Frequently Asked Questions – and Answers

Does solar really work in Washington – isn’t it too cloudy here?

Solar works in all parts of Washington. Anytime there is daylight, the photovoltaic (PV) panels will produce electricity with more power produced on sunny days than on cloudy ones. Because we experience very long hours of daylight and sunny weather in summer, power output in July is about six times greater than December. And, net metering (one for one credit of KWH) allows excess electricity from summer sunshine to be “banked” to reduce subsequent electric bills. Rain and snow help keep the modules clean for less maintenance and higher production. Solar systems operate more efficiently in our cooler temperatures than the warmer temps of places like Arizona.

What is the right size solar system for me?

When we custom design a residential or commercial solar system for you in Washington State, we look at several key factors. First is usable roof space. We take into account setbacks required by law, stay away from shaded areas, and avoid chimneys and skylights. Second, we design the system so that the array’s electrical output per year does not exceed your annual usage of electricity which can be determined from your electricity bill. Third is your budget.

We design options to be both affordable and cost-effective over the long haul. We partner with credit unions who offer a zero-down low-interest solar loan. Each module is approximately 66” by 40” and takes up about 20 square feet, so about 800 square feet of roof space is needed for a 40-module array.

We measure system size in KW (kilowatts). Each solar panel has a wattage rating. Multiply the panel’s number of watts by the total number of panels to get the system size [example: If each solar panel is 300 watts, then a 40 module array is a 12 KW or 1200 watt size solar system]. Regardless of whether your project is residential or a large commercial operation, our electricians in Washington State will tailor the size to meet your goals.

What factors affect the power output of a solar system?

The following factors determine the power output of each solar panel in the system.

  • Azimuth – whether the roof faces south, east or west. South or southwest is best. We measure azimuth in degrees with 180 degrees as due south, east is 90 degrees, west is 270 degrees.
  • Tilt – the pitch or angle of the roof.
  • Location – the longitude and latitude determine average weather which affects typical solar resources over the course of an average year.
  • Shading – we measure how much the solar resource is reduced from 100% due to trees, buildings, wires etc that shade the roof.
  • Wattage – each solar panel is flash tested at the factory to determine the nameplate rating in watts. In general, most of the panels we install today are in the range of 300 to 320 watts each for 60 cell panels.

With these inputs, sophisticated software is used to forecast annual output in kWh for an average year for your specific site.

What happens when there is a power outage?

When there is a power outage or the “grid goes down,” unless you have battery backup, the solar system automatically shuts down. This is a required safety feature to protect utility workers who may be working on the power lines. A solar system is not a source of backup power. [A grid-tied or grid-connected solar energy system requires the presence of the grid in order to function.]

BUT, if batteries are added, then you can rely on battery power during a grid outage. NWES offers two models: Tesla Powerwall or LG Chem. Each functions like a generator but burns no fossil fuel, is silent, and turns on automatically when the power goes out. Batteries significantly increase the total system cost but are not much different in price than adding an automatic turn-on stationery generator. When installed with solar, the battery storage system is eligible for the Investment tax credit (ITC).

I’m not sure how long I will live here. What happens if I want to sell my house a few years after I go solar?

First, your house will be more appealing to a buyer because with solar, it will always have a lower electric bill than a comparable house without solar. Second, if you are receiving a Washington State RESIP Production Incentive, then those payments will go to the subsequent owner – they will need to register with the WSU Energy Program. Payments will have the same end date as if you kept the house. The new owner will benefit from Net Metering. You will already have received the federal income tax credit so you’ve already earned back that portion of your upfront cost. Last, if you received a loan to pay for solar, you need to pay off the loan. A solar array adds more value to your home than it costs. The best thing to do is to leave the solar on the house rather than try to take it with you.

Do you offer a referral fee if I send friends to you?

We offer a referral fee for residential solar systems in Washington State. It is $50 per kW, up to $500. So, if you refer a friend and they buy a 12kW system from us, we will give you $500.

Can you help with financing?

Yes. We recommend working directly with a statewide credit union. Two offer solar loan programs geared for residential or commercial projects. Contact the experts at PSCCU (Puget Sound Cooperative Credit Union) or Generations Credit Union. You can fill out the loan application online. Our Washington State team of electricians will provide you with all the technical details about the system. Upon your approval, they can send your down-payment directly to us. Secure online signatures are used.

What maintenance is required for solar?

One of the best things about a solar array is that it is low maintenance. There are no moving parts to break. The solar panels need to be cleaned when pollen, dust, dirt, pine needles or leaves accumulate. We will provide you with instructions in your Owners Manual (soft brush and water work best). We strongly recommend annual cleaning near the end of pollen season, usually in May when you notice green sticky pollen on the surface, depending on how well the rain has cleaned your panels. You want your system to perform best during the sunny summer months. Use your online monitoring system to see the power output of each panel to make sure there are no problems. NWES offers annual maintenance package for $180/year in which we will come out to your place twice a year to clean the solar panels and inspect the system, or we can clean your modules “a la carte.” Just contact us to schedule this service with our electricians in Washington State.

Can I charge my plug-in electric vehicle from solar?

Yes and No. SolarEdge makes a solar inverter for charging your EV directly from the inverter using a combination of electricity from the sun and grid. Importantly, if you expect to receive an incentive payment through the Washington Renewable Energy Incentive Program (RESIP) or the WA Production Incentive Program, then charging directly from the inverter would divert kWH away from your Production Meter and therefore reduce your incentive payment. Get more info here.

The SolarEdge inverter-connected EV Charger requires the grid to be functioning. It does not work during a power outage.

Can I charge my EV from the Powerwall backup battery when the grid goes down?

You can charge a plug-in electric vehicle from Powerwall storage battery. We must warn you however that charging an EV battery from a house battery will drain the house battery quickly and is fairly inefficient.

Can I charge my plug-in electric vehicle from solar when the grid goes down? Can my house use my EV battery when the grid goes down?

Today, when there is a power outage, you cannot charge an EV at home directly from solar. At this time in December 2020, there is no easy solution that allows your house to operate using your electric vehicle’s battery. 


NW Electric and Solar
18001 73rd Ave NE Kenmore WA 98028
M-F   8 am - 4 pm

© by Northwest Electric and Solar. All rights reserved. | Website Designed by Clean Slate Webs | Hosted by