Tariffs: make timestamp available for formulas

[andig]

Follow-up to #17002, fix #12371.

This PR adds a ts variable of type time.Time that contains the start of the current slot. The timestamp is in local timezone to allow immediate use of ts.Hour() for comparisons.

Could be nicer with traefik/yaegi#1542.

[bartashevich]

@andig , testing this branch and got following error:

[main  ] ERROR 2024/11/24 18:09:37 creating tariff grid failed: cannot create tariff type 'entsoe': _.go:12:2: expected declaration, found charges

Configs:

tariffs:
  grid:
    type: entsoe
    domain: BZN|PT
    securitytoken: xxxx
    charges: 0
    tax: 0
    formula: (price + 0.004 + 0.0028930 + 0.010)*(1 + 0.16) + 0.005

If I remove formula, it works.

[bartashevich]

I've fixed commit that introduced described error, keeping everything else the same and I got it working.

Current issue is that ts.Hour() always returns 23.

I've used following formula:

formula: charges := 0.0860; if ts.Hour() < 8 || ts.Hour() > 22 { charges = 0.0157 }; (price + 0.004 + 0.0028930 + 0.010) * 1.16 + 0.005 + float64(ts.Hour())

For debug purpose I've added float64(ts.Hour()) to formula and result is this:

[andig]

See https://github.com/evcc-io/evcc/pull/17414/files#diff-34973a15082498aae9145173918172786bbd9f17991a8cb38f8009a57339d666R143 and make sure to use the same for ENTSO-E!

[bartashevich]

See https://github.com/evcc-io/evcc/pull/17414/files#diff-34973a15082498aae9145173918172786bbd9f17991a8cb38f8009a57339d666R143 and make sure to use the same for ENTSO-E!

Oh I see, since you've changed in tariff.go I imagined it would be global some how. Sorry, not familiar at all with this framework.

[bartashevich]

What do you need to merge this?