Field of the Invention

[0001] This invention relates to a solar power installation for generating gas es such as hydrogen and oxygen by electrolysis using electrical power from so- lar panel arrays.

Background to the Invention

[0002] Most electrolyser systems for the generation of hydrogen from water in countries where vast tracts of land are available for power generation and energy storage, are powered either by solar arrays or by wind turbines. In hot- ter climates, the arid land is often unproductive for agriculture, but ideal for solar installations, the output of which, being cyclical, should be stored by one of two means - batteries or hydrogen.

[0003] Battery storage is appropriate for static applications up to a certain scale, after which hydrogen is both more economical and more sustainable, and for transportation of stored energy, there is no better medium than hydrogen. This may be done in pressurised cylinders or in cryogenic liquid form.

[0004] Electrolysers which are typically designed for these environments are housed in containers (of which there may be multiples) or, for larger systems, in purpose-built warehouses, etc. Creating such environments for electrolyser technologies leads to significant cost which could be avoided.

[0005] Additionally, such systems are typically powered by expensive and complex voltage and current control technologies which can amount to 30% of the total system cost, and introduce a significant level of end-to-end inefficiency when associated power factors are considered. [0006] DC/DC power conversion technologies are typically required for elec trolyser systems to take the combined electrical outputs from numerous solar panels and convert it to a more usable profile for use by reactor stacks within the system. [0007] The resulting power may be taken off by separate cables which feed individual reactor stacks or connected to a bus-bar from which individual reactor stacks could be powered.

[0008] Both options require significant control technologies to allow distribu- tion of the power to the reactor stacks within a system. High-current switching devices may be deployed to isolate or connect individual reactor stacks where bus-bar technology is used. Alternatively, a complex control system is required to distribute power to separate groups of cables in installations where reactor stacks are separately powered through dedicated cables. [0009] Such systems are required to interpret the input power and convert it to usable output power for the reactor stacks within the system, resulting in a complex and expensive power delivery system.

[0010] Many reactor stacks - particularly those which make use of mem branes to separate the gases at the point of generation - require their power to be supplied within a relatively small range, outside of which their efficiency re duces significantly. This is because the membranes which separate the gases offer resistance to the transfer of ions in the water-decomposition reaction. This renders their use in a distributed system less viable, though not by any means unviable. [0011] Where no membrane exists - as in the mixed-gas type of system, a much greater range of power provision may be accommodated in the efficient generation of hydrogen and oxygen.

[0012] This type of mixed-gas system allows for reductions (from maximum) in both Voltage and current to occur while remaining efficient in driving the wa- ter decomposition reaction (there being no resistance to the passage of ions from membranes), thereby maximising gas production throughout a wide range of solar power input as the Sun travels through its daily path.

[0013] Beyond these factors, installations in such regions require substantial cooling systems to prevent thermal run-away. Containment of technologies, whether in ISO containers or purpose-built structures, worsens the situation considerably as they contribute to thermal gain from the influence of the sun. The cost of chilling a system in such circumstances can be substantial, both in capital outlay and in operating cost, with the associated demand for power po tentially being as high as 50% of that required for the electrolysis process. Summary of the Invention

[0014] A solar power installation according to the invention comprises a pho tovoltaic panel and an electrolyser supplied with electrical power directly from the panel, whereby the electrical power output of the panel is matched to the power requirement of the electrolyser, the electrolyser having a water inlet and a gas outlet connected to gas storage means.

[0015] One aspect of the invention provides a solar power installation com prising a plurality of groups of photovoltaic panels, each group having a respec tive electrolyser mounted adjacent to the group and supplied with electrical power directly from the group whereby the electrical power output of the panels in the group is matched to the power requirement of the electrolyser, each elec trolyser having an inlet connection from a supply of water and an outlet connec tion to a gas manifold.

[0016] The electrolyser system comprises a plurality of reactor stacks with minimal balance of plant (BOP) which are directly linked to solar panel arrays, rather than housed together in a building or container, thereby eliminating ex pensive and inefficient DC/DC conversion technology. In such an installation, units could be arranged to take advantage of shade provided by the solar ar rays.

[0017] In such a system, stacks would be directly electrically linked to an ap- propriate number of solar cells, with the gas thereby produced being provided to downstream purification technologies in ‘bundled’ pipework or manifolded to gether for transmission.

[0018] Water would be supplied to each stack by any of various means from a controlled quality water supply. [0019] In such an arrangement, electrolysers could be located anywhere in a solar array, but will most likely be placed evenly row-to-row in order to efficiently link gas output lines and to allow easy access for maintenance.

[0020] Gas output lines could be buried or carried on overhead gantries for safety.

[0021] A system of this nature would eliminate the need for costly electrical conversion technologies by appropriately scaling electrolyser reactor stacks to match electrical output from solar arrays, such that a row (or partial row) of solar panels would be linked to a reactor stack of appropriate electrical capacity to match the maximum electrical output.

[0022] In such installations, some rows or portions of the solar arrays might be linked to electrolyser stacks, while the remainder are used in the normal way to power the grid or other dedicated power-consuming systems.

[0023] Typically, electrolysers would be connected by pressure-resistant tub- ing such as stainless steel tube to manifolds of larger diameter which would run the length of the installation to a purification system where the gases may be stored either cryogenically or in pressurised vessels.

[0024] Such a concept may be used for any of the types of electrolysis cur rently deployed for such energy storage purposes, including proton exchange membrane (PEM), alkaline membrane or mixed gas systems with cryogenic separation technologies.

[0025] Where installations of this concept are to be installed in desert areas, where night-time temperatures can drop to well below 0°C, trace heating can be installed at each electrolyser, powered by an uninterruptable power supply (UPS) to maintain fluid temperatures at values above those at which water and electrolyte freeze.

[0026] Similarly, gas transmission lines which might carry moist gas may be kept at above freezing temperature with trace heating, should such prove nec essary. [0027] In environments where temperatures can fall below freezing, lines might be buried rather than mounted above ground in order to ensure that they are protected from low temperatures.

[0028] Additionally, unlike containerised systems, systems of this design re quire less cooling energy at the height of the day to maintain optimal operating temperatures.

[0029] In most cases, no matter which technology is to be deployed, it is like ly that moisture would be carried on the gas prior to reaching the storage tech nologies which are placed at a distance from the generation technologies. In this case, there may be intermediate technologies which are designed to re move excess moisture. These could include coalescing filters, differential ve locity dash-pots, cyclone tubes or bubbler technologies.

[0030] Small diameter metal gas lines from the electrolyser stacks might be laid bunched together, arranged in parallel runs, or manifolded into larger diam eter tubes. In the former case, the small diameter tubes could be mounted in groups on overhead gantries or buried underground. In such ‘tube runs’ a sin gle tube will leave the most distant electrolyser, with additional ones added to run alongside as additional electrolysers’ output gas lines are incorporated into the group.

[0031] In the latter case, small diameter tubes would be connected at the closest or most accessible point to a larger diameter stainless steel tube which would progressively convey the gas from multiple electrolysers. This tube might be of consistent diameter for its length, or, alternatively, start at the most distant end as a small diameter tube and progressively step up in diameter as electro lyser outlet tubes are progressively added to the manifold.

[0032] As reactor stacks in such a system are located outside, and not en closed in any building or ISO-type container, there is no danger of leaked hy drogen forming a combustible gas pocket. This renders the total system very much safer and less expensive than enclosed systems, as there is a reduced need for leak detection and associated control system technologies. [0033] Additionally, stacks could be designed to make use of the surround ing ambient air temperature for cooling, thereby significantly reducing the power which would otherwise be required for chilling the circulating water or electro lyte. This could be accomplished by numerous means, including using larger surface area cell plates to create external ‘fins’ to passing ambient air.

[0034] One aspect of the invention provides an installation suitable for use in homesteads and farms and having a single electrolyser unit linked to a panel or panels dimensioned so as to provide matched power for the electrolyser, which is suitably linked to a cryogenic separation unit so as to separate out and store hydrogen for fuelling combustion engines or fuel cells for powering machinery, for example tractors or other farm equipment.

Brief Description of the Drawings

[0035] In the drawings, which illustrate an exemplary embodiment of the in vention: Figure 1 is a perspective view of a solar power array with electrolyser system; and

Figure 2 is an enlarged perspective view of the end of one row in the ar ray of Figure 1.

Detailed Description of the Illustrated Embodiment [0036] Referring first to Figure 1 , the solar array 1 comprises rows of photo voltaic panels 2 directed in conventional manner to receive the maximum amount of solar radiation through the day. Each row has an electrolyser unit 4 located at or adjacent to one end thereof and supplied with electrical power from at least some of the panels in the row such that the power supplied to the electrolyser directly matches the power requirement of the electrolyser without the need for DC/DC conversion. Thus, it may be possible for the power re quirements of the electrolyser for the row to be fulfilled by, say, half of the row, with the remaining panels in the row supplying power for other purposes, for example to the grid, or to a further electrolyser provided at the opposite end of the row. [0037] The electrolysers may suitably be of the membraneless mixed gas type, the gas outlet of each electrolyser being connected to a gas manifold tube 7 conducting the gases to a gas purification, separation and storage system 8, where the gases are dried by any of a number of technologies before the hy- drogen is separated from oxygen by means of cryogenic treatment to liquefy the oxygen leaving gaseous hydrogen to be drawn off. The oxygen is then sepa rately evaporated and stored for industrial or other use. Suitably purified water is supplied to each electrolyser through a separate supply pipe (not shown) and control of the whole system is via control cabinet 9. [0038] Referring now to Figure 2, the electrolyser unit 4 is electrically con nected to the panels 2 via an electrical connection box 5. A water storage tank 3 is supplied with water from a central supply and in turn delivers water to the electrolyser. Gases exit the electrolyser via a gas outlet tube 6 connected to the gas manifold tube 7, which extends along the ends of the rows in the array. The manifold tube may be constructed so as to increase in diameter from the end remote from the gas purification and separation system 8 to allow for the in creasing gas flow volume as each electrolyser is connected in to it.

[0039] By way of example, where the maximum power output of a single panel is 1 kW, the electrolyser would be scaled to accommodate 1 kW of input power. Conversely, where the solar installation has a maximum output of 1 MW, divided (e.g.) into 10 rows of 100kW output, each electrolyser module (compris ing stack, reservoir, BOP and water provision technology) would be scaled to accommodate 100kW of input power.