Four years of invoices and inverter data from a 6.4 kWp zero-export rooftop PV system with a BYD battery: what each part cost, what it saved, and which one was a bad buy.
Rooftop PV, four winters later
€14.5k into DIY solar in 2022, or the same into VUAA?
€14.5k into DIY solar in 2022, or the same into VUAA? ETF would be up ~€12.5k on paper, ~€7k after inflation. But the panels generated 27.7 MWh so far – that’s ~€3.5k of grid power I never bought. real gap: ~€4k and shrinking every year electricity gets pricier. no regrets
60 km EV commute’s spent energy recovered by free solar
Today's 60 km EV commute's spent energy is fully recovered by free solar charging once back home. And it's still only February. Impressive.
7.4MWh solar power production at home in 2025
7.4MWh solar power production at home in 2025, not bad
PV storage using Dala’s battery emulator
Adding this to my “want, but never will have” list, to be used as PV storage using Dala’s battery emulator https://vivnevs.com/products/62kwh-nissan-leaf-battery-pack-180ah-catl-lithium-battery-for-leaf-battery-upgrade
Home-assistant automation to pause solar battery charging
Created a Home-assistant automation to pause the solar battery charging at ~80% and only charge it to 100% at the last possible moment. This is to minimize time spent at full charge, which apparently is bad for the battery. It considers the estimated remaining PV production.
BYD 7.68kWh LiFePO4 solar battery
Data collected over nearly two years shows our BYD 7.68kWh LiFePO4 solar battery operates at an average of 94% efficiency (charged vs discharged). Capacity degradation is at 2%
DEV.BG tech talk: Intelligent Synergy: Heat Pump, PV & Home Assistant
My DEV.BG tech talk on making the heat pump, the PV system and Home Assistant work together – slides and video, in Bulgarian.
6.4kWp @Fronius PV system produced 7.05 MWh
In 2023, our 6.4kWp @Fronius PV system produced 7.05 MWh, fulfilling 60% of our electrical needs and saving us ~920 EUR. Our 7.68kWh BYD battery stored 1.83 MWh for later use and the OhmPilot diverter captured an extra 1.84 MWh, boosting our self-consumption by about 26%. #solar
No grid electricity for 9 out of the last 12 hours
No grid electricity for 9 out of the last 12 hours due to a snowstorm. Running my inverter in emergency power mode off the battery, topping it from the grid whenever it becomes briefly available. Solar production is close to zero, as panels are completely covered with snow. Good news, grid power is up, bad…
Inverter and battery firmware update time
Inverter and battery firmware update time..
Our own solar panels provided for 91% of our energy needs
Relying less on the grid this month, as our own solar panels provided for 91% of our energy needs.
Tomorrow’s PV production estimate for our system
Tomorrow’s PV production estimate for our system is near 44kWh. We’ve sized it to support future EV charging. Currently, we can’t self-consume that much, and grid feed-in is complicated by local bureaucratic obstacles. Hate to see it go to waste.
Old Nissan Leaf batteries to a Fronius GEN24 inverter
Thought I was done with solar system spending, but then someone develops a way to connect old Nissan Leaf batteries to a Fronius GEN24 inverter. Now remains to make a compelling case for this new budget dent to my better half. https://github.com/dalathegreat/BYD-Battery-Emulator-For-Gen24 Repeating in my head: "want != need"
1 MWh solar production milestone for 2023
Passed the 1 MWh solar production milestone for 2023 today. Not bad. My setup is described in this blog post: https://harizanov.com/2023/01/rooftop-pv-installation/
Rooftop PV installation
New blog post: Rooftop PV installation https://harizanov.com/2023/01/rooftop-pv-installation/ #solar #DIY
Rooftop PV installation
Why rooftop solar is a hard sell in Bulgaria and how I did it anyway – the full story of my PV installation, from permits to first kWh.
55kWh Tesla Model 3 battery with Fronius GEN24 solar
Dala's EV Repair managed to configure and use a 55kWh Tesla Model 3 battery with @froniussolar GEN24 #solar inverter. That opens new options for EV battery repurposing after their useful life. https://www.youtube.com/watch?v=-s7lODLDOiQ&ab_channel=Dala%27sEVRepair
Solar production at winter solstice exceeds my expectations
#Solar production at winter solstice exceeds my expectations, a whopping 19.5kWh given it was hazy 10-11am. This is out of a 6.4kWp PV installation in Sofia, Bulgaria.
Solar production dropped to zero
This guy showed up, and solar production dropped to zero last couple days. My panels aren’t easily accessible (rooftop) so that I could remove the snow. Enjoying the winter anyway, forecast is that snow will melt in a day or two.
The solar cell is effectively a diode
The solar cell is effectively a diode, running current through it causes it to heat. Wondering why isn't this effect used by inverters to de-snow panels in the winter? #solar
Node-Red dashboard to control the BYD PV storage battery
Node-Red dashboard to control the BYD PV storage battery behavior over Modbus TCP. Storm is coming and power failure is likely? No problem, force-charge the battery, including from grid, and put it on hold for emergency power backup purposes. Neat 🙂
Depth of Discharge for my PV system’s BYD 7.7kW LFP battery
What is a reasonable Depth of Discharge % for my PV system’s BYD 7.7kW LFP battery,so to maximize its longevity? Should I keep SoC between 20%-80% e.g. 60% DoD?The inverter default battery SoC limit configuration is 5%-100%, but 95% DoD feels like it would be bad for the battery
BYD_BatteryBox HVS 7.7kW battery for my solar system
The @BYD_BatteryBox HVS 7.7kW battery for my solar system arrived today, the order took five months. Installed it myself, that took less than two hours. Still need to put the cables into a channel. All worked right away, slightly surprised 🙂
Excellent PV production from my 6.4kWp installation
Excellent PV production from my 6.4kWp installation, almost 22kWh for the day, including the EV range to cover my commute. #solar is great
Node-RED solar power forecast plus
Using Node-RED's node-red-contrib-solar-power-forecast-plus contribution to plot (light blue line) the estimated max PV generation in ideal conditions for my location/panel orientation/time of year; seems pretty accurate so far. Useful to know what theoretical maximum I have.
DC side surge protection device
Installed a DC side surge protection device to my @froniussolar GEN24 #solar inverter. It comes as retrofit option, installs in under 20 min. A lightning strike nearby can induce damaging voltages in the wires from the rooftop panels 30m away, this SPD takes care of such cases
July solar stats
July #solar stats: 69% of our consumption is self-generated. If we had the 7.7Kw BYD battery (on order) installed, that would have been an easy 100% self sufficiency.
The grim reality of buying anything PV related in 2022
The grim reality of buying anything PV related in 2022, see below the response to an inquiry about a order I made couple months ago. Other sites cite April 2023 for the same product, these guys preordered Nov 2021 and “are optimistic” to deliver this September.. crazy times
Charging an EV 100% on solar PV surplus
Charging an #EV 100% on #solar PV surplus, feels oddly satisfying. @froniussolar
A week on solar energy
A week on #solar energy, 70% of our consumption is solar-generated. Battery (BYD HVS 7.7kW) is ordered but 6-8 months to deliver, which I am told is “the new normal” Export of energy has been set to 0%, the inverter regulates production to match consumption. It is underutilized for the moment, but things will change…
PV generation data from the Fronius solar inverter API
Quick and dirty dashboard update to show PV generation data from the Fronius #solar inverter API on our Raspberry Pi home automation status display