Everything is just ticking along with little fuss.
The biggest change recently is that I registered us for export this April. For the first year and more I didn't bother because the export rates are poor, but we switched to Octopus energy and they have an export tarriff that pays around 15p / kWh. 3x most others. They promised 6 weeks to do the admin which involves getting the DNO to issue a second meter number which is used for the export side, and 6 weeks was what they took.
At this time of year we are now earning enough from this to cover our gas and electricity standing charges, this in addition to it heating the hot water and keeping the battery charged so we are theoretically self sufficient.
Also - last year I changed the hot water tank to a modern one with 180L capacity and twin imersion heaters. I let this heat to 60C and it can absorb 8kWh.
We still have an issue where the setting of the local grid voltage and the resistances in it, mean that when other local solar installations are all working hard, the grid can't spread that power around and we see the voltage rise waay above what it's supposed to be. I've measured 260V+. Never for long, but these spikes cause a properly designed solar system to turn off for a while which is plain irritating and means we actually use a few kWh of paid electricity when we shouldn't have to. I'll have a big argument with the power company over this but just now I have other jobs that are more important. If you are in the planning stage, put a logging voltmeter on your mains for a week and see what it looks like before you start. We have a 253V spike in the middle of the night because they bump it up ready for all the EV's doing an overnight charge on the cheap tarriff.
Lastly, we have a good big battery, handy in winter, bigger than needed in summer, so I've tweaked the settings to run it between 20% capacity minimum and 95% capacity max. This is with a view to maximising it's lifespan. We don't need 16kWh storage in summer.
Here are some of the recent graphs.
Elec consumption since Jan £86
Export since 3rd week April £106
Generation by month since installed in April 2022
You can see what we made (orange) vs what we consume (blue)
The battery stores power, gives back overnight and is enough to carry us through a really lousy day to the next one, so as long as orange is above blue on average we're pretty self sufficient.
For the 6 good months, we get a tankfull of hot water daily - 2 tubs or a bath and a shower - from the solar diverter. The myenergi kit gives an additional insight into the system.
Green yellow red is looking at power in and out of the home as a whole
Week and month view
Notice the red blip ? That was a day when the grid got so high for so long that the inverter turned off and needed a manual reset. I didn't notice so we paid for a days power before I spotted it and cycled all the switches.
The little traces of red elsewhere are mostly overvoltage blips where the inverter recovers itself after taking 10 or 30 minutes out. We have a big battery sized to deliver 6.5kW - so unless we turn on the oven, kettle and microwave all at once cooking dinner or same while the laundry is running, we don't need to draw from the grid.
This graph focusses on power used around the home vs "surplus" shunted into the immersion heaters.
We prioritise home and battery, hot water diverter 2nd, export to grid last.
So effectively we are heating water with elec at an opportunity cost of 15p / kWh.
Arguably we could try to export more, earn some more 15p's to pay for heating the and heat the water with gas instead (6p per kWh / 70% efficient boiler). I think that would be the better deal but with the poor state of the grid we have to limit our exports anyway because we just can't push all the power we make out without contributing to this over voltage problem. Ho hum !
Solar is very very variable, with the seasons and as the clouds go by. I'd say battery storage is essential. Oversizing the system means you are less dependent on the grid in the 3-4 cold months and have lots to spare for hot water and export in summer, but genuinely we can't get rid of what we could make in the height of summer. It would be easier if (when) we have an EV to charge with it too.
Hope this helps.
The biggest change recently is that I registered us for export this April. For the first year and more I didn't bother because the export rates are poor, but we switched to Octopus energy and they have an export tarriff that pays around 15p / kWh. 3x most others. They promised 6 weeks to do the admin which involves getting the DNO to issue a second meter number which is used for the export side, and 6 weeks was what they took.
At this time of year we are now earning enough from this to cover our gas and electricity standing charges, this in addition to it heating the hot water and keeping the battery charged so we are theoretically self sufficient.
Also - last year I changed the hot water tank to a modern one with 180L capacity and twin imersion heaters. I let this heat to 60C and it can absorb 8kWh.
We still have an issue where the setting of the local grid voltage and the resistances in it, mean that when other local solar installations are all working hard, the grid can't spread that power around and we see the voltage rise waay above what it's supposed to be. I've measured 260V+. Never for long, but these spikes cause a properly designed solar system to turn off for a while which is plain irritating and means we actually use a few kWh of paid electricity when we shouldn't have to. I'll have a big argument with the power company over this but just now I have other jobs that are more important. If you are in the planning stage, put a logging voltmeter on your mains for a week and see what it looks like before you start. We have a 253V spike in the middle of the night because they bump it up ready for all the EV's doing an overnight charge on the cheap tarriff.
Lastly, we have a good big battery, handy in winter, bigger than needed in summer, so I've tweaked the settings to run it between 20% capacity minimum and 95% capacity max. This is with a view to maximising it's lifespan. We don't need 16kWh storage in summer.
Here are some of the recent graphs.
Elec consumption since Jan £86
Export since 3rd week April £106
Generation by month since installed in April 2022
You can see what we made (orange) vs what we consume (blue)
The battery stores power, gives back overnight and is enough to carry us through a really lousy day to the next one, so as long as orange is above blue on average we're pretty self sufficient.
For the 6 good months, we get a tankfull of hot water daily - 2 tubs or a bath and a shower - from the solar diverter. The myenergi kit gives an additional insight into the system.
Green yellow red is looking at power in and out of the home as a whole
Week and month view
Notice the red blip ? That was a day when the grid got so high for so long that the inverter turned off and needed a manual reset. I didn't notice so we paid for a days power before I spotted it and cycled all the switches.
The little traces of red elsewhere are mostly overvoltage blips where the inverter recovers itself after taking 10 or 30 minutes out. We have a big battery sized to deliver 6.5kW - so unless we turn on the oven, kettle and microwave all at once cooking dinner or same while the laundry is running, we don't need to draw from the grid.
This graph focusses on power used around the home vs "surplus" shunted into the immersion heaters.
We prioritise home and battery, hot water diverter 2nd, export to grid last.
So effectively we are heating water with elec at an opportunity cost of 15p / kWh.
Arguably we could try to export more, earn some more 15p's to pay for heating the and heat the water with gas instead (6p per kWh / 70% efficient boiler). I think that would be the better deal but with the poor state of the grid we have to limit our exports anyway because we just can't push all the power we make out without contributing to this over voltage problem. Ho hum !
Solar is very very variable, with the seasons and as the clouds go by. I'd say battery storage is essential. Oversizing the system means you are less dependent on the grid in the 3-4 cold months and have lots to spare for hot water and export in summer, but genuinely we can't get rid of what we could make in the height of summer. It would be easier if (when) we have an EV to charge with it too.
Hope this helps.
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