Well yes, I thought someone would pick up on that, however my usage for batteries would be to cover off night time and that usage is about 3-4KWh. So for most of the summer, I wouldn’t be able to use the energy in the battery. So that’s a maximum of £438 assuming I have generate 4KWh spare each day, which for winter would not be possible. Also I’d imagine I will go down the EV route in less than 5 years, so I would be looking at using the car battery to power the house at night.
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I think we’re still a little way off the EV powering the house. There are trials but who knows when these become a product; more than a little disappointing!
There are three main ways I use my battery:
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Powering the house in the evening during the summer (almost self sufficient for 4 or so months)
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Charging overnight and running the house for part of the duller days in the winter; saving me around a pound a day during December/January/February.
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Allowing me to charge my car with my ‘own’ electricity on sunny summer days where the battery backs up the solar panels on the occasion that a cloud is blown across the sun for a few minutes.
Looking forward to moving away from use case 1 to use cases 2 and 3 !
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My friend has PV which generates very little, with not enough surplus to justify a battery. He’s thinking of getting one anyway on the basis that he can use an Octopus variable tariff to charge it off peak and sell back to the grid in the evening peak time. He’s doing the maths and reckons the payback time is quite good.
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I have done several calculations based on different battery sizes, and all scenarios (excluding Octopus scheme considerations) come out at more than 11 years repayment. I am on the FIT tariff (government scheme which closed 2 weeks after my installation), so I do already get about 8p for each KWh produced (£365 for last year), so I’d have to come off that scheme to join Octopus which might be a bit of a gamble. I will keep it under review though (as the government always say 
) for when battery prices hopefully drop more significantly.
The wind turbine’s blade is cracked and needs replacement. That’ll be £19,500 (including VAT and installation, sir). Ouch - at least I only have to pay one third. Worth doing - should get back within a couple of years or so and still another five years’ feed in tariff after that
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That’s a shame. How old is it? Does it relate to the windier weather? Will the new one be stronger?
So this is already the second blade - the first one only lasted two years if I remember correctly. This one lasted 11 years. The nacelle (the thing fastened to the tower and which the blade connects to) was also replaced after just under five years
No idea if it relates to any particular period of windy / windier weather.
Interesting Tim, I guess most of us (me included) get seduced by the generation stats, but not the ongoing expense. I certainly didn’t look at the expected ongoing costs when I bought my batteries or solar panels or heat pumps.
To be fair, I guess the alternative (gas boiler or whatever in the case of ASHP) also has an ongoing cost so a comparison should look at that too. But if you’re paying that every 6 years on average, it makes a dent on the ROI sums.
Are you sure the blade isn’t repairable? Fractures on large offshore turbine blades are quite common, and they are normally repaired in situ. It’s a relatively quick, simple process.
They suggested that may be possible but then said it wasn’t
Id get " they" to provide a proper engineering assesment. I.e. justify their advise/choice of words !
Of course, if they are smart engineers, they will charge you for this assessment of their findings !!
Hope you have made progress with the wind turbine repair.
Octopus Agile was cheap this afternoon! What a terrible day.
Phil
Partial repair only - drilled holes to let the water out last week so at least the turbine is turning. It will be a while before the new blade (which we have paid for. Eek!) can be fitted, as the fields are hideously waterlogged
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Has anyone used Enphase Micro Inverters?. Watched a video from Skill Builder fitting Viridian Solar inset panels which I am thinking of. They fitted Enphase IQ8 under each panel. It does seem to be logical to step down the current to AC for safety reasons and no inverter needed downstairs. Only downside is access if one of the inverters fail but apparently the failure rate is extremely rare
Yes we have for six years now and no fail yet!
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Yes, we have them too and have had no issues.
Thanks. Are you using Viridian Solar in-roof panels?. My other concern is air flow to the inverters under the panel
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Used iq7 for past 2 years, no issues. It is the way to go rather than with a string inverter. And the app allows you to see the performance of each panel.
No, they are panels fitted onto a corrugate iron roof.
I didn’t mention, that we have had the occasional hick-up with data reporting on the Enphase app. Not a biggie and they can reset things remotely.
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I have been monitoring the round trip efficiency of my SolarEdge system for some time. I remember that you have two Powerwalls and wonder whether they give you energy in and out readings. Tesla claim about 88% round trip efficiency.
My inverter has a net meter to give in (charging) and out (to house/grid). I take the DC power reported for the panels and the battery level at midnight. The inverter efficiency is about 95.5%. I get better overall results on days where more solar goes direct to house or grid rather than via the battery.
I have this feeling the whole industry gives more optimistic round trip efficiency figures for batteries than is justified. SolarEdge imply that their DC coupled battery system is more efficient than AC coupled.
If anyone else also has actual round trip efficiency figures then please comment.
My daily figures vary from 80-86%.
Phil