to expand in the future plus when running on batteries it would allow you to meet 6kW of house load rather than 5kW - that probably doesn't happen that often but a kettle and a toaster in the morning is getting close and as long as it's not your DNO that is restricting you to 5kW i'd recommend getting the 6kW inverter instead.
On the batteries, 2 @ 5.18 kWh batteries would give you a usable 9.3kWh capacity at 25C (10.36*0.9 max depth of discharge) - that is within your 7.8kWh maximum daily usage so charging them at a low tariff will mean you will never pay for any peak usage. - That said it's easier and cheaper to add batteries at this stage (and vat free) so if you think in the future your demands may increase (a heat pump for example), i'd recommend getting an extra battery now.
There are quite a few export tariffs available, a very popular one is Octopus Flux - that offers a cheap tariff ~22p/kWh between the hours of 2am and 5am (used to charge the batteries in the winter months), with a peak price between 4pm and 7pm (where you would use your batteries or solar) - the upside to that is the tariff is designed for you to export and get paid at a higher rate between 4pm and 7pm ~30p/kWh and so in summer this is pays very well.
Finally make sure that your installer is an MCS registered company as this is typically mandated when you sign up for export.
Only a couple of small observations, you are going with a 5kW inverter which is more than capable of taking the 12 panels - however a 6kW inverter is the same size, only a few pounds more and would give you the ability to expand in the future plus when running on batteries it would allow you to meet 6kW of house load rather than 5kW - that probably doesn't happen that often but a kettle and a toaster in the morning is getting close and as long as it's not your DNO that is restricting you to 5kW i'd recommend getting the 6kW inverter instead.
On the batteries, 2 @ 5.18 kWh batteries would give you a usable 9.3kWh capacity at 25C (10.36*0.9 max depth of discharge) - that is within your 7.8kWh maximum daily usage so charging them at a low tariff will mean you will never pay for any peak usage. - That said it's easier and cheaper to add batteries at this stage (and vat free) so if you think in the future your demands may increase (a heat pump for example), i'd recommend getting an extra battery now.
There are quite a few export tariffs available, a very popular one is Octopus Flux - that offers a cheap tariff ~22p/kWh between the hours of 2am and 5am (used to charge the batteries in the winter months), with a peak price between 4pm and 7pm (where you would use your batteries or solar) - the upside to that is the tariff is designed for you to export and get paid at a higher rate between 4pm and 7pm ~30p/kWh and so in summer this is pays very well.
Finally make sure that your installer is an MCS registered company as this is typically mandated when you sign up for export.