AU2015101789A4 - Device for Measuring Photovoltaic Energy Intake - Google Patents

Abstract

A device specially designed to assist in the provisioning of sufficient PV panels for solar powered motorised window covering applications. The device measures photovoltaic energy intake and employs an algorithm to produce a reading that is averaged out according to a given time interval. DYNAVEIL PTY LTD 16i

Description

EDITORIAL NOTE 2015101789 There are four pages of description only.

FIELD OF THE INVENTION [01] The present invention relates the field of motorised window coverings, specifically systems that are powered via solar energy harvested from the sun. BACKGROUND TO THE INVENTION [02] Window coverings come in various forms including roller shades, roman shades, venetian blinds, curtains and the like which function to moderate light and visibility through the windows of a home or building. [03] All such window covering types can be motorised, bringing many advantages over manual operated types including: child safety, convenience and comfort. However, difficulty in accessing a suitable power supply has always been a main obstacle to widespread adoption of motorised systems. By using solar power, the difficult and oftentimes costly task of rerouting existing line voltage wiring can be avoided. Such a system requires the fitting of photovoltaic (PV) modules to gather solar energy. As such, it becomes imperative that, in order to achieve completely self-sustained operation, the net energy intake via PV charging must be greater than the net output used for powering the window covering. [04] Since window coverings come in all sorts of sizes to fit various windows, the energy requirement of the motorised system will also vary accordingly. Therefore, the PV energy intake needs to be measured on-site. Traditionally, such measurements were done by taking once-off measurements of the instantaneous charging current or light intensity (lux) levels and then relying on experience to make judgement on the situation. However, energy intake for PVs is dependent on many variables. In addition to being impacted by location, it is also greatly affected by time of day and season, as well as by possible obstacles or window tinting. These challenges highlight the fact that once-off measurements will oftentimes be unreliable for long term usage. [05] In the context of motorised window coverings, no purpose-built device for measuring PV energy intake is known to exist. To achieve comparable reliability using existing methods, sampling of charging current would need to be conducted manually which is impractical both in terms of cost and logistics. The present invention aims to help determine the precise amount of energy that can be collected for any given installation situation. The device, otherwise known as a solar data logger, samples real world charging current at regular intervals before combining the data to give average charge over a given period of time. SUMMARY OF THE INVENTION [06] Since it is impractical to have personnel on-site to constantly monitor PV charging current, the present invention devises a means to automatically sample the charging current at regular intervals. The aim is to provide a clear picture of the real world energy intake for PV applications. Reliability of the data gathered is determined by two factors - sampling interval and sampling duration. Sampling interval should ideally not exceed several minutes, for a smaller sampling interval will better account for weather fluctuations that may occur at any given time. Data can be collected over a period of days, weeks or even months. A longer duration will better represent the overall weather conditions at a given location, including seasonal factors. [07] The solar data logger is to be placed in a fixed position for the duration of the measuring period. Usually, this is a glass window where the measurements are to be taken in preparation for installing a motorised window covering. Where possible, multiple solar data loggers should be placed in as many locations and elevations as possible in order to maximise the reliability of data collected. [08] The present invention provides a device for measuring photovoltaic energy intake, comprising: an outer enclosure, and a means of measuring the charging current derived from a PV panel, and electronic componentry for data processing and storage wherein said device utilises an algorithm to calculate the average daily energy intake over a certain number of days. [09] In a preferred embodiment, the device further integrates all components necessary to function independently of any other equipment. Said components include a mounting fixture, a digital display, an internal rechargeable battery, and a small PV panel to produce a charging current for sampling. BRIEF DESCRIPTION OF THE DRAWINGS [10] Figure 1 shows the front and back sides of a preferred embodiment of the solar data logger. [11] Figure 2 outlines the logical framework of the solar data logger. [12] Figure 3 is the electronic schematic diagram of a preferred embodiment. DESCRIPTION OF PREFERRED EMBODIMENTS [13] Figure 1 shows a front and back view of the solar data logger 10 according to a preferred embodiment, consisting of suction cap 11, suction cap vacuum lock 12, PV sampling panel 13, on/off switch 14, battery charging port 15, battery status LED 16, reading display window 17, display activation button 18, and outer enclosure 19. [14] Suction cap 11 is operated in conjunction with vacuum lock 12 to securely affix the solar data logger onto a smooth flat surface, typically the glass pane of a window. [15] PV sampling panel 13 is used to produce a charging current which is recorded at predetermined intervals by the solar data logger. [16] To conserve battery power and prevent unintentional data logging, power on/off switch 14 is provided. [17] The preferred embodiment is powered by an internal rechargeable battery. This battery is charged via the battery charging port 15. The charge status of the internal rechargeable battery is displayed via the battery status indicator LED 16. [18] The results of the data logging session is shown on the digital display 17, which is activated when the display activation button 18 is pressed. The display is normally powered off to minimise battery consumption. [19] All necessary components are housed in outer enclosure 19. [20] Figure 2 shows the logical framework of a solar data logger. There are two critical measurement units - one for energy (or battery charge), and one for time. In the preferred embodiment, milliamp-hour (mAh) is used as the primary unit for battery charge although it is not strictly a unit of energy. This is done for convenience and is completely appropriate on the premise that the input voltage level for all intended applications is identical. The primary unit of time is day. This is because, for any given motorised window covering system, the intended number of operations per day can be defined. From here, it can then be stated that the daily average energy input must be greater than the daily average energy consumption if the system is to be self-sustaining. [21] The following discussion will be using example numbers for the purpose of clearer explanation. It should not be considered as the sole embodiment conceived. [22] With the purpose of attaining an average daily mAh value, a sampling algorithm is derived. If a sampling interval of 5 minutes is used, the number of samples taken per day would be 288 (60/5 * 24 = 288). Let x be the samples taken throughout the day, where x, is the first sample, x 2 is the second sample, etc. all the way up to x 288 . Each sample is an instantaneous current reading in mA. Total mAh for the day can be calculated using the formula: (x+ x 2 + x 3 +... + x 2 88 ) * 5 / 60 [23] The amount of charge in mAh for each day is stored in memory, the accumulated total of which can then be divided by the total number of days sampled. This will give the average daily battery charge in mAh which, for the intended application, can be treated as the average daily energy input. This will be compared against the expected daily energy consumption (also in mAh) to determine whether or not a given PV configuration is sufficient. [24] When PV sampling panel 13 generates an electrical current from exposure to light, it is then digitised as a voltage signal via an analogue-to-digital converter. Figure 3 shows a typical schematic for a preferred of the solar data logger. Practitioners in the art should be able to construct the electronics layout based on this schematic and the description herein. [25] The PV sampling panel 13 should ideally have a power rating that can be easily extrapolated upon. For example, if the integrated PV is rated at 0.5W and the reading results indicate that it satisfies 25% of the overall energy requirement, then it can be determined that a 2W panel is needed for the actual motorised window covering. [26] The solar data logger can be made in different shapes with different enclosure materials, mounting fixtures or display types. Various elements of the device, such as the display, PV panel or battery, can be decoupled from each other into individual units. [27] The output generated by the solar data logger can also be transmitted through a wired or wireless data transfer medium to another device for further reading, data storage or analysis. The solar data logger can be part of a more sophisticated measuring apparatus.

Claims (7)

1. A device for measuring photovoltaic energy intake, comprising a means of measuring the charging current derived from a PV panel, and electronics componentry for data processing and storage, charaterised in that said device employs an algorithm to deduce a reading that is averaged out according to a given time interval.

2. The device of claim 1, wherein said time interval is given as per day.

3. The device of claim 1, wherein all components necessary for its complete operation are integrated into a single unit enclosure.

4. The device of claim 1, wherein a suction cap is provided for fixating onto smooth surfaces including glass panels.

5. The device of claim 2, wherein buttons are provided to allow a user to individually cycle through the readings of each day.

6. The device of claim 3, wherein a PV panel is further integrated for into the enclosure for sampling purposes, thereby negating the need to connect a separate PV panel.

7. The device of claim 4, wherein an auxiliary input for a separate PV panel is nonetheless provided should the user deem it to be more appropriate.