SELECT
    T1.regelnummer AS regelnummer,
    T1.timestamp AS timestamp,
    T1.OmvormerIndex AS OmvormerIndex,
    T1.Vandaag_Verbruik_kWh AS Vandaag_Verbruik_kWh,
    T1.Vandaag_EnergFromNet_kWh AS Vandaag_EnergFromNet_kWh,
    T1.Vandaag_EnergyFromInstallatie_kWh AS Vandaag_EnergyFromInstallatie_kWh,
    T1.Verbruik_kWh AS Verbruik_kWh,
    T1.EnergFromNet_kWh AS EnergFromNet_kWh,
    T1.EnergyFromInstallatie_kWh AS EnergyFromInstallatie_kWh,
    T1.Verbruik_kWh - (
        SELECT T2.Verbruik_kWh
        FROM ptrp594989_voodevve.ZEIST_2e_Hogeweg_2__Verbruik T2
        WHERE T2.OmvormerIndex = T1.OmvormerIndex
            AND T2.timestamp < T1.timestamp
        ORDER BY T2.timestamp DESC LIMIT 1
    ) AS Used_Today,
    T1.EnergyFromInstallatie_kWh - (
        SELECT T2.EnergyFromInstallatie_kWh
        FROM ptrp594989_voodevve.ZEIST_2e_Hogeweg_2__Verbruik T2
        WHERE T2.OmvormerIndex = T1.OmvormerIndex
            AND T2.timestamp < T1.timestamp
        ORDER BY T2.timestamp DESC LIMIT 1
    ) AS FromSolar_Today,
    T1.EnergFromNet_kWh - (
        SELECT T2.EnergFromNet_kWh
        FROM ptrp594989_voodevve.ZEIST_2e_Hogeweg_2__Verbruik T2
        WHERE T2.OmvormerIndex = T1.OmvormerIndex
            AND T2.timestamp < T1.timestamp
        ORDER BY T2.timestamp DESC LIMIT 1
    ) AS FromNet_Today
FROM ptrp594989_voodevve.ZEIST_2e_Hogeweg_2__Verbruik T1
WHERE (
    SELECT COUNT(0)
    FROM ptrp594989_voodevve.ZEIST_2e_Hogeweg_2__Verbruik T2
    WHERE T2.OmvormerIndex = T1.OmvormerIndex
        AND T2.timestamp < T1.timestamp
) > 0
ORDER BY T1.timestamp DESC, T1.OmvormerIndex;



Version 2 of the Query



SELECT 
    T1.OmvormerIndex AS OmvormerIndex,
    DATE(T1.timestamp) AS date,
    MAX(T1.timestamp) AS timestamp,
    SUM(T1.Verbruik_kWh) AS Verbruik_kWh,
    SUM(T1.EnergyFromInstallatie_kWh) AS EnergyFromInstallatie_kWh,
    SUM(T1.EnergFromNet_kWh) AS EnergFromNet_kWh
FROM
    ptrp594989_voodevve.ZEIST_2e_Hogeweg_2__Verbruik T1
    INNER JOIN (
        SELECT
            OmvormerIndex,
            DATE(timestamp) AS date,
            MAX(timestamp) AS timestamp
        FROM
            ptrp594989_voodevve.ZEIST_2e_Hogeweg_2__Verbruik
        WHERE
            Verbruik_kWh IS NOT NULL
        GROUP BY
            OmvormerIndex,
            DATE(timestamp)
    ) T2 ON T1.OmvormerIndex = T2.OmvormerIndex AND DATE(T1.timestamp) = T2.date AND T1.timestamp = T2.timestamp
GROUP BY
    T1.OmvormerIndex,
    DATE(T1.timestamp)
ORDER BY
    T1.timestamp DESC,
    T1.OmvormerIndex