HOW SOLAR ELECTRICITY WORKS…
1. The ideal orientation for the solar array in New Hampshire is an azimuth (compass heading) of 195 degrees south, and a slope of 35 degrees (between an 8 and 9/12 roof pitch). Neither the azimuth nor the pitch needs to be perfect, but the productivity does fall off progressively as either axis moves away from the ideal.
Roof mounted solar electric panels are generally less expensive and visually less intrusive that ground mounted arrays, but not every home has the good fortune of an near to perfect roof orientation. Ground mounted arrays on the other hand are always installed with the correct orientations and with the advent of bi-facial modules can be far more productive than the more common roof mounts. The third factor that heavily affects solar production is shading. A partial shading is tolerable but just as is the case with orientation, production will fall off as the percentage of shading increases.
The two primary tasks we undertake during the initial site visit are to make certain that you understand how solar electricity works, and to consult with you to determine the best possible placement solution for your particular site and needs. Within few days of our site visit you will receive a well engineered proposal from New Hampshire Solar that will explain all of your viable options and costs in detail and make a recommendation for the one we consider best for your specific needs. The final choice however, are always in your hands!
2.The inverter converts the low voltage DC power coming from the solar array into the 240 volt alternating current that is fed it into your main electrical panel. There are many types of DC/AC inverters and they all have their own particular strengths and weaknesses. Inverters are the one item that may possibly fail during the 40+ lifespan of a solar system, but they also generally have a warranty of 12-25 years so the risk is minimal. Your NH Solar consultant will fully explain your inverter options to you fully and make a recommendation for the one we think is best suited to your requirements.
3. Once the inverter has fed the AC power into your home’s or business’s existing electrical panel, it is available for usage by your electrical appliances. You are now truly harvesting and able to use the ample free power of the sun!
4.Your electrical panel can draw power from the grid through your utility meter, as it did before the solar installation, and also from the solar array during the day when it is producing. Power generated by your solar array that is in excess of what you are consuming at the moment will be fed back into the grid and you will receive credit for that power. This happy give and take of AC power to and from the power supply grid is called net metering. Shortly after the installation of a new solar system, the utility company will visit your home to inspect the solar installation and replace your existing utility meter with a new bi-directional net meter.
An easy way to understand the concept of net metering is to think of the older utility meters that had the spinning counting wheel …do you remember those? The faster the wheel was spinning forward, the more power that was being drawn from the grid, and the higher the utility bill would be on the following month 🙁 After a solar system has been installed the counting wheel will actually have the ability to spin backwards whenever the solar array is producing more power than you are consuming. This will generate credits that will be automatically applied against your next utility billing. The faster the wheel spins backwards, the more credits you will generate, and the lower your utility bill will be the following month 🙂
5 & 6. A solar PV system only produces power during the sun lit daylight hours, but of course your home’s power needs are likely as strong or even stronger during the evening and night. There are three configurations available to meet the 24 hour need for reliable consistent power; grid tied (connected), off grid storage based, and a hybrid grid connected/storage system.
Remaining grid tied after installing a solar power system is by far the most common way of meeting your electrical needs. During the day your solar system will provide most, if not all, of your home or business’s power needs. Any excess power generated by the solar system will feed back into the grid generating credits through net metering. During the nighttime hours your power will be drawn from the grid in a conventional fashion. It is important to note here that the credits you generated during the day with your excess solar power would be applied to your nighttime consumption before you actually begin to generate a bill.
The goal at New Hampshire Solar when we engineer a solar system for you is to hit an annualized balance where all your utility company billings are 100% offset by the daily credits you received as your solar system produced excess energy during the day. At the end of the year this should result in a net zero energy cost for you!
Going totally off grid is an unusual solution, but it is becoming a little more common with each and every passing day. Solar modules (often called “panels”) and inverter costs have plummeted in the last ten years while at the same time the performance and efficiencies of those same components have skyrocketed! This in combination with the advances in home energy storage (batteries) is the primary reason for the relatively recent explosion in the popularity of totally off grid and hybrid grid tied solar PV array installations.
Energy storage is definitely the latest “hot” trend in the renewable electricity field and the benefits aren’t limited to just the consumer that wishes to store all of the power produced by a solar array and go off grid. To be sure, renewable energy storage will likely be the main application for home batteries, but there are other strong compelling reasons to consider adding a battery to your home our business’s power supply. For more details on this please go to “NHEC” tab of this website.
The grid tied hybridstorage system is a relatively new development and carries perhaps the greatest promise for the way in which we produce, store, and consume electrical power. Incorporating a storage battery with a grid tied system allows you to capture the best of both worlds; the high powered constant flow available to be purchased from the utility grid, and the abundant clean energy available from your solar system when the sun is shining bright. Adding a battery will allow you to store the solar power that you have harvested freely during the day for usage during the evening hours. Should the battery be exhausted during those active evening hours the inverter will automatically switch over to the grid and your home will remain constantly powered. Just after dawn the next day the solar array will again begin to generate power and by mid morning it should be able to both fully power your home and begin to recharge your battery. In a perfect world your battery would have enough stored energy to completely power your home through the night and long enough the next morning for the solar array to take over. But of course every day has differing needs and loads and this is where a grid tied hybrid storage power system really shines. You will have automatically controlled access to both the consistant power of the utillty grid, and the clean renewable energy that your system has harvested freely from the sun.
Backup emergency power is another huge advantage to a hybrid system that seems to be high on the list of priorities of every new solar prospect. If the grid power should go out during stormy weather, a basic grid tied solar system without storage capability must also be shut down to prevent the solar power from back feeding into the grid and causing harm to the linemen that are working to restore it.
A hybrid system with energy storage capability will automatically disconnect from the grid to protect the linesmen and switch over your power needs and solar production to an auxiliary essential loads sub panel (much like an automatic generator installation does). Both the storage battery and your solar array can feed power into the essential loads panel. The amount of circuits that can be supported by the essential loads sub panel is somewhat limited, but you would have enough to power your choice of critical needs (water, refridgeration, heat, some lighting, internet). If the outage turned out to be a prolonged event during inclement weather, you may need to use a small generator occasionally to supplement the solar recharging of your battery. But even then you would realize an advantage for you would only need to fire it up long enough to top up the battery. No more listening to a noisy generator running 24/7!
7 RECs. In the 2007 NH Renewable Portfolio Standard, legislation was established that requires all public utilities to procure 24.8% of their energy from renewable sources. Few utility companies have renewable generating projects in the works that will allow them to meet this requirement, however they can also attempt to achieve this 24.8% requirement by purchasing Renewable Energy Credits from clean energy sources. When you install a photovoltaic solar system you will have become a very small scale renewable energy “power plant” and begin generating RECs. For every 1000 kWh that your solar system generates, you will have created 1 REC. As mentioned above the utility companies need these credits in their portfolio and will purchase them from you through certified companies called aggregators . New Hampshire Solar includes the installation of a REC tally meter on your solar electricity system and set you up with an aggregator that will handle the sale of your RECs to the utilities for you. All you will need to do is send the aggregator a photo of your REC meter once a quarter, and a few weeks later a check will arrive in the mail 🙂
Please note that RECs are not the same as the net metering utility company billing credits that you get for excess production that your solar system may feed back into the grid. They are a totally separate entity and can amount to hundreds of additional dollars a year back into your pocket!