I use the forecast provided by my install company. They had some software do it. I've generally found it more accurate than PVGIS-SARAH which is a bit pessimistic. What angle tilt is your roof? With an E/W system in the winter a steeper angle can be slightly worse. My roof is pretty shallow at 24 degrees.
I'd have to do a bit of trig to work it out, but eyeballing it I'd place it at 35 deg. Interestingly I track my stuff pretty well (like most of us I guess) and my actuals verses forecasts for the last three months are as follows.
Fairly close to the estimate in Nov & Dec to be much to a muchness, but Jan was way over (in a good way of course!) I don't have enough data points to know if this is going to be an aberration or the forthcoming trend - but that's the background to my question.
5-10% is within a reasonable deviation I think. Approx 50% means that either Jan was a "stellar" month compared to my forecasts, or the forecast itself might be off as you suggested.
And my trusty sheet says at 35 degrees you will get about 80% of what I get at 24 degrees for E/W panels in Jan.
Phenomenal result for January, you must be pure S facing with zero shading
188kWh for January. I produced my first MWh since install during January.
December Stats
2.7kWp (S), 10kWh battery, 22 deg Slope
Generation – 80.54 kWh Consumed - 310.72 kWh Import – 292.88 kWh Export – 5.74 kWh Eddi - 10.9 kWh Zappi - 0 kWh Meter Readings 04807 (01071 Day - up 29 / 03736 Night - up 288)
Totals so far:
Month | 2020 | 2021 | 2022 | ---------+--------+--------+--------+ January | 75 | 56 | 81 | February | 122 | 142 | | March | 200 | 269 | | April | 279 | 373 | | May | 396 | 430 | | June | 264 | 425 | | July | 261 | 387 | | August | 254 | 264 | | September| 268 | 248 | | October | 151 | 185 | | November | 90 | 78 | | December | 56 | 52 | | ---------+--------+--------+--------+ Total | 2.41 | 2.90 | 0.08 |
233kwh from a 6.9kw array at 175 degrees.
3rd Full Month
Dublin - Lucan - January 22
7.12kW total installed (South: 3.45kW, East, 2.41kW, West 1.38kW(optimisers)). 5KWh Battery, (30 S & 22.5 E/W degree pitch).
Total Generation: 169kWh (70kWh consumed directly, 96kWh into battery, 3KWh to grid (Eddi))
Best Day: January 18th - 11.8kWh
Worst Days: January 13,15,25 - 1.3kWh
Total Consumption: 459kWh (41% Solar:59% Grid)
And yet - I got 20-25% more than you did? Odd. Granted I've 10% more panels, but not sure I get the math behind a 20% drop from 24 degrees to 35 degrees. The angles are too small for that.
It might be some panel efficiency/inverter thing where my installation does better in lower light. Had a similar conversation with Jonathan a few weeks back. My lowest for the month was 1.1 kWhr on Jan 15th. I'd be curious to know what yours was on the same day.
Aside: My max was 5.38 Kwhr on the 26th.
(Just noticed you listed that.....Best day: 24th: 4.3 Worst day:15th: 1.2)
Dunno. Not that I'm complaining - but I always like to know the reasons "why".
2.8KW array, South Facing, Meath ( No Battery installed, 10KW battery on way )
January summary
Generation – 108.9 (Best 11th/12th @ 7.5/7.91, Worst 15th @ 0.4) Export – 26.81 kWh Import – 1458.7 kWh Zappi - 405.2 kWh Import Usage Breakdown (Units) Boost Day Night 268 710 481 €17.53 €167.06 €58.25 Heat Pump (kWh) Compressor 494.8 Output (kWh) Heating 2107.5 Hot Water 498.3 COP 5.3 EV Stats - Zappi - 405.1kWh ( €47.86) ECar Connect - 185.8kWh ( €61.64) Leaf reports - 491.8kWh = 2784.6km €3.93 per 100km
Replied here: https://www.boards.ie/discussion/comment/118564638/#Comment_118564638
2.5kwp system south facing Galway.
Best day 24th 8.2kwh.
Worst day 18th .6 kwh.
Total for month was 91.4 kwh.
Yes , south facing, bit of shading around a chimney, but optimisers on all 4 panels effected, steep pitched roof as well.
8.64kWp on a 6kw inverter,
12 degree roof, NE/SW 50:50
10kwh Battery storage, building the 20kwh one nnw, 20.27c Day/5.83c night
January
Generation : 118kWh
Solar Used Directly : 85.2kWh - €17.27
Solar Used Nightrate : 0kWh - €0
Battery Charged : 26.6kWh
Battery Discharged Day : 20.9kWh - €4.31
Battery Discharge Night : 0kWh - €0
EVSE Divert : 0kWh - €0
Battery Discharged From Grid Charging : 252.3kWh - €32.43
Export : 6.2kWh
Total Savings : €54.01
January was my 2nd full month of production as only installed Mid Nov. However, only discovered towards end of January that my export to grid setting was turned on and set to "0w" meaning my solar production was ramping down once my batteries were full or if the solar production was greater than the charge to my batteries and house load combined so i think both Januarys figures and Decembers figures are lower than they should have been. Issue with export now sorted.
6.2kWp (3.1 southeast /3.1 southwest), 4.8kWh battery, – Galway
Generation – 104kWh
Export – 1kWh
Import – 987kw (includes 148kw of battery charging of night rate for use during the day i think..cant trust solis app!)
Best day – 11th 7.0kWh
Worst day - 14th, 0.6kWh
6.2kWp, SE, Galway
January felt like a very grey month, not a lot of sunshine. 156.38kWh produced. Best day was 24th with 13.14kWh, worst day the 18th (0.41kWh!).
Roll on longer days and higher sun...
Sh1tty month, I have fair degree of shading and also one string generating SFA this time of the year.
Midlands
4.1kWp SW, 3.3kWp NE
1345kW imported (two EV household)
90kWh Generated
83.1kWh consumed
40kWh to Eddi
0kWh to Zappi
Highest was 29th, 5.2kWh
Lowest was 18th, 0.9kWh
9% self sufficient (excluding Evs)
Monthly cash saving €16.85
I was hoping for a little better for January, but with over 90% of my power consumption being created by the panels, I'm not going to complain. I'm kindof aiming to have a 100kWh surplus in the low consumption periods (to account for future installation of pool pumps), I guess I'm a panel shy.
I'll throw up the stats tomorrow. But I just submitted a meter reading for 97 day units and 1400 night, lol.
You might be able to get that lower by exporting 5 or 10w, in case, like mine, it's slightly misreading and is constantly importing a small amount
January Stats
6.2kWp (2.8 south/3.4 west), 20kWh battery, Zappi & Eddi – Donegal
Generation – 95.7kWh (almost the same as last year's 100.6kWh)
Export – 0.9kWh (oops)
Import – 642.2kWh, decrease from 710.9kWh last year.
Best day – 17th 9.0kWh
Worst day - 3rd & 10th, 0.7kWh
Last year I averaged 6.7kWh daily in February compared to January's 3.2kWh so better days lie ahead.
143 KWh for Jan
Monaghan 6.2KWp, lot of cloudy days
6kWp Kildare
Jan stats:
Production 162.5 kWh - Best day = 17th, 13kWh. 6 days below 2kWh
Export 22.2 kWh
import 454.9 kWh
Glad to see the back of January!! February days beginning to show about 50% stronger midday sun...when it shines!
6kWp Clare - Jan Stats
Mine is set to 0 - not causing me any issues AFAIK! This was dealt with recently in the troubeshooting thread i think.
A pretty healthy 367kWh for Feb. Considering its a short month I don't think it was a bad month.
6.1kWp just outside Cork City.
I have inputted my numbers into the PVStats website as well.
Mixed bag for Feb, offline for numerous errors in relation to over voltage and over frequency of the grid, but still managed to produce 369kw in Louth on a 7.8kw system. Best day 29.1kw.
Wow, I was happy with 233 for a 6.4 Kwp..now not so sure. It's still up on Feb last year at 208, but way off your number.
6.9 system. Almost due South.
Thanks to the monthly stats, it made me look closely at my system and I believe I have 2 x dead optimizers. Will hopefully get up on the roof before the weekend
