Solar Panel Store Blog
Solar Boat Lifts: Can I run my boat lift on solar?
“Can I run my boat lift on solar power?” a friend of mine recently asked. “Of course you can” I replied. But my friend had a problem. He bought a used boat lift which happened to run on standard AC power. Ah yes, AC. Alternating current. But no matter, boat lifts are still a great application for solar power. But why?
Why go solar for your boat lift?
Safety. My friend went on to explain that while the seller of his boat lift was fine with running an extension cord from the lift, along the dock, across the yard and to his house outlet, my friend was not. Electrical cords and water don't work well together. And he related the tragic story of a young woman that died from electrocution when an extension cord fell into the lake near her. No doubt, AC wiring can be safely routed to a boat lift, but a plain old extension cord isn't the way to go.
On the other hand, a solar powered boat lift system avoids even the temptation to run extension cords along the dock. Instead, a small solar panel would be mounted to the lift support structure or the immediately adjacent dock. The 12 volt PV wire would connect into an enclosed battery box (or a sheltered area under the lift awning) that ideally would house the battery, the charge controller, and the inverter (if an AC lift). The lift motor would then connect into that inverter (if an AC motor) or the battery (if a DC motor). All nice, close and short connections--out of the way and above the water.
Save $. Unless you have a safely installed AC outlet on your dock next to your boat lift (meaning no jerry-rigged extension cord jobs mentioned above), running an AC circuit to your dock can be an expensive proposition. It may mean trenching, conduit, electrician labor, etc. Those add up fast. A solar-powered DC system also has costs, but should be far less than trenching an AC circuit to your dock, etc. To save the most, start out right by buying a DC powered boat lift. If you buy a traditional AC powered one, then you'll also need to buy an inverter that's beefy enough to handle that AC motor. And since AC motors run at 110V (vs 12V for a DC motor) you'll need more battery storage and a bigger panel to fill them.
So what do I need to know for boat lift solar?
Sun. First, does your boat lift location have good south facing sun? If you're lift sits in the shade all day, solar won't be a good option for you. Even a little shade can reduce energy production, but you can compensate by upsizing your solar panel. Bottom line: understanding your site is key.
Need Batteries. Your boat lift system will be battery-based. You fill your battery with solar DC energy. To ensure your batteries are charged correctly and not damaged by over charging, your solar panel first connects to a solar charge controller. The battery stores the energy until you're ready to lower your boat to the water. The motor draws the energy from the batteries and then the sun refills the batteries. Voila! The key is to get the right kind of battery, keep it fully charged when not in use, and don't discharge it more than the recommended level.
Deep Cycle Batteries. Only use a deep-cycle battery. If the battery is labeled with “cold cranking amps” that's not a good sign. That's what you see on “starting” batteries (like the kind under your car's hood). Why does it matter? Because a deep-cycle battery is designed to power loads that steadily and fully discharge the battery to minimum point (it's depth of discharge (DOD) versus the sudden burst of current required to turn an engine over. Deep cycle batteries are also meant to be steadily recharged to 100% over and over again. Batteries are expensive, so it's important to use the right one for the job.
Volts and Amps. Boat lift motors designed for DC electricity will often require 12 volts, sometimes 24. Most often, a simple, single 12 volt deep cycle battery will be all you'll need. If you do have a 24V system, then you'll need 2 x 12 volt batteries wired in series (meaning the positive terminal of one battery is wired to the negative battery terminal of the other battery. By wiring in series, the battery voltage is doubled. A 12 volt deep cycle battery will list it's capacity in amp hours. As explained below, you'll probably want something close to 100 amp hours as measured by the C/20 rate. Huh? Let's just say for now that the more quickly a battery is discharged, the quicker the capacity is reduced. C/20 means a rate where the battery is fully discharged over 20 hours. That is the typical rate used to measure battery capacity for solar applications.
Flooded or Sealed/AGM/Gel? For a boat lift, the choice of battery type comes down to convenience and cost. A flooded lead-acid battery is cheaper than a sealed battery. But remember that a flooded battery's electrolyte levels must be checked and topped off periodically. Pop the caps and add distilled water. Not hard. But it must be done to ensure the batteries last like they should. A sealed battery may be either a VRLA or AGM or Gel battery. Most common are AGM these days. Without getting too technical, an AGM (or Gel or AGM) battery doesn't require any electrolyte maintenance. Just hook it up and forget it.
Inverter. As mentioned above, if you have an AC powered boat lift (like my friend did) you'll need an inverter to invert the DC power from the batteries to AC electricity that your motor needs. The inverter must be sized to provide the AC watts that your motor needs. Both continuous operating watts and surge watts. Motors often have higher wattage requirements when they start up (surge). A modified sine wave inverter may be sufficient, but you won't go wrong with a pure sine wave inverter. Pure sine wave inverters mimic the same quality AC wave form that your utility provides. Equipment runs best on pure sine inverters.
Sizing. Sizing the solar system components for your boat lift will depend on the specifics of your site, your boat lift specs and how often you use your lift. Once you know the watts of your DC motor, you can calculate the watt hours of stored energy you need each day. Just estimate how many times you'll raise and lower your boat in a typical day x the minutes per lift. Add them up and multiply by your system's watts. Give us a call at SolarPanelStore.com and we can help you size and get the right battery, charge controller and solar panel based on those watt hours. We can also help get you the right mount to attach your panel to your boat lift structure.
Solar boat lifts are a great way to go for safety, cost and simplicity. We're happy to help you with yours. And happy boating!
Can I DIY Solar?
DIY solar? Do-it-yourself? Really? Let's take a step back first. You've heard about solar power. And that solar electric (PV) systems save you money. Solar power is a renewable energy source. It's better for the environment. Good stuff. But expensive right? First there's the equipment. Then design. Then you need someone to install it all? Whew!
Enter DIY Solar. Can't you save money and install a solar electric system yourself? Yes you can! Is it for everyone? No it isn't. For example, don't we all know someone who changes their own brakes? Disks, rotors, pads, calipers. What did your last brake job cost you? $1000? Do you think your buddy saved some cash doing the brakes himself? You bet he did. Probably 50% less than an auto dealer break job. But not everyone knows enough, is bold enough, or mechanically-skilled enough to tackle that job. But many could.
The point is, for people with some DIY experience, some mechanical inclination, some drive to learn and courage to try, installing much of a solar electric system is quite do-able. In fact, we estimate more than half of our customers install the majority of their solar systems DIY. While it is pretty common for them to hire a licensed electrician to perform the final wiring connections of their system to the utility grid (and recommended and often required), they often tackle the rest themselves. And like the backyard mechanic . . . they save a bundle!
If you are reading this article, then you've probably learned that there are different types of solar electric (or solar photovoltaic—PV) systems out there. And some are easier to tackle DIY than others. Systems that are less complex and/or smaller are good PV systems to cut your teeth on. For example, many of our DIY house system customers got their feet wet in solar by putting a system in their RV. On the other hand, a basic residential grid-tie system, while not necessarily small, is quite straight forward compared to designing and installing a completely off-grid or hybrid grid-tie/battery-backup system. Let's compare these different types of solar systems:
Grid-tied systems. With solar's popularity boom in recent years, grid-tied PV systems are the most popular systems,and the most straight forward to design and install. Since these systems simply make DC electricity from the sun and convert it to AC electricity to power your house (and sell excess energy back to the grid), batteries don't enter the picture. And that reduces complexity. No charge controllers, special inverter-chargers, additional shut-offs, sub-panels, etc. Instead, solar panels are simply wired to inverters which are wired to your house's electric panel and a new meter that measures what is sold back to the grid.
Off-grid system. Instead of connecting panels through a smart grid-tie inverter that routes inverted AC electricity where it needs to go (house vs grid), an off-grid system means batteries. The battery bank is usually larger than you expect (although it does vary depending on the size of the load) and needs to be sized correctly to power the home or loads as desired, while maximizing the life of those expensive batteries. But the DC electricity from the panels needs to first charge those batteries via a DC solar charge controller. DC electricity from the panels (if batteries are full) or from the batteries (if sun isn't shining) then flows though the inverter/charger to feed AC electricity to the house's AC loads. When the sun doesn't shine for 2-3 days, the inverter/charger fires up an attached generator to charge the batteries up. More components, more going on, more to learn.
Hybrid System. In our opinion, this is the toughest, most complex and most expensive system to build. Well, short of an AC-coupled system anyway (beyond the scope of this article!). In this hybrid model, components and considerations of a grid-tied system blend with those of a battery-based system. Hybrid systems have traditionally been used to add battery-back up to power certain critical loads when the grid goes down. Instead of using a generator, a battery bank is kept charged and ready by the grid, but then get's refilled by the solar array once the grid fails. Hybrid systems are increasingly used in situations where the excess power cannot be sold back to the grid (Hawaii) or net metering is prohibited or inhibited by the utility. In those cases, battery storage is added to a system to power loads at night and essentially only use grid power for backup. In any event, with the combination of grid and battery components, system-design gets pretty complex and tougher to tackle DIY.
Next steps to DIY Solar.
Now that you understand the types of systems and some of the complexities involved, let's look at next steps in your DIY Solar journey:
Know your goal. This is basically the step we covered above. Understand what you want your system to do. Do you want to cut your utility bill by 100%? 50%? Look at the last 12 months of utility bills to get a feel for how much energy you want the system to produce. Are you just looking to power a small system like a remote water pump? Or power a gate? Knowing your goal is the first step.
Get educated. Learn, learn, learn! Subscribe to Home Power Magazine's digital archive service for great articles to help you DIY Solar. You can find them at www.homepower.com. Keep checking back here on our site (www.solarpanelstore.com) and our sister site (www.cosolar.com) for a current and growing list of articles and blog posts on all kind of solar topics. A good forum to read or post questions on is www.solarpaneltalk.com. Getting informed will help you plan the system for you and learn what questions to ask when you call an expert
Seek Expertise. You will need help designing your system! There are lots of considerations and nuances for your location and goals. As part of the buying process, at SolarPanelStore.com we regularly help our customers think through the options and help design the right system. Because we don't install systems, we do recommend hiring a local, licensed electrician or solar installer that can help you with final wiring connections or other parts of the project as needed. Know your limitations and find those folks up front
Permitting/Requirements. Every state and utility (and HOA) is different, so start early to understand what requirements your local utility and AHG (authority having jurisdiction) have for your system. For example the utility may limit the size of your PV system to a percentage of your historical use.
Incentives. While there are common national programs like the Federal Tax Credit (FTC) and USDA's REAP (Rural Energy for America Program) program, each state and utility have different programs as well. Go to www.dsireusa.org to research what's available to you.
Buying equipment. Buy good equipment from someone who knows what they're doing. We expect reliable, consistent electricity service from the utility, and you'll want the same for your system. We get calls from people buying cheap on Amazon or Home Depot, but then need help but things don't work and they can't get help from those sellers. Since 2002, we at SolarPanelStore.com have worked with our customers all the way through their projects, from concept to maintenance, answering questions, providing advice, pointing to resources and working with manufacturers. And we work hard to be competitive with the bigger guys that don't call you back. You get what you pay for.
Tools. You'll need typical tools used in any home remodeling project, plus some electrical and wiring tools as well. Like an MC4 connection tool, or a Digital Multi Meter to test for voltage and polarity. Again we at SolarPanelStore.com can guide you.
Safety. Obviously solar electric systems involve electricity, which if not handled correctly can cause serious injury or even death. Solar PV systems can involve dangerously high DC current, so taking safety seriously is very important. And lifting large solar panels and mounting them atop poles or roofs involves ladders and risk of falls. So get familiar with good safety practices described in articles at Home Power.
By no means is DIY Solar a piece of cake. But with some skill, courage, willingness to learn, and keeping these points in mind, you're well on your way to going solar!
Solar Made Simple
We'll dig deeper into PV in a later post, but to keep things simple we often just describe our focus as solar electric products or systems. By focusing on PV, we exclude other types of solar energy applications like solar thermal (using the sun to heat water or other fluids circulating in pipes), concentrated solar (utility scale reflecting of sunlight to concentrate heat), wind power (which is really derived from the sun heating the Earth's atmosphere, which causes wind), etc.
This diagram boils solar electricity down to its core. Of course the devil is in the details for any particular use, but it really helps to understand these principles because they underly all solar projects.
This is solar made simple after all, but isn't starting with the sun a little too basic? Well maybe. But seeing solar panels mounted on a north-facing roof tends to change one's mind. There is a lot more to this topic, but to keep it simple, we need sun to make solar electricity. And we'll need collectors, which we'll cover in a minute. But first, the more direct sun on those collectors, the better.
- Sunny days. The more sunny days the better. Cloudy, rainy climates mean less sun to make energy.
- Longer days. The longer the sun is up, the more energy can be made. So places closer to the equator with longer days mean more solar energy. Same thing with summer days vs. winter days.
- Direction. Collectors need to face the sun. In the northern hemisphere, that mean pointing south. As close to south as possible. The more those collectors point other directions (southwest, west, etc) the less direct sun they receive, and the less energy they produce.
- Shade. Like clouds, shade is bad for solar energy production. Depending on the equipment chosen, a very small amount of shade may really reduce the amount of energy produced (like a chimney or a branch above a roof). But some equipment can really minimize these losses.
- Angle. The optimum angle for maximum energy production varies by latitude and season. It's more complicated than this, but think flat at the equator and steeper as you go north.
Sun and the Panel
The next step in the solar PV chain is to collect the sun's energy keeping the above points in mind. How do we do this? Solar panels of course! “Solar module” is the more correct term, but most people still call them solar panels. A solar panel is really a grouping of solar cells. Those cells are what make up the grid-like pattern you see on a solar panel. You may read or hear about 36, 60 or 72-cell solar panels. Usually, the more cells means a larger panel which produces more energy.
The PV effect creates electricity in each solar cell when the sun's rays contact the silicon in the cell. The electrical current flows through ribbon-like wires that connect the cells within the panel. Those wires exit the solar panel through wire “leads” connected to terminal inside a junction box on the rear of the panel.
There are different types of solar panels. Most commonly used for a multitude of applications are the rigid style made up of silicon solar cells covered by tempered glass with an aluminum frame and an insulating back sheet. There are also “thin-film” style panels that are semi-flexible, plastic-like material that may be glued to a roof or embedded in a device. The composition of the solar cells may also vary and will certainly continue to evolve, but the standard today is silicone-based material.
So thanks to the miraculous photovoltaic effect, electricity is birthed of sunlight and silicone. Solar made simple. Got it. So you can just plug a TV into the solar panel's outlet and you're good to go right? Not quite. First, the solar panels aren't usually next to a TV (or other appliances) since the best direct sun is often on top of a house or mounted on a pole or rack away from the house. So the electricity generated from that panel needs to be routed to where it can be used. That happens through conductors or “wire” that connects to the leads of each solar panel. Often there is more than one panel involved, which we call an “array” that need to be wired into groups called “strings” in order to match the voltage and current from the array with the right equipment downstream.
But not just any old wire will do. It has to be rated to carry DC current at certain levels at certain temperatures in certain environments (hot roofs vs underground). So what is DC current or electricity? DC is “direct current” electricity. It's direct because electrons flow in only one direction. It's also the form that batteries store. But it doesn't travel long distances well. On the other hand, AC current (“alternating current”) is a form of electricity where the electrons alternate directions and travels over long distances without the losses of DC current. Accordingly, utilities specialize in producing and supplying AC electricity to homes and businesses to power almost everything.
Storage or Work
Once produced and moved from the solar panel, DC electricity must either be stored or put to work. The options really boil down to these:
- Option 1: DC electricity directly connected to power a DC appliance (or “load”)
- Option 2: DC electricity stored in a battery to power a DC appliance later
- Option 3: DC electricity “inverted” or transformed into AC electricity to power AC loads
- Option 4: DC electricity inverted into AC electricity and “sold” back to the utility grid
- Option 5: DC electricity stored in a battery, then later inverted into AC electricity to power AC loads
Option 1 is the most simple, but of limited utility. “PV Direct” systems only supply power while the sun shines. And the loads must be able to handle variable power depending on the strength of the sunlight and shade. Well water pumps and attic fans are typical examples.
Option 2 is the typical system for RVs, boats, and other remote “off-grid” power needs (lighting, remote pumps, instruments, telecom, sensors, etc).
Option 3 & 4 happens in a typical “grid-tied” residential system. The house uses solar energy to power AC loads while the sun shines or sells it back to the grid if not needed.
Option 5 is the most complex scenario and is the system used for off-grid homes, or grid-tied homes with battery back-up systems (a/k/a hybrid systems).
Knowledge is Power
While the sun is certainly power, so is knowledge! Knowing the basics of solar electric systems, you can make better-informed plans and decisions about how to employ solar systems for your project. You can have more efficient phone discussions with us about what are looking to do. You can better evaluate a contractor's proposal. And frankly, you stand a better chance of being happy with the end result.
- Dan Baldwin
- Tags: Solar Basics