How long does a solar inverter last? What’s the replacement cost?

Inverter warranties are 10-15 years, depending on the make and model. Inverter replacement costs are hard to forecast 15 years out. The inverter manufacturers are just now starting a price war similar to what the solar panel manufacturers went through over the past three years. So costs for equivalent models will likely fall considerably over the next 15 years. However, more and more value-added features are getting built into inverters, so those additional features will likely offset the price reductions going forward.

Do I have to clean my solar panels?

We had this question from a customer: Given that there isn’t too much rain to help with the cleaning, what is the typical solar panel maintenance attention that you would anticipate – is solar panel cleaning just typically wetting them down with hoses, or hand scrubbing? Dust obviously and a lot of birds out there. Every other day, once a week, once a month? What is the accessibility (between panels, etc.).

And here is our answer: For most of our customers there is little to no maintenance whatsoever, other than a weekly or monthly check of the production numbers to make sure the system is still operating. They make no noise either on or off, so unless someone pays attention to the monitoring alerts you won’t notice if the system goes offline. We can have the system set up to send automatic email alerts to us and you so such events won’t get missed.

Washing: In the Midwest, with lots of rain, it is typically not cost effective to wash modules. In CA, however, it is generally considered cost effective to wash modules one to two times per year. First wash is best done in late May, early June. Second wash is optional, depending on rain. A good spray from a hose is usually sufficient.

Random birds are not much problem. But if birds make a habit of visiting one spot, then that spot will need some scrubbing.

Solar panel accessibility depends on your goals and priorities. The CA fire code requires walking space all around the edges and a few pathways between arrays. But this still leaves large portions in which individual solar panels would be hard to reach. The panels are usually butted tightly up against each other. Our trained installers can walk on them, but I would not want an untrained or inexperienced person walking on them. So, you should stand in the walkways and spray with a strong hose.

Alternatively, it is possible to purchase automated washing systems, but whether or not they’re cost effective depends a lot on the design detail. Suffice it to say, this is something easily solved and not too costly.

Solar power during a utility blackout

“What about solar during a utility failure?”

For safety, grid interactive solar systems are designed to immediately disconnect and shut off if a utility grid failure is sensed. The system will automatically restart a few minutes after grid power is restored. As a result, no power will be available from the solar panels during utility outages. This protects utility workers who may be out working on power lines.

With new SMA transformerless inverters, a solar system can provide limited daytime power during a blackout. These inverters can be connected to household loads — like a fridge, lights, computers — and make up to 1,500 watts available while the sun shines.

Solar energy systems can provide around-the-clock, independent backup power during utility outages if they are connected to an appropriately-sized battery bank to absorb and store the energy they produce. Natural gas and propane generators are another option for backup power. We have installed solar panels and a generator on numerous jobs, when secure power is an absolute must-have.

Solar maintenance

Solar maintenance requirements are minimal.

Solar electric systems require no regular maintenance. The system operates silently and reliably for years, the same as the electricity we expect from the utility company.

Dirt and dust accumulation on the panels will reduce energy generation slightly. Customers who wash their solar panels typically notice about a 1% increase in power immediately following the wash, but washing is not necessary. Normal rain and wind are sufficient to remove most dust and debris.

Periodic monitoring of system performance is usually all that is required to ensure that the system is operating properly. Solar performance monitoring can be done manually, but for large public systems, automatic Internet-based solar monitoring is recommended. This allows remote solar monitoring by maintenance personnel, the solar installer and any other interested parties. Internet-based monitoring can also provide interactive solar performance displays for the public, and a cool way to show off your solar.

 

Solar is intermittent

Solar electric provides intermittent power production — meaning, it produces electricity when the sun shines, but not at night. Solar energy systems must work in conjunction with some other power source (or incorporate energy storage, like batteries) to provide a round-the-clock energy solution.

That’s why most of the systems we design and install are grid-connected. The utility grid becomes your energy storage device — when the sun isn’t shining, the grid powers you. When the sunshine is strong, you add power to the grid.

People often ask, “Why not just add batteries?” And off course we can do that, and have built many solar energy systems with battery backup. But many solar users who started off-grid with batteries have migrated to grid-connected systems, for reasons of economy, ease of use, convenience, and long-term energy planning. Grid-connected solar currently offers the shortest and best return on investment (ROI), in most cases.

We are happy to provide strong reliable battery-backup solutions for our customers who need them. But adding battery storage to a solar system adds substantial a cost and maintenance burden to an otherwise low cost, maintenance free system.

Can solar save the grid?

There is widespread agreement that solar electric systems improve the capacity and reliability of  your regional electric grid.

Solar electric systems generate the most power when the sun is strongest, during midday and afternoon hours. That is also the time when demand on the electric grid is highest. Solar energy systems can help the utility meet this peak demand. Distributed PV installations at multiple sites can produce power where needed, lowering transmission losses and further reducing the strain on the grid.

A study by Richard Perez (1) posits that the Northeast U.S. Power Blackout of August 14 2003  may have been avoided if local solar power systems amounting to just a few percent of regional peak loads had been available.

(1) Richard Perez et. al. “Availability of Dispersed Photovoltaic Resource During the August 14th 2003 Northeast Power Outage”

 

Solar can improve local air quality

A solar electric system generates the most power when the sun is strongest, during midday and afternoon hours. That is also the time when demand for electricity is highest.

To meet this afternoon peak demand, utilities fire up smaller “dispatchable” power plants that are often more expensive to run and more polluting than the larger, base load generating plants.

Powering a home or business with solar energy can reduce the utility’s peak load and reduce the peak generation by the utility. This results in lower overall energy costs and cleaner air. Having many small grid-connected solar arrays also increases the capacity and stability of the grid.

For every 1 kW of solar power installed, utility power plant emissions are reduced approximately 1500 pounds per year. Over a thirty-year life, each 1kW of solar power prevents 21 tons of CO2 emissions from being released by conventional energy sources.

Are solar panels noisy?

How noisy are solar panels? When operating, solar panels make no noise. They have no moving parts. Solar energy systems generate electricity in complete silence.

 

How reliable is solar?

People often ask, “Is solar reliable?” Solar energy systems are highly reliable and have low maintenance costs. Solar electric systems installed by well-qualified solar installers typically have reliability rates above 98%.

 

How can solar protect against rising energy costs?

Solar offers a fixed-cost hedge against future energy cost increases. It makes your future energy costs more predictable, and lower.

Solar energy systems have high up-front cost, but once installed, the fuel (the sun) is free forever. Due to the thirty-year system life and very low maintenance costs, once the system is purchased, the cost of energy is fixed at a known quantity. This compares with conventional electric energy costs, which have been rising at around 5% per year and may be expected to rise even faster in the future. Conventional energy prices, with their dependence on fossil fuels (coal, gas, and oil) are subject to the volatility of those markets, as well as any future costs of environmental remediation or carbon emissions penalties.

Several states have tiered energy prices in which the price per kWh of electrical energy consumption is lowest at night (when demand is lowest) and highest during the afternoon (when demand is highest). Because solar systems produce maximum energy during midday and afternoon hours, solar electric systems offset the highest-priced energy in a tiered pricing market. In Ohio, a solar electric system is a great bet on future adoption of tiered pricing in the Ohio markets. Install solar now, and if tiered pricing comes in, you’re equipped to offset the highest-cost energy and thereby save the most money on your electric bill.