Can Portable Solar Panels Power a House | Power Output, Storage Capacity, Usage Limits

Portable type solar panels usually power at 100–400W, can be upgraded through parallel connection to 1–2 kW, suitable for small household daily appliances power supply.

Cooperate with 2–5kWh energy storage cell, can support lighting, TV, refrigerator etc. 4–8 hours.

Affected by light greatly, cloudy days or nighttime need to rely on cell energy storage or city electricity backup.

Power Output

See understand parameters

Manufacturers in the laboratory measure portable solar panel's nominal power adopting standard test conditions, light intensity set at 1000 watts/square meter, air mass 1.5, cell sheet working temperature fixed at 25 degrees Celsius. Bought home's 400-watt portable panel for outdoor extremely hard-to-reach environment requirements. July in Florida or Arizona's backyard, the air environment temperature reaches 35 degrees Celsius, dark colored monocrystalline silicon panel absorbs infrared radiation, surface working temperature will soar to 55 degrees Celsius to 65 degrees Celsius between.

The market for common monocrystalline silicon panel's maximum power temperature coefficient is approximately at -0.35%/degree Celsius to -0.45%/degree Celsius interval. Assume purchased a 400-watt panel with a temperature coefficient of -0.40%/degree Celsius. When the surface temperature reaches 65 degrees Celsius, compared to 25 degrees Celsius laboratory baseline, the high out 40 degrees Celsius. 40 multiplied by -0.40% produces 16% power loss. Panel heating loses 64 watts of output power, not calculating any cable transmission resistance's situation under, the physical highest output ceiling is forcibly suppressed to 336 watts.

Angle not right head

Portable solar panels extremely rely on sunlight's incident angle. Sunlight presents 90 degrees perfectly vertical illuminating panel surface, only then can capture 100% of usable solar radiation. The sun in the sky every 1 hour moves about 15 degrees, morning 8 o'clock arranged good fixed portable panel, arriving at afternoon 1 o'clock will appear serious angle deviation. Power's loss follows a cosine curve law, panel and sunlight appear 15 degrees' dislocation, power generation efficiency drops 3.4%. Deviation reaches 30 degrees, loss rate expands to 13.4%.

When the incident angle tilt reaches 45 degrees, nearly 30% of the power generation amount disappears. Residing in the north latitude 40 degrees area, winter sun runs close to the horizon's position, panel's optimal tilt angle needs to reach 55 degrees around. The portable panel behind's fixed bracket usually can only provide fixed 45-degree support, 10 degrees' physical drop will additionally cause 1.5% radiation reception loss.

· Continuously for 3 hours, not artificially adjust panel orientation, sun shifts 45 degrees will lead to total output falling below nominal value's 70%.

· Winter solstice day noon's effective photovoltaic radiation amount is often only has summer solstice day's 50% to 60%.

· Outdoor wind sand on panel surface accumulates out 0.1 millimeters thick dust layer, light refraction rate's change will cause short circuit current drop 4% to 7%.

· Tree branches or building's wires on panel cast down a strip only occupying a total area of 5% of the shadow, if not equipped with a bypass diode, the entire block panel's output will plummet 50%.

Actual loss

The first is the solar energy charging controller. A cheap portable kit pairs with a PWM (pulse width modulation) controller, and the electric energy conversion efficiency hovers at 70% to 80% between. Change equipment to MPPT (maximum power point tracking) controller, conversion efficiency can climb to 98% to 99%.

One block can produce 350 watts of direct current's panel in sunlight, through PWM controller after only one cell can send over 260 watts, MPPT equipment can keep 343 watts. Cable is consuming energy, wire longer, wire diameter thinner, voltage drop more serious. Use standard 10 AWG specification's copper wire, take 20 amperes' current to transmit to 30 feet outside's outdoor power source, will produce about 3.5% voltage drop, panel end output's 18 volts voltage arrives at the cell end, only leaving 17.3 volts.

Energy storage power source inside's inverter responsible for taking cell inside's direct current and converting it into 110 volts or 120 volts' household alternating current. Regular inverter's conversion efficiency is 85% to 90%. Convert 300 watts of direct current produces 30 to 45 watts of heat energy dissipation. Finally, household appliances can use electricity amount not enough 260 watts.

Aging: How to calculate

The portable panel outer layer commonly uses ETFE or PET plastic film, reduced weight, and towards ultraviolet ray's anti-aging ability largely weakened. Roof glass panel first year degradation rate about 2%, subsequently every year degrades 0.5%, 25 years later still can maintain 84% power generation ability. Adopt PET material's portable panel in long-term outdoor sun exposure under, head 12 months' efficiency loss rate at 5% to 8% between.

Experience 500 times above's folding and unfolding actions after, connecting monocrystalline silicon cell sheet's internal copper foil soldering ribbon produces naked eye cannot see's tiny metal fatigue cracks, leading to internal electrical resistance increase 10% to 15%. One block brand new state under short circuit current can reach 20 amperes' folding board, high frequency use 3 years later, maximum output current shrinks to 16.5 amperes. Planning family off-grid electricity usage budget time, must take 20% hardware aging margin in advance calculate inside.

· Nominal power 400 watts' folding panel, serve 3rd year's highest expected output should according to 280 watts to 300 watts' standard to calculate.

· Drive one machine continuous running power 1200 watts' household appliance, count in inverter 15% conversion loss, cell pack must maintain 1411 watts' continuous discharge.

· Fill 1411 watt-hours' electricity amount consumption, use one machine's actual input electricity amount of 250 watts' panel, needs 5.6 hours not have any cloud layer blocking full load illumination.

Grid connection and series connection

Take 3 blocks of 200-watt panels connected in series, voltage unceasingly superimposes, 20 volts add 20 volts again, add 20 volts, becomes 60 volts, current maintains 10 amperes, not change. High voltage low current mode largely reduces transmission cable's heating, let 50 feet long distance extension cord's voltage drop control at 2% within. Series array in performance worst panel will limit all panels' current.

If the number 1 panel by the chimney is blocked, the output current drops to 3 amperes, exposed to sunlight under number 2 and number 3 panels will also be pulled down to 3 amperes, 600 watts array's total power shrinks to 180 watts below. Adopt parallel connection method, voltage locks at 20 volts, current superimposes to 30 amperes. Certain one block panel being blocked will not affect other panels' current output. Bear 30 amperes' huge current, must change to use more thick 8 AWG or 6 AWG specification cable, use thin wire will cause serious wire heating, causing 8% to 10% heat energy loss, even burn destroy insulation layer.

Storage Capacity

Understand electricity amount conversion

Market's outdoor portable energy storage equipment usually uses watt-hours to calibrate capacity, small parts independent batteries adopt ampere-hours to mark out. 1 piece 12 volts 100 ampere-hour cell pack, contains 1200 watt-hours' physical capacity. Cope with whole house basic electricity usage, 1000 watt-hours' equipment in power outage scenario under is cup of water on a burning cart of firewood.

1 machine rated power 150 watts' household refrigerator, compressor every day runs about 8 to 10 hours, 24 hours electricity consumption amount falls between 1200 watt-hours and 1500 watt-hours. Giving 4 machines smart phones full charge consumes about 60 watt-hours, router whole day open needs 240 watt-hours, night time light up 3 lamps 10 watts' LED light bulbs 5 hours consumes 150 watt-hours. Add the total minimum limit loads, single day total electricity consumption amount breaks through 1800 watt-hours.

Purchase capacity time needs according to actual electricity consumption amount's 1.5 times configure reserve amount, cope with continuous 48 hours no effective illumination's situation. Choose to buy nominal capacity at 3000 watt-hours above's equipment is more steady and safe. Part brands support series parallel capacity expansion module, can take initial's 3600 watt-hours main machine connect into two 3600 watt-hours' sub packs, total capacity expands to 10800 watt-hours. Take capacity to 10 degrees electricity (kWh) level, purchase budget will soar from 1500 US dollars to 5000 US dollars above, total volume occupation reaches 0.4 cubic meters, weight exceeds 100 kilograms.

Cell pick which kind

The market mainly circulates ternary lithium cell and lithium iron phosphate cell two mainstream specifications. Ternary lithium cell possesses high energy density, every kilogram 200 watt-hours to 250 watt-hours, equipment weight is lighter, suitable for mobile carry. High energy density accompanies relatively low thermal runaway temperature threshold, suffering puncture or exceeding 200 degrees Celsius high temperature time exists catch fire risk. Charge discharge cycle reaches 500 times to 800 times after, internal usable capacity will permanently degrade to initial state's 80% below.

Lithium iron phosphate cell's energy density stays at every kilogram 140 watt-hours to 160 watt-hours, same equal 3000 watt-hours capacity's equipment, lithium iron phosphate machine model will be compared to ternary lithium machine model heavy about 8 to 12 kilograms. Its thermal stability is extremely excellent, and the thermal runaway temperature exceeds 500 degrees Celsius. Its life cycle's length is extremely prominent, in standard room temperature under according to 0.5C discharge rate, cycle charge discharge reaches 3000 times, even 3500 times after, still can maintain 80% above's healthy capacity. Every day, charge discharge 1 time, lithium iron phosphate equipment can use about 9 to 10 years.

Discharge has reservation

Cell internal nominal physical capacity and appliance actual can absorb's usable electricity amount exist hard difference value. Cell management system strictly forbids cell cell electricity amount being thoroughly squeezed dry, over discharge will cause irreversible crystallization damage. System set up discharge depth limit. Lead-acid cell's discharge depth is usually stuck at 50%, one 1000 watt-hour lead-acid cell can only discharge 500 watt-hours. Lithium iron phosphate cell's discharge depth can be relaxed to 90%. Spend money bought back's 3000 watt-hours equipment, most bottom layer's 300 watt-hours electricity amount by system deadly locked, only 2700 watt-hours can be allocated to alternating current socket use. High power output will produce serious voltage drop, further squeeze actual usable capacity.

Use 3000 watts of power to connect into an electric heating wire dryer, the cell pack's internal voltage will drop from normal 51.2 volts instantly to 47 volts or even lower. Big current discharge time, cell internal resistance produces a large amount of Joule heat, temperature rise triggers heat dissipation fan full speed running, fan itself every hour consumes 10 watts to 15 watts' electricity. Actual output to dryer's total electricity amount maybe only has nominal capacity's 82% to 85%. Use appliance's power more big, cell discharge empty's time more short, calculate derived total output watt-hours number also then more low.

Calculate standby loss

Inverter responsible for taking direct current and converting it into 110 volts household alternating current. As long as the alternating current output's switch is pressed down, even if the socket is not connected to any plug, the inverter will be in standby state, just eating 15 watts to 25 watts' electricity. 24 hours not shut down, out of thin air evaporates 360 watt-hours to 600 watt-hours' reserve electricity. System built-in Wi-Fi module, Bluetooth communication chip, LCD display screen as well as cell management system's monitor motherboard, add up's fixed static power consumption at 3 watts to 5 watts between.

Take one machine full electricity state's 2000 watt-hours portable energy storage equipment place in warehouse inside not care, according to every month 2% to 3%'s chemical self-discharge rate calculate, add on standby motherboard's weak power consumption, half a year later, the cell inside probably only left 80% to 85% of the electricity amount. Power outage before if not have in advance plug on wall to supplement electricity, truly put to use time will face serious electricity amount shortage. Many equipment support UPS uninterruptible power supply mode, plug into a city electricity socket to maintain full electricity, and internal bypass circuit every hour produces 2 watts to 4 watts' power grid electric energy consumption.

Usage Limits

Carry not move big pieces

Household appliance's nameplate usually marks two power numerical values, one is continuous running power, another one is startup peak power. Bring with compressor or large electric motor's equipment, in power on running's most initial 0.5 seconds to 2 seconds inside, need to absorb rated power 3 times to 5 times' instantaneous current. One machine ordinary 1/2 horsepower household well water pump, pump water time's continuous load approximately at 1000 watts, but it starts that one instant will burst out 3500 watts to 4000 watts' instantaneous demand.

Currently, the mainstream market's portable energy storage power source, even if it is selling at a high price, reaching 2500 US dollars' 2000 watt-hours flagship machine model, its built-in inverter's continuous output upper limit is usually locked at 2000 watts to 2400 watts, peak power nominally reaches 4000 watts, but can only reluctantly maintain 0.1 seconds. Attempt to use this machine's power source to start a well water pump, long reaching 2 seconds' 3500 watts high load will instantly strike through the inverter's overload protection threshold.

The internal micro controller will in 10 milliseconds inside cut off the alternating current output, the panel's red color fault light lights up, leading to the water pump motor issue out a burst of muffled buzzing sound after thoroughly strike. Even if it only has 150 watts of running power, the household old-style refrigerator's compressor start time also needs approximately 800 watts to 1000 watts' impulse force, if at the same time, a 1200-watt microwave oven and a 100-watt TV are connected to the socket, the refrigerator suddenly starts superimposing 2100 watts instantaneous total current, similarly will trigger system trip power off.

When configuring off-grid electricity use equipment list time, must take all appliances' startup peak power add total, ensure total numerical value not exceed portable power source inverter rated continuous power's 1.2 times, otherwise frequent overload power off will accelerate inverter internal IGBT transistor's physical aging, take originally 5 years' design expected life shorten to not arrive 18 months.

Place cannot place open

One block output power 400 watts' four-fold monocrystalline silicon panel, completely flat spread on lawn after's physical size is approximately length 94 inches (about 2.4 meters), width 28 inches (about 0.7 meters), single block occupies ground area reaches 1.68 square meters. Plan one set containing 4 blocks of 400-watt panels, 1600-watt emergency charging array, add on every block panel in order to prevent mutual block shadow must reserve's 20 inches (about 0.5 meters) spacing, total altogether need to consume at least 8 to 10 square meters' pure flat empty land.

In a typical American residential area, the backyard often receives a 6-foot-high wooden fence, adjacent to two-story high buildings' roofs, as well as surrounding height exceeding 15 feet's oak trees' serious blocking. Morning 9 o'clock and afternoon 4 o'clock, the sun's height angle is lower than 35 degrees, the fence and tree crown project's narrow long shadow will easily cover the drop lawn's 30% to 40% panel area.

Many communities are subject to Homeowner Association (HOA) regulations, which strictly forbid facing the street's front yard lawn at will, bringing with reflective nature's industrial product equipment. If forced to take these four blocks, the total weight reaches 60 pounds (about 27 kilograms), the panels all squeeze on the narrow second-floor south-facing balcony, mutually overlapping panels will lead to photovoltaic absorption rate plummet 40%, 1600 watts' array actual output even 600 watts cannot reach.

Solar panels towards shadow's sensitivity extremely high, merely block live whole array area's 5%, if not have configured micro inverter or sufficient amount's bypass diode, due to series circuit's wooden bucket effect, overall power generation power will cliff style drop 50% above, equivalent to every day losing nearly 3 degrees electricity's potential power supply amount.

Connect power grid illegal

Take portable energy storage equipment and produce electricity and connect it to the family's original wall socket, faces extremely strict physical limits and electrical regulations constraints. Power outage time in order to save trouble, some people will spend 20 US dollars in a hardware store to purchase one root, two ends, all are male heads' non-standard power wire (commonly called “suicide cord”), one end plug into a portable power source's 120 volts alternating current output hole, another end directly shove into the living room wall's 15 amperes standard socket, attempt to light up the whole house's electric lights.

Reverse send electricity's operation violates "National Electrical Code" (NEC)'s mandatory standard, brings with extremely big's catch fire hidden danger. The household distribution box inside's circuit breaker is one-way designed, 120 volts' current through the wall's 14 AWG copper wire reverse transmit, total load exceeds 1800 watts, and the wire will heat up to 80 degrees Celsius in a few minutes, melt insulation outer skin, trigger wall inside electrical fire.

Portable power source output's electric energy will pass through the house's outdoor electricity meter, one way pour backward back to the street's public transformer, by transformer instantly step up voltage to 7200 volts' high voltage electricity. This is right now near a telephone pole on a conducting power outage repair operation, thinking line already cut power's electricity workers cause extremely serious life threats.

Compliant and safe's doing method is spend 300 to 500 US dollars to purchase one UL certification's manual Transfer Switch, and additionally pay 400 to 800 US dollars' electrician hourly wage fee, take it hard-wired install at the main distribution panel beside, thoroughly cut off the outdoor power grid's physical connection after, again take portable power source's 30 amperes plug connect into a specific independent circuit on.

Carry not hold wind rain

Install on roof's hard glass module adopts aviation grade aluminum alloy frame and stainless steel bolts fixed on load-bearing wooden beam, able to bear every hour 140 miles (about 225 kilometers/hour)'s category four hurricane tearing. Adopt cloth surface folding craft's portable panel, single block 400 watts' weight is extreme compressed to 35 pounds (about 16 kilograms) within.

The panel back face usually only relies on two to three velcro fixed's simple fabric bracket to maintain a 45-degree tilt angle. Gust wind speed reaches every hour 20 miles (about 32 kilometers/hour) time, wide big's panel surface will produce huge's aerodynamic lift force. Wind direction from panel back face blows come, fragile's folding bracket in bear exceeding 15 pounds' thrust force after will instantly bend collapse, whole panel is overturned on the ground, surface's ETFE protection film on rough asphalt road surface or crushed stones on scrape out depth reaching 0.5 millimeters' scratches, directly reduce 6% light transmittance.

The great majority of portable panel's waterproof dustproof grade stays at IP65 level, only can resist low pressure water column's occasional spray. Encounter continuous rainfall amount exceeding 2 inches (about 50 millimeters)'s rainstorm day, lawn on's accumulated water submerge over panel bottom's junction box, moisture from gap seep into internal's direct current connection head, will trigger positive negative pole short circuit burn destroy whole block panel, cause high reaching 800 US dollars' single block hardware purchase fee loss.