Add max (power used – power generated) to statistics page to optimize the grid connection


#1

The max (power used – power generated (=PV)) is relevant for the connection that you need e.g. 3x16A, 3x25A, 3x35A, 3x50A, 3x63A, 3x 80A, etc (17kW, 24kW, 34kW, 43kW, 54kW, etc).

In the Netherlands (and elsewhere?) you pay extra for a bigger grid connection.

If you add a PV system the max net power usage decreases and sometimes a smaller grid connection is possible. It is useful to know for a longer period what the net peak power usage is.

So please add max (power used – power generated) per lifetime, year, etc to the statistics page.

Best regards,
Kasper


#2

Are you referring to Power (W) or Energy (Wh) ?

There are already energy export and import figures on the statistics page. Power changes throughout the day and net power data is not recorded.


#3

I mean kW not kWh.

Max generation per day etc is there but that is not what I’m looking for.

From the live page:

Date Time Energy Efficiency Power Average Normalised Temperature Voltage Energy Used Power Used
15/08/17 11:00 138.738kWh 0.540kWh/kW 14,588W 14,588W 0.057kW/kW 20.4C - 1,127.750kWh 202,494W

Max (power used-power) over 3 months, one year, lifetime, etc
In this example at 11:00 202,494-14,5880=187 kW

For big PV sites the min value is also relevant.

For this grid connection the max is 211kW now, it was (prior to the PV installation and other changes) 300+ kW


#4

It sounds like you might be asking for peak/min export and import power values for various time periods. This would be so that you can use that information to better size your grid inter-connect, or know what you’ll be charged if you have to pay peak demand fees. Is that right?


#5

Correct. The typical yearly fee we have to pay for a grid connection based on the maximum power used or feed into the grid in the Netherlands:

3x35A €936
3x50A €1.367
3x63A €1.805
3x80A €2.235

If we know that we only need a 3x80A grid connection for the feed in peak of a few minutes a year on a sunny day, we can automatically reduce the output of the inverters for those minutes or switch some equipment on. We can then downscale the grid connection to e.g. 3x63A and spend the money on more PV panels.

The same for import power in the winter, if there is a peak above e.g. 3x63A, switch some equipment off.

Best regards,
Kasper


#6

Currently only max power generation is recorded so it is not possible to generate statistics of

    max(generation power) - max(consumption power)

#7

I see the data I need, I only don´t know how to get it out.

We have SolarEdge inverters and a SolarEdge Modbus Meter on our site.

The SolarEdge Modbus meter is used for production, consumption or import/export monitoring and for Export Limitation.

Power used and power generated is stored on a 15 min interval basis in the PV database.

  Max((power used) – (power generated)) 

and

  Min((power used) – (power generated))

Over a year tells me what grid connection I need.

See eg. https://pvoutput.org/intraday.jsp?id=52387&sid=49339&dt=20170901

Maybe Power used is not vissible for everyone.


#8

The data can be viewed on a 5-minute level, but power used is not recorded on a daily level so it is not possible to easily summarise the information over longer periods of time when generating statistics.


#9

I want too reinitialize this discussion:

Is the issue that it takes too much computer power to calculate this using the 5 or 15 min data over a longer period (~month(s) or year(s))?

If so, I assume it can be done by adding cells in the database with this data per day or month since it reduces the required computer power?

A change in the DB is not easy, but I think I adds to the value of PVoutput, since this data is not available from other sources and it can also be applied on historical data.

Also without this option PVoutput is a very nice site. It is inverter manufacturer independent and offers more options than their sites (eg. www.sunnyportal.com and monitoring.solaredge.com).


#10

It’s not a simple change, both the min/max must be tracked every 5-minutes.

If this feature is implemented it will only be an opt-in option and only apply to new data.


#11

Sorry, I’m not a DB expert, can you explain the issue?
Why is min max data required at a 5 min interval if you want to know it per day, month, year or other period?

(I changed my Watching settings, didn’t get a notification from your reply)


#12

The only way to find the peak export / generation each of each day is to analyse every 5-minute interval within those days. If a new interval is uploaded/received it must be compared against all existing intervals.


#13

Will this work?:

For each day add a cell max_power_used_day (Defined as the maxium power (W) from the network that goes through the kWh-meter that day) in the DB,

max_power_used_day = power used - power generated

update that value during each upload that day.

Same for min_power_used_day.

This can be done for new (and historical?) data
So you only need 2 data cells per day instead of +2 cells *24 h *60 min /15 min=192

Result (max, min per period [W]) can then be presented on the statistics page.

(watching settings now work)


#14

The implementation will only support future data.


#15

Thanks. That will do.


#16

Do you still have plans to implement this?


#17

Possibly, if we can find a efficient way of doing it without impacting others.

To clarify for data on 2018-10-01, MAX is 13,837W and MIN is -27,226W and do you need to recorded at what time min and max occurred.


#18

To clarify for data on 2018-10-01, MAX is 13,837W and MIN is -27,226W and do you need to recorded at what time min and max occurred.

correct.

The min and max per day, year, … or user specified period is handy. The day on which it occurs is important, the exact time is less relevant.

First step is to figure out how many amps we need; on Oct 1st, MIN is 27kW which requires 3x40A, while we have 3x80A.

Second step is to figure out when and why peaks occur and how to prevent them.

If I can help by playing with a excel dump of the 15 min data for one year for the Malden site to see what is handy…


#19

Thanks - this should be enough information to work on for now.


#20

would you not be able to add them to the extended data and then select highest and lowest on the summary section of extended data settings. and would be able to view it from the daily weekly months tabs in extended data