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AI Overview     Based on your query, here is an explanation of solar thermal power for hot water, how "watts" and "watt-hours" apply, and how to represent this information using BBCode for a forum or web page. Solar thermal power for hot water Solar thermal systems heat water directly using sunlight, rather than converting it to electricity first. Because of this, the energy output is measured in heat units, not electrical units. How it works: Solar thermal collectors (flat-plate or evacuated-tube panels) on a roof absorb solar radiation to heat a fluid. This fluid then circulates through a heat exchanger to transfer the heat to a domestic hot water tank.High efficiency: Solar thermal collectors can convert up to 80% of the sun's energy into heat for water, which is a much higher conversion rate than typical photovoltaic (PV) panels. However, this is not an apples-to-apples comparison, as PV produces electricity, which can be used for a wider variety of purposes."Watts" in context: When discussing solar thermal systems, the term "watts" (\(W\)) is used to describe the instantaneous rate of heat transfer, typically expressed as thermal kilowatts (\(kW_{th}\)). A common conversion factor is \(0.7\) \(kW_{th}\) per square meter of collector area. Electrical watts (\(W\)) are only relevant for the small amount of power needed to run pumps and system controls. Calculating and expressing energy output For solar thermal, it is most accurate to measure the total energy output over time. Watt-hours (\(Wh\)): This is a unit of energy equal to the power in watts multiplied by the time in hours. For solar thermal, this would represent the total thermal energy (\(Wh_{th}\)) produced. For example, a system with a peak thermal output of 3.5 \(kW_{th}\) that runs for 5 hours would produce \(3,500\) \(W_{th}\) * \(5\) hours = \(17,500\) \(Wh_{th}\), or \(17.5\) \(kWh_{th}\) of thermal energy.Standard ratings: The Solar Rating & Certification Corporation (ICC-SRCC) provides standard ratings for collectors in both thermal kilowatt-hours per day and thousands of BTU per day. A typical system might produce 10–15 \(kWh_{th}\) per panel per day. BBCode for formatting BBCode is a simple markup language used on many web forums. Here is how to format text related to solar thermal power calculations for a forum post. Bold: Thermal Power:Italic: Energy output can vary based on conditions.List:bbcode

• Panel Type: Evacuated Tube

• Peak Output: 3.5 kW[sub]th[/sub]

• Total Daily Energy: 17.5 kWh[sub]th[/sub] (over 5 sun-hours)

Formatted example:bbcodeMy Solar Thermal System Performance

This is an example of the output from a solar thermal system used for hot water.

• Collector Type: Evacuated Tube

• Gross Area: 3.5 m[sup]2[/sup]

• Rated Thermal Power: ~2.5 kW[sub]th[/sub] (Standard conditions)

• Typical Daily Energy Output:

  • Summer (High Radiation): 15-20 kWh[sub]th[/sub]

  • Winter (Low Radiation): 5-10 kWh[sub]th[/sub]

AI Overview     To calculate the energy output of a solar thermal hot water system, use the specific heat formula to find the thermal energy needed to heat the water. Then, account for the system's efficiency and BBCode units. Step 1: Calculate the thermal energy needed Use the specific heat formula to determine the energy required to heat a specific volume of water:Energy (in Joules) = mass (m) × specific heat of water (c) × change in temperature (ΔT) Variables: Mass (m): The mass of water you need to heat. A common conversion is 1 kilogram (kg) per liter (L) of water.Specific heat of water (\(c\)): A constant value of approximately 4.186 Joules per gram per degree Celsius (\(4186\text{\ J/kg}\degree \text{C}\)).Change in temperature (\(\Delta T\)): The desired hot water temperature minus the incoming cold water temperature, in degrees Celsius. Example calculation:To find the energy (in Joules) required to heat 100 liters of water from 10°C to 55°C: Mass (m): \(100\text{\ L}\times 1\text{\ kg/L}=100\text{\ kg}\)Specific heat (\(c\)): \(4186\text{\ J/kg}\degree \text{C}\)Change in temperature (\(\Delta T\)): \(55\degree \text{C}-10\degree \text{C}=45\degree \text{C}\) Equation:Energy (J) = \(100\text{\ kg}\times 4186\text{\ J/kg}\degree \text{C}\times 45\degree \text{C}\)Energy (J) = \(18,837,000\text{\ J}\) Step 2: Convert to Watt-hours (Wh) Energy is commonly measured in kilowatt-hours (kWh) or watt-hours (Wh). There are 3.6 million Joules in a kilowatt-hour. Convert from Joules to Watt-hours:1 Watt-hour = 3600 Joules Equation:Energy (Wh) = \(18,837,000\text{\ J}\div 3600\text{\ J/Wh}\)Energy (Wh) = \(5232.5\text{\ Wh}\) Step 3: Estimate for BBCode formatting To represent this calculation in BBCode format, which is often used on forums and is a variation of HTML, you would structure the output with bolding for emphasis, and use code blocks if available for formulas. Example BBCode: Calculating Solar Thermal Power for Hot Water

1. Calculate Thermal Energy Needed
Energy (in Joules) = mass * specific heat * temperature change
- Mass: 100kg (for 100L of water)
- Specific Heat: 4186 J/kg°C
- Temperature Change: 45°C (from 10°C to 55°C)

Energy (J) = 100 * 4186 * 45 = 18,837,000 J

2. Convert to Watt-hours (Wh)
1 Wh = 3600 J

Energy (Wh) = 18,837,000 / 3600 = 5232.5 Wh
Additional factors affecting output The calculation above is for the thermal energy required, not the solar panel output. To get a more realistic estimate of the solar thermal system's performance, you must also consider: System efficiency: Real-world systems lose energy. A factor should be applied to account for these losses.Irradiation: The amount of available sunshine, which varies by location, time of day, and weather.Collector area: The size of the solar collector panels directly impacts the amount of heat absorbed.Solar fraction: The percentage of the total hot water load that the solar thermal system is expected to provide. For a more comprehensive analysis, you can use specialized software or online calculators, such as the one offered by the U.S. Department of Energ

BTU (British Thermal Unit) Calculations

1 BTU=1 DEGREE FARENHEIT INCREASE IN ONE POUND OF WATER.

8.34 POUNDS IN ONE GALLON

BTU EXAMPLE:
Incoming water 50F outgoing water 120F 120 - 50 = DELTA T 70F
BTU's for 1 gallon of water is 70 (delta T) * 8.34 (pounds per gallon) = 583.8 BTU's
Flow Rate 2 Gallons per Minute
2 Gallons * 60 minutes = 120 Gallons per hour
120 Gallons * 583.8 BTU's per Gallon = 70,056 BTU's per Hour

Solar Constant (measured outside the earth's atmosphere by satellite) is about 1.3 kilowatts (1,366 watts) per square meter (kW/m²)
The maximum value is about 1 Kw (1,000 watts) per sq meter, measured at the earth's exposed surface, when the sun is directly overhead.

Solar Insolation Maximum sun energy (irradiance) reaching the surface of the earth over a given time period.

kWh (kiloWatt hour) to BTU examples:
1 kWh = 3,412 btu's (per square meter when the sun is directly overhead)
90,000 btu's x 0.00029307108 = 26.37 kWh

Correct Flow Rates for Evacuated Tube Collector

0.026 to 0.066 Gallons per Minute per Tube
0.1 to 0.25 Liters per Minute per Tube

Volume Equivalents

231 CUBIC INCHES PER GALLON

7.481 GALLONS PER CUBIC FOOT

1.02 GALLONS PER 100' OF ½" PIPE

2.29 GALLONS PER 100' OF ¾" PIPE

4.08 GALLONS PER 100' OF 1" PIPE

Energy Conversions

1 kWh (kilo watt hours) = 3412.1415 BTU's

1 BTU = 0.00029307108 kWh

Btu Content of Common Energy Units

1 barrel (42 gallons) of crude oil = 5,800,000 Btu
1 gallon of gasoline = 124,000 Btu (based on U.S. consumption, 2008)
1 gallon of diesel fuel = 139,000 Btu
1 gallon of heating oil = 139,000 Btu
1 barrel of residual fuel oil = 6,287,000 Btu
1 cubic foot of natural gas = 1,028 Btu (based on U.S. consumption, 2008)
1 gallon of propane = 91,000 Btu
1 short ton of coal = 19,988,000 Btu (based on U.S. consumption, 2008)
1 kilowatthour of electricity = 3,412 Btu
Formulas

DELTA T = TEMPERATURE DIFFERENCE BETWEEN TWO VALUES (100F-90F = 10F DELTA T)

C TO F CONVERSION (C*1.8) + 32 = F

F TO C CONVERSION (F - 32.0) / 1.8 = C

LBS * 0.453592 = KILOGRAMS

KILOGRAMS * 2.204623 = POUNDS

GALLONS * 3.785412 = LITERS

LITERS * 0.264272 = GALLONS

QUARTS * 0.946353 = LITERS

LITERS * 1.056688 = QUARTS

Following the Space Shuttle Columbia disaster in 2003, President George W. Bush announced the Vision for Space Exploration in 2004, which started the transition away from the Space Shuttle and toward new deep-space exploration programs. However, the program announced in 2004 was the now-canceled Constellation program—not Artemis. The Space Shuttle did not fully retire until 2011, and the Artemis program was not established until 2017.

2004: Vision for Space Exploration and the Constellation program

The decision:
In January 2004, after the loss of Space Shuttle Columbia and its crew, President Bush announced the Vision for Space Exploration. This initiative called for the Space Shuttle fleet to be retired after completing assembly of the International Space Station (ISS).

The goal:
The Vision set out a plan for developing a new crewed vehicle to return humans to the Moon and later travel to Mars and beyond.

The program:
The Constellation program was formed in 2005 to fulfill this vision. It involved the development of two new launch vehicles, the Ares I for crew and the Ares V for cargo, as well as the Orion crew capsule and the Altair lunar lander.
The path from Constellation to Artemis

Constellation's cancellation:
Following an independent review that found Constellation to be over budget and behind schedule, President Barack Obama formally canceled the program in 2010.

The start of Artemis:
In 2017, President Donald Trump established the Artemis program. The new program repurposed the Orion crew capsule from the Constellation program and adapted much of the launch hardware to create the Space Launch System (SLS).

The end of the Space Shuttle
Final flights:
The Space Shuttle program continued flying missions to assemble the ISS after the 2004 announcement.

Official retirement:
The program officially ended with the landing of Space Shuttle Atlantis on July 21, 2011. A six-year gap followed where American astronauts relied on Russian Soyuz vehicles to get to the ISS, before the Commercial Crew Program began.

Duffy's comments follow months of mounting pressure within NASA to speed up its Artemis lunar program and push SpaceX to make greater progress on its Starship lunar lander, while China progresses toward its own goal of sending humans to the moon by 2030.
It represents a major shift in NASA's lunar strategy, starting a new competitive juncture in the program for a crewed moon lander just two years before the scheduled landing date. Blue Origin is widely expected to compete for the mission, while Lockheed Martin (LMT.N), opens new tab has indicated it would convene an industry team to heed NASA's call.
Starship, picked by NASA in 2021 under a contract now worth $4.4 billion, faces a 2027 moon landing deadline that agency advisers estimate could slip years behind schedule, citing competing priorities. Musk sees Starship as crucial to launching larger batches of Starlink satellites to space and eventually ferrying humans to Mars, among other missions.

"They do remarkable things, but they're behind schedule," Duffy said of SpaceX's lunar lander work, adding President Donald Trump wants to see the mission take place before his White House term ends in January 2029.
The move is a significant change under the agency's acting leadership, and as the White House and Duffy begin to reopen the nomination process for a permanent administrator. Billionaire entrepreneur and SpaceX customer-astronaut Jared Isaacman, an ally of Musk's, is in talks to reclaim his nomination that had been yanked by Trump over the summer.
Musk shrugged off the specter of more competition in a social media post.
"SpaceX is moving like lightning compared to the rest of the space industry," the SpaceX CEO wrote on X, replying to a user on Monday. "Moreover, Starship will end up doing the whole Moon mission. Mark my words."

The mission involving SpaceX, Artemis 3, would be the first human lunar landing since Apollo 17 in 1972.
Bezos' space company Blue Origin, with its Blue Moon lander in development, has a similar lunar landing contract awarded by NASA in 2023 but for later Artemis moon missions. The company had protested NASA's initial decision to only pick SpaceX in 2021 and fought for years to convince the agency and lawmakers to select another proposal as a redundancy.
Duffy's reference to Blue Origin on Monday suggests Bezos' space company could contend for Artemis 3.
Blue Origin has been developing its Blue Moon lander in Florida with relatively little public attention under a contract worth roughly $3 billion. SpaceX has been developing Starship in Texas in a whirlwind campaign of test-to-failure demonstration missions, but NASA has grown uneasy with a lack of progress on lunar lander-specific development milestones.

NASA's multibillion-dollar Artemis program is a series of missions involving multiple contractors aimed at returning humans to the moon for a long-term presence there. Artemis 3 has been planned for 2027 with SpaceX's Starship.
Artemis 2, opens new tab, a 10-day flight around the moon and back involving systems built by Boeing (BA.N), opens new tab, Northrop Grumman (NOC.N), opens new tab and Lockheed Martin (LMT.N), opens new tab, is on track for April and could get moved up to February, he added.
Bezos and Blue Origin CEO Dave Limp reportedly spoke with Trump over the summer when the Republican president was feuding with Musk, a supporter in the 2024 election who was tapped to lead efforts to cut the federal government known as DOGE.

The current approved annual Starship launch rate is 25, following an approval by the FAA in May 2025. This is a significant increase from the previous limit of five, and SpaceX's goal is to increase this further to a weekly launch cadence, which could be achieved in 2026. However, the actual launch rate has been much lower than the approved maximum, with a total of five orbital flights by mid-October 2025.

Approved rate:
The FAA has approved up to 25 annual Starship/Super Heavy orbital launches from the Boca Chica launch site.
Previous rate: Before the recent approval, the limit was five launches per year.

Actual rate:
By mid-October 2025, only five Starship orbital launch attempts had been made, and no further launches were planned for the remainder of 2025.

Future goal:
SpaceX aims for a launch rate of up to 48 per year (one launch per week), potentially starting in April 2026, contingent on resolving technical issues and achieving full reusability.

Executive Summary

Undocumented immigrants are not eligible for federally funded Affordable Care Act (ACA) Marketplace coverage or premium tax credits under current U.S. law; this is consistently stated across official guidance and recent analyses dated October 2025 through January 2026. Mixed-status households can enroll eligible, lawfully present family members and apply for subsidies on their behalf, but that process does not extend ACA subsidies to undocumented individuals themselves

The "Yuri's Night Mars Society" refers to The Mars Society's support for and participation in Yuri's Night, a global celebration of spaceflight that takes place annually on April 12th. The Mars Society, an international nonprofit organization dedicated to the exploration and settlement of Mars, uses the event to promote space education and STEM excitement, often participating in local celebrations or encouraging members to host their own events.
Yuri's Night: This is a worldwide annual event celebrating spaceflight history on April 12th, commemorating both Yuri Gagarin's first human spaceflight in 1961 and the first Space Shuttle launch in 1981.
The Mars Society's involvement: The Mars Society has a history of partnering with Yuri's Night events to promote space and STEM activities.
Event types: These can include large public events at museums and NASA centers, as well as smaller, community-based gatherings like parties, movie screenings, or barbecues.
Goals: The collaboration aims to spark interest in space exploration and education, particularly focusing on future human journeys to Mars

SpaceNut,

If we're going to add that much metal to an already energy-intensive device like a photovoltaic cell, why not build a simpler and more robust solar thermal concentrator?

AI Overview
On average, a U.S. home consumes approximately 1.2 to 1.25 kilowatt-hours (kWh) per hour. This figure is an average calculated from yearly data and represents the overall rate of energy usage, but actual consumption varies throughout the day and seasonally.
For instance, the average 2022 annual consumption of electricity was 10,791 kWh per household.
10,791 kWh per year / 365 days = ~29.56 kWh per day
29.56 kWh per day / 24 hours = ~1.23 kWh per hour
Factors affecting average hourly electrical use
Hourly electrical usage fluctuates significantly depending on several factors:
Time of day: Demand for electricity is typically highest during the afternoon and evening hours when occupants are home, cooking, and using appliances like air conditioning.
Season and climate: A home's biggest energy drain is typically from heating or cooling systems. Homes in hot climates use more energy for air conditioning in the summer, while those in cold climates use more for heating in the winter.
Appliance usage: The average hourly consumption changes depending on which appliances are being used. High-wattage devices like air conditioners, electric ovens, and clothes dryers consume significant power when running.
Household size: A larger household typically has more occupants and appliances, leading to higher overall energy use.
For a more accurate comparison, the U.S. Energy Information Administration (EIA) notes that a single-family detached home in the South consumes much more electricity than an apartment in the Northeas

AI Overview
Concentrated solar thermal (CST) energy is not feasible for residential electricity generation due to its high cost and complexity. It is almost exclusively used for large-scale, utility-level power plants. For a U.S. home, the standard solution for converting sunlight into usable electricity is a photovoltaic (PV) panel system, typically including battery storage.
Here is a BBCode guide on how to size a residential solar PV system based on average hourly electrical consumption.
Sizing Residential Solar Photovoltaic (PV) for a U.S. Home
For the average U.S. home, which uses roughly 30 kWh per day, a solar PV system will need a capacity of around 6 kW. This can vary significantly depending on your location, lifestyle, and home size.
Step 1: Determine Your Hourly and Daily Energy Needs
Locate your total energy usage: Review your last 12 months of utility bills to find your annual kilowatt-hour (kWh) usage. Using a year's worth of data accounts for seasonal spikes, such as higher air conditioner use in summer.
Calculate your daily average: Divide your total annual kWh by 365 to get your average daily consumption.
Estimate your hourly usage: Divide your daily average by 24 hours to find your average hourly consumption. However, note that a battery storage system is necessary to provide power during the night, as solar panels only generate electricity during daylight hours.
Step 2: Find Your Peak Sun Hours
Look up your location's peak sun hours: Use a map or a tool from the National Renewable Energy Laboratory (NREL) to find the average number of "peak sun hours" per day in your area. These are the hours where the solar intensity is high enough to generate the maximum power from your panels.
Step 3: Calculate the Required System Size (in kW)
Calculate the ideal daily output: Divide your average daily kWh usage by your area's peak sun hours.
Add a buffer for inefficiency: Multiply the result by 1.2 (or 120%) to account for energy losses from the wiring, inverter, and system degradation over time. This gives you the size of the system in kilowatts (kW).
Consider future use: If you plan to add a new electric vehicle or appliance, increase your system size to account for the additional load.
Step 4: Estimate the Number of Panels
Find your panel wattage: Look up the rated wattage (W) of the specific solar panels you are considering. A common residential panel has a wattage between 300W and 450W.
Determine the number of panels: Divide your required system size (in watts) by the panel's wattage.

Required System Size (in watts) / Panel Wattage (in watts) = Number of Panels

Note: A 1 kW system is 1,000 watts.
Step 5: Account for Energy Storage
Determine battery needs: For full backup power, your battery storage capacity (in kWh) should roughly match your average daily energy consumption. For example, a home using 25 kWh daily might start with a 10–15 kWh battery and expand later.
Consider discharge rate: Batteries have a discharge rate that affects how many appliances can be run simultaneously. This is especially important for running heavy-duty items like an air conditioner.
Example Calculation for an Average U.S. Home
Assumptions:
Daily Consumption: 30 kWh
Peak Sun Hours: 5 (varies by location)
Panel Wattage: 400 W
Calculation:
Required Power Output: 30 kWh / 5 h = 6 kW
Adjusted for Inefficiency: 6 kW x 1.20 = 7.2 kW
Required Number of Panels: (7.2 x 1,000 W) / 400 W = 18 panels
Approximate Battery Storage: ~25 kWh for a full day of backup

AI Overview     To size a solar thermal concentrator for a daily thermal energy demand of 40 kWh, you need to consider several key variables, most importantly the average daily peak sun hours for your specific location. The aperture area, or the size of the collector, is directly dependent on the amount of available sunshine and the system's efficiency. Calculation overview The general formula to find the required aperture area of the concentrator is:\(Area=\frac{Total~Daily~Energy~Required}{(Solar~Irradiance)\times (System~Efficiency)}\)Here is a breakdown of the steps involved in the calculation. 

Step 1: Determine average daily solar irradiance Find the average daily peak sun hours for your location. This is a measure of the amount of solar radiation available per day, often expressed in \(kWh/m^{2}/day\). You can find this data from solar radiation maps or resources like the National Renewable Energy Laboratory (NREL). Example: For a location with 5 peak sun hours, the daily solar irradiance is approximately \(5~kWh/m^{2}/day\). 

Step 2: Estimate system efficiency The overall efficiency of a concentrating solar thermal system can vary based on several factors, including: The type of concentrator (e.g., parabolic dish, trough).Optical losses from reflections and the receiver.Thermal losses from the receiver to the environment. For a preliminary estimate, a thermal efficiency (Eta) of about 80% is a reasonable starting assumption. It is important to note that this is a conservative value; a real-world system will have many loss factors. You may also need to budget for additional losses, such as a 20% overhead, to account for real-world inefficiencies. 

Step 3: Calculate the required collector area Using the daily energy demand of 40 kWh, the location's average daily solar irradiance, and the estimated system efficiency, you can calculate the required aperture area. Formula:\(Area~(m^{2})=\frac{40~kWh}{(Peak~Sun~Hours~in~kWh/m^{2})\times (Efficiency)}\)Example calculation:Let's assume your location has an average of 5 peak sun hours (\(5~kWh/m^{2}/day\)) and you estimate a system efficiency of 80% (0.80). \(Area~(m^{2})=\frac{40~kWh/day}{(5~kWh/m^{2}/day)\times (0.80)}\)\(Area~(m^{2})=\frac{40~kWh/day}{4~kWh/m^{2}/day}\)\(Area~(m^{2})=10~m^{2}\)In this example, you would need a concentrator with an aperture area of approximately 10 square meters. Additional factors for refined sizing For a more precise sizing, consider these additional factors: 

Seasonal variation:
Your calculation is based on an average day. Energy production will be higher in summer and lower in winter. For consistent year-round performance, you must size the system based on the minimum sun hours for your location.

Tracking systems:
A concentrator's performance is highly dependent on how well it tracks the sun. One-axis or two-axis tracking systems will yield more energy than a stationary collector, but also increase complexity and cost.

Thermal storage:
Storing excess thermal energy in a tank allows you to use the energy when the sun is not shining. The storage size should be matched to your usage patterns and the solar field to optimize daily operation.

Collector type:
Different concentrator designs have different efficiencies and space requirements. Common types include parabolic troughs, dishes, and linear Fresnel collectors.

Safety factors:
It is often wise to oversize the system slightly to account for cloudy days, system degradation over time, and other inefficiencies