H F Posted November 10, 2019 Share Posted November 10, 2019 We hit our 5 MWh milestone on our solar PV system a short while ago. Almost 13 tonnes of CO2 saved from going into the atmosphere. Link to comment Share on other sites More sharing options...
SteamyTea Posted November 10, 2019 Share Posted November 10, 2019 (edited) Interested in how you calculated the 13 tonnes of carbon dioxide. There were many times this year when we had very low fossil fuel usage, this reduced the carbon dioxide per MWh considerably. There are also regional variations. A quick look at intensity.org.uk shows that the South East, where you are, has a CI of 245g/kWh. South West, where I am is 78g/kWh. So your 5 MWh is worth 1225 kg saving, mine is 390 kg. A third of yours. Makes investing in personal RE for carbon dioxide saving rather marginal. @Ed Davies is the person that has looked at marginal differences in grid intensity. Edited November 10, 2019 by SteamyTea Link to comment Share on other sites More sharing options...
H F Posted November 10, 2019 Author Share Posted November 10, 2019 Yikes! You impress me with your meticulous calculations. I didn’t do anything to work it out. Just used SolarEdge’s app that spits the info out. Assumed it would be correct. Link to comment Share on other sites More sharing options...
Ed Davies Posted November 10, 2019 Share Posted November 10, 2019 Lots of ways to calculate this but whatever, it looks like there's a decimal point slip in there so it's probably more like 1.3 tonnes rather than 13 tonnes of CO₂. The current carbon index of the grid (total CO₂ emissions / total generation) is not very interesting from this point of view. Generally speaking, low-carbon power sources (renewables and nuclear) do their thing at whatever rate they can manage at the moment then gas makes up the difference. This means that any additional renewable generation (used sensibly) directly reduces the amount of gas burned so should really be “scored” at minus the emissions rate for a closed-cycle gas turbine, not the grid average at that moment. 2 Link to comment Share on other sites More sharing options...
H F Posted November 10, 2019 Author Share Posted November 10, 2019 (edited) I think you’re right Ed. My iPad app says 12k (as per the screen grab). iPhone app says 1.2k. I’ll let SolarEdge know about this. Edited November 10, 2019 by Home Farm 1 Link to comment Share on other sites More sharing options...
SteamyTea Posted November 10, 2019 Share Posted November 10, 2019 33 minutes ago, Ed Davies said: This means that any additional renewable generation (used sensibly) directly reduces the amount of gas burned so should really be “scored” at minus the emissions rate for a closed-cycle gas turbine, not the grid average at that moment. I agree with that. Though sometimes harder to work out on a time series. I think it could be worked out from the GridWatch data as that gives generation by type at the 5 minute interval, as well as demand. Link to comment Share on other sites More sharing options...
joth Posted November 10, 2019 Share Posted November 10, 2019 1 hour ago, Home Farm said: We hit our 5 MWh milestone on our solar PV system a short while ago. Almost 13 tonnes of CO2 saved from going into the atmosphere. Nice! Thanks for sharing this. How long was it since installed? Could you explain the various numbers here? I guess 6.16kWp is max power it's ever generated, 3.87kW is current live power? Was your ASHP running at the time this image captured (or cooker on)? If so nice to have caught an unusual example of the getting over half of the space heating load from solar. 1 Link to comment Share on other sites More sharing options...
H F Posted November 10, 2019 Author Share Posted November 10, 2019 (edited) We’ve been running since March. 6.16kW is our full array - max we can produce. 3.87 is what we were producing when I took the screen grab. 6.3 is what we were consuming power wise - that would have been ASHP and dryer running... maybe even dishwasher. So we were offsetting half our power requirement with solar. Edited November 10, 2019 by Home Farm 1 Link to comment Share on other sites More sharing options...
H F Posted March 6, 2020 Author Share Posted March 6, 2020 Our solar PV panels have been up for just under a year and according to the SolarEdge app we’ve saved pumping just under 1,500 kg of CO2 into the atmosphere, producing 5.7MWh of electricity in the process. Not bad I think. Link to comment Share on other sites More sharing options...
ProDave Posted March 6, 2020 Share Posted March 6, 2020 I didn't realise your panels were so new, I thought they were on the house when you bought it? So no FIT for you then? Link to comment Share on other sites More sharing options...
H F Posted March 6, 2020 Author Share Posted March 6, 2020 We got the panels up the week before FiT expired, so we registered just in time. Link to comment Share on other sites More sharing options...
MikeGrahamT21 Posted March 6, 2020 Share Posted March 6, 2020 Yeah 13T sounds a bit optimistic. I've saved 10T apparently, just nearing 14MWh Link to comment Share on other sites More sharing options...
H F Posted March 6, 2020 Author Share Posted March 6, 2020 I think there was a calculation issue when I first posted. My 1.5 tonnes sounds more realistic. What app are you using Mike? Link to comment Share on other sites More sharing options...
MikeGrahamT21 Posted March 6, 2020 Share Posted March 6, 2020 (edited) Its Sunny Portal, from SMA, links into my SMA inverter. They even give one solar coin for every MWh I generate, not that they are worth anything at the moment! lol Edited March 6, 2020 by MikeGrahamT21 Link to comment Share on other sites More sharing options...
Jeremy Harris Posted March 6, 2020 Share Posted March 6, 2020 The calculation isn't easy, given the wide variation in grid CO2 emissions from day to day and even hour to hour during the day. Probably the best way to look at it is to estimate your total household emissions and subtract the emissions saved by the PV generation, to get an idea of the true impact. I was asked to give a talk in our village hall a while ago, about our build (turned out to be surprisingly popular - standing room only). When putting together the presentation I tried hard to think of a way to enable people to visualise CO2 emissions. The best thing I could come up with was to convert emissions that were saved, both from designing a low energy house, and the saving from PV generation, into trees. A mature tree sequesters roughly 20 to 25 kg of CO2 a year, in the form of carbon locked up in the timber. The SAP calculations for our house give a CO2 "emissions" figure of -0.9 tonnes/year. This equates to the CO2 sequestration from about 40 mature trees. All those who knew our site could see that we couldn't possible fit 40 trees on it, so it was pretty clear that our house was, at least in terms of CO2 emissions, less harmful to the environment than if it was planted with mature trees. 2 Link to comment Share on other sites More sharing options...
H F Posted March 6, 2020 Author Share Posted March 6, 2020 9 hours ago, MikeGrahamT21 said: Its Sunny Portal, from SMA, links into my SMA inverter. They even give one solar coin for every MWh I generate, not that they are worth anything at the moment! lol What are solar coins? Are they like crypto? Link to comment Share on other sites More sharing options...
MikeGrahamT21 Posted March 9, 2020 Share Posted March 9, 2020 Yeah its a cryptocurrency, they give you one coin for each MWh you generate, but they are worthless pretty much, I suppose theres always a chance they could increase in value, unlikely id say! Link to comment Share on other sites More sharing options...
H F Posted March 9, 2020 Author Share Posted March 9, 2020 25 minutes ago, MikeGrahamT21 said: Yeah its a cryptocurrency, they give you one coin for each MWh you generate, but they are worthless pretty much, I suppose theres always a chance they could increase in value, unlikely id say! That’s what they said about Bitcoin. Link to comment Share on other sites More sharing options...
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